Method for regeneration and activity improvement of syngas conversion catalyst

A method is disclosed for the treatment of single particle iron-containing syngas (synthes.s gas) conversion catalysts comprising iron, a crystalline acidic aluminosilicate zeolite having a silica to alumina ratio of at least 12, a pore size greater than about 5 Angstrom units and a constraint index of about 1-12 and a matrix. The catalyst does not contain promoters and the treatment is applicable to either the regeneration of said spent single particle iron-containing catalyst or for the initial activation of fresh catalyst. The treatment involves air oxidation, hydrogen reduction, followed by a second air oxidation and contact of the iron-containing single particle catalyst with syngas prior to its use for the catalytic conversion of said syngas. The single particle iron-containing catalysts are prepared from a water insoluble organic iron compound.

CROSS REFERENCE TO RELATED CASES 
This application is related to application Ser. No. 970,307 filed Dec. 18, 
1978 entitled "Conversion of Synthesis Gas with Iron-Containing Catalyst" 
which describes and claims the catalyst with which the instant application 
is concerned, as well as the conversion of syngas over said catalyst. 
BACKGROUND OF THE INVENTION 
Field of the Invention 
This invention is concerned generally with processes for converting 
synthesis gas, i.e. mixtures of gaseous carbon oxides with hydrogen or 
hydrogen donors, to hydrocarbon mixtures and more specifically, with 
catalyst treatment. 
Processes for the conversion of coal and other hydrocarbons, such as 
natural gas, to a gaseous mixture consisting essentially of hydrogen and 
carbon monoxide and/or dioxide are well known. Those of major importance 
depend either on the partial combustion of the fuel with an 
oxygen-containing gas or on the high temperature reaction of the fuel with 
steam, or on a combination of these two reactions. An excellent summary of 
the art of gas manufacture, including synthesis gas, from solid and liquid 
fuels is given in Encyclopedia of Chemical Technology, Edited by 
Kirk-Othmer, Second Edition, Volume 10, pages 353-433 (1966), Interscience 
Publishers, New York, New York. 
It is also well known that synthesis gas will undergo conversion to 
reduction products of carbon monoxide, such as hydrocarbons, at from about 
300.degree. F. to about 850.degree. F., under from about one to one 
thousand atmospheres pressure, over a fairly wide variety of catalysts. 
The Fischer-Tropsch process, for example, which has been most extensively 
studied, produces a range of liquid hydrocarbons, a portion of which have 
been used as low octane gasoline. Catalysts that have been studied for 
this and related processes include those based on iron, cobalt, nickel, 
ruthenium, thorium, rhodium and osmium, or their oxides. 
Recently, it has been discovered that the conversion of synthesis gas into 
valuable products can be greatly enhanced by employing a special type of 
crystalline alumino-silicate zeolite exemplified by ZSM-5 in admixture 
with a conventional Fischer-Tropsch catalyst. Thus, for example, in U.S. 
Pat. No. 4,086,262, there is disclosed a process for the conversion of 
syngas by passing the same at elevated temperature over a catalyst which 
comprises an intimate mixture of a Fischer-Tropsch component and a special 
type of zeolite such as ZSM-5. Said patent points out that the products 
produced are hydrocarbon mixtures which are useful in the manufacture of 
heating oil, high octane gasoline, aromatic compounds, and chemical 
intermediates. 
Although U.S. Pat. No. 4,086,262 is primarily directed to multi-particle 
composite catalysts, i.e., the crystalline aluminosilicate component (one 
particle) is physically admixed with the Fischer-Tropsch component 
(another particle), nevertheless, Example 5 of said patent does disclose a 
single particle iron-containing catalyst in an alumina matrix. 
As can well be appreciated, the patent and technical literature relating to 
the Fischer-Tropsch process, is, indeed, extensive and the various 
catalysts reported in the prior art have been used by themselves as well 
as in admixture with catalytically inactive supports such as kieselguhr. 
Although the reasons for using catalytically inactive supports have 
varied, nevertheless, it would appear that one reason for using the same 
was that it resulted in increased surface area of the Fischer-Tropsch 
component upon which it was deposited or admixed and that it also aided in 
controlling the heat requirements of the overall exothermic reactions. 
It is also known in the art to admix a Fischer-Tropsch component with a 
material, such as silica-alumina which is known to be catalytically active 
for the conversion of hydrocarbons. 
Copending application Ser. No. 970,307, filed Dec. 18, 1978 (the entire 
disclosure of which is incorporated by reference) is directed towards the 
use of a water-insoluble iron derivative of an organic compound such as 
iron oxalate to prepare single particle catalysts and the discovery that 
such catalysts are far more effect for the conversion of syngas than the 
corresponding catalysts made from water-soluble iron salts. 
DESCRIPTION OF PREFERRED EMBODIMENTS 
The novel process of this invention is directed towards the treatment of 
the single particle iron-containing catalysts of aforementioned Ser. No. 
970,307, filed Dec. 18, 1978. The novel treatment of this invention is 
applicable either to enhance the activity of the fresh iron-containing 
catalysts or to restore the activity of said catalysts which had become 
deactivated during use in the conversion of syngas. 
The novel process of this invention involves carrying out four steps in 
sequence which can be defined as first oxidizing either the fresh or spent 
catalyst in a stream of flowing air at a pressure in the range of about 
0-200 psig for 0.1 to 16 hours at temperatures between 500.degree. and 
1,000.degree. F. The second step resides in reducing the treated catalyst 
in a stream of flowing hydrogen at pressures in the range of 0-200 psig 
for 0.1 to 16 hours at temperatures between 500.degree. and 1,000.degree. 
F. The third step involves reoxidizing said previously reduced catalyst by 
contacting the same in a stream of air at pressures in the range of from 
0-200 psig for 0.1 to 16 hours at temperatures between 500.degree. and 
1,000.degree. F. The fourth step in the novel treatment process of this 
invention involves activation of the catalyst by treatment of the same 
with syngas at atmospheric pressure and at temperatures of about 
550.degree.-650.degree. F. for periods of time ranging from about 1/2 hour 
up to about 24 hours. 
It is pointed out however, that the first step of air oxidation can be 
omitted in the regeneration of spent catalyst which is not highly coked, 
i.e. it has only been used in short cycles. The first step is always 
necessary for the activation of fresh catalyst. 
It is recognized that it is notoriously old in the Fischer-Tropsch art to 
reactivate spent catalysts by a wide variety of techniques which include 
not only oxidation, but also reduction. One representative patent in this 
area is U.S. Pat. No. 2,273,864 which discloses a method for reactivating 
catalysts comprising subjecting the catalyst to at least one sequence of 
oxidizing and reducing steps above 700.degree. F. and thereafter 
subjecting the catalyst to at least one sequence of oxidizing and reducing 
steps below 700.degree. F. It is to be noted however, that the novel 
process of this invention contains very critical steps which must be 
performed in the sequence previously mentioned. Additionally, the novel 
process of this invention is applicable to a specific type of 
Fischer-Tropsch catalyst which had been prepared utilizing a water 
insoluble organic iron compound. For reasons which are not completely 
understood, it has been found that it is absolutely necessary when 
utilizing catalysts of this type to have the aforementioned pretreatment 
with syngas immediately prior to the use of these catalysts for the 
processing of said syngas. In other words, although one of the steps in 
the novel process of this invention involves treatment of the catalyst 
with hydrogen, it is absolutely critical that this hydrogen treatment step 
not be the last step prior to use of the catalyst in syngas conversion. 
The vast majority of prior art reactivation processes, no matter what the 
particular sequence, generally uses as a last step therein treatment of 
the catalyst with hydrogen immediately prior to its use for the conversion 
of syngas. Although this technique may very well be effective in treatment 
of iron-containing Fischer-Tropsch catalysts prepared by conventional 
techniques, nevertheless, it is totally inapplicable to the single 
particle Fischer-Tropsch catalyst prepared from water insoluble organic 
compounds which are utilized in the process of this invention. 
The regeneration process of this invention results in the restoration of 
activity of the spent catalyst to an unusually high degree and enables the 
catalyst to be regenerated many times without any significant adverse 
effects. 
The novel process of this invention is concerned with contacting synthesis 
gas with either a fixed bed or fluid catalyst which comprises at least 
three separate components which are present in a single particle as 
opposed to a mixture of three separate particles. The catalyst with which 
this invention is concerned comprises iron, an acidic crystalline 
aluminosilicate zeolite having a pore size of about 5 Angstrom units, a 
silica alumina ratio of at least 12, and a constraint index of about 1-12 
(preferably ZSM-5) and a siliceous matrix material. The crystalline 
aluminosilicates employed are fully set forth in aforementioned U.S. Pat. 
No. 4,086,262 which is herein incorporated by reference. The preferred 
class of zeolites used is exemplified by ZSM-5, ZSM-11, ZSM-12, etc. As 
has heretofore been stated, the manner in which the iron is introduced 
into the catalyst is of prime importance. 
The matrix portion of the single particle fluid catalyst is not narrowly 
critical and suitable matrices include silica, alumina, silica-alumina, 
silica-zirconia, silica-magnesia, etc. 
One surprising feature of the instant catalysts is that they are unpromoted 
and yet they still exhibit high activity with little or no evident aging, 
and, in fact, are capable of converting syngas to a naphtha product while 
producing no more than 30 weight percent of methane plus ethane, based on 
total hydrocarbons. In fact, the use of promoters, which the prior art 
found necessary in previous iron-containing catalysts, is definitely not 
preferred due to the fact that most promoters are alkaline in nature and 
they have a tendency to migrate to the acidic crystalline aluminosilicate 
zeolite component and to decrease the activity of the same. Therefore, it 
would appear that the single particle catalyst of the instant invention 
represents a significant departure from the teachings of the prior art in 
that not only are alkaline promoters not necessary for sustained operation 
but, in fact, are detrimental to the activity of the zeolitic component. 
The single particle iron-containing catalyst can be prepared by adding the 
appropriate acidic crystalline aluminosilicate previously defined and a 
water insoluble iron derivative of an organic iron to a hydrogel before 
drying, homogenizing the same, and thereafter forming either fixed bed or 
fluid catalysts by conventional techniques. 
The water-insoluble derivatives of organic compounds include 
water-insoluble organic iron salts such as the oxalate, the formate, as 
well as mixtures thereof. 
The amount of water-insoluble iron derivative of an organic compound which 
is added is not narrowly critical and an amount sufficient to produce 2.5 
to 20 weight percent and more preferably 2.5 to 10 weight percent based on 
the finished catalyst is used. 
One embodiment for catalyst preparation resides in the in situ formation of 
the water insoluble organic iron derivative in the hydrogel, In this 
embodiment a water soluble iron salt such as iron sulfate is added to the 
hydrogel followed by treatment with oxalic, formic or gluconic acid in 
order to form the organic salt in situ. 
Following the addition of the water insoluble organic iron salt, (either 
directly or prepared in situ), the catalyst can be formulated into a fixed 
bed catalyst or, preferably, into a fluid catalyst by conventional 
techniques. 
It is to be understood that methods of making fluidized catalysts 
containing crystalline aluminosilicate zeolites and siliceous matrices are 
well known in the art. Thus, for example, a composite of the crystalline 
alumino-silicate zeolite and a siliceous matrix can be made by admixing an 
aqueous alkali metal silicate with or without a particulate weighting 
agent, such as kaolin clay, desirably as a dispersion in water so as to 
intimately mix the clay particles with the alkali metal silicate. This 
admixing is conveniently done at room temperature, although, of course, 
higher or lower temperatures may be employed if desired. The mixture is 
then heated, generally to a temperature of from 100.degree.-160.degree. F. 
and acid is added to adjust the pH to from about 8-10. The temperature is 
maintained for a time of about 1-6 hours or longer. At this point, if a 
silica-zirconia weighting agent (e.g. clay) matrix is desired, a zirconium 
salt is added, desirably as an aqueous solution thereof. Acid is then 
added to reduce the pH to about 4-7 and form a silica gel weighting agent 
or a silica gel-zirconia gel weighting agent slurry, which is then admixed 
with a slurry of the acidic crystalline aluminosilicate zeolite and the 
water insoluble organic iron salt previously described. The resulting 
composite is then homogenized and then treated with a source of ammonium 
ions or hydrogen ions in order to reduce the sodium content to a low level 
which is desirably less than about 0.1% sodium and then spray dried to 
produce fluid size particles. 
As is generally known in fluid catalysts for catalytic cracking, the 
catalyst additionally includes a weighting agent. The most preferred 
weighting agent is kaolin clay. Other weighting agents may be substituted 
in whole or in part for the kaolin clay so long as the weighting agents 
are not detrimental to the finished catalyst. 
The relative proportion of crystalline aluminosilicate zeolite to matrix is 
not narrowly critical and it can range from about 5-40 weight percent of 
the matrix. 
As has been indicated earlier, the crystalline aluminosilicate zeolite, the 
iron component and the matrix are then thoroughly mixed in a form of an 
aqueous slurry in order to homogenize the same and thereafter subdivided 
and dried to form the desired particles. A particularly good method of 
making microspherical particles (e.g. of particle size of about 1-200 
microns) especially suitable for use in the fluidized process of this 
invention is spray-drying, preferably under high pressure, e.g., of the 
order of about 200-2,000 psig and preferably from about 1,000-1,500 psig. 
The spray-drying temperature is ordinarily within the range of 
200.degree.-1,000.degree. F. The temperature used will depend on such 
factors as the quantity of material to be dried and the quantity of air 
used in the drying. The evaporization rate will vary depending on the 
quantity of air used in the drying. The temperature of the particles which 
are being dried is preferably within the range of 150.degree.-300.degree. 
F. at the completion of the drying. 
The drying is preferably affected by a process in which the particles to be 
dried and a hot air stream are moving in the same direction for the entire 
drying period (concurrent drying) or where the hot stream flows in the 
opposite direction (countercurrent drying), or by semi-concurrent drying. 
It is to be understood that spray-drying to form fluidized catalysts is 
well known in the art and a representative procedure is described in U.S. 
Pat. No. 3,553,104, the entire contents of which are incorporated by 
reference. 
The iron-containing catalysts are thereafter heated in order to decompose 
the organic iron compound. The temperature utilized is not critical and it 
can range from 115.degree. F. to 1200.degree. F. for periods of time 
ranging from about 1 to 48 hours. 
Another embodiment for catalyst preparation resides in a modification 
involving the in situ formation of the water insoluble organic iron salt. 
In this embodiment, a water-soluble iron salt such as ferrous sulfate or 
iron gluconate is added to an alumina dispersion followed by addition of 
an appropriate organic acid such as oxalic acid in order to form an 
alumina-iron oxalate composition. This composition can be used as the 
source of iron by the addition of the same to the hydrogel-containing 
matrix and crystalline aluminosilicate zeolite followed by processing in 
the manner previously described. 
A particularly desirable embodiment resides in the use of matrices made 
from mixtures of colloidal silica and colloidal alumina instead of 
conventional procedures in which sodium silicate and aluminum sulfate are 
employed. In this embodiment colloidal alumina is added to colloidal 
silica which usually contains a slurry of a weighting agent such as clay. 
Crystalline aluminosilicate zeolite and water-insoluble organic iron salt 
are added followed by homogenizing and spray-drying in the manner 
previously described. 
The acidic crystalline aluminosilicate component of the catalyst is 
characterized by a pore dimension greater than about 5 Angstroms, i.e., it 
is capable of sorbing paraffins, and it has a silica-to-alumina ratio of 
at least 12 and a constraint index within the range of 1 to 12. Zeolite A, 
for example, with a silica-to-alumina ratio of 2.0 is not useful in this 
invention, and it has no pore dimension greater than about 5 Angstroms. 
The crystalline aluminosilicates herein referred to, also known as 
zeolites, constitute an unusual class of natural and synthetic minerals. 
They are characterized by having a rigid crystalline framework structure 
composed of an assembly of silicon and aluminum atoms, each surrounded by 
a tetrahedron of shared oxygen atoms, and a precisely defined pore 
structure. Exchangeable cations are present in the pores. 
The acidic crystalline aluminosilicate component preferably is in the 
hydrogen form. 
The catalysts referred to herein utilize members of a special class of 
zeolites exhibiting some unusual properties. They are very active even 
with silica-to-alumina ratios exceeding 30. This activity is surprising 
since catalytic activity of zeolites is generally attributed to framework 
aluminum atoms and cations associated with these aluminum atoms. These 
zeolites retain their crystallinity for long periods in spite of the 
presence of steam even at high temperatures which induce irreversible 
collapse of the crystal framework of other zeolites, e.g. of the X and A 
type. Furthermore, carbonaceous deposits, when formed, may be removed by 
burning at higher than usual temperatures to restore activity. In many 
environments the zeolites of this class exhibit very low coke forming 
capability, conducive to very long times on stream between burning 
regenerations. 
An important characteristic of the crystal structure of this class of 
zeolites is that it provides constrained access to, and egress from, the 
intra-crystalline free space by virtue of having a pore dimension greater 
than about 5 Angstroms and pore windows of about a size such as would be 
provided by 10-membered rings of oxygen atoms. It is to be understood, of 
course, that these rings are those formed by the regular disposition of 
the tetrahedra making up the anionic framework of the crystalline 
aluminosilicate, the oxygen atoms themselves being bonded to the silicon 
or aluminum atoms at the centers of the tetrahedra. Briefly, the preferred 
zeolites useful in this invention comprise, in combination: a 
silica-to-alumina ratio of at least about 12; and a structure providing 
constrained access to the crystalline free space. 
The silica-to-alumina ratio referred to may be determined by conventional 
analysis. This ratio is meant to represent as closely as possible, the 
ratio in the rigid anionic framework of the zeolite crystal and to exclude 
aluminum in the binder or in cationic or other form within the channels. 
Although zeolites with a silica-to-alumina ratio of at least 12 are 
useful, it is preferred to use zeolites having higher ratios of at least 
about 30. Such zeolites, after activation, acquire an intracrystalline 
sorption capacity for normal hexane which is greater than that for water, 
i.e. they exhibit "hydrophobic" properties. It is believed that this 
hydrophobic characteristic is advantageous in the present invention. 
The zeolites useful as catalysts in this invention freely sorb normal 
hexane and have a pore dimension greater than about 5 Angstroms. In 
addition, there structure must provide constrained access to some larger 
molecules. It is sometimes possible to judge from a known crystal 
structure whether such constrained access exists. For example, if the only 
pore windows in a crystal are formed by 8-membered rings of oxygen atoms, 
then access by molecules of larger cross-section than normal hexane is 
substantially excluded and the zeolite is not of the desired type. 
Zeolites with windows of 10-membered rings are preferred, although 
excessive puckering or pore blockage may render these zeolites 
substantially ineffective. Zeolites with windows of 12-membered rings do 
not generally appear to offer sufficient constraint to produce the 
advantageous conversions desired in the instant invention, although 
structures can be conceived, due to pore blockage or other causes, that 
may be operative. 
Rather than attempt to judge from crystal structure whether or not a 
zeolite possesses the necessary constrained access, a simple determination 
of the "constraint index" may be made by continuously passing a mixture of 
equal weight of normal hexane and 3-methylpentane over a small sample, 
approximately 1 gram or less, of zeolite at atmospheric pressure according 
to the following procedure. A sample of the zeolite, in the form of 
pellets or extrudate, is crushed to a particle size about that of coarse 
sand and mounted in a glass tube. Prior to testing, the zeolite is treated 
with a stream of air at 1,000.degree. F. for at least 15 minutes. The 
zeolite is then flushed with helium and the temperature adjusted between 
550.degree. F. and 950.degree. F. to give an overall conversion between 
10% and 60%. The mixture of hydrocarbons is passed at 1 liquid hourly 
space velocity (i.e. 1 volume of liquid hydrocarbon per volume of catalyst 
per hour) over the zeolite with a helium dilution to give a helium to 
total hydrocarbon mole ratio of 4:1. After 20 minutes on stream, a sample 
of the effluent is taken and analyzed, most conveniently by gas 
chromatography, to determine the fraction remaining unchanged for each of 
the two hydrocarbons. 
The "constraint index" is calculated as follows: 
##EQU1## 
The constraint index approximates the ratio of the cracking rate constants 
for the two hydrocarbons. Catalysts suitable for the present invention are 
those which employ a zeolite having a constraint index from 1.0 to 12.0. 
Constraint Index (CI) values for some typical zeolites including some not 
within the scope of this invention are: 
______________________________________ 
CAS C.I. 
______________________________________ 
Erionite 38 
ZSM-5 8.3 
ZSM-11 8.7 
ZSM-35 6.0 
TMA Offretite 3.7 
ZSM-38 2.0 
ZSM-12 2 
Beta 0.6 
ZSM-4 0.5 
Acid Mordenite 0.5 
REY 0.4 
Amorphous 
silica-alumina 0.6 
______________________________________ 
The above-described Constraint Index is an important and even critical, 
definition of those zeolites which are useful to catalyze the instant 
process. The very nature of this parameter and the recited technique by 
which it is determined, however, admit of the possibility that a given 
zeolite can be tested under somewhat different conditions and thereby have 
different constraint indexes. Constraint index seems to very somewhat with 
severity of operation (conversion). Therefore, it will be appreciated that 
it may be possible to so select test conditions to establish multiple 
constraint indexes for a particular given zeolite which may be both inside 
and outside the above-defined range of 1 to 12. 
Thus, it should be understood that the parameter and property "Constraint 
Index" as such value is used herein as an inclusive rather than exclusive 
value. That is, a zeolite when tested by any combination of conditions 
within the testing definition set forth hereinabove to have a constraint 
index of 1 to 12 is intended to be included in the instant catalyst 
definition regardless that the same indentical zeolite, tested under other 
defined conditions may give a constraint index value outside of 1 to 12. 
The class of zeolites defined herein is exemplified by ZSM-5, ZSM-11, 
ZSM-12, ZSM-35, and ZSM-38, and other similar materials. Recently issued 
U.S. Pat. No. 3,702,886 describing and claiming ZSM-5 is incorporated 
herein by reference. 
ZSM-11 is more particularly described in U.S. Pat. No. 3,709,979, the 
entire contents of which are incorporated herein by reference. 
ZSM-12 is more particularly described in U.S. Pat. No. 3,832,449, the 
entire contents of which are incorporated herein by reference. 
ZSM-35 is described in U.S. Pat. No. 4,016,245 and ZSM-38 is described in 
U.S. Pat. No. 4,046,859, both of which are incorporated herein by 
reference. 
Conversion of syngas is carried out at temperatures ranging from about 
500.degree.-600.degree. F. and more preferably from 550.degree. to about 
580.degree. F. The novel process of this invention is carried out at gas 
hourly space velocities (GHSV), ranging from 400 to 20,000 and more 
desirably from 500 to 6,000, based on fresh feed and total catalyst 
volume. Hydrogen to carbon oxides ratios can vary from 0.5:1 to 2:1 and 
more preferably are about 1:1, pressures ranging from 50 to 1,000 psig and 
more preferably from 150 to 400 psig are employed. 
It is to be understood that although this invention has been described with 
reference to iron only, the catalyst can contain minor amounts of 
additional substances such as tin, phosphorus and tungsten, rare earth, 
vanadium, manganese, molybdenum, etc.

The following examples will illustrate the novel process of this invention. 
EXAMPLE 1 
A fluid catalyst matrix was prepared by adding 10,722 grams Q-Brand sodium 
silicate to a slurry of 930 grams kaolin clay in 112.5 lbs H.sub.2 O. 
After heating to 120.degree. F., 1012 grams of 97% H.sub.2 SO.sub.4 was 
added. At pH 10.51 the gel was heated to 140.degree. F. for two hours and 
a solution of 186.6 grams aluminum sulfate in 746 cc H.sub.2 O was added, 
followed by 166.7 grams of sodium zirconium silicate in 1617 cc H.sub.2 O. 
The pH was adjusted to 4.58 by addition of H.sub.2 SO.sub.4 and left to 
stand overnight. 
EXAMPLE 2 
The catalyst of this example was prepared by filtering one-half of the gel 
matrix prepared in Example 1. The filter cake was slurried with 300 grams 
(NH.sub.4).sub.2 SO.sub.4 in 6 liters of water, filtered again, and washed 
with water until the washings were free of sulfate. The gel was 
homogenized with the addition of 1132 grams of low sodium ZSM-5 zeolite 
(30.6% solid content) in 3400 cc H.sub.2 O and 1204 grams ferrous oxalate 
dihydrate, and the mixture spray dried. An air calcination for 3 hours at 
1000.degree. F. gave the finished catalyst which contained 9.9% iron. 
Other properties are listed below: 
______________________________________ 
PROPERTIES 
OF IRON/ZSM-5 FLUID SYN GAS CATALYSTS 
Composition, Wt. % 
______________________________________ 
SiO.sub.2 73.8 
Al.sub.2 O.sub.3 6.1 
Fe.sub.2 O.sub.3 (Fe) 
14.2 (9.9) 
ZnO.sub.2 .about.1.5 
HZSM-5 .about.30 
______________________________________ 
Composition, Wt. % 
SiO.sub.2 /Al.sub.2 O.sub.3 (zeolite) 
70/1 
Surface Area, m.sup.2 /g 
287 
Particle Density, g/cc 
.575 
Real Density, g/cc 
2.65 
Packed Density, g/cc 
0.35 
Pore Volume, cc/g 
0.91 
TICLE SIZE DISTRIBUTION 
Microns Calculated Wt % 
0-20 2.2 
0-30 4.3 
0-40 9.1 
0-60 28.8 
0-80 56.4 
0-100 79.3 
Mean Diameter 75.6 
Attrition Index 
(0-20) 21.7 
______________________________________ 
EXAMPLE 3 
The mixed silica-alumina sol catalyst was prepared by adding 2000 grams 
Ludox-LS.RTM. silica sol in 1535 cc of water to a clay dispersion 
containing 348.8 grams WP kaolin in 4677 cc H.sub.2 O. An alumina 
dispersion prepared by the addition of 666.7 grams Dispal-M.RTM. alumina 
to 40 grams of 70% nitric acid+6040 cc water was then added to the 
above-prepared silica-clay mixture, followed by 3268 grams of the low 
sodium form of ZSM-5 in 2488 cc H.sub.2 O. Finally, a slurry containing 
1049 grams ferrous oxalate dihydrate in 2489 cc H.sub.2 O was added and 
the mixture was then homogenized and spray-dried. The fluid catalyst was 
heated in nitrogen at ca. 1100.degree. F. for three hours followed by a 
final air calcination for three hours at 1000.degree. F. The finished 
catalyst contained 9.1% iron. Other properties are listed below: 
Table 
______________________________________ 
Composition, wt % 
SiO.sub.2 21 
Al.sub.2 O.sub.3 21 
Clay 11 
HZSM-5 34 
Fe.sub.2 O.sub.3 13 
Real density, g/cc 2.72 
Packed density, g/cc 0.50 
Pore volume, cc/g 0.48 
Zeolite/iron wt ratio 3.8 
Particle size, microns Wt % 
0-20 0.6 
0-30 9.6 
0-40 28.2 
0-60 61.1 
0-80 78.1 
0-100 86.2 
Mean particle diameter 53.0 microns 
______________________________________ 
Examples 4-7 will illustrate the novel process of this invention will 
regard to catalyst activation as well as comparisons with other methods of 
catalyst activation in connection with the syngas conversion. 
In all cases, the catalyst of Example 2 was used and syngas (1:1 H.sub.2 
/CO) was converted at 575.degree. F., 200 psig and 575 GHSV. 
The specific activation treatments as well as the results obtained in 
syngas conversion are shown in the table below. 
Table 
__________________________________________________________________________ 
Example 4 5 6 7 
Stream Days 
0.9 0.9 1.8 1.9 
0 psig 
200 psig 
0 psig Air-950.degree. F- 0 psig 
Treatment, 16Hr 
H.sub.2 -950.degree. F. 
H.sub.2 -950.degree. F. 
H.sub.2 /CO-610.degree. F. 
+ H.sub.2 /CO-610.degree. F. 
CO Conversion, % 
&lt;1 &lt;1 &lt;1 78 (64) 
H.sub.2 Conversion, % 
&lt;1 &lt;1 &lt;1 65 (59) 
Selectivity, % 
C.sub.1 + C.sub.2 
-- -- -- 31 (29) 
C.sub.5 + -- -- -- 50 (54) 
__________________________________________________________________________ 
() indicates fresh catalyst data using standard activation with H.sub.2 
/CO at 610.degree. F. as disclosd in copending application Serial Number 
970,307 filed December 18, 1978 
It is observed that hydrogen treatment either at zero or 200 psig 
completely deactivates the catalyst. Further the standard activation 
procedure of H.sub.2 /CO synthesis gas at 610.degree. F., failed to 
activate the catalyst after exposure to hydrogen. However, an oxygen 
treatment (initial temperature 750.degree. F. in 10% air, final conditions 
16 hr-100% air-950.degree. F.) of this deactivated catalyst followed by 
the standard activation in synthesis gas yielded an active catalyst. 
Comparisons with fresh catalyst show a 14% higher CO conversion (78 vs 
64). 
EXAMPLE 8 
The fixed bed version of the catalyst of Example 2 was evaluated for the 
conversion of syngas (1:1 H.sub.2 /CO) at 575.degree. F., 200 psig, and 
575 GHSV. The fresh air calcined catalyst was activated by treatment with 
1:1 H.sub.2 /CO for 16 hours at 610.degree. F. and 0 psig. The results 
calcined during 5 cycles as presented. Regeneration after cycles 1-3 was 
accomplished by treatment with air for 16 hours at 950.degree. F. and 0 
psig. Regeneration after cycle 4 was accomplished in accordance with the 
instant invention and was as follows: 
(1) air for 16 hours at 950.degree. F., 0 psig 
(2) Hydrogen for 16 hours at 750.degree. F., 0 psig 
(3) Air for 16 hours at 950.degree. F., 0 psig (4) H.sub.2 /CO for 16 hours 
at 610.degree. F., 0 psig 
The results are shown in the following table. 
TABLE 
______________________________________ 
REGENERATION OF CATALYST 
Cycle 1 2 3 4 5 
Fresh 
______________________________________ 
Days on Stream 
1.9 5.9 1.9 5.9 1.9 5.9 1.9 5.9 1.9 5.8 
% Conversion 
CO 64 64 65 65 59 57 51 49 68 71 
H.sub.2 59 58 61 62 60 59 53 58 62 63 
% HC Selectivity 
C.sub.1 + C.sub.2 
29 34 33 37 32 35 31 37 36 38 
C.sub.5 + 54 59 59 58 52 49 52 45 45 44 
% C.sub.5 = in C.sub.5 
13 39 12 30 13 30 14 24 15 21 
Fraction 
% MeC.sub.4 = in C.sub.5 = 
87 82 80 80 79 78 79 76 80 78 
C.sub.6 + Aromatics 
43 21 41 26 44 26 43 35 45 40 
______________________________________ 
As can be seen, the activity for CO conversion dropped from 64 wt.% to 49% 
at the end of cycle 4 when only air regeneration was used. However, the 
regeneration procedure of this invention after cycle 4 resulted in even 
higher activity than the fresh catalyst 71% versus 64%. 
EXAMPLE 9 
The fixed bed version of the catalyst of Example 3 was evaluated for syngas 
conversion using different regeneration techniques. The test conditions as 
well as the results obtained are shown in the following table. 
______________________________________ 
Aging and Regeneration of Catalyst 
(Processing H.sub.2 /CO at 575.degree. F., 200 psig and 1000 GHSV) 
Cycle Fresh 2.sup.(a) 
3.sup.(a) 
4.sup.(b) 
5.sup.(c) 
______________________________________ 
Stream Days 1.9 5.9 1.9 5.9 1.9 3.9 1.8 5.8 0.9 
CO Conversion, % wt 
90 89 91 90 74 65 93 93 88 
H.sub.2 Conversion, % wt 
70 70 70 71 65 61 69 73 68 
HC Selectivity, % wt 
C.sub.1 + C.sub.2 
38 37 40 43 42 41 43 44 44 
C.sub.5 + 44 47 42 39 39 40 38 37 36 
Olefins in C.sub.5 
Fraction, % wt 
15 23 11 17 18 22 16 21 16 
Aromatics in C.sub.6 + , 
% wt 41 25 31 26 31 26 38 30 41 
______________________________________ 
.sup.(a) Regeneration: 2 Hrs, 2% O.sub.2, 750.degree. F., 0 psig. 
.sup.(b) (16 Hr, H.sub.2, 750.degree. F., 0 psig) + (16 Hr, Air, 
950.degree. F., 0 psig) + (16 Hr, H.sub.2 /CO, 610.degree. F., 0 psig) 
##STR1## 
(16 Hr, H.sub.2 /CO, 600.degree. F., 0 psig) 
Following the third cycle the catalyst was subjected to a procedure similar 
to that used in the reactivation of catalyst in Example 8 where the 
sequence was one of air oxidation-hydrogen reduction-air oxidation. In 
this current procedure the initial oxidation was eliminated and the coked 
catalyst was treated in flowing hydrogen for 16 hours at 750.degree. F. 
The air regeneration for 16 hours at 950.degree. F. was followed by the 
standard activation in synthesis gas, H.sub.2 /CO, at 610.degree. F. 
Comparisons with fresh and regenerated catalyst at 1.8 and 5.8 days on 
stream indicate that the activity for carbon monoxide conversion was 
completely restored using this procedure. The C.sub.1 and C.sub.2 yields, 
however, increased slightly while C.sub.5 + yields decreased. Also of 
interest is the conclusion that a coked catalyst need not be air 
regenerated prior to the reduction step. 
After catalyst reactivation total process time was 10.8 days. At this point 
an initial step was taken toward optimizing the regeneration procedure. 
Time (16 hrs) and temperature (750.degree. F.) of hydrogen treatment of 
the used catalyst remained the same; however, air regeneration was 
conducted for one hour in 10% air at 750.degree. F. followed by four 
additional hours in 100% air at 850.degree. F. As is evidenced by the data 
the milder regeneration conditions employed were successful in 
reactivating the catalyst.