# Patent

## Title
Process for the production of acrylic acid from propane

## Abstract

The invention concerns a method for producing acrylic acid from propane, which consists in passing a gas mixture including propane, water, vapor, and optionally an inert gas and/or molecular oxygen, on a catalyst of formula (I): Mo1VaSbbNbcSidOx, wherein: a ranges between 0.006 and 1, inclusively; b ranges between 0.006 and 1, inclusively; c ranges between 0.006 and 1, inclusively; d ranges between 0 and 3.5, inclusively; and x is the amount of oxygen bound to the other elements and depends on their state of oxidation, for oxidizing propane into acrylic acid, and which is carried out in the presence of molecular oxygen, the propane/molecular oxygen mol ratio in the initial gas mixture is not less than 0.5.

## Background
The present invention relates to the production of acrylic acid from propane in the presence or in the absence of molecular oxygen.
It is known from European patent application No. EP-A-608838 to prepare an unsaturated carboxylic acid from an alkane with a catalytic oxidation reaction, in vapor phase, in the presence of a catalyst containing a mixed metal oxide comprising as essential components, Mo, V, Te, O, as well as at least one element chosen from the group constituted by niobium, tantalum, tungsten, titanium, aluminium, zirconium, chromium, manganese, iron, ruthenium, cobalt, rhodium, nickel, palladium, platinum, antimony, bismuth, boron, indium and cerium, these elements being present in very precise proportions. The reaction can be implemented using a gaseous mixture composed of the alkane, oxygen, an inert gas and water vapor presenting the following molar proportions:

    
    
        alkane/oxygen/inert gas/water vapor=1/0.1-10/0-20/0.2-70 and preferably 1/1-5/0-10/5-40.
    
    


Moreover, European patent application No. EP-A-895809 describes catalysts based on oxides comprising molybdenum, vanadium, niobium, oxygen, tellurium and/or antimony, as well as at least one other element such as iron or aluminium. These catalysts can be used for the conversion of propane to acrylic acid, in the presence of molecular oxygen, as illustrated in Examples 9 and 10. Example 9, in particular, describes the oxidation of propane using a catalyst having the formula

Mo1V0.33Nb0.11Te0.22On 

from a gas flow composed of propane, oxygen, helium and a flow of water vapor, according to a molar ratio propane/oxygen/helium/water vapor of approximately 1/3.2/12.1/14.3. In such a gas flow, the flow of reactive gas has a very low concentration of propane. Consequently the recycling of the unconverted propane is much more difficult because this unconverted propane is too diluted in the reaction flow.

The aim of the invention is to propose a process for the production of acrylic acid from propane, in the presence or in the absence of molecular oxygen, which allows a higher conversion of propane to be obtained while retaining good acrylic acid selectivity.
The inventors have discovered that this aim can be achieved by passing a gaseous mixture comprising propane, water vapor, as well as optionally an inert gas and/or molecular oxygen, over a particular catalyst. When operating in the presence of molecular oxygen the oxidation is carried out under conditions such that the oxygen of the gaseous mixture is in a substoichiometric proportion in relation to the propane introduced, which probably allows the catalyst to act in a similar way to a redox system and provides the oxygen which is lacking so that the reaction is carried out in a satisfactory way.
The advantages of this novel process are the following:—

    
    
        the limitation of the overoxidation of the products formed which takes place in the presence of too great a quantity of molecular oxygen; according to the present invention, due to the fact of operating in substoichiometry, the formation of COx (carbon monoxide and carbon dioxide), degradation products, is reduced, which allows the acrylic acid selectivity to be increased;
        the acrylic acid selectivity is maintained at a good level;
        the conversion is increased without loss of selectivity;
        the catalyst undergoes only a low reduction and therefore a small loss of its activity; it can easily be regenerated by heating in the presence of oxygen or a gas containing oxygen after a certain period of use; after regeneration, the catalyst regains its initial activity and can be used in another reaction cycle;
        moreover, the separation of the stages of reduction of the catalyst and of regeneration of the latter can be provided which allows the partial pressure of propane to be increased, such a partial supply pressure of propane being little limited by the existence of an explosive zone created by the propane+oxygen mixture, because the later is present in molecular form in substoichiometric proportions;
        moreover, this process allows reduction of the formation of products produced by hydration, in particular propionic acid, acetone and acetic acid.
    
    


The subject of the present invention is therefore a process for the production of acrylic acid from propane, in which a gaseous mixture containing propane, water vapor, optionally an inert gas, and/or molecular oxygen is passed over a catalyst of formula (I):

Mo1VaSbbNbcSidOx  (I)

in which:

    
    
        a is comprised between 0.006 and 1, inclusive;
        b is comprised between 0.006 and 1, inclusive;
        c is comprised between 0.006 and 1, inclusive;
        d is comprised between 0 and 3.5, inclusive; and
        x is the quantity of oxygen bound to'the other elements and depends on their oxidation state.

in order to oxidize the propane to acrylic acid, and when operating in the presence of molecular oxygen, the molar ratio propane/molecular oxygen in the initial gaseous mixture is greater than 0.5.

    
    


Such a process allows an acrylic acid selectivity of close to 60% and a high conversion of propane to be obtained simultaneously. Moreover, it can easily be implemented in a fluidized bed or in a moving bed and the injection of the reagents can be carried out at different points of the reactor, so as to be outside of the flammability zone while having a high propane concentration and, consequently, a high catalyst productivity.
According to a particularly advantageous embodiment, the process according to the invention comprises the following stages:
I/ In the Absence of Molecular Oxygen
When the initial gaseous mixture is devoid of molecular oxygen, the propane is oxidized according to the following redox reaction (A):

SOLIDoxidized+PROPANE→SOLIDreduced+ACRYLIC ACID  (A)

II/ In the Presence of Molecular Oxygen

    
    
        a) the initial gaseous mixture is introduced into a first reactor with a moving catalyst bed,
        b) at the outlet of the first reactor, the gases are separated from the catalyst;
        c) the catalyst is returned into a regenerator;
        d) optionally the gases are introduced into a second reactor with a moving catalyst bed;
        e) if appropriate, at the outlet of the second reactor, the gases are separated from the catalyst and the acrylic acid contained in the separated gases is recovered;
        f) if appropriate, the catalyst is returned into the regenerator; and
        g) the regenerated catalyst from the regenerator is reintroduced into the first reactor and, if appropriate, the second reactor;
    
    


According to another advantageous embodiment of the invention, the reactor or reactors are also provided with a cocatalyst.
According to another advantageous embodiment of the invention, the process comprises the repetition, in a reactor provided with the catalyst of formula (I) and, if appropriate, with a cocatalyst, of the cycle comprising the following successive stages:

    
    
        1) a stage of injection of the gaseous mixture as defined above;
        2) a stage of injection of water vapor and, if appropriate, of inert gas;
        3) a stage of injection of a mixture of molecular oxygen, water vapor and, if appropriate, inert gas; and
        4) a stage of injection of water vapor and, if appropriate inert gas.
    
    


According to an improvement of the advantageous embodiment which has just been described, the cycle comprises an additional stage which precedes or follows stage 1) and during which a gaseous mixture corresponding to that of stage 1) is injected but without the molecular oxygen, the molar ratio propane/molecular oxygen then being calculated globally for stage 1) and this additional stage.
According to an advantageous embodiment of the improvement which has just been presented, the additional stage precedes stage 1) in the cycle.
Other characteristics and advantages of the invention will now be described in detail in the following description which is given with reference to the single attached figure which diagramatically represents an apparatus which is suitable for the implementation of an advantageous embodiment of the process according to the invention.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a simplified schematic representation of process steps according to an embodiment of the present invention;
FIG. 2 is a schematic representation of a reactor assembly used in conjunction with an embodiment of the present invention; and
FIG. 3 is a schematic representation of a muffle furnace for a steel capacitor used in conjunction with an embodiment of the present invention.



DETAILED DESCRIPTION OF THE INVENTION
According to the invention, in the alternatives where molecular oxygen is introduced, because the molar ratio propane/molecular oxygen in the initial gaseous mixture is greater than or equal to 0.5, the conversion of the propane to acrylic acid using the catalyst is carried out by oxidation, probably according to the following concurrent reactions (A) and (B):

    
    
        the standard catalytic reaction (B):

CH3—CH2—CH3+2O2→CH2═CH—COOH+2H2O  (B)

        and the aforementioned redox reaction (A):

SOLIDoxidized+CH3—CH2—CH3→SOLIDreduced+CH2═CH—COOH  (A)

    
    


The propane/water vapor volume ratio in the initial gaseous mixture is not critical and can vary within wide limits.
Similarly, the proportion of inert gas, which can be helium, krypton, a mixture of these two gasses, or nitrogen, carbon dioxide, etc., is also not critical and can also vary within wide limits.
The proportions of the constituents of the initial gaseous mixture are generally as follows (in molar ratios):

    
    
        propane/oxygen/inert(He—Kr)/H2O (vapor)=1/0.05-2/1-10/1-10

Preferably, they are 1/0.1-1/1-5/1-5.

Yet more preferably, they are 1/0.167-0.667/2-5/2-5. As particularly beneficial proportions the following may also be cited:

        1/0.2-0.4/4-5/4-5.
    
    


Generally, reactions (A) and (B) are carried out at a temperature of 200 to 500° C., preferably from 250 to 450° C., yet more preferably from 350 to 400° C. The pressure in the reactor or reactors is generally from 1.01×104 to 1.01×106 Pa (0.1 to 10 atmospheres), preferably from 5.05×104 to 5.05×105 Pa (0.0-5 atmospheres).
The residence time in the reactor, or if there are several, in each reactor, is generally from 0.01 to 90 seconds, preferably from 0.1 to 30 seconds.
The catalyst corresponds to the following formula (I):

Mo1VaSbbNbcSidOx  (I)

in which:

    
    
        a is comprised between 0.006 and 1, inclusive;
        b is comprised between 0.006 and 1, inclusive;
        c is comprised between 0.006 and 1, inclusive;
        d is comprised between 0 and 3.5, inclusive; and
        x is the quantity of oxygen bound to the other elements and depends on their oxidation state.

Advantageously:

        a is comprised between 0.09 and 0.8, inclusive;
        b is comprised between 0.04 and 0.6, inclusive;
        c is comprised between 0.01 and 0.4, inclusive; and
        d is comprised between 0.4 and 1.6, inclusive.
    
    


The oxides of the different metals included in the composition of the catalyst of formula (I) can be used as raw materials in the preparation of this catalyst, but the raw materials are not limited to the oxides; among the raw materials which can be used there may be mentioned, as non-limitative examples:

    
    
        in the case of molybdenum, ammonium molybdate, ammonium paramolybdate, ammonium heptamolybdate, molybdic acid, molybdenum halides or oxyhalides such as MoCl5, organometallic compounds of molybdenum such as molybdenum alkoxides such as Mo(OC2H5)5, acetylacetone molybdenyl;
        in the case of vanadium, ammonium metavanadate, vanadium halides or oxyhalides such as VCl4, VCl5 or VOCl3, organometallic compounds of vanadium such as vanadium alkoxides such as VO(OC2H5)3;
        in the case of antimony for example antimony oxide (antimony trioxide), in particular of the senarmontite variety, antimony trisulphate, (Sb2(SO4)3) or an antimony chloride (antimony trichloride, antimony pentachloride);
        in the case of niobium, niobic acid, niobium tartrate, niobium hydrogen oxalate, oxotrioxalatoammonium niobate {(NH4)3[NbO(C2O4)3].1.5H2O}, niobium and ammonium oxalate, niobium oxalate and tartrate, niobium halides or oxyhalides such as NbCl3, NbCl5 and organometallic compounds of niobium such as niobium alkoxides such as Nb(OC2H5)5, Nb(O-n-Bu)5;

and, generally, all the compounds which are able to form an oxide by calcination, namely, the metallic salts of organic acids, the metallic salts of mineral acids, the metal complex compounds, etc.

    
    


The source of silicon is generally constituted by colloidal silica and/or polysilicic acid.
According to particular embodiments, the catalyst of formula (I) can be prepared by mixing aqueous solutions of niobic acid, oxalic acid, ammonium heptamolybdate, ammonium metavanadate, antimony oxide, under stirring, by the addition, if appropriate, of colloidal silica, then by precalcinating under air at a temperature comprised between 280 and 340° C., preferably at approximately 300-320° C. and by calcinating under nitrogen at approximately 600° C.
Preferably, in the thus-prepared catalyst of formula (I):

    
    
        a is comprised between 0.09 and 0.8, inclusive;
        b is comprised between 0.04 and 0.6, inclusive;
        c is comprised between 0.01 and 0.4, inclusive; and
        d is comprised between 0.4 and 1.6, inclusive.
    
    


More particularly, the process for the preparation of the catalyst of formula (I) is implemented by the preparation of a solution of niobic acid, oxalic acid, preparation of a solution of molybdenum, vanadium, antimony and optionally silica, a mixture of the 2 solutions produces the formation of a gel, drying of the gel obtained produces the formation of a precursor of formula (I′) below, precalcination then calcination.
More precisely, according to a particularly preferred process, the catalyst can be prepared by implementing the following stages:

    1) dissolution in water of a source of vanadium, for example, ammonium metavanadate, under stirring and optionally by heating;
    2) addition to the previously obtained solution of a source of antimony, for example antimony oxide in particular the senarmonite variety;
    3) addition of a source of molybdenum, for example, ammonium heptamolybdate;
    4) reaction of the solution obtained, under reflux;
    5) addition of an oxidizing agent such as hydrogen peroxide;
    6) if appropriate, addition of silica;
    7) addition of a solution prepared by mixing, under heating, a source of niobium, for example, niobic acid, with oxalic acid;
    8) reaction of the reaction mixture under reflux and preferably under inert atmosphere, until a gel is obtained;
    
        drying of the gel obtained which leads to a precursor;
    
    
    9) precalcination of the precursor; and
    10) calcination of the precalcinated gel in order to obtain the catalyst.

As a variant, instead of having three successive stages 1), 2) and 3), these stages are combined by introducing the sources of vanadium, antimony and molybdenum into cold water and stirring in order to obtain a solution.



Preferably, in stage 5), hydrogen peroxide is added until an orange-coloured limpid solution is obtained.
In the alternative processs below:

    
    
        the drying (for example of stage 9) can be carried out in an oven in a thin layer, by atomization, freeze-drying, zeodration, with microwaves, etc.
        the precalcination can be carried out under air flow at 280-300° C. or under static air at 320° C., in a fluidized bed, in a rotary furnace in a so-called aerated fixed bed, so that the catalyst pellets are separated from each other in order to prevent them from fusing during precalcination or possibly during calcination;
        the calcination is preferably carried out under very pure nitrogen and at a temperature close to 600° C., for example in a rotary furnace or in a fluidized bed and for a duration which can be 2 hours.
    
    


The catalyst obtained at the end of the calcination can be ground in order to produce smaller particles. If the grinding is continued until a powder constituted by particles of approximately the size of a micron is obtained, the powder can subsequently be returned to its form using a binding agent such as for example silica in the form of polysilicic acid, the suspension then being dried again, for example by atomization.
According to a more particularly preferred embodiment of the invention, the precalcination is carried out:

    
    
        either at a temperature of less than 300° C. under an air flow of at least 10 ml/min/g of catalyst;
        or at a temperature ranging from 300 to 350° C. under an air flow less than 10 ml/min/g of catalyst.
    
    


According to a particularly preferred embodiment, the precalcination is carried out:

    
    
        at approximately 320° C. under an air flow less than 10 ml/min/g; or
        at approximately 290° C. under an air flow of approximately 50 ml/min/g.

Regeneration of the Catalyst

    
    


During the redox reaction (B), the catalyst undergoes reduction and a progressive loss of its activity. This is why, once the catalyst has at least partially changed to the reduced state, its regeneration is carried out according to reaction (C):

SOLIDreduced+O2→SOLIDoxidized  (C)

by heating in the presence of oxygen or a gas containing oxygen at a temperature of 250 to 500° C., for a time necessary for the reoxidation of the catalyst.

The proportions of the constituents of the regeneration gaseous mixture are generally as follows (in molar ratios):

    
    
        oxygen/inert(He—Kr)H2O(vapor)=1/1-10/0-10

Preferably, they are 1/1-5/0-5.

    
    


Instead of using the oxygen alone, dry air (21% O2) can be used. Instead of or in addition to the water vapor, moist air can thus be used.
The regeneration temperature is generally from 250 to 500° C.
Generally the process is carried out until the reduction ratio of the catalyst is comprised between 0.1 and 10 g of oxygen per kg of catalyst.
This reduction ratio can be monitored during the reaction through the quantity of products obtained. Then the equivalent quantity of oxygen is calculated. It can also be monitored through the exothermicity of the reaction. The reduction ratio can also be monitored through the quantity of oxygen consumed in the regenerator.
After regeneration, which can be carried out under temperature and pressure conditions which are identical to, or different from those of the reactions (A) and (B), the catalyst regains an initial activity and can be reintroduced into the reactors.
The reactions (A) and (B) and the regeneration (C) can be carried out in a standard reactor, such as a fixed bed reactor, a fluidized bed reactor or a moving bed reactor.
Thus the reactions (A) and (B) and the regeneration (C) can be carried out in a device with two stages, namely a reactor and a regenerator which operate simultaneously and in which two catalyst loadings alternate periodically.
The reactions (A) and (B) and the regeneration (C) can also be carried out in the same reactor by alternating the periods of reaction and regeneration.
Preferably, the reactions (A) and (B) and the regeneration (C) are carried out in a reactor with a moving catalyst bed, in particular in a vertical reactor, the catalyst then preferably moving from the bottom upwards.
An operating process with only one passage of the gas or with recycling of the gas can be used.
According to a preferred embodiment, the propylene produced and/or the propane which has not reacted are recycled (or returned) to the inlet of the reactor, i.e. they are reintroduced at the inlet of the reactor, in a mixture or in parallel with the initial mixture of propane, water vapor and if appropriate inert gas or gases.
Use of an Apparatus with Two Reactors and a Regenerator
According to an advantageous embodiment of the invention, the process according to the invention is used in an apparatus such as the one represented in the attached figure.
The initial gaseous mixture comprising propane, molecular oxygen, water vapor as well as, if appropriate, an inert gas, is introduced into a first reactor (Riser 1) containing the moving catalyst bed.
Then, at the outlet of the first reactor, the effluents are separated into gases and the moving catalyst bed.
The catalyst is sent into a regenerator.
The gases are introduced into a second reactor (Riser 2) also containing a moving catalyst bed.
At the outlet of the second reactor, the effluents are separated into gases and the moving bed catalyst.
The catalyst is sent into a regenerator.
The gases are treated in a known way, generally by absorption and purification, with a view to recovering the acrylic acid produced.
The regenerated catalyst is reintroduced into the first reactor as well as into the second reactor.
The process thus operates continuously, the circulation of the catalyst between the reactors and the regenerator is carried out in a regular and generally continuous way.
Of course, the single regenerator can be replaced by two or more regenerators.
Moreover, it is possible to add, after the second reactor, other reactors which also have a catalyst circulating between each of these reactors and the regenerator or other regenerators.
Preferably, the first and second reactors are vertical and the catalyst is transported upwards by the gas flow.
An operating process with only one passage of gases or with recycling of the products leaving the second reactor can be used.
According to a preferred embodiment of the invention, after treatment of the gas originating from the second reactor, the propylene produced and/or the propane which has not reacted are recycled (or returned) to the inlet of the reactor, i.e. they are reintroduced at the inlet of the first reactor, in a mixture or in parallel with the initial mixture of propane, oxygen, water vapor and, if appropriate, inert gas or gases.
Use of a Cocatalyst
According to another advantageous embodiment of the invention, the gaseous mixture also passes over a cocatalyst.
This has the advantage of reducing the production of propionic acid, which is generally a by-product of the conversion reaction and which poses problems in certain applications of acrylic acid when it is present in too great a quantity.
Thus, the propionic acid/acrylic acid ratio is greatly reduced at the outlet of the reactor.
Moreover, the formation of acetone, which is also a by-product of the production of acrylic acid from propane, is reduced.
To this end, at least one of the reactors comprises a cocatalyst with the following formula (II):

Mo1Bia′Feb′Coc′Nid′Ke′Sbf′Tig′Sih′Ca1′Nbj′Tek′PbI′Wm′Cun′  (II)

in which:

    
    
        a′ is comprised between 0.006 and 1, inclusive;
        b′ is comprised between 0 and 3.5, inclusive;
        c′ is comprised between 0 and 3.5, inclusive;
        d′ is comprised between 0 and 3.5, inclusive;
        e′ is comprised between 0 and 1, inclusive;
        f′ is comprised between 0 and 1, inclusive;
        g′ is comprised between 0 and 1, inclusive;
        h′ is comprised between 0 and 3.5, inclusive;
        i′ is comprised between 0 and 1, inclusive;
        j′ is comprised between 0 and 1, inclusive;
        k′ is comprised between 0 and 1, inclusive;
        l′ is comprised between 0 and 1, inclusive;
        m′ is comprised between 0 and 1, inclusive; and
        n′ is comprised between 0 and 1, inclusive.
    
    


Such a cocatalyst can be prepared in the same way as the catalyst of formula (I).
The oxides of the different metals included in the composition of the cocatalyst of formula (II) can be used as raw materials in the preparation of this cocatalyst, but the raw materials are not limited to the oxides; as other raw materials, the corresponding nitrates can be mentioned in the case of nickel, cobalt, bismuth, iron or potassium.
Generally, the cocatalyst is present in the form of a moving bed and preferably it is regenerated and circulates, if appropriate, in the same way as the catalyst.
Preferably, in the cocatalyst of formula (II):

    
    
        a′ is comprised between 0.01 and 0.4, inclusive;
        b′ is comprised between 0.2 and 1.6, inclusive;
        c′ is comprised between 0.3 and 1.6, inclusive;
        d′ is comprised between 0.1 and 0.6, inclusive;
        e′ is comprised between 0.006 and 0.01, inclusive.
        f′ is comprised between 0 and 0.4, inclusive;
        g′ is comprised between 0 and 0.4, inclusive;
        h′ is comprised between 0.01 and 1.6, inclusive;
        i′ is comprised between 0 and 0.4, inclusive;
        j′ is comprised between 0 and 0.4, inclusive;
        k′ is comprised between 0 and 0.4, inclusive;
        l′ is comprised between 0 and 0.4, inclusive;
        m′ is comprised between 0 and 0.4, inclusive; and
        n′ is comprised between 0 and 0.4, inclusive.
    
    


The weight ratio of the catalyst to the cocatalyst is generally greater than 0.5 and preferably at least 1.
Advantageously, the cocatalyst is present in the two reactors.
The catalyst and the cocatalyst are present in the form of solid catalytic compositions.
They can each be in the form of pellets, generally of 20 to 300 μm in diameter, the catalyst and cocatalyst pellets generally being mixed before implementation of the process according to the invention.
The catalyst and the cocatalyst can also be present in the form of a solid catalytic composition composed of pellets each of which comprises both the catalyst and the cocatalyst.
EXAMPLES
The following examples illustrate the present invention without limiting its scope.
In the formulae given in Example 1, x is the quantity of oxygen bound to the other elements and depends on their oxidation states.
The conversions, selectivities and yields are defined as follows



  
    
      
        
          
            Conversion
            ⁢
            
              
            
            ⁢
            
              (
              %
              )
            
          
        
      
      
        
          
            of
            ⁢
            
              
            
            ⁢
            the
            ⁢
            
              
            
            ⁢
            propane
          
        
      
    
    =
    
      
        
          Number
          ⁢
          
            
          
          ⁢
          of
          ⁢
          
            
          
          ⁢
          moles
          ⁢
          
            
          
          ⁢
          of
          ⁢
          
            
          
          ⁢
          propane
          ⁢
          
            
          
          ⁢
          having
          ⁢
          
            
          
          ⁢
          reacted
        
        
          Number
          ⁢
          
            
          
          ⁢
          of
          ⁢
          
            
          
          ⁢
          moles
          ⁢
          
            
          
          ⁢
          of
          ⁢
          
            
          
          ⁢
          propane
          ⁢
          
            
          
          ⁢
          introduced
        
      
      ×
      100
    
  




  
    
      
        
          
            Selectivity
            ⁢
            
              
            
            ⁢
            
              (
              %
              )
            
          
        
      
      
        
          
            for
            ⁢
            
              
            
            ⁢
            acrylic
            ⁢
            
              
            
            ⁢
            acid
          
        
      
    
    =
    
      
        
          Number
          ⁢
          
            
          
          ⁢
          of
          ⁢
          
            
          
          ⁢
          moles
          ⁢
          
            
          
          ⁢
          of
          ⁢
          
            
          
          ⁢
          acrylic
          ⁢
          
            
          
          ⁢
          acid
          ⁢
          
            
          
          ⁢
          formed
        
        
          Number
          ⁢
          
            
          
          ⁢
          of
          ⁢
          
            
          
          ⁢
          moles
          ⁢
          
            
          
          ⁢
          of
          ⁢
          
            
          
          ⁢
          propane
          ⁢
          
            
          
          ⁢
          having
          ⁢
          
            
          
          ⁢
          reacted
        
      
      ×
      100
    
  




  
    
      
        
          
            Yield
            ⁢
            
              
            
            ⁢
            
              (
              %
              )
            
          
        
      
      
        
          
            of
            ⁢
            
              
            
            ⁢
            acrylic
            ⁢
            
              
            
            ⁢
            acid
          
        
      
    
    =
    
      
        
          Number
          ⁢
          
            
          
          ⁢
          of
          ⁢
          
            
          
          ⁢
          moles
          ⁢
          
            
          
          ⁢
          of
          ⁢
          
            
          
          ⁢
          acrylic
          ⁢
          
            
          
          ⁢
          acid
          ⁢
          
            
          
          ⁢
          formed
        
        
          Number
          ⁢
          
            
          
          ⁢
          of
          ⁢
          
            
          
          ⁢
          moles
          ⁢
          
            
          
          ⁢
          of
          ⁢
          
            
          
          ⁢
          propane
          ⁢
          
            
          
          ⁢
          introduced
        
      
      ×
      100
    
  



The selectivities and yields relating to the other compounds are calculated in a similar way.

The conversion ratio is the weight of catalyst (in kg) required to convert 1 kg of propane.

Example 1 (comparative)
A catalyst was prepared in the following way.
5.35 g of ammonium paramolybdate and 1.33 g of antimony trisulphate (Sb2(SO4)3) are successively added under stirring to 30 ml of water heated to 80° C. Stirring is continued for 15 minutes. Separately, a solution containing 10 mmoles of vanadium is prepared by dissolving 2.63 g of hydrated vanadyl sulphate in 10 ml of distilled water heated to 80° C. The second solution is added to the first and the mixture is stirred for 15 minutes before being introduced into a 70 ml autoclave covered with Teflon®. Then nitrogen is bubbled through for 5 minutes so that it substitutes the air present in the autoclave, before it is closed. The autoclave is then set at 175° C. for 24 hours. After this period, the autoclave is cooled down with tap water for 10 minutes. The black-purple solid obtained in the autoclave is separated from the solution by filtration, thoroughly washed with distilled water and dried for 12 hours at 80° C. The precursor thus obtained is then precalcinated under air at 280° C. for 2 hours, then calcinated under nitrogen flow (25 ml/h/g) at 600° C. for 2 hours. In this way catalyst 1 is obtained. This catalyst is tested. The results are shown in Tables 2 and 3.
Example 2 (comparative)
A catalyst was prepared in the following way.
5.35 g of ammonium paramolybdate and 0.55 g of a 31% solution of hydrogen peroxide and 0.74 g of antimony trioxide are successively added to 20 ml of water heated to 80° C. under stirring. Stirring is continued for 60 minutes until the antimony oxide is dissolved. Separately, a solution containing 12 mmoles of vanadium is prepared by dissolving 3.16 g of hydrated vanadyl sulphate in 10 ml of distilled water heated to 80° C. The second solution is added to the first and 1.89 g of oxalic acid in powder form is added to the solution. The mixture is stirred for 10 minutes before being introduced into a 70 ml autoclave covered with Teflon®. Then nitrogen is bubbled through for 5 minutes so that it substitutes the air present in the autoclave, before the latter is closed. The autoclave is then set at 175° C. for 48 hours.
After this period, the autoclave is cooled down with tap water for 10 minutes. The black-purple solid obtained in the autoclave is separated from the solution by filtration, thoroughly washed with distilled water and dried for 12 hours at 80° C. The precursor thus obtained is then calcinated under nitrogen flow (25 ml/h/g) at 600° C. for 2 hours. In this way catalyst 2 is obtained. This catalyst is tested. The results are shown in Tables 2 and 3.
Example 3
A catalyst was prepared in the following way.
5.35 g of ammonium paramolybdate and 0.55 g of a 31% solution of hydrogen peroxide and 0.74 g of antimony trioxide are successively added to 20 ml of water heated to 80° C. under stirring. Stirring is continued for 60 minutes until the antimony oxide is dissolved. Separately, a solution containing 9 mmoles of vanadium is prepared by dissolving 2.37 g of hydrated vanadyl sulphate in 10 ml of distilled water heated to 80° C. A third solution containing 3 mmoles of niobium is prepared simultaneously by dissolving under stirring, 1.94 g of hydrated niobium oxalate in 10 ml of distilled water heated to 80° C. The second solution is added to the first and stirred continuously for 5 minutes. Finally, the solution containing niobium is added. The mixture is stirred for 10 minutes before being introduced into a 70 ml autoclave covered with Teflon®. Then nitrogen is bubbled through for 5 minutes so that it substitutes the air present in the autoclave, before the latter is closed. The autoclave is then set at 175° C. for 48 hours.

After this period, the autoclave is cooled down with tap water for 10 minutes. The black-purple solid obtained in the autoclave is separated from the solution by filtration, thoroughly washed with distilled water and dried for 12 hours at 80° C. The precursor thus obtained is then calcinated under nitrogen flow (25 ml/h/g) at 600° C. for 2 hours. In this way catalyst 3 is obtained. This catalyst is tested under the same conditions as the other catalysts. The results are shown in Tables 2 and 3.

Example 4
A catalyst was prepared in the following way.
5.35 g of ammonium paramolybdate and 0.55 g of a 31% solution of hydrogen peroxide and 0.74 g of antimony trioxide are successively added to 20 ml of water heated to 80° C. under stirring. Stirring is continued for 60 minutes until the antimony oxide is dissolved. Separately, a solution containing 12 mmoles of vanadium is prepared by dissolving 3.16 g of hydrated vanadyl sulphate in 10 ml of distilled water heated to 80° C. A third solution containing 1.5 mmoles of niobium is simultaneously prepared by dissolving under stirring, 0.97 g of hydrated niobium oxalate in 10 ml of distilled water heated to 80° C. The second solution is added to the first and stirred continuously for 5 minutes. Finally, the solution containing niobium is added. The mixture is stirred for 10 minutes before being introduced into a 70 ml autoclave covered with Teflon®. Then nitrogen is bubbled through for 5 minutes so that it substitutes the air present in the autoclave, before the latter is closed. The autoclave is then set at 175° C. for 48 hours.
After this period, the autoclave is cooled down with tap water for 10 minutes. The black-purple solid obtained in the autoclave is separated from the solution by filtration, thoroughly washed with distilled water and dried for 12 hours at 80° C. The precursor thus obtained is then calcinated under nitrogen flow (25 ml/h/g) at 600° C. for 2 hours. In this way catalyst 4 is obtained. This catalyst is tested under the same conditions as catalyst 3. The results are shown in Tables 2 and 3.
Example 5 (comparative)
A catalyst was prepared in the following way.
2.0008 g of hot (90° C.) ammonium metavanadate is dissolved in 45 ml of water. Then 1.2149 g of antimony trioxide (senarmontite phase) and 10.0142 g of ammonium heptamolybdate are added. The mixture is taken to reflux under argon, the temperature is set at 70° C. and the solution is left under stirring for 14 hours. The resulting mixture is opaque blue-black. 2 ml of 30% hydrogen peroxide is added using a syringe and the solution is left under stirring. The colour progressively changes to orange passing through khaki green tones. A light precipitate is then distinguished in a dark orange solution. In parallel, 1.7254 g of oxalic acid was dissolved in 20 ml of water and this solution is added to the first, which remained at 70° C., without a change of colour or appearance being observed. The pH of the solution is then 3 to 4. The mixture is left to mature for another 30 minutes, then it is dried in the oven for 12 hours at 110° C. The amorphous precursor is then precalcinated under air (15 ml/min/g) at 300° C., for 4 hours, then calcinated under nitrogen flow (15 ml/min/g) for 2 hours at 600° C. In this way catalyst 5 is obtained. This catalyst is tested under the same conditions as the other catalysts. The results are shown in Table 4.
Example 6


    
    
        Catalyst 6 is prepared in the same way as catalyst 5, except that 0.75 g of niobic acid is dissolved in the oxalic acid solution, by heating it at 70° C. for 2 hours.
    
    


This solution is centrifuged before being mixed with the solution containing the other elements. The results are shown in Table 4.
Example 7
A catalyst was prepared in the following way.
5.35 g of ammonium paramolybdate is added under stirring to 20 ml of water heated to 80° C. Separately, a solution containing 15 mmoles of vanadium is prepared by dissolving 3.94 g of hydrated vanadyl sulphate in 20 ml of distilled water heated to 80° C. The second solution is added to the first and the mixture is then stirred for 10 minutes before being introduced into a 70 ml autoclave covered with Teflon®. Then nitrogen is bubbled through for 5 minutes so that it substitutes the air present in the autoclave, before the latter is closed. The autoclave is then set at 175° C. for 24 hours.
After this period, the autoclave is cooled down with tap water for 10 minutes. The black-blue solid obtained in the autoclave is separated from the solution by filtration, thoroughly washed with distilled water and dried for 12 hours at 80° C. The precursor thus obtained is then calcinated under nitrogen flow (25 ml/h/g) at 500° C. for 2 hours. In this way catalyst 7 is obtained. This catalyst is tested under the same conditions as the other catalysts.







TABLE 1







Summary table of the different preparations










Composition of the



Example No.
solution (without oxygen)
Process of preparation





Example 1
Mo1.0V0.33Te0.17
Hydrothermal synthesis


Example 2
Mo1.0V0.40Sb0.17
Hydrothermal synthesis


Example 3
Mo1.0V0.30Sb0.17Nb0.10
Hydrothermal synthesis


Example 4
Mo1.0V0.40Sb0.17Nb0.05
Hydrothermal synthesis


Example 5
Mo1.0V0.30Sb0.15
Evaporation drying


Example 6
Mo1.0V0.30Sb0.15Nb0.08
Evaporation drying


Example 7
Mo0.1V0.50
Hydrothermal synthesis
















TABLE 2







Oxidation of propane at 320° C. on antimony catalysts









Conversion

Yield


(%)
Selectivity (%)
(%)















Ex.

Acrylic


Acetic


Acrylic


No.
C3H8
acid
C3H6
Acetone
acid
CO
CO2
acid


















1
9.74
34.3
19.6
5.88
17.0
14.0
9.25
3.34


2
13.1
12.1
19.3
2.05
23.5
21.1
21.9
1.59


3
10.2
44.1
26.9
3.45
10.3
7.89
7.33
4.50


4
21.6
40.0
15.0
2.00
16.0
13.0
13.0
8.64


7
11.1
5.41
19.5
0.97
20.4
33.1
20.6
0.60
















TABLE 3







Oxidation of propane at 360° C. on antimony catalysts









Conversion

Yield


(%)
Selectivity (%)
(%)















Ex.

Acrylic


Acetic


Acrylic


No.
C3H8
acid
C3H6
Acetone
acid
CO
CO2
acid


















1
20.8
33.9
15.3
1.70
17.5
17.6
14.0
7.05


2
21.9
11.0
14.7
1.23
22.8
24.7
25.5
2.41


3
21.2
45.1
17.7
1.07
11.8
13.1
11.3
9.56


4
37.8
19.0
8.0
1.00
21.0
24.0
27.0
7.18


7
23.4
4.21
11.4
0.27
14.8
41.4
27.9
0.98
















TABLE 4







Oxidation of propane on the evaporation-drying catalysts












Reaction

Selectivity (%)
Yield (%)
















Ex.
temp.
Conv. %
Acrylic


Acetic


Acrylic


No.
° C.
C3H8
acid
C3H6
Acetone
acid
CO
CO2
acid



















5
320
9.76
27.1
30.2
5.20
13.0
13.4
11.1
2.33


6
320
7.21
24.0
35.7
2.91
13.4
13.3
10.7
1.73


5
360
15.6
29.4
19.8
1.77
15.2
17.8
16.0
5.06


6
360
23.8
25.1
18.7
0.59
11.9
23.9
19.9
5.96









In the case of examples 1 and 3, the effluents of the test are collected for 4 hours in an ice-trap. 2 analyses by chromatography coupled with a mass spectrometer are carried out per sample.
5 main products are detected per sample: acetone, water, acetic acid, propionic acid and acrylic acid.
The molar ratios propionic acid/acrylic acid are thus calculated for each sample, for reaction temperatures of 320° C. and 360° C. The average of the two analyses carried out per sample is given in Table 5 below.







TABLE 5







Molar ratio Propionic acid/Acrylic acid









Example
320° C.
360° C.





1
6.49%
1.64%


3
6.36%
1.42%









It is noted that the molar ratio decreases with an increase in the temperature and the presence of niobium in the composition of the catalyst.
Example 8
Preparation of a Catalyst A of Formula: Mo1V0.30Sb0.15Nb0.10Si0.93Ox and its Precursor.
Synthesis of the Precursor
This synthesis allows the preparation of approximately 100 g of dry precursor.
Stage 1: Dissolution-precipitation
Solution A
12.3 g (0.1052 mol V) of ammonium metavanadate (AMV) are placed in solution in 260 ml of demineralised water, in a 1 liter glass SVL® reactor, under stirring, in an oil bath thermostatically controlled at 128° C. A yellow solution is obtained. 7.7 g (0.0528 mol Sb) of Sb2O3 are added to the limpid solution (small addition of water in order to rinse the funnel), then 61.8 g of ammonium heptamolybdate (AHM, 0.3501 moles of Mo) are added. After the addition of AHM, the reactor is flushed with nitrogen, the reaction is stirred continuously, at reflux, for 4 hours. Gradually a blue-black solution is obtained.

Solution B

6 g (0.0530 mol) of an aqueous solution of H2O2 at 30 wt.-% is then added slowly (approximately 30 minutes). In order to obtain-a limpid orange solution, two drops of pure oxygenated water are added.

Solution C

Then 49.1 g of Ludox® AS40 silica (nSi=0.327 mole) is added in one go, and the solution becomes slightly cloudy. The solution formed is called solution C.

Solution D

A solution D is prepared at the same time as solution A. 100 g of distilled water, 5.9 g of niobic acid marketed by the Brazilian company CBMM i.e. nNb=0.035 mol, and 13.2 g of Prolabo oxalic acid i.e. nOxalate=0.105 mole is introduced into a 500 ml beaker. The mixture is heated at 60° C. under stirring for 2 hours, then taken to 30° C. The solution is then centrifuged at 6200 r.p.m. for 12 minutes in order to obtain a limpid solution.

Solution D is added to solution C in one go. A fluid gel is obtained which is orange then yellow. Stirring is continued for 30 minutes under nitrogen flow, under reflux.
Stage 2: Drying
The gel is then dried in a ventilated oven overnight, on plates covered with Teflon®, at 130° C. 86.3 g of dry precursor are recovered. The precursor is in the form of sheets, black on the top and a thin green film underneath. In this way a precursor is obtained.

Stage 3: Heat Treatment

30 g of precursor obtained previously are precalcinated at 305° C. with an air flow rate of 18.7 ml/min/g.

After calcination, at 601° C. under a nitrogen flow rate of 49.8 ml/min/g, a weight of calcinated solid of 24.6 g is obtained. This catalyst is called CATALYST A.

Example 9
Preparation of a Catalyst B with the Formula: Mo1V0.30Sb0.15Nb0.10Si0.76Ox and its Precursor.
Synthesis of the Precursor
The process is carried out as in Example 8, but with;


    
    
        30.75 g (0.2630 mole of V) of ammonium metavanadate (MVA);
        19.25 g (0.1321 mole of Sb) of Sb2O3;
        154.5 g (0.8753 mole of Mo) of ammonium heptamolybdate (AHM);
        15.25 g (0.146 mol) of an aqueous solution of H2O2 at 30 wt.-%;
        100 g of Ludox® AS40 silica (nsi=0.6667 mole);
        14.75 g of CBMM niobic acid i.e. nNb=0.088 mole; and
        33.0 g of Prolabo® oxalic acid i.e. nOxalate=0.262 mol.

259 g of dry precursor are recovered. The precursor is in the form of black sheets on the top and thin yellow-green films underneath.

25 g of this precursor are precalcinated at 321° C. under static air for 4 hours, then calcinated at 598° C. at a flow rate of nitrogen of 51.85 ml/min/g for 2 hours.

A weight of 20.30 g of calcinated solid is obtained. This catalyst is called catalyst B.

    
    


Example 10
Preparation of a Catalyst C with the Formula: Mo1V0.30Sb0.15Nb0.10Si0.93Ox and its Precursor.
Synthesis of the Precursor
A 10 liter reactor with a double jacket is used. The diagram of the installation is given in FIG. 2. The installation comprises the reactor with a double jacket 1, equipped with a draw off 2 and an oil bath 3 thermostatically controlled at 140° C. (so that the temperature inside the reactor is approximately 99° C.), a stirrer 4 designed to operate at 125 r.p.m., an inlet 5 for the reagents, an inlet 6 for the nitrogen, a cooler 7 connected to a vent 8.

2600 g of water, 123 g of ammonium metavanadate (1.052 mole), 77 g of antimony oxide (0.528 mol), and 618 g of ammonium heptamolybdate (3.501 mole) is introduced cold under stirring and under nitrogen flow. After the start of heating, the mixture quickly changes to green, then to blue-black.

After stabilization of the internal temperature of the reactor (T=99° C.), 4 hours of stirring of the solution allow it to be perfectly homogeneous. 60 g of oxygenated water diluted in 500 g of water are added so as to obtain a limpid orange solution (oxidation of all the cations present).

30 minutes later, 491 g (3.27 mole) of colloidal silica is introduced as well as a solution of niobic acid (59 g, 0.5 mol) and oxalic acid (132 g, 1.05 mol) previously heated for two hours and centrifuged (12 minutes at 6200 r.p.m.).

Another 30 minutes later, the heating is stopped but stirring is continued overnight in order to retain a homogeneous solution. The mixture has taken on a yellow colouring and the consistence of a gel.

Forming

A laboratory atomizer (ATSELAB® by Sodeva) is used.

The atomization takes place in an air atmosphere.

The working parameters are globally:

    
    
        flow rate of nitrogen of the order of 40 m3/h;
        flow rate of slurry of the order of 2600 g/h;
        inlet temperature of the gas: 290° C.;
        outlet temperature of the gas: 134° C.

The increase in the rate of dry material in the slurry is carried out in a rotary evaporator to 30.8 wt.-%.

A fraction comprised between 40 and 160 μm is recovered in the chamber which corresponds to the precursor.

Heat Treatment

26.6 g of the fraction obtained previously, i.e. the precursor, are precalcinated for 4 hours at 316° C. under static air in order to produce a precalcinated solid.

The precalcinated solid is then calcinated for 2 hours at 598° C. under a flow rate of nitrogen of 49.83 ml/g/min and thus produces 21 g of catalyst called CATALYST C.

    
    


Example 11
Catalyst Tests
a) Apparatus
In order to simulate the process according to the invention, simulations were carried out in the laboratory in a laboratory fixed bed reactor, by generating propane pulses and oxygen pulses.
The following are loaded from the bottom to the top of a vertical reactor with cylindrical shape and made of pyrex:

    
    
        a first height of 2 ml of silicon carbide in the form of particles of 0.125 mm in diameter,
        a second height of 5.00 g of catalyst in the form of particles of 0.02 to 1 mm diluted with 10 ml of silicon carbide in the form of particles of 0.125 mm in diameter,
        a third height of 2 ml of silicon carbide in the form of particles of 0.125 mm in diameter, and
        a fourth height of silicon carbide in the form of particles of 1.19 mm in diameter, so as to fill all of the reactor.

b) Tests of Catalyst A

1) Operating Process

    
    


The reactor is heated to 250° C. and the vaporizer to 200° C. The electric initiation of the water pump is initiated.
Once the reactor and the vaporizer have reached the temperatures given above, the water pump is actuated and the reactor temperature is raised to 400° C. and it is left for 30 minutes so that the hot point is stabilized.
Then, oxygen is introduced in 10 pulses of 23 seconds each in order to sufficiently oxidize the catalyst. The catalyst is considered to be totally oxidized when the temperature of the hot spot has stabilized, i.e. when there is no more exothermal activity due to the reaction (by monitoring the catalyst temperature measured using a thermocouple placed in the catalyst bed, the fluctuations in temperature can be seen as a function of the pulses).
Then the measurements relating to the production of acrylic acid itself can be carried out.
For each balance, liquid samples are taken. Gas samples are also taken using gas bags, each sample representing a certain number of cycles.
Each small gas-washing bottle (with a 25 ml capacity and filled with 20 ml of water) is equipped with a gas bag, and when the bottle is connected to the outlet of the reactor (as soon as the liquid bubbles), the bag is open and the chronometer is started.
In order to verify the oxidation state of the catalyst, another series of ten 23-second pulses of oxygen is carried out. It shows that the oxidation state of the solid has been maintained during the balancing.
The liquid effluents are analyzed on a HP 6890 chromatograph, after having carried out a specific calibration.
The gases are analyzed during the balancing on a Chrompack micro-GC chromatograph.
An assay of the acidity is carried out on each bottle, in order to determine the exact number of moles of acid produced during each microbalancing and to validate the chromatographic analyses.
i) Test TA1
This is a test of the oxidation of propane carried out in the absence of molecular oxygen. This test was carried out with partial pressures of propane and oxygen corresponding to the following ratios:
For the oxidation: propane/He—Kr/H2O: 10/45/45
For the regeneration: O2/He—Kr/H2O: 20/45/45, with a flow rate of He—Kr of 4.262 Nl/h (Nl/h=normal liters per hour), i.e. liters/h at 0° C. and at atmospheric pressure) and at a temperature of 400° C.
In this test, a redox balance is composed of 60 cycles. A redox cycle represents:

    
    
        12.2 seconds of propane in a continuous flow of helium-krypton/water,
        45 seconds of continuous flow of helium-krypton/water,
        20 seconds of oxygen in a continuous flow of helium-krypton/water,
        45 seconds of continuous flow of helium-krypton/water.

For each balance, 4 liquid samples are carried out, each representing 15 cycles and 4 gas samples using gas bags, each sample representing 15 cycles.

ii) Test TA2

This is also a test of the oxidation of propane carried out in the absence of molecular oxygen.

    
    


In this test, the duration of the propane pulse (as well as that of the oxygen) is modified during the balance thus allowing observation of the behaviour of the catalyst when in a more or less rich redox mixture. The duration of the oxygen pulse is still twice as great as that of propane, and with a double flow rate, in order to keep the catalyst oxidized.
The partial pressures of propane and oxygen remain the same as in the preceding test TA1:
For the oxidation: propane/He—Kr/H2O: 10/45/45
For the regeneration: O2/He—Kr/H2O: 20/45/45, with a flow rate of He—Kr of 4.262 Nl/h at a temperature of 400° C.
In this example of 60 cycles the balance is divided into six microbalances in the following way:
2 First Microbalances of 7 and 8 Cycles:


    10 seconds of propane in a flow of He—Kr/H2O,
    45 seconds under He—Kr,
    20 seconds of O2 in a flow of He—Kr,
    45 seconds under He—Kr.

3rd Microbalance of 15 Cycles:

    5 seconds of propane in a flow of He—Kr/H2O,
    50 seconds under He—Kr,
    10 seconds of O2 in a flow of He—Kr,
    55 seconds under He—Kr.

4th Microbalance of 8 Cycles:

    2 seconds of propane in a flow of He—Kr/H2O,
    50 seconds under He—Kr,
    4 seconds of O2 in a flow of He—Kr,
    55 seconds under He—Kr.

5th Microbalance of 8 Cycles:

    20 seconds of propane in a flow of He—Kr/H2O,
    45 seconds under He—Kr,
    40 seconds of O2 in a flow of He—Kr,
    45 seconds under He—Kr.

6th Microbalance of 7 Cycles:

    30 seconds of propane in a flow of He—Kr/H2O,
    45 seconds under He—Kr,
    60 seconds of O2 in a flow of He—Kr,

45 seconds under He—Kr.

The durations of the pulses which have just been given are theoretical.

iii) Test TA3



In this test the oxidation of propane is carried out in the presence of molecular oxygen, at 400° C.
The duration of the injection of oxygen in the propane pulse is varied by preserving the constant pressures of propane and of oxygen.
The balance of 40 cycles in this case is broken down as follows:
10 cycles of 30 s of propane+5 s of O2 (the oxygen being injected at the start of the injection of propane), with the proportions propane/O2/He—Kr/H2O of 30/30/45/45, with a flow of helium-krypton of 4.262 Nl/h.
Then there is an intermediate pulse composed only of the flow of carrier gas He—Kr/H2O of 60 s, then an oxygen pulse with the proportions O2/He—Kr/H2O of 20/45/45, for 60 s and another intermediate pulse of He—Kr/H2O of 60 s.
Then there is another series of 10 cycles of 30 s of propane+10 s of oxygen, with the proportions propane/O2/He—Kr/H2O of 30/30/45/45, with a flow of helium-krypton of 4.262 Nl/h. Then there is an intermediate pulse composed only of the flow of carrier gas He—Kr/H2O of 60 s, then an oxygen pulse with the proportions O2/He—Kr/H2O=20/45/45, for 60 s and another intermediate pulse of He—Kr/H2O of 60 s.
Then, there is another series of 10 cycles of 30 s of propane+15 s of O2, with the proportions propane/O2/He—Kr/H2O of 30/30/45/45, with a flow of helium-krypton of 4.262 Nl/h. Then there is an intermediate pulse composed only of the flow of carrier gas He—Kr/H2O of 60 s, then an oxygen pulse with the proportions O2/He—Kr/H2O=20/45/45, for 60 s and another intermediate pulse of He—Kr/H2O of 60 s.
Then, there is another series of 10 cycles of 30 s of propane+20 s of O2, with the proportions propane/O2/He—Kr/H2O of 30/30/45/45, with a flow of helium-krypton of 4.262 Nl/h. Then there is an intermediate pulse composed only of the flow of carrier gas He—Kr/H2O of 60 s, then an oxygen pulse with the proportions O2/He—Kr/H2O of 20/45/45, for 60 s and another intermediate pulse of He—Kr/H2O of 60 s.
As in the test TA2, the durations of the pulses which have just been given are theoretical.
2) Results
The results of the tests TA1, TA2 and TA3 are shown in the tables below.
In these tables, the theoretical durations of the pulses are no longer shown as they were previously, but the corresponding real durations which were calculated using a specific calibration.









TABLE 6









Test











TA1
TA2
TA3














Conditions in the reaction
10/45/45
10/45/45
30 + 30/45/45


propane/He—Kr/H2O or


propane + O2/He—Kr/H2O


Conditions in regeneration
20/45/45
20/45/45
20/45/45


O2/He—Kr/H2O


Comments
Standard
Variation in the duration of the
Variation in the duration of the



test
injection of propane during the balance
injection of O2 in the propane





pulse. O2 injection at the start





of the propane injection

















Summary
Average
Flask 4
Flask 3
Flask 2
Flask 5
Flask 6
Flask 1
Flask 2
Flask 3
Flask 4


Number of CYCLES
60
15
15
8
8
7
10
10
10
10


Duration of the propane pulse
12.2
4.4
7.6
12.9
22.5
32.8
33
33.6
33.7
32.7


Duration of the oxygen pulse
—
—
—
—
—
—
5
10
15
20


injected into the propane


Yields (%)


Acetaldehyde
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00


Propylaldehyde
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00


Acetone
0.17
0.17
0.16
0.16
0.16
0.18
0.15
0.15
0.15
0.15


Acrolein
0.02
0.03
0.02
0.03
0.02
0.02
0.01
0.01
0.01
0.02


Allyl alcohol
0.02
0.03
0.02
0.00
0.00
0.00
0.00
0.00
0.00
0.00


Allyl acrylate
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00


Acetic acid
1.40
1.97
1.47
1.46
1.06
1.09
0.63
0.74
0.75
0.82


Propionic acid
0.11
0.15
0.12
0.13
0.08
0.09
0.05
0.06
0.06
0.07


Acrylic acid
11.43
15.80
11.79
10.25
7.88
7.50
3.68
5.21
5.77
6.59


Carbon monoxide
1.66
2.26
1.80
1.68
1.24
1.07
0.64
0.70
0.80
0.90


Carbon dioxide
0.81
1.23
0.87
0.91
0.75
0.60
0.83
0.44
0.50
0.56


Propylene
3.56
3.56
3.70
3.65
3.57
3.44
3.34
3.57
3.76
3.87


Propane
79.60
75.02
80.04
82.11
85.21
85.74
90.58
89.26
87.76
87.01


Carbon balance (%)
98.8
100.2
100.0
100.4
100.0
99.7
99.9
100.1
99.6
100.0


















TABLE 7









Test











TA1
TA2
TA3














Conditions in the reaction
10/45/45
10/45/45
30 + 30/45/45


propane/He—Kr/H2O or


propane + O2/


He—Kr/H2O


Conditions in regeneration
20/45/45
20/45/45
20/45/45


O2/He—Kr/H2O


Comments
Standard
Variation in the duration of the
Variation in the duration of the



test
propane pulse during the balance
injection of O2 in the propane pulse

















Summary
Average
Flask 4
Flask 3
Flask 2
Flask 5
Flask 6
Flask 1
Flask 2
Flask 3
Flask 4


Number of CYCLES
60
15
15
8
8
7
10
10
10
10


Duration of the propane
12.2
4.4
7.6
12.9
22.5
32.8
33
33.6
33.7
32.7


injection


Duration of the oxygen






5
10
15
20


pulses injected into the


propane


Selectivities (%)


Acetaldehyde
0.00
0.00
0.00
0.00
0.00
0.00
0.04
0.03
0.00
0.03


Propanaldehyde
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00


Acetone
0.91
0.66
0.78
0.89
1.05
1.28
1.58
1.39
1.26
1.14


Acrolein
0.12
0.13
0.12
0.15
0.13
0.14
0.14
0.12
0.12
0.12


Allyl alcohol
0.10
0.13
0.08
0.00
0.00
0.00
0.04
0.03
0.03
0.03


Allyl acrylate
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00


Acetic acid
7.31
7.81
7.38
8.00
7.17
7.82
6.71
6.77
6.33
6.30


Propionic acid
0.56
0.58
0.58
0.70
0.53
0.64
0.58
0.56
0.53
0.51


Acrylic acid
59.56
62.69
59.14
56.10
53.45
53.60
39.37
47.83
48.88
50.82


Carbon monoxide
8.64
8.98
9.01
9.22
8.41
7.64
6.88
6.39
6.78
6.93


Carbon dioxide
4.22
4.88
4.35
4.97
5.07
4.32
8.88
4.04
4.24
4.33


Propylene
18.56
14.13
18.56
19.96
24.19
24.57
35.78
32.83
31.83
29.80


Quantity of O2 consumed
0.32
0.158
0.207
0.321
0.436
0.589
1.16
1.30
1.43
1.56


(g O/kg catalyst)


μmole of propane for
131.8
47.5
82.1
139.4
243.1
354.4
1072
1091
1094
1062


1 cycle


μmole O2 added per cycle
—
—
—
—
—
—
158
317
475
634


μmole of O2 consumed
—
—
—
—
—
—
363
405
448
488


(products formed)/cycle


Propane conversion ratio
4233
9584
6942
4565
3166
2253
1107
971
852
803


(kg/catalyst/kg converted


propane)









In test TA3, where the operation takes place in the presence of molecular oxygen, it is noted that the yields of acid acrylic increase much more quickly, as a function of the addition of oxygen in the propane pulse, than the yields in COx and acetic acid. A substantial gain in acrylic acid selectivity results. A lowering of the selectivity of hydration products is also observed (acetone, propionic acid).
The addition of oxygen also leads to a gain in conversion ratio which thus changes from 1107 to 803 kg/kg.
c) Tests of Catalyst B
1) Operating Process
The apparatus used is the one described in Example 11 a).
i) Tests TB 1 and TB2
Catalyst B is tested under the same conditions and in the same way as for test TA1.
ii) Test TB3
Catalyst B is tested under the same conditions and in the same way as for test TA3 (presence of molecular oxygen).
iii) Tests TB4 to TB6
In the case of test TB4, catalyst B is tested under the same conditions and in the same way as for test TA2, at 420° C.
In the case of tests TB5 and TB6, there is simply modification of the content of propane during the oxidation and of oxygen during the regeneration.
iv) Tests TB7
In this test, the oxidation of propane is carried out in the presence of molecular oxygen, at 420° C.
The duration of the injection of oxygen in the propane pulse is varied by keeping the pressures of propane and of oxygen constant.
The oxygen is injected at the end of the propane pulse to see if there is an influence on the catalytic performances compared to an injection at the start of the pulse.
The balance of 40 cycles is broken down as follows:
10 cycles of 30 s of propane+20 s of O2 (the oxygen being injected at the end of the propane pulse), with the proportions propane/O2/He—Kr/H2O of 30/30/45/45, with a flow of helium-krypton of 4.27 Nl/h.
Then there is an intermediate pulse composed only of the flow of carrier gas He—Kr/H2O of 60 s, then a pulse of O2 with the proportions O2/He—Kr/H2O=20/45/45, for 60 s and another pulse of carrier gas of 60 s.
Then, there is another series of 10 cycles of 30 s of propane+15 s of oxygen, with the proportions propane/O2/He—Kr/H2O of 30/30/45/45, with a flow of helium-krypton of 4.27 Nl/h. Then there is an intermediate pulse composed only of the flow of carrier gas He—Kr/H2O of 60 s, then an oxygen pulse with the proportions O2/He—Kr/H2O=20/45/45, for 60 s and another intermediate pulse of carrier gas of 60 s. Then, there is another series of 10 cycles of 30 s of propane+10 s of O2, with the proportions propane/O2/He—Kr/H2O of 30/30/45/45, with a flow of helium-krypton of 4.27 Nl/h. Then there is an intermediate pulse composed only of the flow of carrier gas He—Kr/H2O of 60 s, then a pulse of O2 with the proportions O2/He—Kr/H2O=20/45/45, for 60 s and another intermediate pulse of carrier gas of 60 s.
Then, there is another series of 10 cycles of 30 s of propane+5 s of O2, with the proportions propane/O2/He—Kr/H2O of 30/30/45/45, with a flow of helium-krypton of 4.27 Nl/h. Then there is an intermediate pulse composed only of the flow of carrier gas He—Kr/H2O of 60 s, then a pulse of O2 with the proportions O2/He—Kr/H2O=20/45/45, for 60 s and another intermediate pulse of carrier gas of 60 s.

v) Tests TB8

In this test, there is also oxidation of the propane in the presence of molecular oxygen.
There is comparison of the effect of the injection of oxygen at the end and at the start of the propane pulse by keeping constant pressures of propane and of oxygen but also a constant duration of injection of oxygen in the propane pulse.
The balance of 40 cycles is broken down as follows:
10 cycles of 30 s of propane+20 s of O2 (the oxygen being injected at the end of the propane pulse), with the proportions propane/O2/He—Kr/H2O of 30/30/45/45, with a flow of helium-krypton of 4.27 Nl/h. Then there is an intermediate pulse composed only of the flow of carrier gas He—Kr/H2O of 60 s, then an intermediate pulse of O2 with the proportions O2/He—Kr/H2O=20/45/45, for 60 s and another intermediate pulse of carrier gas of 60 s.
Then, there is another series of 10 cycles of 30 s of propane+20 s of oxygen (O2 being injected at the end of the propane pulse), with the proportions propane/O2/He—Kr/H2O of 30/30/45/45, with a flow of helium-krypton of 4.27 Nl/h. Then there is an intermediate pulse composed only of the flow of carrier gas He—Kr/H2O of 60 s, then an intermediate pulse of oxygen with the proportions O2/He—Kr/H2O=20/45/45, for 60 s and another intermediate pulse of carrier gas of 60 s.
10 cycles of 30 s of propane+20 s of O2 (the oxygen being injected at the start of the propane pulse), with the proportions propane/O2/He—Kr/H2O of 30/30/45/45, with a flow of helium-krypton of 4.27 Nl/h. Then, there is an intermediate pulse composed only of the flow of carrier gas He—Kr/H2O of 60 s, then, an intermediate pulse of O2 with the proportions O2/He—Kr/H2O=20/45/45, for 60 s and another intermediate pulse of carrier gas of 60 s.
Then, there is another series of 10 cycles of 30 s of propane+20 s of O2 (the oxygen being injected at the start of the propane pulse), with the proportions propane/O2/He—Kr/H2O of 30/30/45/45, with a flow of helium-krypton of 4.27 Nl/h. Then, there is an intermediate pulse composed only of the flow of carrier gas He—Kr/H2O of 60 s, then an intermediate pulse of O2 with the proportions O2/He—Kr/H2O==20/45/45, for 60 s and another intermediate pulse of carrier gas of 60 s.
2) Results of the Tests
a) Tests TB1 and TB2









TABLE 8









Test










TB1
TB2













Conditions in the reaction propane/He—Kr/H2O
10/45/45
10/45/45


Conditions in regeneration O2/He—Kr/H2O
20/45/45
20/45/45


Temperature (° C.)
400
420


Summary
Average
Average


Number of CYCLES
60
60


Duration of the injection of propane
12.06
12.06


Yields (%)


Acetaldehyde
0.00
0.00


Propanaldehyde
0.00
0.00


Acetone
0.22
0.17


Acrolein
0.00
0.01


Allyl alcohol
0.00
0.00


Allyl acrylate
0.00
0.00


Acetic acid
2.04
2.72


Propionic acid
0.08
0.04


Acrylic acid
13.0
15.3


Carbon monoxide
2.48
4.47


Conditions in the reaction propane/He—Kr/H2O
10/45/45
10/45/45


Conditions in regeneration O2/He—Kr/H2O
20/45/45
20/45/45


Temperature (° C.)
400
420


Summary
Average
Average


Number of CYCLES
60
60


Duration of the injection of propane
12.06
12.06


Carbon dioxide
1.44
2.92


Propylene
3.42
3.69


Propane
74.7
71.2


Carbon balance (%)
97.4
100.5


Selectivities (%)


Acetaldehyde
0.00
0.00


Propanaldehyde
0.00
0.00


Acetone
0.99
0.59


Acrolein
0.00
0.03


Allyl alcohol
0.00
0.00


Allyl acrylate
0.00
0.00


Acetic acid
8.99
9.25


Propionic acid
0.33
0.15


Acrylic acid
57.4
52.2


Carbon monoxide
10.9
15.2


Carbon dioxide
6.3
10.0


Propylene
15.1
12.6


Quantity of O2 consumed (g O/kg catalyst)
0.42
0.59


μmole of propane for 1 cycle
135.9
135.9


Propane conversion ratio
3309
2904


(kg catalyst/kg converted propane)









A better conversion is observed at 420° C. than at 400° C. The acrylic acid selectivity changes from 57.4% to 52.2% when the temperature is modified. A clear decrease (division by two) of the selectivities of acetone and propionic acid is observed.
The fact of increasing the temperature allows the conversion to be increased and the formation of hydration products as well as the conversion ratio to be decreased.
The conversion ratio changes from 3300 to 2900 kg/kg by changing from 400 to 420° C.
b) Tests TB4 to TB6
The results appear in the two tables below.
It is observed that the increase in the partial pressure of propane and/or of the duration of the injection of propane leads to a decrease in the yield of acrylic acid, but to the same yield of hydration products. The selectivities of hydration products therefore increase with the reduction of the catalyst. The selectivities of acrolein and propylene also increase with the reduction of the catalyst. The reduced catalyst becomes less active.









TABLE 9









Test










TB4
TB5





Conditions in the reaction
10/45/45
20/45/45


propane/He—Kr/H2O


Conditions in regeneration
20/45/45
20/45/45


O2/He—Kr/H2O















Summary
Flask 4
Flask 3
Flask 2
Flask 5
Flask 6
Flask 4
Flask 3
Flask 2


Number of CYCLES
15
15
8
8
7
15
15
8


Duration of the injection
4.5
7.4
12.35
21.4
30.6
4.4
7.5
12.6


of propane


Yields (%)


Acetaldehyde
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00


Propanaldehyde
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00


Acetone
0.15
0.16
0.20
0.22
0.24
0.20
0.21
0.23


Acrolein
0.00
0.00
0.00
0.00
0.02
0.00
0.02
0.02


Allyl alcohol
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00


Allyl acrylate
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00


Acetic acid
3.56
2.67
2.71
2.53
2.28
2.84
2.62
2.30


Propionic acid
0.05
0.05
0.05
0.04
0.04
0.05
0.05
0.04


Acrylic acid
24.00
19.06
15.96
11.84
9.81
15.61
13.39
10.03


Carbon monoxide
5.75
4.73
3.97
3.20
2.74
3.86
3.28
2.56


Carbon dioxide
3.40
2.48
2.51
2.15
2.00
2.38
2.16
2.05


Propylene
3.26
3.57
3.62
3.71
3.67
3.82
3.76
3.81


Propane
60.36
67.20
70.96
76.34
79.25
71.46
74.03
79.25


Carbon balance (%)
100.5
99.9
100.0
100.0
100.0
100.2
99.5
100.3












Test












TB5
TB6







Conditions in the reaction
20/45/45
30/45/45



propane/He—Kr/H2O



Conditions in regeneration
20/45/45
30/45/45



O2/He—Kr/H2O
















Summary
Flask 5
Flask 6
Flask 4
Flask 3
Flask 2
Flask 5
Flask 6



Number of CYCLES
8
6?
15
15
8
8
7



Duration of the injection
22.7
31.8
4.35
6.85
12.3
21.8
29.9



of propane



Yields (%)



Acetaldehyde
0.00
0.00
0.00
0.00
0.00
0.01
0.01



Propanaldehyde
0.00
0.00
0.00
0.00
0.00
0.00
0.00



Acetone
0.25
0.25
0.21
0.20
0.24
0.24
0.23



Acrolein
0.02
0.02
0.02
0.02
0.03
0.02
0.02



Allyl alcohol
0.00
0.00
0.00
0.00
0.00
0.00
0.00



Allyl acrylate
0.00
0.00
0.00
0.00
0.00
0.00
0.00



Acetic acid
1.74
1.56
2.67
2.00
1.89
1.37
1.21



Propionic acid
0.04
0.04
0.05
0.04
0.04
0.04
0.03



Acrylic acid
6.84
5.80
13.60
8.88
8.00
5.28
4.44



Carbon monoxide
1.67
1.46
3.32
2.58
1.88
1.21
1.07



Carbon dioxide
1.40
1.29
2.34
2.07
1.59
1.10
0.96



Propylene
3.77
3.55
3.88
3.85
3.84
3.65
3.42



Propane
84.20
85.95
74.10
80.27
82.75
87.11
88.50



Carbon balance (%)
99.9
99.9
100.2
99.9
100.3
100.0
99.9



















TABLE 10









Test










TB4
TB5





Conditions in the reaction
10/45/45
20/45/45


Propane/He—Kr/H2O


Conditions in regeneration
20/45/45
20/45/45


O2/He—Kr/H2O















Summary
Flask 4
Flask 3
Flask 2
Flask 5
Flask 6
Flask 4
Flask 3
Flask 2


Number of cycles
15
15
8
8
7
15
15
8


Duration of the injection
4.5
7.4
12.35
21.4
30.6
4.4
7.5
12.6


of propane


Yields (%)


Acetaldehyde
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00


Propanaldehyde
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00


Acetone
0.37
0.48
0.68
0.94
1.13
0.70
0.83
1.11


Acrolein
0.00
0.00
0.00
0.00
0.11
0.00
0.08
0.12


Allyl alcohol
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00


Allyl acrylate
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00


Acetic acid
8.86
8.17
9.34
10.66
10.97
9.89
10.27
10.91


Propionic acid
0.11
0.15
0.18
0.19
0.21
0.19
0.20
0.21


Acrylic acid
59.77
58.26
54.99
49.96
47.15
54.27
52.54
47.64


Carbon monoxide
14.31
14.45
13.69
13.52
13.16
13.41
12.86
12.17


Carbon dioxide
8.47
7.58
8.66
9.08
9.60
8.26
8.46
9.74


Propylene
8.11
10.91
12.47
15.66
17.67
13.29
14.76
18.11


Quantity of oxygen consumed
0.305
0.397
0.586
0.815
1.012
0.387
0.578
0.793


(g O/kg catalysts)


μmole of propane/1 cycle
50.7
83.4
139.2
241.2
344.9
94.0
160.2
269.1


Propane conversion ratio
5659
4159
2815
1994
1590
4243
2736
2038


(kg catalyst/kg converted


propane)












Test












TB5
TB6







Conditions in the reaction
20/45/45
30/45/45



Propane/He—Kr/H2O



Conditions in regeneration
20/45/45
30/45/45



O2/He—Kr/H2O
















Summary
Flask 5
Flask 6
Flask 4
Flask 3
Flask 2
Flask 5
Flask 6



Number of cycles
8
6
15
15
8
8
7



Duration of the injection
22.7
31.8
4.35
6.85
12.3
21.8
29.9



of propane



Yields (%)



Acetaldehyde
0.00
0.00
0.00
0.00
0.00
0.05
0.06



Propanaldehyde
0.00
0.00
0.00
0.00
0.00
0.00
0.00



Acetone
1.58
1.80
0.79
1.02
1.37
1.87
2.00



Acrolein
0.14
0.16
0.08
0.10
0.14
0.18
0.17



Allyl alcohol
0.00
0.00
0.00
0.00
0.00
0.00
0.00



Allyl acrylate
0.00
0.00
0.00
0.00
0.00
0.00
0.00



Acetic acid
11.04
11.19
10.22
10.18
10.81
10.59
10.66



Propionic acid
0.26
0.26
0.20
0.21
0.24
0.29
0.28



Acrylic acid
43.51
41.51
52.14
45.22
45.69
40.89
38.98



Carbon monoxide
10.62
10.48
12.72
13.12
10.72
9.36
9.40



Carbon dioxide
8.88
9.20
8.97
10.55
9.09
8.53
8.46



Propylene
23.97
25.39
14.87
19.60
21.94
28.24
29.99



Quantity of oxygen consumed
0.998
1.232
0.525
0.617
0.934
1.141
1.360



(g O/kg catalysts)



μmole of propane/1 cycle
484.7
679.1
141.3
222.5
399.5
708.0
971.1



Propane conversion ratio
1486
1193
3110
2593
1652
1247
1019



(kg catalyst/kg converted



propane)










c) Tests TB3, TB7 and TB8

The results appear in the three tables below.
It is observed that the addition of molecular oxygen allows a clear decrease in the conversion ratio while maintaining a good selectivity. There is a change from 2904 kg of catalyst/kg of converted propane for a standard test to 1019 kg of catalyst/kg of converted propane for a test with variation of pulse duration (30 s of propane with propane or oxygen/He—Kr/H2O: 30 or 30/45/45). With the addition of oxygen it is from 460 to 500 kg of catalyst/kg of converted propane.
It is advantageous to add oxygen which allows not only a further decrease of the conversion ratio, but also an increase in the acrylic acid selectivities. It is observed that the catalyst, even reduced, can remain dehydrogenating.









TABLE 11









Test











TB3
TB7
TB8














Conditions in the
30 + 30/45/45
30 + 30/45/45
30 + 30/45/45


reaction propane +


O2/He—Kr/H2O


Conditions in
20/45/45
20/45/45
20/45/45


regeneration


O2/He—Kr/H2O


Comments
Variation in the duration of the
Variation in the duration of the
Duration of O2 injection into the



injection of O2 in the propane
injection of O2 in the propane
constant propane pulse. Injection



pulse
pulse. Injection of O2 at the end
of O2 at the end of the pulse then




of the pulse
at the start of the pulse



















Summary
Flask 1
Flask 2
Flask 3
Flask 4
Flask 1
Flask 2
Flask 3
Flask 4
Flask 1
Flask 2
Flask 3
Flask 4


Number of CYCLES
10
10
10
10
10
10
10
10
10
10
10
10


Duration of the
33.3
34.4
34.2
34.6
34.4
36.5
34.2
33.6
34.4
34.3
34.6
35


injection of propane


Duration of the oxygen
5
10
15
20
20
15
10
5
20
20
20
20


pulse injected into the


propane pulse


Yields (%)


Acetaldehyde
0.01
0.01
0.01
0.00
0.01
1
0.01
0.01
0.00
0.00
0.00
0.00


Propanaldehyde
0.00
0.00
0.00
0.00
0.00

0.00
0.00
0.00
0.00
0.00
0.00


Acetone
0.20
0.20
0.19
0.16
0.06

0.08
0.05
0.15
0.15
0.17
0.17


Acrolein
0.02
0.02
0.02
0.02
0.02

0.02
0.01
0.02
0.02
0.02
0.02


Allyl alcohol
0.00
0.00
0.00
0.00
0.00

0.00
0.00
0.00
0.00
0.00
0.00


Allyl acrylate
0.00
0.00
0.00
0.00
0.00

0.00
0.00
0.00
0.00
0.00
0.00


Acetic acid
1.48
1.55
1.68
1.76
1.76

1.51
1.42
1.77
1.69
1.89
1.87


Propionic acid
0.03
0.04
0.04
0.04
0.04

0.04
0.03
0.04
0.04
0.04
0.04


Acrylic acid
6.86
8.30
9.86
11.04
10.33

6.98
5.57
10.64
10.21
11.54
11.40


Carbon monoxide
1.61
1.73
2.02
2.34
2.42

1.79
1.50
2.69
2.54
2.53
2.47


Carbon dioxide
1.37
1.41
1.52
1.77
1.95

1.59
1.36
2.08
1.98
2.02
2.00


Propylene
3.70
3.99
4.17
4.27
4.09

3.70
3.49
4.06
4.08
4.20
4.22


Propane
84.96
82.92
80.65
78.78
79.61

84.51
86.81
78.74
79.38
77.79
77.78


Carbon balance (%)
100.2
100.2
100.1
100.2
100.3

100.2
100.2
100.2
100.1
100.2
100.0










Conditions in the
30 + 30/45/45
30 + 30/45/45
30 + 30/45/45


reaction propane +


O2/He—Kr/H2O


Conditions in
20/45/45
20/45/45
20/45/45


regeneration


O2/He—Kr/H2O


Comments
Variation in the duration of the
Variation in the duration of the
Duration of O2 injection into the



injection of O2 in the propane
injection of O2 in the propane
constant propane pulse. Injection



pulse
pulse. Injection of O2 at the end
of O2 at the end of the pulse then




of the pulse
at the start of the pulse



















Summary
Flask 1
Flask 2
Flask 3
Flask 4
Flask 1
Flask 2
Flask 3
Flask 4
Flask 1
Flask 2
Flask 3
Flask 4


Number of CYCLES
10
10
10
10
10
10
10
10
10
10
10
10


Duration of the
33.3
34.4
34.2
34.6
34.4
36.5
34.2
33.6
34.4
34.3
34.6
35


injection of propane


Duration of the
5
10
15
20
20
15
10
5
20
20
20
20


O2 pulses


injected into the


propane pulse


Selectivities (%)


Acetaldehyde
0.05
0.03
0.03
0.02
0.02
1
0.04
0.05
0.02
0.02
0.02
0.02


Propanaldehyde
0.00
0.00
0.00
0.00
0.00

0.00
0.00
0.00
0.00
0.00
0.0


Acetone
1.33
1.15
0.96
0.77
0.31

0.49
0.38
0.71
0.74
0.77
0.78


Acrolein
0.12
0.13
0.11
0.10
0.09

0.11
0.11
0.07
0.07
0.07
0.07


Allyl alcohol
0.00
0.00
0.00
0.00
0.00

0.00
0.0
0.00
0.00
0.00
0.00


Allyl acrylate
0.00
0.00
0.00
0.00
0.00

0.00
0.0
0.00
0.00
0.00
0.00


Acetic acid
9.69
8.98
8.60
8.21
8.52

9.59
10.56
8.24
8.18
8.42
8.44


Propionic acid
0.21
0.22
0.21
0.19
0.20

0.23
0.25
0.19
0.21
0.19
0.19


Acrylic acid
44.85
48.11
50.59
51.56
49.94

44.48
41.42
49.59
49.28
51.48
51.34


Carbon monoxide
10.56
10.06
10.34
10.95
11.69

11.41
11.15
12.52
12.27
11.30
11.11


Carbon dioxide
8.99
8.20
7.80
8.27
9.42

10.11
10.15
9.72
9.54
8.99
9.03


Propylene
24.21
23.12
21.37
19.93
19.80

23.53
25.94
18.94
19.68
18.75
19.02





1An analysis problem was detected on flask 2, for this reason the results obtained are not shown.






d) Tests of Catalyst C

1) Operating Process

The apparatus used is that described in Example 11 a).

i) Test TC1

Catalyst C is tested in the same way as for test TA1. The conditions are the same with the exception of the flow rate of He—Kr which is 4.27 Nl/h and the temperature of the test which is 420° C.

ii) Tests TC2 to TC4

In the case of test TC2, the catalyst C is tested under the same conditions and in the same way as for test TA2. In the case of tests TC3 and TC4, there is simply modification of the content of propane during the oxidation and of oxygen during the regeneration.

These three tests were carried out at 420° C. and with a flow rate of He—Kr of 4.27 Nl/h.

iii) Test TC5

Catalyst C is tested in the same way as for test TA3 (presence of molecular oxygen). The conditions are also identical except for the flow rate of He—Kr which is now 4.27 Nl/h. The temperature is 420° C.

iv) Test TC6

Catalyst C is tested in the same way as for test TB7. The conditions are identical.

v) Test TC7

Catalyst C is tested in the same way as for test TB8. The conditions are identical except for the flow rate of He—Kr which is 4.27 Nl/h and the temperature of the test which is 420° C.

2) Results

a) Tests TC1 to TC4

The results are shown in the two tables below.

It is observed, as for catalyst B, that the selectivity of propionic acid and acetone increases with the partial pressure of propane, i.e. the more the catalyst is reduced the less selective it is.

The kinetics of initial oxygen consumption is very fast, then appears to develop as a function of the time.










TABLE 12









Test











TC1
TC2
TC3





Conditions in the reaction
10/45/45
10/45/45
20/45/45


propane + O2/He—Kr/H2O


Conditions in regeneration
20/45/45
20/45/45
20/45/45


O2/He—Kr/H2O


Comments
Standard
Variation of the duration of the
Variation of the duration of the



test
propane pulse in the mixture
propane pulse in the mixture
















Summary
Average
Flask 4
Flask 3
Flask 2

Flask 6
Flask 4
Flask 3
Flask 2


Number of CYCLES
60
15
15
8
8
7
15
15
8


Duration of the injection
12.2
4.45
7.7
12.5
22.2
31.8
4.45
7.6
12.65


of propane


Yields (%)


Acetaldehyde
0.03
0.00
0.00
0.00
0.00
0.01
0.00
0.01
0.01


Propanaldehyde
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00


Acetone
0.16
0.11
0.13
0.15
0.19
0.20
0.17
0.19
0.21


Acrolein
0.02
0.00
0.00
0.00
0.00
0.01
0.00
0.02
0.02


Allyl alcohol
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00


Allyl acrylate
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00


Acetic acid
2.74
3.42
2.77
2.80
2.52
2.19
3.10
2.75
2.42


Propionic acid
0.04
0.04
0.04
0.04
0.04
0.04
0.05
0.04
0.04


Acrylic acid
16.06
24.30
19.19
15.15
11.46
9.12
16.65
13.41
9.91


Carbon monoxide
4.71
6.30
5.31
4.77
3.27
2.82
4.22
3.54
2.73


Carbon dioxide
3.25
3.79
3.01
3.24
2.32
2.11
2.81
2.67
2.28


Propylene
3.60
3.20
3.50
3.59
3.70
3.67
3.70
3.75
3.76


Propane
69.81
59.24
65.71
70.26
76.66
79.99
68.93
73.96
78.60


Carbon balance (%)
100.4
100.4
99.6
100.0
100.2
100.2
99.6
100.3
100.0












Test












TC3
TC4







Conditions in the reaction
20/45/45
30/45/45



propane + O2/He—Kr/H2O



Conditions in regeneration
20/45/45
30/45/45



O2/He—Kr/H2O



Comments
Variation of the
Variation of the duration of the




duration of the
propane pulse in the mixture




propane pulse




in the mixture
















Summary
Flask 5
Flask 6
Flask 4
Flask 3
Flask 2
Flask 5
Flask 6



Number of CYCLES
8
6
15
15
8
8
7



Duration of the injection
22.5
32.5
4.25
7.4
12.3
21.8
30.4



of propane



Yields (%)



Acetaldehyde
0.01
0.01
0.01
0.01
0.01
0.01
0.01



Propanaldehyde
0.00
0.00
0.00
0.00
0.00
0.00
0.00



Acetone
0.23
0.25
0.18
0.21
0.21
0.21
0.20



Acrolein
0.02
0.02
0.02
0.02
0.02
0.01
0.02



Allyl alcohol
0.00
0.00
0.00
0.00
0.00
0.00
0.00



Allyl acrylate
0.00
0.00
0.00
0.00
0.00
0.00
0.00



Acetic acid
1.86
1.86
2.75
2.48
1.99
1.49
1.31



Propionic acid
0.04
0.04
0.04
0.04
0.04
0.03
0.03



Acrylic acid
6.69
6.31
13.29
10.33
7.66
5.11
4.12



Carbon monoxide
1.77
1.52
3.81
2.93
2.12
1.39
1.23



Carbon dioxide
1.64
1.39
2.90
2.49
2.00
1.36
1.18



Propylene
3.69
3.47
3.82
3.74
3.78
3.56
3.36



Propane
84.11
85.42
73.47
78.08
82.48
86.82
88.72



Carbon balance (%)
100.0
100.3
100.3
100.3
100.3
100.0
100.2













Test











TC1
TC2
TC3





Conditions in the reaction
10/45/45
10/45/45
20/45/45


propane + O2/He—Kr/H2O


Conditions in regeneration
20/45/45
20/45/45
20/45/45


O2/He—Kr/H2O


Comments
Standard
Variation of the duration of the
Variation of the duration of the



test
propane pulse in the mixture
propane pulse in the mixture
















Summary
Average
Flask 4
Flask 3
Flask 2
Flask 5
Flask 6
Flask 4
Flask 3
Flask 2


Number of CYCLES
60
15
15
8
8
7
15
15
8


Duration of the injection
12.2
4.45
7.7
12.5
22.2
31.8
4.45
7.6
12.65


of propane


Selectivities (%)


Acetaldehyde
0.09
0.00
0.00
0.00
0.00
0.06
0.00
0.06
0.06


Propanaldehyde
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00


Acetone
0.53
0.27
0.37
0.52
0.82
1.01
0.56
0.74
1.01


Acrolein
0.06
0.00
0.00
0.00
0.00
0.07
0.00
0.07
0.09


Allyl alcohol
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00


Allyl acrylate
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00


Acetic acid
8.97
8..30
8.15
9.40
10.71
10.87
10.11
10.42
11.31


Propionic acid
0.14
0.09
0.11
0.13
0.18
0.19
0.15
0.16
0.19


Acrylic acid
52.46
59.03
56.53
50.95
48.76
45.19
54.23
50.83
46.36


Carbon monoxide
15.38
15.31
15.65
16.03
13.92
13.98
13.73
13.41
12.75


Carbon dioxide
10.63
9.21
8.86
10.91
9.87
10.46
9.16
10.11
10.67


Propylene
11.76
7.78
10.32
12.06
15.73
18.16
12.06
14.21
17.57


Quantity of O2 consumed
0.627
0.310
0.434
0.628
0.836
1.019
0.428
0.625
0.825


(g O/kg catalyst)


μmole propane for 1 cycle
135.3
49.3
85.4
138.6
246.1
352.5
95.0
162.3
270.1


Propane conversion ratio
2783
5655
3884
2759
1980
1612
3854
2693
1969


(kg catalyst/kg converted


propane)












Test












TC3
TC4







Conditions in the reaction
20/45/45
30/45/45



propane + O2/He—Kr/H2O



Conditions in regeneration
20/45/45
30/45/45



O2/He—Kr/H2O



Comments
Variation of the
Variation of the duration of the




duration of the
propane pulse in the mixture




propane pulse




in the mixture
















Summary
Flask 5
Flask 6
Flask 4
Flask 3
Flask 2
Flask 5
Flask 6



Number of CYCLES
8
6
15
15
8
8
7



Duration of the injection
22.5
32.5
4.25
7.4
12.3
21.8
30.4



of propane



Selectivities (%)



Acetaldehyde
0.06
0.07
0.05
0.06
0.06
0.06
0.08



Propanaldehyde
0.00
0.00
0.00
0.00
0.00
0.00
0.00



Acetone
1.42
1.70
0.67
0.96
1.19
1.56
1.77



Acrolein
0.10
0.12
0.06
0.09
0.10
0.10
0.13



Allyl alcohol
0.00
0.00
0.00
0.00
0.00
0.00
0.00



Allyl acrylate
0.00
0.00
0.00
0.00
0.00
0.00
0.00



Acetic acid
11.65
12.48
10.25
11.14
11.17
11.34
11.44



Propionic acid
0.23
0.25
0.17
0.18
0.20
0.24
0.22



Acrylic acid
42.00
42.43
49.54
46.43
42.99
38.75
35.95



Carbon monoxide
11.10
10.23
14.21
13.15
11.88
10.56
10.74



Carbon dioxide
10.29
9.37
10.80
11.18
11.20
10.34
10.34



Propylene
23.15
23.34
14.25
16.81
21.21
27.05
29.33



Quantity of O2 consumed
1.033
1.363
0.548
0.776
0.993
1.220
1.454



(g O/kg catalyst)



μmole propane for 1 cycle
480.5
694.0
138.0
240.3
399.5
708.0
987.3



Propane conversion ratio
1490
1125
3108
2160
1626
1220
1022



(kg catalyst/kg converted



propane)










b) Tests TC5 to TC7

The results are shown in the three tables below.

It is observed that the addition of oxygen at the start of the propane pulse, rather than at the end of the pulse, leads to a small gain in acrylic acid selectivity, which appears to result from a lower COx selectivity.










TABLE 13









Test











TC5
TC6
TC7





Conditions in the
30 + 30/45/45
30 + 30/45/45
30 + 30/45/45


reaction propane +


O2/He—Kr/H2O


Conditions in
20/45/45
20/45/45
20/45/45


regeneration


O2/He—Kr/H2O


Comments
Variation in the duration of the O2
Variation in the duration of the O2
Duration of the O2 injection in the



injection in the propane pulse - O2
injection in the propane pulse - O2
constant propane pulse - O2 injection



injection at the start of the pulse
injection at the end of the pulse
at the end of the pulse then at the





start of the pulse



















Summary
Flask 1
Flask 2
Flask 3
Flask 4
Flask 1
Flask 2
Flask 3
Flask 4
Flask 1
Flask 2
Flask 3
Flask 4


Number of CYCLES
10
10
10
10
10
10
10
10
10
10
10
10


Duration of the
32.6
33
32.9
34
34.9
35.4
34.7
33.6
33.9
34.5
33.9
34


injection of propane


Duration of the
5
10
15
20
20
15
10
5
20
20
20
20


O2 pulses injected


into the propane


Yields (%)


Acetaldehyde
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0


Propanaldehyde
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0


Acetone
0.2
0.2
0.2
0.2
0.1
0.1
0.2
0.2
0.1
0.1
0.2
0.2


Acrolein
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0


Allyl alcohol
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0


Allyl acrylate
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0


Acetic acid
1.6
1.8
2.0
2.0
1.8
1.6
1.6
1.5
1.9
1.9
2.0
2.0


Propionic acid
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0


Acrylic acid
6.7
8.6
10.2
11.6
10.5
7.9
6.6
5.1
11.4
11.1
11.9
12.0


Carbon monoxide
1.8
2.1
2.4
2.7
2.9
2.4
2.0
1.7
3.1
2.9
2.8
2.9


Carbon dioxide
1.6
1.8
2.0
2.1
2.3
2.0
1.7
1.5
2.5
2.3
2.4
2.3


Propylene
3.6
3.9
4.1
4.2
4.1
3.9
3.7
3.4
4.1
4.2
4.2
4.3


Propane
84.4
81.5
79.0
77.3
78.2
82.2
84.1
86.6
76.5
77.6
76.4
76.1


Carbon balance (%)
100.1
100.0
99.9
100.2
100.1
100.2
100.0
100.1
99.8
100.1
100.0
99.8












Test











TC5
TC6
TC7





Conditions in the
30 + 30/45/45
30 + 30/45/45
30 + 30/45/45


reaction propane +


O2/He—Kr/H2O


Conditions in
20/45/45
20/45/45
20/45/45


regeneration


O2/He—Kr/H2O


Comments
Variation in the duration of the O2
Variation in the duration of the O2
Duration of the O2 injection in the



injection in the propane pulse - O2
injection in the propane pulse - O2
constant propane pulse - O2 injection



injection at the start of the pulse
injection at the end of the pulse
at the end of the pulse then at the





start of the pulse



















Summary
Flask 1
Flask 2
Flask 3
Flask 4
Flask 1
Flask 2
Flask 3
Flask 4
Flask 1
Flask 2
Flask 3
Flask 4


Number of CYCLES
10
10
10
10
10
10
10
10
10
10
10
10


Duration of the
32.6
33
32.9
34
34.9
35.4
34.7
33.6
33.9
34.5
33.9
34


injection of propane


Duration of the oxygen
5
10
15
20
20
15
10
5
20
20
20
20


pulses injected into the


propane (s)


Selectivities (%)


Acetaldehyde
0.08
0.06
0.05
0.05
0.05
0.05
0.07
0.09
0.05
0.04
0.04
0.04


Propanaldehyde
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00


Acetone
1.36
1.09
0.88
0.73
0.64
0.81
1.13
1.53
0.60
0.64
0.66
0.67


Acrolein
0.13
0.11
0.10
0.10
0.10
0.10
0.13
0.14
0.11
0.11
0.10
0.10


Allyl alcohol
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00


Allyl acrylate
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00


Acetic acid
10.50
9.81
9.35
8.90
8.45
8.78
9.85
11.20
8.21
8.24
8.57
8.58


Propionic acid
0.20
0.19
0.19
0.18
0.17
0.18
0.21
0.22
0.16
0.17
0.16
0.17


Acrylic acid
42.8
46.5
49.0
50.7
48.1
43.9
41.8
37.7
48.9
49.1
50.7
50.5


Carbon monoxide
11.5
11.6
11.7
11.7
13.4
13.3
12.7
12.3
13.3
12.8
11.8
12.0


Carbon dioxide
10.2
9.6
9.4
9.3
10.4
11.1
11.0
11.4
10.9
10.4
10.0
9.9


Propylene
23.1
21.0
19.4
18.3
18.6
21.7
23.1
25.4
17.8
18.5
18.0
18.0












Test











TC5
TC6
TC7





Conditions in the
30 + 30/45/45
30 + 30/45/45
30 + 30/45/45


reaction propane +


O2/He—Kr/H2O


Conditions in
20/45/45
20/45/45
20/45/45


regeneration


O2/He—Kr/H2O


Comments
Variation in the duration of the O2
Variation in the duration of the O2
Duration of the O2 injection in the



injection in the propane pulse - O2
injection in the propane pulse - O2
constant propane pulse - O2 injection



injection at the start of the pulse
injection at the end of the pulse
at the end of the pulse then at the





start of the pulse



















Summary
Flask 1
Flask 2
Flask 3
Flask 4
Flask 1
Flask 2
Flask 3
Flask 4
Flask 1
Flask 2
Flask 3
Flask 4


Number of CYCLES
10
10
10
10
10
10
10
10
10
10
10
10


Duration of the
32.6
33
32.9
34
34.9
35.4
34.7
33.6
33.9
34.5
33.9
34


injection of propane


Duration of the
5
10
15
20
20
15
10
5
20
20
20
20


02 pulses injected


into the propane (s)


Quantity of oxygen
2.25
2.69
3.08
3.52
3.53
2.91
2.47
2.00
3.67
3.56
3.62
3.66


consumed


(g O/Kg catalyst)


μmoles of propane for
1059
1072
1069
1104
1133
1150
1127
1091
1101
1120
1101
1104


1 cycle


μmoles of O2 added
158
317
475
634
634
475
317
158
634
634
634
634


per cycle


μmoles of oxygen
704
843
963
1101
1104
911
773
625
1153
1119
1140
1152


consumed (products


formed)/cycle


Propane conversion
681
575
504
467
454
556
623
740
435
457
433
427


ratio (kg catalyst/kg


converted propane)









Example 12
Preparation of the Precursor of a Catalyst of Formula: Mo1V0.3Sb0.15Nb0.1Si0.760x 
Stage 1: Dissolution-precipitation
Solution A
The assembly illustrated in FIG. 2 is used which comprises a 1 liter reactor of the SVL type equipped with a stirrer connected to a motor and a water cooler containing Raschig rings.
A nitrogen supply is installed on the reactor and a gas washing bottle is placed at the outlet of the cooler. The heating is ensured by a thermostatically controlled oil bath. 12.3 g of ammonium metavanade (AMV) (i.e. 0.1052 mole of vanadium) are placed in solution in 260 ml of demineralised water, in the reactor, under stirring. A yellow solution is obtained. 7.7 g of Sb2O3 (i.e. 0.0528 mole of antimony) are added to the limpid solution, then 61.8 g of ammonium heptamolybdate (AHM) (i.e. 0.3501 mole of molybdenum) are added. After the addition of AHM, the reactor is placed under nitrogen flow, the reaction is maintained under stirring, at reflux, for 4 hours. A black solution is gradually obtained; the reaction is considered to be complete after 1 hour. The solution obtained is called solution A.

Solution B

6.1 g (0.0532 mole) of an aqueous solution of H2O2 at 30% by weight is dissolved in 98 g of water, and are then added to solution A over 2 to 3 minutes. The solution becomes limpid orange in 4-5 minutes. Then 40 g of Ludox silica (0.2663 mole of Si) are added in one go and the solution becomes cloudy. The solution formed is called solution B.

Solution C

Solution C is prepared at the same time as solution A: 13.2 g (0.1047 mole) of oxalic acid and 5.9 g of niobic acid (i.e. 0.0351 mole of Nb) are dissolved under stirring at 80° C., in 100 g of water, over 2 hours. This solution is then centrifuged at 6200 r.p.m. for 12 minutes, in order to obtain a limpid solution C.

Then, solution C is added to solution B, in one go. A fluid gel is obtained which is orange then yellow. Stirring is continued for 30 minutes under nitrogen flow, under reflux.

2) Stage 2: Drying

The gel obtained previously is dried in a ventilated oven, on Teflon-covered plates, overnight, at 130° C. 104.2 g of dry precursor are recovered. This precursor, hereafter called P1, is in the form of sheets, black on the top with a green film underneath

Example 13
Preparation of the Precursors P2 to P15
The process is carried out as indicated in Example 12, except for the conditions shown in the following Table 14, in which the appearances of the precursors obtained are also shown.







TABLE 14 





Summary of the precursor synthesis



















Solution B:



Solution A
addition of oxygenated water
















Duration of stirring

Time of






of solution (Mo, V,

introduction
Colour


Precursor
Mounting
Sb/Mo
Sb) in hours
H2O2/Mo
of H2O2
change





P2
Three necked flask
0.15
5
0.15
 5 h
orange



with magnetic stirrer


diluted




P3
SVL
0.15
5
0.15
 2 mn
orange






diluted




P4
SVL
0.15
3
0.15
2–3 mn
orange






diluted

in 5 mn


P5
SVL
0.15
2
0.15
2–3 mn
orange






diluted

in 5–7 mn


P1
SVL
0.15
4
0.15
2–3 mn
orange






diluted

in 2–3 mn


P6
SVL
0.15
5
0.15
2–3 mn
orange






diluted

in 4–5 mn


P7
SVL
0.15
4
0.15

orange






diluted

in 2–3 mn


P8
SVL
0.23
4
0.23
In two goes
cloudy






diluted

orange


P9
SVL
0.23
4
0.23
1–2 minutes
brown






diluted

green


P10
SVL
0.23
5
0.23
NA
black






diluted

dark








purple


P11
SVL
0.15
4
0.15

orange






diluted

in 5








minutes


P12
SVL
0.15
4
0.15

Orange






diluted


P13
SVL
0.15
4
0.15

Orange






diluted




P14
SVL
0.23
4
0.23

slow,






diluted

orange


P15
SVL
0.15
4
0.15

slow,






diluted

orange














Solution B: addition of oxygenated water
Solution C
Appearance of












Precursor
Limpidity
Remark
Si/Mo
Remark
precursor





P2
No
yellow precipitate
0.76

black, green







underneath


P3
Yes
transferred to a heated three-
0.76

black with some




necked flask before introduction


traces of green




of H2O2, still limpid


P4
Yes
transferred to a heated three-
0.76
Ox/Mo: 0.28
black




necked flask before introduction




of H2O2


P5
Yes
transferred to a heated three-
0.76
Ox/Mo: 0.28
black




necked flask before introduction




of H2O2


P1
Yes
no transfer
0.76

black


P6
Yes

0.76
Heated for 1 h30


P7
Yes

0.76

black, green







underneath


P8
no
+ a few drops of H2O2
0.76

black, green







underneath


P9
no

0.76

black, green







underneath


P10
no
addition of H2O2 in solution C
0.76
solution C
black, finer






added directly
than usual






before the silica


P11
yes

0.76
no niobium,
black, dark






heated to 30° C.
khaki green







underneath


P12
Yes
+ a few drops of H2O2
0.76


P13
yes, then
new bottle, same batch + 20
0.76
heated for
black, green



cloudy
drops H2O2

1h15
underneath,







entirely green







area


P14
yes
+20 drops of H2O2
0.76

fine black,







green







underneath


P15
yes
+2 drops of H2O2
0.93
new batch of
black with






oxalic acid
yellow parts









Example 14
Precalcination and Calcination of the Precursors P1 to P15
The precalcinations and the calcinations are carried out in combustion boats under flow of air and of nitrogen respectively, in steel capacitors. These capacitors are directly installed in muffle furnaces and the air or nitrogen is supplied via the flue. An internal thermometer well allows precise monitoring of the temperature. The cover prevents air returning towards the catalyst (see FIG. 3).

The precursors P1 to P15 obtained in Examples 12 and 13 are precalcinated at 300° C., for 4 hours, under air flow, then calcinated at 600° C., for 2 hours under nitrogen flow of 50 ml/mn/g in a muffle furnace. The calcinations

The following conditions for heat treatment of the precursors are studied:

    
    
        calciner;
        flow rate of precalcination air in ml/min/g;
        calcination temperature variation gradient in ° C./min.

These conditions are shown in Table 15 below.

    
    









TABLE 15







Heat treatment of the precursors (for weights of 25 to 30 g)











Calcination slopes under N2



Precalcination flow
(° C./min)













Catalyst
Precursor
rate (ml/min/g)
1
2
5
10
















C2
P2
50.4






C3
P3
47






C4
P4
47






C5
P5
47






C1
P1
48.5






C6
P6
45.8











C7
P7
44.9






C8
P7
45







C9
P7
47.2








C10
P7
47









C11
P7
0







C12
P7
10







C13
P7
20.1







C14
P7
51.6







C15
P8
46.9






C16
P8
47.1







C17
P8
45.5








C18
P8
48









C19
P8
21.15









C20
P8
10.55









C21
P8
20.9







C22
P8
10.5







C23
P9
45.2







C24
P10
47.2







C25
P11
46







C26
P12
45.7







C27
P13
47.5







C28
P14
47







C29
P15
50.7







C30
P15
50.3







C31
P15
34.8







C32
P15
18.7














Example 15
Tests of the Catalysts Obtained
a) Apparatus
In order to simulate the process according to the invention, simulations were carried out in the laboratory in a laboratory fixed bed reactor.
The following are therefore loaded from the bottom to the top of a vertical reactor with cylindrical shape and made of pyrex:


    
    
        a first height of 1 ml of silicon carbide in the form of particles of 0.125 mm in diameter,
        a second height of 5 g of catalyst in the form of particles of 0.02 to 1 mm diluted with 10 ml of silicon carbide in the form of particles of 0.125 mm in diameter,
        a third height of 1 ml of silicon carbide in the form of particles of 0.125 mm in diameter, and
        a fourth height of silicon carbide in the form of particles of 1.19 mm in diameter, so as to fill all of the reactor.

b) Test Conditions

    
    


The catalyst is simultaneously supplied with propane and with oxygen. The helium acts as diluent gas and water is vaporized in the gaseous flow.
The catalysts are tested at 380° C., 390° C. and 400° C. with a ratio propane/O2/He—Kr/H2O of 10/10/45/45. The total flow rate of the gaseous flow rises to 8.65 Nl/h.
The reactor is placed in an isothermal furnace. It is supplied with propane, oxygen and helium by mass flowmeters. An HPLC pump and a vaporizer ensure the production of vapor.
Thermocouples are placed in the furnace to allow their regulation, and in the reactor to measure the “hot spot”, i.e. the highest temperature in the catalyst bed.
c) Results of the Tests
Only the results of the tests carried out at 400° C. are given. It is at this temperature that it was observed that the best results were generally obtained.
The results of the tests are recorded in Tables 16 and 17 below in which the yields are only calculated on the basis of the routine chromatographic analyses. The selectivities are calculated as being the yield of a given product over the sum of the yields of products.

The carbon balances are used to ensure the homogeneity of the data. They are considered to be acceptable for values comprises between 95 and 105%.

The yield calculations are based on the krypton content of the gas. Measurement of the flow rate of dry gas at the outlet of the reactor allows calculations to be made based on this flow rate of gas. The yield calculations can thus be validated.

The yields and selectivities of each of the products assayed are given, as well as the yield of acid, obtained by assay with 0.1N soda. This is a pseudo-yield obtained supposing that all the acids formed have 3 carbon atoms.








TABLE 16





Summary table of the yields produced by the catalysts


Yields - TTUc (%)

























Reaction temp
Hotspot temp.
TTG
TTG O2
Carbon
Oxygen





Catalyst
(° C.)
(° C.)
(ΣTTU)
(ΣTTU)
balance
balance
Acetaldehyde
Propanaldehyde
Acetone





C5
400
413
19.5
42.8
100.9
101.6
0.0
0.0
0.1


C4
400
417
18.2
41.4
97.2
99.1
0.0
0.0
0.1


C1
400
413.6
16.9
36.4
100.3
100.2
0.0
0.0
0.1


C3
400
411.9
18.3
38.9
101.0
100.8
0.0
0.0
0.1


C2
400
410
16.0
32.5
99.3
99.1
0.0
0.0
0.2


C6
400
424
20.4
47.6
102.5
99.7
0.0
0.0
0.1


C7
400
411
17.3
35.5
100.2
100.4
0.0
0.0
0.1


C8
400
409.3
16.1
33.0
99.2
94.1
0.0
0.0
0.1


C9
400
416
16.1
34.0
104.3
99.9
0.0
0.0
0.2


C10
400
420
19.1
41.6
103.3
100.0
0.0
0.0
0.2


C12
400
410.7
15.7
32.2
97.3
97.5
0.0
0.0
0.1


C14
400
405.2
17.7
36.5
99.3
99.6
0.0
0.0
0.3


C26
400
411
17.0
36.1
99.4
99.8
0.0
0.0
0.1


C30
400
409.5
13.5
25.5
99.4
99.8
0.0
0.0
0.1


C32
400
410
17.0
32.3
99.9
99.8
0.0
0.0
0.1


C23
400
410
15.6
29.6
100.6
100.9
0.0
0.0
0.1


C16
400
408.8
13.3
25.3
101.0
98.7
0.0
0.0
0.1


C17
400
411.1
20.3
42.9
99.2
98.9
0.0
0.0
0.2


C18
400
411.1
20.1
42.5
99.0
98.5
0.0
0.0
0.2


C28
400
410
16.6
33.5
102.9
98.8
0.0
0.0
0.1


C25
400
405
3.9
4.9
98.9
99.8
0.0
0.0
0.0


C24
400
401.8
12.3
21.1
106.4
104.3
0.0
0.0
1.2


C27
400
410.4
16.0
31.1
99.6
99.8
0.0
0.0
0.1
























Allyl
Allyl
Acetic
Propionic
Acrylic





Acid per


Catalyst
Acrolein
alcohol
acrylate
acid
acid
acid
CO
CO2
Propylene
Propane
CO + CO2
assay





C5
0.0
0.0
0.0
2.4
0.1
7.3
2.8
2.2
4.6
81.4
5.0
10.1


C4
0.0
0.0
0.0
2.3
0.1
6.5
3.0
2.1
4.0
78.9
5.2
10.2


C1
0.0
0.0
0.0
1.7
0.1
6.1
2.5
1.8
4.4
83.4
4.3
9.1


C3
0.0
0.0
0.0
2.0
0.1
7.4
2.4
1.8
4.6
82.7
4.2
9.9


C2
0.1
.0
0.0
1.5
0.1
6.6
1.9
1.4
4.2
83.3
3.3
8.7


C6
0.0
0.0
0.0
2.3
0.1
7.0
3.6
2.7
4.5
82.1
6.4
10.6


C7
0.0
0.0
0.0
1.7
0.0
7.3
2.1
1.5
4.5
82.9
3.6
9.7


C8
0.0
0.0
0.0
1.6
0.1
6.1
2.1
1.5
4.5
83.1
3.6
8.7


C9
0.0
0.0
0.0
1.7
0.1
5.9
2.2
1.7
4.3
88.2
3.9
8.8


C10
0.0
0.0
0.0
2.0
0.1
7.7
2.8
2.0
4.3
84.2
4.8
10.6


C12
0.0
0.0
0.0
1.6
0.1
5.6
2.1
1.5
4.7
81.6
3.6
8.2


C14
0.0
0.0
0.0
1.9
0.2
7.7
2.1
1.5
4.1
81.5
3.6
10.1


C26
0.0
0.0
0.0
1.9
0.1
6.9
2.3
1.6
4.1
82.5
3.9
9.9


C30
0.0
0.0
0.0
1.1
0.0
6.1
1.3
0.9
4.0
85.9
2.2
7.9


C32
0.1
0.0
0.0
1.1
0.1
9.0
1.4
0.9
4.3
82.9
2.3
10.8


C23
0.0
0.0
0.0
1.2
0.1
7.5
1.4
1.0
4.4
85.0
2.4
8.9


C16
0.1
0.0
0.0
1.0
0.1
5.6
1.4
0.9
4.0
87.8
2.4
7.5


C17
0.1
0.0
0.0
1.8
0.1
9.7
2.4
1.8
4.2
78.9
4.2
12.3


C18
0.0
0.0
0.0
1.8
0.1
9.6
2.4
1.8
4.2
78.9
4.2
12.3


C28
0.0
0.0
0.0
1.4
0.1
7.4
1.9
1.4
4.4
86.4
3.2
9.4


C25
0.0
0.0
0.0
0.2
0.0
0.6
0.3
0.2
2.5
95.0
0.4
1.0


C24
0.1
0.0
0.0
0.6
0.1
5.9
0.7
0.5
3.3
94.1
1.2
7.4


C27
0.0
0.0
0.0
1.4
0.1
7.4
1.6
1.1
4.3
83.6
2.7
9.6
















TABLE 17





Summary table of the selectivities of the catalysts


Selectivities (%)
























Reaction
Hotspot

TTG







temp
temp.
TTG (Total
O2 (Total
Carbon
Oxygen




Catalyst
(° C.)
(° C.)
TTU)
TTU)
balance
balance
Acetaldehyde
Propanaldehyde





C5
400
413
19.5
42.8
100.9
101.6
0.0
0.0


C4
400
417
18.2
41.4
97.2
99.1
0.1
0.0


C1
400
413.6
16.9
36.4
100.3
100.2
0.0
0.0


C3
400
411.9
18.3
38.9
101.0
100.8
0.0
0.0


C2
400
410
16.0
32.5
99.3
99.1
0.3
0.0


C6
400
424
20.4
47.6
102.5
99.7
0.0
0.0


C7
400
411
17.3
35.5
100.2
100.4
0.0
0.0


C8
400
409.3
16.1
33.0
99.2
94.1
0.0
0.0


C9
400
416
16.1
34.0
104.3
99.9
0.0
0.0


C10
400
420
19.1
41.6
103.3
100.0
0.0
0.0


C12
400
410.7
15.7
32.2
97.3
97.5
0.0
0.0


C14
400
405.2
17.7
36.5
99.3
99.6
0.0
0.0


C26
400
411
17.0
36.1
99.4
99.8
0.0
0.0


C30
400
409.5
13.5
25.5
99.4
99.8
0.1
0.0


C32
400
410
17.0
32.3
99.9
99.8
0.0
0.0


C23
400
410
15.6
29.6
100.6
100.9
0.0
0.0


C16
400
408.8
13.3
25.3
101.0
98.7
0.0
0.0


C17
400
411.1
20.3
42.9
99.2
98.9
0.0
0.0


C18
400
411.1
20.1
42.5
99.0
98.5
0.0
0.0


C28
400
410
16.6
33.5
102.9
98.8
0.0
0.0


C25
400
405
3.9
4.9
98.9
99.8
0.1
0.1


C24
400
401.8
12.3
21.1
106.4
104.3
0.0
0.0


C27
400
410.4
16.0
31.1
99.6
99.8
0.0
0.0























Allyl
Allyl
Acetic
Propionic
Acrylic





Catalyst
Acetone
Acrolein
alcohol
acrylate
acid
acid
acid
CO
CO2
Propylene





C5
0.6
0.1
0.0
0.0
12.5
0.5
37.2
14.4
11.0
23.6


C4
0.8
0.2
0.0
0.0
12.6
0.4
35.6
16.7
11.7
21.8


C1
0.7
0.1
0.0
0.0
10.4
10.4
10.4
10.4
10.4
10.4


C3
0.7
0.1
0.0
0.0
10.7
0.3
40.3
13.3
9.8
24.9


C2
1.0
0.5
0.0
0.0
9.2
0.8
41.2
12.1
8.6
26.3


C6
0.7
0.2
0.0
0.0
11.3
0.3
34.4
17.8
133
21.8


C7
0.8
0.1
0.0
0.0
9.6
0.3
42.1
12.2
8.8
26.2


C8
0.9
0.2
0.1
0.1
10.0
0.4
37.8
13.2
9.3
28.0


C9
1.2
0.1
0.0
0.0
10.4
0.5
37.0
13.5
10.7
26.5


C10
0.8
0.1
0.0
0.0
10.6
0.4
40.6
14.5
10.5
22.5


C12
0.9
0.2
0.0
0.0
10.3
0.4
35.4
13.4
9.8
29.7


C14
1.6
0.0
0.0
0.0
10.7
1.0
43.2
11.6
8.5
23.4


C26
0.7
0.1
0.0
0.0
11.2
0.3
40.9
13.6
9.4
23.9


C30
0.6
0.1
0.0
0.0
8.2
0.3
45.0
9.6
6.3
29.8


C32
0.8
0.1
0.0
0.0
6.7
0.4
52.8
8.1
5.5
25.6


C23
0.6
0.1
0.0
0.0
7.4
0.3
48.0
9.0
6.3
28.2


C16
0.7
0.4
0.0
0.0
7.7
0.6
42.4
10.6
7.1
30.5


C17
0.9
0.4
0.0
0.0
8.7
0.7
47.8
11.9
8.8
20.8


C18
0.9
0.0
0.0
0.0
8.8
0.7
47.6
12.1
8.9
21.0


C28
0.7
0.1
0.0
0.0
8.2
0.4
44.9
11.2
8.2
26.3


C25
1.0
0.4
0.1
0.0
5.9
0.6
16.6
7.0
4.0
64.1


C24
9.9
0.4
0.0
0.0
4.9
0.5
47.9
5.5
4.3
26.6


C27
0.8
0.2
0.0
0.0
8.5
0.4
46.1
10.0
6.9
27.2









Example 16
Precursors P16 of the catalyst of formula Mo1V0.3Sb0.15Nb0.1Si0.76Ox are prepared according to the operating process given in Example 12.
From these precursors P16, a series of catalysts is prepared which are tested.
The precalcination and calcination conditions of the precursor P16 are shown in Tables 18 and 19 below.
1) Stage 1: Dissolution-precipitation
Solution A
The assembly illustrated in FIG. 2 is used which comprises a 1 liter reactor of the SVL type equipped with a stirrer connected to a motor and a water cooler containing Raschig rings. A nitrogen supply is installed on the reactor and a gas washing bottle is placed at the outlet of the cooler. The heating is ensured by a thermostatically controlled oil bath.
30.75 g of ammonium metavanade (AMV) (i.e. 0.2629 mole of vanadium) is placed in solution in 650 ml of demineralised water, in the reactor, under stirring.
A yellow solution is obtained. 19.25 g of Sb2O3 (i.e. 0.1321 mole of antimony) are added, with 154.5 g of ammonium heptamolybdate (AHM) (i.e. 0.8753 mole of molybdenum) are added. After the addition, the reactor is placed under nitrogen flow, the reaction is maintained under stirring, at reflux, for 4 hours. A black solution is gradually obtained; the reaction is considered to be complete after 1 hour.

The solution obtained is called solution A.

Solution B

15.25 g (0.1346 mole) of an aqueous solution of H2O2 30% by weight is dissolved in 90 g of water, and is then added to solution A over 5 minutes. The solution becomes limpid orange in 4-5 minutes. Then 100 g of Ludox AS 40® silica (0.6667 mole of Si) is added in one go and the solution becomes slightly cloudy. The solution formed is called solution B.
Solution C
Solution C is prepared at the same time as solution A: 33.0 g (0.2618 mole) of oxalic acid and 14.75 g of niobic acid (i.e. 0.0877 mole of Nb) are dissolved under stirring at 66° C., in 250 g of water, over 2 hours. This solution is then centrifuged at 6200 r.p.m. for 12 minutes, in order to obtain a limpid solution C.
Then, solution C is added to solution B, in one go. A fluid gel is obtained which is orange then yellow. Stirring is continued for 30 minutes under nitrogen flow, under reflux.
2) Stage 2: Drying
The gel obtained previously is dried in a ventilated oven, on Teflon-covered plates, overnight, at 130° C. 259 g of dry precursor are recovered. This precursor is in the form of sheets, black on the top with a green film underneath.
Thus the precursor is obtained which is hereafter called P16.
Table 18 shows the yields of carbon (TTUc), with TTGC=ΣTTUC and TTG02=ΣTTUo, the acidities measured by assay with soda, the carbon and oxygen balances.
Table 19 shows the carbon selectivities.







TABLE 18





Yields of the products obtained during the catalyst tests


Yields - TTUc (%)






















Calcination
Flow rate
Oven






temp
of air
temperature
Hot
TTG =
TTG O2 =


Catalyst
(° C.)
(ml/mn/gca)
(° C.)
temperature (° C.)
total TTU
total TTU





C33
280
0
400
412
16.5
35.0


C34
280
10.6
400
411
15.6
31.6


C35
290
0
400
412
16.5
34.5


C36
290
10.6
400
411
15.5
30.9


C37
300
0
400
410
14.4
28.1


C38
300
10
400
411
15.7
32.2


C39
300
20.1
400
413
16.7
34.4


C40
300
51.6
400
405
17.7
36.5


C41
320
0
400
414
23.5
48.7


C42
320
0
420
438
29.6
67.3


C43
320
10
400
414
21.6
44.2


C44
280
21.2
400
413
20.5
45.6


C45
290
19.1
400
414
16.9
35.7


C46
320
19.2
400
413
18.1
39.4


C47
280
49.2
400
415
18.3
39.8


C48
290
52.9
400
414
20.9
46.7


C49
320
51.6
400
412
16.1
36.2



















C
O




Allyl
Allyl


Catalyst
balance
balance
Acetaldehyde
Propanaldehyde
Acetone
Acrolein
alcohol
acrylate





C33
98.4
102.1
0.0
0.0
0.1
0.0
0.0
0.0


C34
98.8
103.2
0.0
0.0
0.1
0.0
0.0
0.0


C35
99.3
103.0
0.0
0.0
0.1
0.0
0.0
0.0


C36
98.2
102.1
0.0
0.0
0.1
0.0
0.0
0.0


C37
99.6
98.1
0.0
0.0
0.1
0.1
0.0
0.0


C38
97.3
97.5
0.0
0.0
0.1
0.0
0.0
0.0


C39
98.1
101.6
0.0
0.0
0.1
0.0
0.0
0.0


C40
99.3
99.6
0.0
0.0
0.3
0.0
0.0
0.0


C41
99.5
103.1
0.0
0.0
0.2
0.0
0.0
0.0


C42
98.7
101.6
0.0
0.0
0.1
0.0
0.0
0.0


C43
00.0
102.5
0.0
0.0
0.2
0.0
0.0
0.0


C44
99.5
101.8
0.0
0.0
0.2
0.0
0.0
0.0


C45
96.3
95.8
0.0
0.0
0.0
0.0
0.0
0.0


C46
99.2
95.7
0.0
0.0
0.0
0.0
0.0
0.0


C47
101.1
99.9
0.0
0.0
0.1
0.0
0.0
0.0


C48
99.1
01.8
0.0
0.0
0.1
0.0
0.0
0.0


C49
98.0
99.1
0.0
0.0
0.0
0.0
0.0
0.0






















Acetic
Propionic
Acrylic




CO +
Acid per



Catalyst
acid
acid
acid
CO
CO2
Propene
Propane
CO2
assay







C33
1.9
0.1
5.3
2.6
1.9
4.6
81.9
4.5
8.3



C34
1.5
0.1
5.8
2.0
1.5
4.5
83.2
3.6
8.1



C35
1.7
0.1
5.7
2.4
1.8
4.6
82.7
4.2
8.3



C36
1.5
0.1
6.0
2.0
1.4
4.5
82.7
3.4
8.2



C37
1.2
0.1
5.5
1.7
1.3
4.5
85.2
2.9
7.9



C38
1.6
0.1
5.6
2.1
1.5
4.7
81.6
3.6
8.2



C39
1.6
0.1
6.7
2.1
1.6
4.5
81.4
3.7
9.2



C40
1.9
0.2
7.7
2.1
1.5
4.1
81.5
3.6
10.1



C41
2.1
0.1
12.8
2.4
1.7
4.2
76.0
4.2
15.5



C42
2.6
0.0
15.0
4.3
3.1
4.5
69.0
7.4
18.5



C43
1.8
0.1
11.3
2.3
1.7
4.3
78.4
3.9
13.8



C44
2.0
0.1
9.5
2.5
1.9
4.3
79.1
4.4
12.9



C45
1.6
0.1
7.2
2.1
1.6
4.2
79.4
3.7
9.7



C46
1.7
0.0
8.8
2.1
1.5
3.9
81.2
3.6
11.2



C47
1.6
0.1
8.6
2.2
1.6
4.2
82.8
3.8
11.0



C48
2.0
0.1
10.1
2.5
1.9
4.2
78.2
4.4
12.9



C49
1.8
0.0
6.4
2.3
1.6
3.8
81.9
3.9
9.0

















TABLE 19





Selectivities of the products obtained in the catalyst tests


Selectivities (%)

























Calcination
Flow rate or air
Oven
Hot
TTG =
TTG O2 =
C
O



Catalyst
temp (° C.)
(ml/mn/gca)
temperature (° C.)
temp. (° C.)
total TTU
total TTU
balance
balance
Acetaldehyde





C33
280
0
400
412
16.5
35.0
98.4
102.1
0.0


C34
280
10.6
400
411
15.6
31.6
98.8
103.2
0.1


C35
290
0
400
412
16.5
34.5
99.3
103.0
0.1


C36
290
10.6
400
411
15.5
30.9
98.2
102.1
0.0


C37
300
0
400
410
14.4
28.1
99.6
98.1
0.0


C38
300
10
400
411
15.7
32.2
97.3
97.5
0.0


C39
300
20.1
400
413
16.7
34.4
98.1
101.6
0.0


C40
300
51.6
400
405
17.7
36.5
99.3
99.6
0.0


C41
320
0
400
414
23.5
48.7
99.5
103.1
0.0


C42
320
0
420
438
29.6
67.3
98.7
101.6
0.0


C43
320
10
400
414
21.6
44.2
100.0
102.5
0.0


C44
280
21.2
400
413
20.5
45.6
99.5
101.8
0.0


C45
290
19.1
400
414
16.9
35.7
96.3
95.8
0.1


C46
320
19.2
400
413
18.1
39.4
99.2
95.7
0.0


C47
280
49.2
400
415
18.3
39.8
101.1
99.9
0.0


C48
290
52.9
400
414
20.9
46.7
99.1
101.8
0.0


C49
320
51.6
400
412
16.1
36.2
98.0
99.1
0.1



























Acetic
Propionic
Acrylic





Catalyst
Propanaldehyde
Acetone
Acrolein
Allyl alcohol
Allyl acrylate
acid
acid
acid
CO
CO2
Propene





C33
0.0
0.7
0.1
0.0
0.0
11.5
0.3
32.2
15.7
11.6
27.8


C34
0.0
0.9
0.1
0.0
0.0
9.7
0.3
37.2
13.1
9.8
28.8


C35
0.0
0.7
0.1
0.0
0.0
10.5
0.3
34.8
14.6
11.0
27.9


C36
0.0
0.9
0.1
0.0
0.0
9.6
0.3
38.6
12.8
8.9
28.9


C37
0.0
0.8
0.4
0.0
0.0
8.5
0.7
38.0
11.7
8.7
31.1


C38
0.0
0.9
0.2
0.0
0.0
10.3
0.4
35.4
13.4
9.8
29.7


C39
0.0
0.9
0.1
0.0
0.0
9.7
0.4
39.9
12.6
9.3
27.0


C40
0.0
1.6
0.0
0.0
0.0
10.7
1.0
43.2
11.6
8.5
23.4


C41
0.0
0.8
0.1
0.0
0.0
8.8
0.3
54.5
10.4
7.3
17.9


C42
0.0
0.4
0.1
0.0
0.0
8.7
0.1
50.6
14.5
10.6
15.1


C43
0.0
0.7
0.1
0.0
0.0
8.5
0.3
52.3
10.5
7.7
20.0


C44
0.0
0.8
0.1
0.0
0.0
9.7
0.3
46.6
12.4
9.2
20.9


C45
0.0
0.2
0.1
0.0
0.0
9.7
0.3
42.8
12.5
9.6
24.7


C46
0.0
0.3
0.1
0.0
0.0
9.5
0.3
48.4
11.5
8.3
21.7


C47
0.0
0.3
0.1
0.0
0.0
9.0
0.3
46.9
11.9
8.7
22.9


C48
0.0
0.3
0.1
0.0
0.0
9.5
0.3
48.3
11.9
9.3
20.3


C49
0.0
0.2
0.1
0.0
0.0
11.5
0.2
39.9
14.4
10.1
23.6









It is therefore seen that the best results are obtained with a precalcination at 320° C. and under a zero flow rate of air, followed by a calcination at 600° C. for 2 hours under a flow rate of nitrogen of 50 ml/mn/g.

## Claims

1. Process for the production of acrylic acid from propane, wherein a gaseous mixture comprising propane, water vapor, and optionally an inert gas,
either in the absence of oxygen,
or in the presence of molecular oxygen, wherein when operating in the presence of molecular oxygen the molar ratio propane/molecular oxygen in the initial gaseous mixture is greater than or equal to 0.5;
is passed over a catalyst of formula (I):


Mo1VaSbbNbcSidOx  (I)


in which:
a is between 0.006 and 1, inclusive;
b is between 0.006 and 1, inclusive;
c is between 0.006 and 1, inclusive;
d is between 0 and 3.5, inclusive; and
x is the quantity of oxygen bound to the other elements and depends on their oxidation state,

in order to oxidize the propane to acrylic acid.

2. Process according to claim 1, in which the molar proportions of the constituents of the initial gaseous mixture are as follows:


propane/O2/inert gas/H2O (vapor)=1/0.05-2/1-10/1-10.

3. Process according to claim 1, in which the molar proportions of the constituents of the initial gaseous mixture are as follows:


propane/O2/inert gas/H2O (vapor)=1/0.1-1/1-5/1-5.

4. Process according to claim 1, in which, in the catalyst of formula (i):
a is between 0.09 and 0.8, inclusive;
b is between 0.04 and 0.6, inclusive;
c is between 0.01 and 0.4, inclusive; and
d is between 0.4 and 1.6, inclusive.

5. Process according to claim 1, wherein the oxidation reactions are carried out at a temperature of 200 to 500° C.

6. Process according to claim 1, wherein the oxidation reaction is carried out at a temperature of 250 to 450° C.

7. Process according to claim 1, wherein the oxidation reactions are carried out at a pressure of 1.01×104 to 1.01×106 Pa (0.1 to 10 atmospheres).

8. Process according to claim 1, wherein the oxidation reactions are carried out at a pressure of 5.05×104 to 5.05×105 Pa (0.5-5 atmospheres).

9. Process according to claim 1, which is used until there is a reduction ratio of the catalyst comprised between 0.1 and 10 g of oxygen per kg of catalyst.

10. Process according to claim 1, wherein once the catalyst has at least partially changed to the reduced state, its regeneration is carried out according to reaction (C):


SOLIDreduced+O2→SOLIDoxidized  (C)

by heating in the presence of oxygen or a gas containing oxygen at a temperature of 250 to 500° C., for a period necessary for the reoxidation of the catalyst.

11. Process according to claim 10, wherein the oxidation and the regeneration (C) reactions are carried out in a device with two stages, namely a reactor and a regenerator which operate simultaneously and in which two catalyst loads alternate periodically.

12. Process according to claim 10, wherein the oxidation and the regeneration (C) reactions are carried out in the same reactor alternating the periods of reaction and regeneration.

13. Process according to claim 10, wherein the oxidation and the regeneration (C) reactions are carried out in a reactor with a moving bed.

14. Process according to claim 1, in which:
a) the initial gaseous mixture is introduced into a first reactor with a moving catalyst bed,
b) at an outlet of the first reactor, the gaseous mixture is separated from the catalyst;
c) the catalyst is returned into a regenerator;
d) optionally, the gaseous mixture is introduced into a second reactor with a moving catalyst bed;
e) if the gases are introduced into a second reactor with a moving catalyst bed, at an outlet of the second reactor, the are gaseous mixture is separated from the catalyst and the acrylic acid contained in the separated gaseous mixture is recovered;
f) if the gases are introduced into a second reactor with a moving catalyst bed, the catalyst of the second reactor is returned into the regenerator; and
g) regenerated catalyst from the regenerator is reintroduced into the first reactor and, if the gases are introduced into a second reactor with a moving catalyst bed, into the second reactor.

15. Process according to claim 14, in which the first and second reactors are vertical and the catalyst is moved upwards by the gas flow.

16. Process according to claim 1, wherein the oxidation reactions are carried out with a residence time of 0.01 to 90 seconds in each reactor.

17. Process according to claim 1, wherein the oxidation reactions are carried out with a residence time of 0.1 to 30 seconds.

18. Process according to claim 1, wherein propylene produced or the propane which has not reacted or both are recycled to an inlet of a reactor, or if there are several reactors, to an inlet of a first reactor.

19. Process according to claim 1, in which a reactor, or when there are several reactors, at least one of the reactors, also comprises a cocatalyst corresponding to the following formula (II):


MoIBia′Feb′Coc′Nid′Ke′Sbf′Tig′Sih′Ca1′Nbj′Tek′PbI′Wm′Cun′  (II)


in which:
a′ is between 0.006 and 1, inclusive
b′ is between 0 and 3.5, inclusive;
c′ is between 0 and 3.5, inclusive;
d′ is between 0 and 3.5, inclusive;
e′ is between 0 and 1, inclusive;
f′ is between 0 and 1, inclusive;
g′ is between 0 and 1, inclusive;
h′ is between 0 and 3.5, inclusive;
i′ is between 0 and 1, inclusive;
j′ is between 0 and 1, inclusive;
k′ is between 0 and 1, inclusive;
l′ is between 0 and 1, inclusive;
m′ is between 0 and 1, inclusive; and
n′ is between 0 and 1, inclusive.

20. Process according to claim 19, in which the cocatalyst is regenerated and circulates in the same way as the catalyst.

21. Process according to claim 19, in which, in the cocatalyst of formula (II):
a′ is between 0.01 and 0.4, inclusive;
b′ is between 0.2 and 1.6, inclusive;
c′ is between 0.3 and 1.6, inclusive;
d′ is between 0.1 and 0.6, inclusive;
e′ is between 0.006 and 0.01, inclusive;
f′ is between 0 and 0.4, inclusive;
g′ is between 0 and 0.4, inclusive;
h′ is between 0.01 and 1.6, inclusive
i′ is between 0 and 0.4, inclusive;
j′ is between 0 and 0.4, inclusive;
k′ is between 0 and 0.4, inclusive;
l′ is between 0 and 0.4, inclusive;
m′ is between 0 and 0.4, inclusive; and
n′ is between 0 and 0.4, inclusive.

22. Process according to claim 19, in which, a weight ratio of the catalyst to the cocatalyst greater than 0.5 is used.

23. Process according to claim 19, in which, a weight ratio of the catalyst to the cocatalyst of at least 1 is used.

24. Process according to claim 19, in which the catalyst and the cocatalyst are mixed.

25. Process according to claim 19, in which the catalyst and the cocatalyst are present in the form of pellets, each pellet comprising both the catalyst and the cocatalyst.

26. Process according to claim 1, comprising the repetition, in a reactor provided with the catalyst of formula (I) defined in claim 1, and, or the cocatalyst of formula (II) defined in claim 19, of the cycle comprising the following successive stages:
1) a stage of injection of the gaseous mixture as defined in claim 1;
2) a stage of injection of water vapor and, if appropriate, inert gas;
3) a stage of injection of a mixture of molecular oxygen, water vapor and, optionally, inert gas; and
4) a stage of injection of water vapor and, optionally, inert gas.

27. Process according to claim 26, wherein the cycle comprises an additional stage which precedes or follows stage 1) and during which a gaseous mixture corresponding to that of stage 1) but without molecular oxygen is injected, the molar ratio propane/molecular oxygen then being calculated globally for stage 1) and this additional stage.

28. Process according to claim 27, wherein the additional stage precedes stage I) in the cycle.

29. Process according to claim 26, wherein the reactor is a reactor with a moving bed.

30. Process for the production of acrylic acid from propane, wherein a gaseous mixture comprising propane, water vapor, and optionally an inert gas,
either in the absence of oxygen,
or in the presence of molecular oxygen, wherein when operating in the presence of molecular oxygen the molar ratio propane/molecular oxygen in the initial gaseous mixture is greater than or equal to 0.5; is passed over a catalyst of formula (I):


Mo1VaSbbNbcSidOx  (I)


in which:
a is between 0.006 and 1, inclusive;
b is between 0.006 and 1, inclusive;
c is between 0.006 and 1, inclusive;
d is between 0 and 3.5, inclusive; and
x is the quantity of oxygen bound to the other elements and depends on their oxidation state,

in order to oxidize the propane to acrylic acid,
and in which:
a) the initial gaseous mixture is introduced into a first reactor with a moving catalyst bed,
b) at an outlet of the first reactor, gases are separated from the catalyst;
c) the catalyst is returned into a regenerator;
d) optionally, the gases are introduced into a second reactor with a moving catalyst bed;
e) if the gases are introduced into a second reactor with a moving catalyst bed, at an outlet of the second reactor, the gases are separated from the catalyst and the acrylic acid contained in the separated gases is recovered;
f) if the gases are introduced into a second reactor with a moving catalyst bed, the catalyst of the second reactor is returned into the regenerator; and
g) regenerated catalyst from the regenerator is reintroduced into the first reactor and, if the gases are introduced into a second reactor with a moving catalyst bed, into the second reactor.

31. Process according to claim 30, in which the molar proportions of the constituents of the initial gaseous mixture are as follows:


propane/O2/inert gas/H2O(vapor)=1/0.05-2/1-10/1-10.

32. Process according to claim 30, in which, in the catalyst of formula (I):
a is between 0.09 and 0.8, inclusive;
b is between 0.04 and 0.6, inclusive;
c is between 0.01 and 0.4, inclusive; and
d is between 0.4 and 1.6, inclusive.

33. Process for the production of acrylic acid from propane, wherein a gaseous mixture comprising propane, water vapor, and optionally an inert gas,
either in the absence of oxygen,
or in the presence of molecular oxygen, wherein when operating in the presence of molecular oxygen the molar ratio propane/molecular oxygen in the initial gaseous mixture is greater than or equal to 0.5;
is passed over a catalyst of formula (I):


Mo1VaSbbNbcSidOx  (I)


in which:
a is between 0.006 and 1, inclusive;
b is between 0.006 and 1, inclusive;
c is between 0.006 and 1, inclusive;
d is between 0 and 3.5, inclusive; and
x is the quantity of oxygen bound to the other elements and depends on their oxidation state,

in order to oxidize the propane to acrylic acid,
comprising repetition, in a reactor provided with the catalyst of formula (I) above, of a cycle comprising the following successive stages:
1) a stage of injection of the gaseous mixture as defined above;
2) a stage of injection of water vapor and, optionally, inert gas;
3) a stage of injection of a mixture of molecular oxygen, water vapor and, optionally, inert gas; and
4) a stage of injection of water vapor and, if appropriate, inert gas.

34. Process according to claim 33, in which, in the catalyst of formula (I):
a is between 0.09 and 0.8, inclusive;
b is between 0.04 and 0.6, inclusive;
c is between 0.01 and 0.4, inclusive; and
d is between 0.4 and 1.6, inclusive.

35. Process according to claim 33, wherein the cycle comprises an additional stage which precedes or follows stage 1) and during which a gaseous mixture corresponding to that of stage 1) but without molecular oxygen is injected, the molar ratio propane/molecular oxygen then being calculated globally for stage 1) and this additional stage.

36. Process according to claim 33, wherein the additional stage precedes stage I) in the cycle.