Patent Description:
Propylene and butadiene are important chemical raw materials, which are usually obtained from naphtha cracking and steam cracking. The main sources of propylene are co-production of ethylene with propylene and by-product of refinery. The main source of butadiene is the further processing of C4 by-product produced in ethylene cracking process. In recent years, the technologies of methanol to olefin (MTO), methanol to propylene (MTP), ethane dehydrogenation to ethylene and propane dehydrogenation to propylene have been rapidly developed. There is an obvious tendency of raw material lightening in global olefin production, which will lead to the shortage of C4 resources. Therefore, it is necessary to develop a process that can produce propylene and C4 olefins with a high selectivity to meet market demand.

The fixed-bed methanol-to-olefin technology (<CIT>) was developed by LURGI AG in Germany. The technology utilized a ZSM-<NUM> molecular sieve catalyst from Sud-Chemie AG to carry out methanol-to-olefin reaction in a fixed-bed reactor. The selectivity of propylene was close to <NUM>%, and the by-products were ethylene, liquefied petroleum gas and gasoline.

The DMTO technology developed by Dalian Institute of Chemical Physics used a SAPO molecular sieve as catalyst, a dense-phase circulating fluidized-bed reactor and a methanol aqueous solution as raw material. The yield of ethylene and propylene in the product was about <NUM>%, and more than <NUM>% of C4 hydrocarbons were yielded as by-products.

Patent <CIT> discloses a method of preparing propylene and C4 hydrocarbons from methanol in a circulating fluidized-bed using a ZSM-<NUM> catalyst. The process features are that the raw material methanol and most of C1, C2 and C5 hydrocarbons in the product are entered into the circulating fluidized-bed reactor together, and propylene, C4 hydrocarbons, hydrocarbons of C6 and above and by-products are retrieved as final products.

Patent <CIT> discloses a method for preparing olefins from methanol or dimethyl ether. The method includes the conversion of methanol or dimethyl ether, the alkylation of ethylene and methanol, and the catalytic cracking of components heavier than C4. Catalyst <NUM> is used for the methanol or dimethyl ether conversion and the ethylene and methanol alkylation in one reactor, and catalyst <NUM> is used for the catalytic cracking of components heavier than C4 in another reactor.

The methods disclosed in patents <CIT> and <CIT> share a common feature, that is, the selectivity of target products (propylene and C4) is increased through the recycling of light fractions (hydrocarbons with a carbon number of no more than <NUM>). The alkylation of ethylene with methanol is the main reaction in the recycling reaction of the light fractions mentioned above.

The acidic molecular sieve catalysts can be used in both MTO reaction and alkylation of olefins. However, the rate of the MTO reaction is much higher than that of the alkylation of olefins. We have found that a fresh SAPO catalyst has a high activity, which is more beneficial to the alkylation of olefins. After a carbon deposition of catalyst, the reaction rate of alkylation of olefins will decrease rapidly.

Methanol is not only the raw material for the alkylation of olefins, but also the raw material for the MTO reaction. Therefore, the alkylation of olefins is necessarily accompanied by the MTO reaction. The MTO reaction will lead to a carbon deposition and lower activity of catalyst, which will hence inhibit the alkylation of olefins. An increase in the alkylation rate of olefins can reduce the content of light fractions in the product gas, and thus the unit volume production capacity of the reactor can be increased.

The methods disclosed in patents <CIT> and <CIT> do not refer to the reactor structure, nor do they clarify the flow modes of catalyst and raw material and the raw material distribution in the reactor. The method disclosed in patent <CIT> uses a SAPO catalyst. The examples show that the mass ratio of methanol to light fractions is <NUM>:<NUM>-<NUM>. Thus, it can be seen that the content of light fractions is very high and the unit volume production capacity of reactor is very low. A ZSM-<NUM> catalyst is used in the method disclosed in patent <CIT>. The content of hydrocarbons of C6 and above in the product is relatively high. The content of light fractions in the product gas is not disclosed in this method.

From the above analysis, it can be seen that the main reactions for the preparation of propylene and C4 hydrocarbons from methanol are the MTO reaction and the alkylation of olefins. Therefore, the key to improve the selectivity of propylene and C4 hydrocarbons lies in a catalyst design and a reactor design. Avoiding the inhibition of the MTO reaction to the alkylation of olefins through an optimization in the reactor design is one of the important methods to improve the economics of methanol to propylene and C4 hydrocarbons. <CIT> discloses a fluidised-bed reactor for producing methanol.

In view of the problem of low reaction rate of ethylene alkylation, the present invention provides a new method and device for increasing the reaction rate of ethylene alkylation in the process of preparing propylene and C4 hydrocarbons from methanol. Being used in the production of propylene and C4 hydrocarbons from oxygen-containing compounds, the method has the advantages of high yield of propylene and C4 hydrocarbons and good process economics.

To achieve the above purposes, one aspect of the present invention as indicated in claim <NUM> provides a turbulent fluidized-bed reactor - for preparing propylene and C4 hydrocarbons from oxygen-containing compounds. The turbulent fluidized-bed reactor comprises a reactor shell (<NUM>), n reactor feed distributors (<NUM>-<NUM>-<NUM>-n), a reactor gas-solid separator <NUM> (<NUM>), a reactor gas-solid separator <NUM> (<NUM>), a reactor heat extractor (<NUM>), a product gas outlet (<NUM>) and a reactor stripper (<NUM>), wherein the lower part of the turbulent fluidized-bed reactor (<NUM>) is a reaction zone, the upper part of the turbulent fluidized-bed reactor (<NUM>) is a settling zone, the n reactor feed distributors (<NUM>-<NUM>~<NUM>-n) are disposed in the reaction zone from bottom to top, the reactor heat extractor (<NUM>) is disposed in the reaction zone, the reactor gas-solid separator <NUM> (<NUM>) and the reactor gas-solid separator <NUM> (<NUM>) are placed in the settling zone or outside the reactor shell (<NUM>), the reactor gas-solid separator <NUM> (<NUM>) is equipped with a regenerated catalyst inlet, the catalyst outlet of the reactor gas-solid separator <NUM> (<NUM>) is located at the bottom of the reaction zone, the gas outlet of the reactor gas-solid separator <NUM> (<NUM>) is located in the settling zone, the inlet of the reactor gas-solid separator <NUM> (<NUM>) is located in the settling zone, the catalyst outlet of the reactor gas-solid separator <NUM> (<NUM>) is placed in the reaction zone, the gas outlet of the reactor gas-solid separator <NUM> (<NUM>) is connected to the product gas outlet (<NUM>), the reactor stripper (<NUM>) passes through the reactor shell from outside to inside at the bottom of the turbulent fluidized-bed reactor and is opened in the reaction zone of the turbulent fluidized-bed reactor (<NUM>), a reactor stripping gas inlet (<NUM>) is arranged at the bottom of the reactor stripper (<NUM>), and a spent catalyst outlet is arranged at the bottom of the reactor stripper.

The n reactor feed distributors (<NUM>-<NUM>∼<NUM>-n) of the turbulent fluidized-bed reactor (<NUM>) are disposed in the reaction zone from bottom to top, and <NUM><n<<NUM>.

In a preferred embodiment, the horizontal height of opening of the reactor stripper (<NUM>) in the reactor shell (<NUM>) is higher than <NUM>/<NUM> the height of the reaction zone, so as to avoid the direct entry of fresh catalyst into the reactor stripper.

In a preferred embodiment, the reactor gas-solid separator <NUM> (<NUM>) and the reactor gas-solid separator <NUM> (<NUM>) are cyclone separators.

The present invention further provides a device for preparing propylene and C4 hydrocarbons from oxygen-containing compounds, comprising the turbulent fluidized-bed reactor (<NUM>) described above and a fluidized-bed regenerator (<NUM>) for regenerating a catalyst.

In a preferred embodiment, the fluidized-bed regenerator (<NUM>) is a turbulent fluidized-bed regenerator.

In a preferred embodiment, the fluidized-bed regenerator (<NUM>) comprises a regenerator shell (<NUM>), a regenerator feed distributor (<NUM>), a regenerator gas-solid separator (<NUM>), a regenerator heat extractor (<NUM>), a flue gas outlet (<NUM>) and a regenerator stripper (<NUM>), wherein the lower part of the fluidized-bed regenerator (<NUM>) is a regeneration zone, the upper part of the fluidized-bed regenerator (<NUM>) is a settling zone, the regenerator feed distributor (<NUM>) is placed at the bottom of the regeneration zone, the regenerator heat extractor (<NUM>) is placed in the regeneration zone, the regenerator gas-solid separator (<NUM>) is placed in the settling zone or outside the regenerator shell (<NUM>), the inlet of the regenerator gas-solid separator (<NUM>) is disposed in the settling zone, the catalyst outlet of the regenerator gas-solid separator (<NUM>) is disposed in the regeneration zone, the gas outlet of the regenerator gas-solid separator (<NUM>) is connected to the flue gas outlet (<NUM>), and the inlet of the regenerator stripper (<NUM>) is connected to the bottom of the regenerator shell (<NUM>);.

Another aspect of the present invention provides a method for preparing propylene and C4 hydrocarbons from oxygen-containing compounds, including:.

In a preferred embodiment, the method described in the present invention is carried out using the above-mentioned device for preparing propylene and C4 hydrocarbons from oxygen-containing compounds.

In a preferred embodiment, the spent catalyst passes through the reactor stripper (<NUM>), the inclined spent catalyst pipe (<NUM>), the spent catalyst sliding valve (<NUM>) and the spent catalyst lift pipe (<NUM>) into the settling zone of the fluidized-bed regenerator (<NUM>);.

The main characteristics of the turbulent fluidized-bed reactor in the present invention are that the light fractions enter from the reactor feed distributor at the bottom-most, the oxygen-containing compound enters from n reactor feed distributors respectively, and the regenerated catalyst directly enters the bottom of the reaction zone. On one hand, in the lower part of the reaction zone, the catalyst has a high activity, which is advantageous to the alkylation of ethylene, propylene and methanol; on the other hand, because of the multi-stage feeding of the oxygen-containing compounds, the case where most of the conversion reactions of the oxygen-containing compounds are completed in a small region of the lower part of the reaction zone is avoided, so that the concentration of the oxygen-containing compounds is more uniform in most of the reaction zone, weakening the inhibition of MTO reaction to the alkylation of olefins. Therefore, the turbulent fluidized-bed reactor in the present invention can effectively improve the alkylation reaction rate of olefins, and the unit volume production capacity of the reactor is high.

In the method for preparing propylene and C4 hydrocarbons from oxygen-containing compounds of the present invention, the MTO reaction produces ethylene, propylene, and the like, and the alkylation of olefins consumes ethylene, propylene, and the like. Since the reaction rate of ethylene alkylation is high, the content of light fractions in the product gas is low, and the circulating amount of the light fractions is low. In the method of the present invention, the circulating amount of the light fractions is <NUM>-<NUM> wt. % of the feeding amount of the oxygen-containing compound.

In the method of the present invention, <NUM> wt. % or more of the light fractions are circulated in the system, and the release rate of the light fractions affects the composition of the product gas in the equilibrium state. In the equilibrium state, the product gas consists of <NUM>-<NUM> wt. % propylene, <NUM>-<NUM> wt. % C4 hydrocarbons, <NUM>-<NUM> wt. % light fractions, <NUM>-<NUM> wt. % propane and <NUM>-<NUM> wt. % hydrocarbons with <NUM> or more carbons. The light fractions contain more than <NUM> wt. %, e.g. ><NUM> wt. % ethylene, and other components include methane, ethane, hydrogen, CO and CO<NUM>.

In a preferred embodiment, the catalyst contains a SAPO molecular sieve, and the catalyst simultaneously has the functions of catalyzing methanol to olefins and alkylation of olefins.

In a preferred embodiment, the carbon content of the regenerated catalyst is less than <NUM> wt. %, and further preferably, the carbon content of the regenerated catalyst is less than <NUM> wt.

In a preferred embodiment, the carbon content of the spent catalyst is <NUM>-<NUM> wt. %, and further preferably, the carbon content of the spent catalyst is <NUM>-<NUM> wt.

In a preferred embodiment, the reaction conditions in the reaction zone of the turbulent fluidized-bed reactor (<NUM>) are as follows: the apparent linear velocity of gas is in a range from <NUM>/s to <NUM>/s, the reaction temperature is in a range from <NUM>□ to <NUM>□, the reaction pressure is in a range from <NUM> kPa to <NUM> kPa, and the bed density is in a range from <NUM>/m<NUM> to <NUM>/m<NUM>.

In a preferred embodiment, the reaction conditions in the regeneration zone of the fluidized-bed regenerator (<NUM>) are as follows: the apparent linear velocity of gas is in a range from <NUM>/s to <NUM>/s, the regeneration temperature is in a range from <NUM> to <NUM>, the regeneration pressure is in a range from <NUM> kPa to <NUM> kPa, and the bed density is in a range from <NUM>/m<NUM> to <NUM>/m<NUM>.

In a preferred embodiment, the oxygen-containing compound is methanol and/or dimethyl ether; the regeneration medium is any one of air, oxygen-poor air or water vapor or a mixture thereof; the reactor stripping gas, the regenerator stripping gas, the spent catalyst lifting gas and the regenerated catalyst lifting gas are water vapor or nitrogen.

<FIG> is a schematic diagram of a device for preparing propylene and C4 hydrocarbons from oxygen-containing compounds according to an embodiment of the present invention.

The reference numerals in the figure are listed as follows:
<NUM>- turbulent fluidized-bed reactor; <NUM>- reactor shell; <NUM>- reactor feed distributors (<NUM>-<NUM>~<NUM>-n); <NUM>- reactor gas-solid separator <NUM>; <NUM>- reactor gas-solid separator <NUM>; <NUM>- reactor heat extractor; <NUM>- product gas outlet; <NUM>- reactor stripper; <NUM>- reactor stripping gas inlet; <NUM>- inclined spent catalyst pipe; <NUM>- spent catalyst sliding valve; <NUM>- spent catalyst lift pipe; <NUM>- spent catalyst lifting gas inlet; <NUM>- fluidized-bed regenerator; <NUM>- regenerator shell; <NUM>-regenerator feed distributor; <NUM>- regenerator gas-solid separator; <NUM>- regenerator heat extractor; <NUM>- flue gas outlet; <NUM>- regenerator stripper; <NUM>- regenerator stripping gas inlet; <NUM>- inclined regenerated catalyst pipe; <NUM>-regenerated catalyst sliding valve; <NUM>- regenerated catalyst lift pipe; <NUM>- regenerated catalyst lifting gas inlet.

In a specific embodiment, the schematic diagram of the device according to the present invention for preparing propylene and C4 hydrocarbons from oxygen-containing compounds is shown in <FIG>, which comprises:.

In the above embodiment, the fluidized-bed regenerator (<NUM>) may be a turbulent fluidized-bed regenerator; the reactor gas-solid separator <NUM> (<NUM>), the reactor gas-solid separator <NUM> (<NUM>) and the regenerator gas-solid separator (<NUM>) may be cyclone separators.

In a specific embodiment, the method according to the present invention for preparing propylene and C4 hydrocarbons from oxygen-containing compounds includes the following steps:.

In order to better illustrate the present invention and facilitate the understanding of the technical scheme of the present invention, comparative examples and representative but non-restrictive examples of the present invention are listed as follows:.

The present example is a comparative example. The device shown in <FIG> is used, but the turbulent fluidized-bed reactor (<NUM>) does not contain the reactor gas-solid separator <NUM> (<NUM>), and the regenerated catalyst lift pipe (<NUM>) is directly connected to the settling zone of the turbulent fluidized-bed reactor (<NUM>).

The turbulent fluidized-bed reactor (<NUM>) contains three reactor feed distributors (<NUM>-<NUM>∼<NUM>-<NUM>), the reactor gas-solid separator <NUM> (<NUM>) is placed outside the reactor shell (<NUM>), and the horizontal height of the inlet of the reactor stripper (<NUM>) is at <NUM>/<NUM> height of the reaction zone. The reaction conditions in the reaction zone of the turbulent fluidized-bed reactor (<NUM>) are as follows: the apparent linear velocity of gas is about <NUM>/s, the reaction temperature is about <NUM>, the reaction pressure is about <NUM> kPa, and the bed density is about <NUM>/m<NUM>.

The reaction conditions in the regeneration zone of the fluidized-bed regenerator (<NUM>) are as follows: the apparent linear velocity of gas is about <NUM>/s, the regeneration temperature is about <NUM> □, the regeneration pressure is about <NUM> kPa, and the bed density is about <NUM>/m<NUM>.

The catalyst contains a SAPO molecular sieve. The carbon content of the spent catalyst is about <NUM>%, and the carbon content of the regenerated catalyst is about <NUM> wt.

The oxygen-containing compound is methanol, and the regeneration medium is air; the reactor stripping gas, the regenerator stripping gas, the spent catalyst lifting gas and the regenerated catalyst lifting gas are water vapor.

The circulating amount of the light fractions is <NUM> wt. % of the feeding amount of methanol, and <NUM> wt. % of the light fractions are circulated in the system.

The composition of the product gas discharged from the turbulent fluidized-bed reactor (<NUM>) is: <NUM> wt. % propylene, <NUM> wt. % C4 hydrocarbons, <NUM> wt. % light fractions, <NUM> wt. % propane and <NUM> wt. % hydrocarbons with <NUM> or more carbons. The light fractions contain <NUM> wt. % ethylene and <NUM> wt. % methane, ethane, hydrogen, CO, CO<NUM>, and the like.

The composition of the product gas discharged from the separation system is: <NUM> wt. % propylene, <NUM> wt. % C4 hydrocarbons, <NUM> wt. % light fractions, <NUM> wt. % propane and <NUM> wt. % hydrocarbons with <NUM> or more carbons.

The device shown in <FIG> is used. The turbulent fluidized-bed reactor (<NUM>) contains three reactor feed distributors (<NUM>-<NUM>∼<NUM>-<NUM>), the reactor gas-solid separator <NUM> (<NUM>) is placed outside the reactor shell (<NUM>), and the horizontal height of the inlet of the reactor stripper (<NUM>) is at <NUM>/<NUM> height of the reaction zone. The reaction conditions in the reaction zone of the turbulent fluidized-bed reactor (<NUM>) are as follows: the apparent linear velocity of gas is about <NUM>/s, the reaction temperature is about <NUM>□, the reaction pressure is about <NUM> kPa, and the bed density is about <NUM>/m<NUM>.

The present example is different from Example <NUM> (comparative example) merely in that the regenerated catalyst enters the bottom of the turbulent fluidized-bed reactor and contacts firstly with the light fractions, while in Example <NUM>, the regenerated catalyst enters the settling zone of the turbulent fluidized-bed reactor. Comparing the present example with Example <NUM>, it can be seen that the conversion rate of light fractions can be greatly improved when the catalyst is contacted firstly with the light fractions. The light fractions discharged from the separation system in present example is only <NUM>% of that in the comparative example. Therefore, the device of the present invention effectively improves the reaction rate of ethylene alkylation.

The device shown in <FIG> is used. The turbulent fluidized-bed reactor (<NUM>) contains four reactor feed distributors (<NUM>-<NUM>~<NUM>-<NUM>), the reactor gas-solid separator <NUM> (<NUM>) is placed in the settling zone, and the horizontal height of the inlet of the reactor stripper (<NUM>) is at <NUM>/<NUM> height of the reaction zone. The reaction conditions in the reaction zone of the turbulent fluidized-bed reactor (<NUM>) are as follows: the apparent linear velocity of gas is about <NUM>/s, the reaction temperature is about <NUM>□, the reaction pressure is about <NUM> kPa, and the bed density is about <NUM>/m<NUM>.

The device shown in <FIG> is used. The turbulent fluidized-bed reactor (<NUM>) contains six reactor feed distributors (<NUM>-<NUM>~<NUM>-<NUM>), the reactor gas-solid separator <NUM> (<NUM>) is placed in the settling zone, and the horizontal height of the inlet of the reactor stripper (<NUM>) is at <NUM>/<NUM> height of the reaction zone. The reaction conditions in the reaction zone of the turbulent fluidized-bed reactor (<NUM>) are as follows: the apparent linear velocity of gas is about <NUM>/s, the reaction temperature is about <NUM> □, the reaction pressure is about <NUM> kPa, and the bed density is about <NUM>/m<NUM>.

The oxygen-containing compound is dimethyl ether, and the regeneration medium is oxygen-poor air; the reactor stripping gas, the regenerator stripping gas, the spent catalyst lifting gas and the regenerated catalyst lifting gas are nitrogen.

The circulating amount of the light fractions is <NUM> wt. % of the feeding amount of dimethyl ether, and <NUM> wt. % of the light fractions are circulated in the system.

Claim 1:
A turbulent fluidized-bed reactor for preparing propylene and C4 hydrocarbons from oxygen-containing compounds, comprising a reactor shell, n reactor feed distributors, a first reactor gas-solid separator, a second reactor gas-solid separator, a reactor heat extractor, a product gas outlet and a reactor stripper, wherein the lower part of the turbulent fluidized-bed reactor is a reaction zone, the upper part of the turbulent fluidized-bed reactor is a settling zone, the n reactor feed distributors are disposed in the reaction zone, the reactor heat extractor is disposed in the reaction zone, the first reactor gas-solid separator and the second reactor gas-solid separator are placed in the settling zone or outside the reactor shell, the first reactor gas-solid separator is equipped with a regenerated catalyst inlet, the catalyst outlet of the first reactor gas-solid separator is located at the bottom of the reaction zone, the gas outlet of the first reactor gas-solid separator is located in the settling zone, the inlet of the second reactor gas-solid separator is located in the settling zone, the catalyst outlet of the second reactor gas-solid separator is placed in the reaction zone, the gas outlet of the second reactor gas-solid separator is connected to the product gas outlet, the reactor stripper passes through the reactor shell from outside to inside at the bottom of the turbulent fluidized-bed reactor and is opened in the reaction zone of the turbulent fluidized-bed reactor, a reactor stripping gas inlet is arranged at the bottom of the reactor stripper, and a spent catalyst outlet is arranged at the bottom of the reactor stripper;
wherein the n reactor feed distributors are disposed in the reaction zone from bottom to top, and <NUM><n<<NUM>.