WO2009055996A1

WO2009055996A1 - A process for producing propylene

Info

Publication number: WO2009055996A1
Application number: PCT/CN2008/000491
Authority: WO
Inventors: Yue Qi; Zhongmin Liu; Jinzhe Li; Zhihui Lv; Lixin Yang; Peng Tian; Bing Li; Cuiyu Yuan
Original assignee: Dalian Institute Of Chemical Physics, Chinese Academy Of Sciences
Priority date: 2007-10-31
Filing date: 2008-03-12
Publication date: 2009-05-07
Also published as: CN101367699B; CN101367699A

Abstract

Disclosed is a process for producing propylene, which places at least two reaction zones and comprises the following steps: a) catalytically cracking C4 or higher hydrocarbons in the presence of a solid acidic catalyst to produce hydrocarbons products comprising ethylene and propylene in the first reaction zone; b) reacting methanol and/or dimethyl ether with gas containing ethylene in the presence of a solid acidic catalyst to produce products comprising propylene and higher hydrocarbons in the second reaction zone; c) using at least a portion of ethylene from the products of the first reaction zone as raw materials of the second reaction zone, and using at least a portion of C4 or higher hydrocarbons from the products of the second reaction zone as raw materials of the first reaction zone.

Description

Method for preparing propylene

Technical field

The present invention relates to a process for producing propylene. Background technique.

Propylene is an important basic raw material for petrochemicals. The source of propylene has long been dependent on ethylene cracking units and FCC units. As the propylene growth rate continues to exceed the ethylene growth rate, people continue to improve the traditional propylene production process to further increase propylene yield. Increasing propylene production on existing plants is limited by raw material composition, plant handling capacity, plant modification and operating costs, so the development of new propylene-producing processes is an important direction to meet the growing demand for propylene. In recent years, new processes have been developed to produce propylene from different raw materials, such as propylene dehydrogenation to propylene, ethylene and butenes to disproportionate propylene, high carbon number cracking to lower olefins, and methanol to olefins (MTO). Methanol to propylene (MTP), ethylene and an alkylating agent are co-fed to produce terpene.

High-carbon olefins, especially high-carbon olefin materials containing more olefins (such as FCC gasoline and mixed C4), which are converted into propylene-based low-carbon olefins by catalytic cracking, have received extensive attention in recent years. A new process with commercial potential. The advantage of this conversion process is that the types of raw materials that can be utilized are abundant, the value is low, and the ratio of propylene/ethylene in the product is high, and the whole process has good economy. A number of patents have published methods for the production of propylene by catalytic conversion of high carbon number olefins.

US Patent 6,222,087 B1 discloses a process for converting a feedstock containing C4-C7 olefins and alkanes to a lower olefin, the catalyst being a P-modified ZSM-5 or/and ZSM-11 molecular sieve having a silica-alumina ratio of greater than 300 . The dense phase fluidized bed process is carried out under the conditions of a temperature of 510-704 ° C, a reaction pressure of between 8 bar and a WHSV of between l and Ohr. The yield of low carbon olefins is higher than 20%, up to 30%, and the ratio of propylene/ethylene can be over 3.0.

EP 0109059 discloses a process for the conversion of C4-C12 olefins to propylene. The catalyst used is a ZSM-5 or a ZSM-11 molecular sieve having a silica to alumina ratio of less than or equal to 300, a WHSV of more than 50 h, and a reaction temperature of 400 to 600 °C. The total yield of ethylene and propylene is 36-44%, and the yield of propylene is 30-40%.

US Patent 5,171,921 and EP0511013 A3 disclose a technique for converting high carbon number mixed hydrocarbons (containing olefins and alkanes) to lower olefins at a reaction temperature of 500-700 ° C, WHSV between ΙΟ-100 hr· ¹ , catalyst It contains ZSM-5 with a silica-alumina ratio of 20-60 and is subjected to P modification and steam aging treatment. U.S. Patent 5,981,819 discloses a technique for converting a material containing a C4-C7 olefin to propylene. The reaction material is mixed with water vapor into a fixed bed reactor to contact with the molecular sieve catalyst, and the feed water/oil ratio is

0.5:1-3:1, the reaction temperature is 380-500'C. The molecular sieve has a Si/Al atomic ratio of 10-200. More than 60% of the olefins in the feed are converted to propylene and butene. WO 01/05909 A1 discloses a process similar to that described above for converting a C4-C8 olefin containing material to a lower olefin.

U.S. Patent 2003/0139636 A1 discloses a process for the conversion of olefin-containing materials to propylene. The catalysts used were rare earth or metal modified SAPO, MeAPO, MeASPO, ELAPO and ELASPO.

CN 1600757 discloses a process for the production of light olefins, in particular propylene, from a hydrocarbon feedstock containing C4-C6 olefins, which is contacted with a ZSM-5/ZSM-11 zeolite catalyst having a modified silica-alumina ratio of greater than 30. In order to produce a light olefin effluent, the selectivity of the light olefin is above 60%, the yield is 40-55%, and the reaction conditions are a temperature of 500-650 ° C, a space velocity of 1-50, and a pressure of 0.1-8 atm.

CN 1490288 discloses a process for the catalytic cracking of propylene to produce propylene from C4 and above, which mainly solves the problems of low selectivity, low yield and poor catalyst stability of propylene in the target product existing in the prior art. The catalyst used was ZSM-5 with a silica to alumina ratio of 50-1000, and a certain amount of sodium halide was added during the crystallization of the molecular sieve. The reaction conditions are a temperature of 400-600 ° C, a liquid space velocity of 10-50 hr-l, and a pressure of 0-0.15 MPa.

Another new process for the production of propylene with good application prospects is to co-feed ethylene with a thiolation reagent (such as methanol or / and dimethyl ether) to generate a thiolation reaction on the catalyst to form propylene. Hydrocarbon products within.

Studies have found that olefins can react with methanol to increase the carbon number of olefins (Svelle et al, J. Catal. 224 (2004), 115-123, J. Catal. 234 (2005), 385-400. ):

CHjOH + C _n H _2n = C _n +lH _2n+2 +H ₂ 0

The above types of alkylation reactions can also occur between sulfhydrylating agents such as olefins or / and dimethyl ether. In particular, the reaction of ethylene with an alkylating agent produces propylene. This type of reaction provides a new way to produce propylene. The advantage of this approach is that one carbon atom that produces propylene is derived from relatively inexpensive methanol or / and dimethyl ether, reducing the cost of propylene production. If low-value ethylene raw materials such as catalytic cracking dry gas are used, the economics of the method can be further improved.

U.S. Patent No. 3,906,054 discloses a process for the alkylation of olefins by contacting an olefin with a catalyst in the presence of a guanidation reagent having a silica to alumina ratio of at least 12 and having a P content of at least 0.78%. The olefins which can be alkylated include ethylene, propylene, butene-2 and isobutylene, and useful thiolation reagents are methanol, dimethyl ether and chloroformamidine.

World Patent WO 2005/056504 A1 discloses a high efficiency system starting from ethylene and methanol or/and dimethyl ether. In the case of propylene, ethylene and methanol or/and dimethyl ether are reacted in the presence of a catalyst to form propylene. It is characterized in that the amount of ethylene flowing out of the reaction system is less than the amount of ethylene added to the reaction system. At the same time, the propylene yield can be up to 40 mol% or more based on the number of moles of methanol entering the reaction system or twice the number of moles of dimethyl ether.

Chinese Patent Application No. 200610112555.0 discloses a process for preparing propylene, which is characterized in that: a raw material containing ethylene is in the presence of a methylating agent under a specific reaction condition and a molecular sieve having a micropore diameter of 0.3-0.5 nm. The catalyst contacts to form a product containing propylene. The propylene selectivity in the product can reach more than 70%.

Both of the above methods produce other by-products while generating propylene. The process of cracking high-carbon hydrocarbons to produce low-carbon olefins produces more ethylene by-products. The separation and purification of ethylene can only rely on cryogenic equipment, involving huge construction investment, thereby greatly reducing the economics of the entire process. Alkylation reagents such as ethylene with methanol or/and dimethyl ether can be alkylated on the surface of the acidic catalyst to produce propylene. However, other reactions can also occur on the same catalyst. For example, the product propylene can also be used with hydrazine. group of reagent to generate butene, similarly, can be further generated butene and alkyl with the generation of C ₅ or more hydrocarbon reagent; generating a number of these higher hydrocarbons in the economics of the process poor. Summary of the invention

It is an object of the present invention to provide a process for producing propylene.

In order to achieve the above object, the present invention provides a method for producing propylene, characterized in that at least two reaction zones are provided, including:

a) in the first reaction zone, a hydrocarbon having a carbon number of not less than 4 undergoes a catalytic cracking reaction on a solid acidic catalyst, and is converted into a hydrocarbon product including ethylene and propylene;

b) in the second reaction zone, methanol (or / and dimethyl ether) and a gas containing ethylene are reacted on a solid acidic catalyst to be converted to a product containing propylene and a higher carbon number hydrocarbon;

c) at least a portion of the ethylene in the product of the first reaction zone is used as a feedstock for the second reaction zone, and at least a portion of the hydrocarbons having a carbon number of not less than 4 are used as a feedstock for the first reaction zone;

The reaction condition of the first reaction zone is: the reaction temperature is 350-750 ° C, the preferred reaction temperature is 400-700 ° C, the reaction pressure is 0.01-0.8 MPa, and the preferred reaction pressure is 0.1-0.45 MPa; .

The reaction conditions of the second reaction zone are: the reaction temperature is 300-600 ° C, the preferred reaction temperature is 350-550 ° C, the reaction pressure is 0.01-0.8 MPa, and the lower reaction pressure is 0.1-0.45 MPa. The molar ratio of ethylene/methanol or ethylene/2 times dimethyl ether is 0.05-5, and the preferred molar ratio is 0.1-5. The method, wherein the solid acidic catalyst is a product obtained by modifying at least one silica-alumina molecular sieve or silicoaluminophosphate molecular sieve having acidity, or modifying the molecular sieve according to the above-mentioned characteristic molecular sieve element, or a plurality of A mixture of molecular sieves characterized.

The method, wherein the solid acidic catalyst has a molecular sieve content of 10% by weight to 90% by weight.

The method wherein the solid acid catalyst is formed by one or more of a binder comprising silica, alumina or clay.

The method wherein the reactor forms of the first reaction zone and the second reaction zone each employ a fluidized bed.

The method, wherein the hydrocarbon having a carbon number of not less than 4 is liquefied gas, naphtha, gasoline, condensate, light diesel oil, hydrogenated tail oil or kerosene, or the carbon number in the conversion process of claim 1. A hydrocarbon product of less than 4.

The method wherein the ethylene-containing gas in the second reaction zone is ethylene derived from a process of hydrocarbon cracking, acetonitrile dehydrogenation or methanol conversion to olefins, or ethylene and C1-C3 hydrocarbons or carbon from the above process. A mixture of oxides or a product containing a olefin in the conversion process of claim 1.

The method, wherein the hydrocarbons having a carbon number of not less than 4 in the first reaction zone or/and ethylene in the second reaction zone are respectively derived from the products in the conversion process of claim 1. detailed description

According to the present invention, two different conversion processes of propylene as a target product, namely, high-carbon hydrocarbon catalytic cracking to propylene and ethylene and methanol (or / and dimethyl ether) co-feed to produce propylene, combined, each will At least a part of the by-products obtained by the process are used as raw materials for the other process, and the by-products obtained in the two processes are fully utilized, the utilization of the raw materials is improved, and finally the propylene product is obtained with high selectivity. The advantage of this method is that the two processes can share certain equipment. For example, although the reaction conversion process can be carried out in different reactors or reaction zones, the product separation can be carried out in the same set of separation systems, and the process Most of the ethylene produced in the process is further converted to propylene, and the yield of ethylene in the final product is very low, and it is not necessary to carry out recovery and refining, and it is not necessary to construct a cryogenic separation device. This can save a lot of investment, reduce energy consumption, and improve the economics of the entire process.

According to the present invention, at least two reaction zones are provided, including: a) in the first reaction zone, a hydrocarbon having a carbon number of not less than 4 undergoes a catalytic cracking reaction on a solid acidic catalyst, and is converted into a hydrocarbon product including ethylene and propylene. b) In the second reaction zone, methanol (or / and dimethyl ether) and a gas containing ethylene are reacted on a solid acidic catalyst to convert to a product containing propylene and higher carbon number hydrocarbons; c) the first reaction Among the products of the zone, at least a part of ethylene is used as a raw material of the second reaction zone, and at least a part of the hydrocarbons having a carbon number of not less than 4 in the product of the second reaction zone is used as a raw material of the first reaction zone. In the method, the catalyst comprises at least one silica-alumina molecular sieve or silicoaluminophosphate molecular sieve having acidity, or a product obtained by modifying the molecular sieve of the above characteristic molecular sieve element, or a plurality of molecular sieves satisfying the above characteristics. mixture.

In the process described, the molecular sieve content of the catalyst may range from 10% by weight to 90% by weight.

In the method described, the catalyst may be formed by one or more of binders including silica, alumina or clay.

In the process described, both the first reaction zone and the second reaction zone may be in the form of a fluidized bed. In the method, the hydrocarbon having a carbon number of not less than 4 in the first reaction zone may be liquefied gas, naphtha, gasoline, condensate, light diesel oil, hydrogenated tail oil or kerosene, or the conversion process of the present invention. A hydrocarbon product having a carbon number of not less than 4.

In the method, the gas containing ethylene in the second reaction zone may be ethylene derived from a process such as hydrocarbon cracking, ethane dehydrogenation or methanol conversion to olefins, or ethylene and C1-C3 hydrocarbons from the above process. Or a mixture of carbon oxides, or a product containing ethylene during the conversion of the present invention.

In the process, the hydrocarbons having a carbon number of not less than 4 in the first reaction zone or / and ethylene of the second reaction zone are respectively derived from the product of the conversion process of the present invention.

In the method, the reaction condition of the first reaction zone may be: the reaction temperature is 350-750 ° C, preferably 400-700 ° C, and the reaction pressure is 0.01-0.8 MPa, preferably 0.1. -0.45 MPa.

In the method, the reaction conditions of the second reaction zone may be: a reaction temperature of 300 to 600 ° C, preferably 350 to 550. C, the reaction pressure is 0.01-0.8 MPa, preferably 0.1-0.45 MPa, and the ethylene/methanol (or 2 times dimethyl ether) molar ratio is 0.05-10, preferably 0.1-5;

The invention is described in detail below by means of examples, but the invention is not limited to the examples.

Example 1

Catalyst A: ZSM-5 molecular sieve (Fushun Petrochemical Company catalyst plant), mixed with clay, aluminum sol and silica sol (both purchased from Zhejiang Yuda Chemical Co., Ltd.) and dispersed into slurry in water, spray-formed into particle size Microspheres distributed in the range of 20-100 microns. The above microspheres were calcined at 600 Torr for 4 hours and then heated at 800 ° C for 10 hours under a steam atmosphere to obtain catalyst A. The ZSM-5 content in the catalyst was 30% by weight.

The butene catalytic cracking reaction is carried out in a micro fluidized bed reactor. The reaction conditions are as follows: The catalyst loading is 10g, the reaction temperature is 600 °C, and the raw material is Futeng Petrochemical Company butene-2 (purity 98%, cis, anti-butene-2 each 50% by weight), feed airspeed 1.0 Hr- ¹ , the reaction pressure is 0.1 MPa, using water vapor as the reaction diluent gas, and the feed ratio of water to butene _ ₂ is 1.5:1. The reaction product was analyzed by Varian CP-3800 gas chromatography, Plot column and hydrogen flame detector at a sampling time of 6 minutes. The results of the butene cleavage reaction are shown in Table 1. Under the above reaction conditions, the conversion of butene was 79.9%, and the selectivity of propylene in the product was 34.72% by weight. Table 1: Results of catalytic cracking of butene in Example 1

Yield / wt% ethylene propylene C 1-C3 alkane CH ₄ C ₅ C ₆ +

22.46 34.72 8.48 2.5 6.04 8.2 Conversion rate (%) 79.9 Example 2

Catalyst B: using SAPO-34 molecular sieve (Dalian Institute of Chemical Physics) mixed with clay, aluminum sol and silica sol (both purchased from Zhejiang Yida Chemical Co., Ltd.) and dispersed into slurry in water, particle size distribution after spray molding It is a microsphere of 20-100 microns. The above microspheres were calcined at 600 ° C for 4 hours to be the catalyst B. The content of SAPO-34 in the catalyst was 30% by weight.

The co-feed reaction of ethylene and methanol is carried out in a microfluidizer reactor. The reaction conditions are as follows: The catalyst loading is 10 g, the reaction temperature is 400 ° C, and the raw materials are methanol (analytically pure, Shenyang Lianbang State Reagent Factory) and ethylene (purity 99.5%, Ministry of Chemical Industry Bright Special Gas Research Institute) mixture. MPa。 The composition of the raw material is ethylene: methanol = 0.52: 0.48 (carbon ratio), the feed space velocity in methanol is 1.0 hr - ¹ , the reaction pressure is O. lMPa. The reaction product was analyzed by Varian CP-3800 gas chromatography, Plot column and hydrogen flame detector at a sampling time of 6 minutes.

The results of the co-feed reaction of ethylene and methanol are shown in Table 2. Under the above reaction conditions, the ethylene conversion was 33.98%, the methanol conversion was 100%, and the yield of propylene in the product was 61.75% (% by number, based on methanol).

Table 2: Reaction results of ethylene and methanol co-feed in Example 2

Yield (<% by %, based on methanol CH ₄ C23⁄4 C3H6 C3H8 C4 C5 ⁺ )

0.62 1.33 61.75

Ethylene conversion rate (%) 33.98

Methanol conversion rate (%) 100

Example 3:

A methanol- or dimethyl ether and a mixed olefin having a carbon number of 4-5 is used as a raw material to produce propylene. The apparatus is designed to adopt a fluidized bed-regenerator system in both reaction zones, and a catalyst A and a catalyst 8 are respectively used. Different anti The product of the zone can be separated by the same separation system. The contact time in each reaction zone was substantially the same as in Examples 1 and 2, so the feed conversion and product selectivity were calculated according to Examples 1 and 2, and the coke yield was ignored.

In the first reaction zone, a flow rate of 80 tons / hour of mixed olefin feedstock with a carbon number of 4-5 (of which 29.6 tons / hour from the second reaction zone of the product, 20.8 tons / hour for the separation cycle used unconverted The raw material and the product having a carbon number of 4 to 5 in the reaction zone and 29.6 ton / hr of an additional supplementary material are contacted with the catalyst A. The reaction temperature is 600 °C, the feed space velocity is 0.3-0.5 hr- ¹ , the reaction pressure is 0.25 MPa, and the water vapor is used as the reaction diluent gas. The feed ratio of water to raw material is 1.5:1. The material flowing out of the reaction zone is separated to obtain 27.8 tons/hour of propylene, 18 tons/hour of ethylene, 6.8 tons/hour of C1-C3 terpene hydrocarbons, and 20.8 tons/hour of hydrocarbons having a carbon number of 4-5 (including The unconverted raw materials and the hydrocarbons having a carbon number of 4 to 5 produced in the reaction zone) and 6.6 tons of the hydrocarbon products having a carbon number of not less than 6. All of the ethylene enters the second reaction zone, and all of the hydrocarbons having a carbon number of 4-5 are returned to the raw materials of the reaction zone.

In the second reaction zone, a flow rate of 52 tons / hour of ethylene (34 tons / hour is the unconverted feedstock used in the separation cycle, 18 tons / hour from the first reaction zone) and 110 tons / hour of methanol (or 79 Tons/hour of dimethyl ether) are in contact with Catalyst B. The reaction temperature was 400 ° C, the feed space velocity was 0.6-0.9 hr ^-1 in terms of dimethyl ether, and the reaction pressure was 0.25 MPa. The material flowing out of the reaction zone is separated to obtain 30 tons/hour of propylene, 34 tons/hour of unconverted raw material ethylene, 6.4 tons/hour of C1-C3 terpene hydrocarbon, and 29.6 tons/hour of hydrocarbon having a carbon number of not less than 4. Class (mainly hydrocarbons with a carbon number of 4-5). All of the ethylene is returned to the raw materials in the reaction zone, and the hydrocarbons having a carbon number of not less than 4 are all entered into the first reaction zone.

The overall material balance of the unit is as follows: 29.6 tons/hour of hydrocarbons with a carbon number of 4-5 and 110 tons/hour of methanol (or 79 tons/hour of dimethyl ether), 57.8 tons/hour of propylene, 6.6 tons/hour Hydrocarbons having a carbon number of not less than 6 and 13.2 ton / hr of C1-C3 anthracene hydrocarbon. The propylene yield in the whole process was 74.5 carbon %.

Comparative example 1

A mixed olefin having a carbon number of 4 to 5 is a raw material for producing propylene, and the apparatus is designed in the form of a fluidized bed-regenerator system using Catalyst A. The contact time in the reaction zone was substantially the same as in Example 1, so that the raw material conversion rate and product selectivity were in accordance with Example 1, and the coke yield was ignored.

A mixed olefin feedstock with a carbon number of 4-5 at a flow rate of 100 tons/hour (of which 26 tons/hour is a product of unconverted raw materials and a carbon number of 4-5 by separation and recycling, and an additional feed of 74 tons/hour) ) in contact with the catalyst. The reaction temperature is 600 Ό, the feed space velocity is 0.3-0.5 hr- ¹ , the reaction pressure is 0.25 MPa, and water vapor is used as the reaction diluent gas. The feed ratio of water to raw material is 1.5:1. The material flowing out of the reaction zone is separated to obtain 34.8 tons/hour of propylene, 22.5 tons/hour of ethylene, 8.5 tons/hour of C1-C3 terpene hydrocarbons, and 26 tons/hour of hydrocarbons having a carbon number of 4-5 (including Unconverted raw materials and hydrocarbons having a carbon number of 4 to 5 in the reaction zone) and 8.2 tons of hydrocarbons having a carbon number of not less than 6 Product. The hydrocarbons having a carbon number of 4-5 are all returned to the raw materials.

The overall material balance of the unit is as follows: Inflow unit 74 tons/hour of olefins with a carbon number of 4-5, efflux unit 34.8 tons/hour of propylene, 22.5 tons/hour of ethylene, 8.5 tons/hour of C1-C3 alkane, and 8.2 tons Hydrocarbon products with a carbon number of not less than 6. The propylene yield in the whole process was 47% by carbon.

Claims

Rights request

A method for producing propylene, characterized in that at least two reaction zones are provided, comprising:

The reaction conditions of the first reaction zone are: reaction temperature is 350-750 ° C, reaction pressure is 0.01-0.8 MPa; wherein the reaction conditions of the second reaction zone are: reaction temperature is 300-600 ° C, reaction pressure is 0.0 】-0.8 MPa, ethylene / methanol, or ethylene / 2 times dimethyl ether molar ratio of 0.05-5.

2. The method according to claim 1, wherein the solid acidic catalyst is a product obtained by modifying at least one silica-alumina molecular sieve or silicoaluminophosphate molecular sieve having acidity, or modifying the molecular sieve of the above-mentioned characteristic molecular sieve element. Or a mixture of a plurality of molecular sieves meeting the above characteristics.

3. The method of claim 2, wherein the solid acidic catalyst has a molecular sieve content of from 10% by weight to 90% by weight.

4. The method of claim 1, wherein the solid acidic catalyst is formed by one or more of a combination comprising a silica, alumina or clay binder.

5. The method of claim 1 wherein the reactor forms of the first reaction zone and the second reaction zone each employ a fluidized bed.

6. The method according to claim 1, wherein the hydrocarbon having a carbon number of not less than 4 is liquefied gas, naphtha, gasoline, condensate, light diesel oil, hydrogenated tail oil or kerosene, or the conversion of claim 1. A hydrocarbon product having a carbon number of not less than 4 in the process.

7. The method of claim 1 wherein the ethylene-containing gas in the second reaction zone is ethylene derived from a process of hydrocarbon cracking, acetonitrile dehydrogenation or methanol conversion to olefins, or ethylene and C1-from the above process. A mixture of C3 hydrocarbons or carbon oxides, or a product containing ethylene during the conversion of claim 1.

8. The method of claim 1, wherein the hydrocarbons having a carbon number of not less than 4 in the first reaction zone or/and ethylene of the second reaction zone are respectively derived from the product of the conversion process of claim 1.

The method according to claim 1, wherein the reaction conditions of the first reaction zone are: a reaction temperature of -700 ° C and a reaction pressure of 0.1 - 0.45 MPa.

10. The method according to claim 1, wherein the reaction conditions of the second reaction zone are: a reaction temperature of -550 ° C, a reaction pressure of 0.1 - 0.45 MPa, ethylene / methanol, or ethylene / 2 times of dimethyl ether The molar ratio is 0.1-5.