WO2009055997A1

WO2009055997A1 - Process of producing propylene from starting materials of ethylene and methanol (or/and dimethyl ether)

Info

Publication number: WO2009055997A1
Application number: PCT/CN2008/000492
Authority: WO
Inventors: Yue Qi; Jinzhe Li; Zhongmin Liu; 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: CN101367693B; CN101367693A

Abstract

Disclosed is a process of producing propylene from starting materials of ethylene and methanol (or/and dimethyl ether), which is characterized in that the gas containing methanol (or/and dimethyl ether) and the gas containing ethylene are contacted together with catalyst which has a pore diameter of 0.3 nm-0.5 nm and a saturated NH3 adsorption amount of 0.8 mmol/g-2.5 mmol/g at 200 °C, to obtain the products containing propylene; wherein the reaction conditions are as follows: the molar ratio of ethylene/methanol (or 2 times dimethyl ether) is 0.1-2, the reaction temperature is 300-600 °C and the reaction pressure is 0.01-0.8 MPa. The propylene yield of products may be more than 60 C% based on the methanol..

Description

Method for preparing propylene from ethylene and methanol (or / and dimethyl ether) as raw materials

The present invention relates to a process for producing propylene from a gas containing methanol (or / and dimethyl ether) and ethylene. Background technique

Propylene is an important basic raw material for petrochemicals. For a long time, propylene sources have relied on ethylene crackers and FCC plants. As propylene growth rates continue to exceed ethylene growth rates, the increase in propylene production on existing plants is limited by raw material composition, plant handling capacity, plant modification and operating costs. The new process to increase propylene production is an important direction to meet the growing demand for propylene.

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

CH ₃ OH + C _n H _2n = C _n+1 H _2n+2 +3⁄40

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 an alkylating agent having a silica to alumina ratio of at least 12, modified by P, with 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 WO2005/056504 A1 discloses a process for the efficient preparation of propylene starting from ethylene and methanol or/and dimethyl ether by reacting ethylene with methanol or/and dimethyl ether 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 pore diameter of 0.3-0.5 nm. The catalyst of the molecular sieve is contacted to form a product containing propylene. The propylene selectivity in the product can reach more than 65%. A thiolation reagent such as ethylene with methanol or/and dimethyl ether can be thiolated 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 combined with an alkane. The base reagent reacts to form butene, and the resulting butene can be further reacted with a thiolation reagent to form.

Further, C ₅ or more hydrocarbons; in addition, an alkylating agent such as methanol or/and dimethyl ether can directly form a low-carbon olefin (generally referred to as an MTO process) including ethylene and propylene on an acidic catalyst. The thiolation reagent itself converts on one hand to produce acetamidine, counteracts the ethylene feedstock consumed in the thiolation reaction, and on the other hand produces propylene at a lower selectivity, reducing the propylene selectivity throughout the process. Therefore, in the process of co-feeding ethylene and an alkylating agent to produce propylene, various side reactions exist not only reduce the selectivity of propylene, but also reduce the conversion of ethylene in the raw material. In order to inhibit the direct conversion of the thiolation reagent, a higher ratio of the raw material ethylene/hydrazide reagent is usually used to achieve higher propylene selectivity, which requires a large amount of unconverted ethylene to be recycled repeatedly, which reduces the process. Economic. Summary of the invention

SUMMARY OF THE INVENTION An object of the present invention is to provide a process for producing propylene from a gas containing methanol (or / and dimethyl ether) and ethylene.

The method provided by the present invention is characterized in that: methanol (or/and dimethyl ether) and a gas containing ethylene are combined with a pore diameter of 0.3 nm to 0.5 nm, and at 20 (the ammonia saturated adsorption amount is TC) The catalyst is contacted at a pressure of from 0.8 mmol/g to 2.5 mmol/g to form a product containing propylene.

In a preferred aspect of the invention, the catalyst comprises at least one silica-alumina molecular sieve having a pore diameter of 0.3-0.5 nm and an ammonia-saturation adsorption amount of 0.8 mmol/g to 2.5 mmol/g at 200 ° C or A silicon phosphorus aluminum molecular sieve, or a product obtained by modifying a molecular sieve having the above characteristics by an element other than a skeleton constituent element, or a mixture of a plurality of molecular sieves satisfying the above characteristics.

In a preferred aspect of the invention, the catalyst may have a molecular sieve content of from 10% by weight to 90% by weight.

In a preferred aspect of the invention, the catalyst is bonded and formed using a binder comprising one or more of silica, alumina or clay.

In a preferred aspect of the invention, the specific reaction conditions are: ethylene / methanol (or 2 times dimethyl ether) molar ratio of 0.1-2, reaction temperature of 300-600 'C, preferably 350-550 ° C, The reaction pressure is from 0.01 to 0.8 MPa, preferably from 0.1 to 0.45 MPa.

In the process of the invention, the catalytic conversion involved can be carried out in a fluidized bed, fixed bed or moving bed reactor.

According to the process of the present invention, the yield of propylene in the product is determined by methanol (or 2 dimethyl ether). 60. More than %. detailed description:

According to the present invention, a gas containing methanol (or/and dimethyl ether) and ethylene is used as a raw material to suppress side reactions in the reaction process of methanol (or/and dimethyl ether) and ethylene by two routes, which can be lower. The propylene product is obtained in a high yield at an ethylene/methanol (or 2x dimethyl ether) ratio.

One of the ways to achieve the above object is to use the shape selectivity of the molecular sieve to inhibit further thiolation of the product propylene. There are well-sized pores in the molecular sieve structure. When the molecular linearity of the reactants and products is close to the pore size in the crystal, the selectivity of the catalytic reaction often depends on the corresponding size of the molecule and the pore size. This selectivity is called shape selective catalysis. By selecting a molecular sieve catalyst of a certain pore size, larger molecules in the product mixture, such as hydrocarbons above C ₄ , are difficult to diffuse out of the pores of the molecular sieve catalyst, thereby enhancing the propylene in the product of the reaction of ethylene and methanol or/and dimethyl ether. The selectivity.

Another way to achieve this is to inhibit the direct conversion of alkylating agents such as methanol or / and dimethyl ether. Recent studies have shown that the conversion of methanol/dimethyl ether to olefins on acidic catalysts occurs through a "carbon pool mechanism": the pores or cages of the catalyst are highly reactive polysubstituted aromatic hydrocarbons (ie "carbon pools"). These polysubstituted aromatic hydrocarbons are rapidly methylated with methanol or/and dimethyl ether and then further dealkylated to liberate ethylene or propylene molecules. The rate and number of carbon pool formation on the catalyst determines the direct conversion rate of methanol or / and dimethyl ether. The formation of a carbon pool involves reactions such as hydrogen transfer and cyclization, and requires a plurality of acid centers adjacent to each other to be catalyzed together. Our research has found that by ensuring a sufficiently high conversion of raw materials, by appropriately reducing the number of acid centers of the catalyst and increasing the distance between the acid centers, the formation of carbon pools can be reduced, thereby suppressing methanol or/and dimethyl ether. Direct conversion yields a higher propylene yield at a lower feedstock ethylene/hydrazide ratio. The above requirements can only be met if the acid center concentration of the catalyst is within a certain range. In the field of molecular sieve research, the amount of basic molecular adsorption under certain conditions is an effective indicator for characterizing the number of molecular sieve acid centers. In the present invention, the number of acid centers of the catalyst is represented by a unit weight molecular sieve at 20 (the ammonia saturated adsorption amount of TC).

According to the present invention, a raw material containing methanol (or/and dimethyl ether) and ethylene has a pore diameter of 0.3 nm to 0.5 nm, and an ammonia saturated adsorption amount at 0.8 ° C is 0.8 mmol/g to 2.5 mmol/ The gram of catalyst contacts to form a product containing propylene.

In the method, the catalyst may contain at least one silica-alumina molecular sieve or silicon having a pore diameter of 0.3-0.5 nm and an ammonia-saturation adsorption amount of 0.8 mmol/g to 2.5 mmol/g at 200 °C. a product obtained by modifying a phosphorus-aluminum molecular sieve, or a molecular sieve conforming to the above characteristics, by an element other than a skeleton constituent element, or a plurality of points satisfying the above characteristics a mixture of sub-screens.

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

In the method, the catalyst may be bonded and formed by using an adhesive comprising one or more of silica, alumina or clay.

In the process described, the catalytic conversion process involved can be carried out in a fluidized bed, fixed bed or moving bed reactor. The reaction conditions are: ethylene/methanol (or 2 dimethyl ether) molar ratio of 0.1-2, reaction temperature of 300-600 Torr, preferably 350-550 ° C, reaction pressure of 0.01-0.8 MPa, preferably 0.1 -0.45 MPa.

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

Example 1

Catalyst A uses SAPO-34 molecular sieve (Dalian Institute of Chemical Physics, Chinese Academy of Sciences, microporous pore size about 0.4nm, ammonia saturated adsorption capacity of 1.36mmol / gram at 200 ° C) and clay, aluminum sol and silica sol (both purchased from Zhejiang Yuda Chemical Co., Ltd. mixes and disperses into a slurry in water, and is spray-molded into microspheres with a particle size distribution of 20-100 microns. The above microspheres were calcined at 600 Torr for 4 hours to form catalyst A. The SAPO-34 content in the catalyst was 30% by weight.

The ammonia saturation adsorption measurement procedure of the above SAPO-34 molecular sieve at 20CTC is as follows: The instruments used are Microchem's Autochem 2910 chemisorption analyzer and the Swiss PFeiffer Omnistar 300 online mass spectrometer. Catalyst 0.2g, activated in He atmosphere at 40Ό40m/min for 30 min, then cooled to 200 °C to adsorb ammonia to saturation, purged for 30 min, then desorbed to 600 ° at a rate of 10 ° C / min C, TCD and mass spectrometry simultaneously detect the ammonia gas released by the catalyst during the heating process, and the amount of ammonia removed by the integration is the ammonia saturated adsorption amount of the molecular sieve at 200 °C.

The ethylene and methanol co-feed reaction is carried out in a fixed fluidized bed microreactor. The reaction conditions were as follows: Catalyst A was charged at 10 g, and the reaction temperature was 400 ° C. The raw materials were methanol (analytically pure, Shenyang Federal Reagent Factory) and ethylene (purity 98%, Ministry of Chemical Industry, Guangming Special Gas Research Institute) mixture. The raw material composition was ethylene/methanol = 0.5 (molar ratio), the feed space velocity was 1.0 hr ^-1 in terms of methanol, and the reaction pressure was 0.1 MPa. 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 reaction are shown in Table 1. Under the above reaction conditions, the ethylene conversion was 19.27%, the methanol conversion was 100%, and the yield of propylene in the product was 62.61% (0% by weight, based on methanol). Table 1: Reaction results of Example 1

Yield (% by number, based on methanol) CH ₄ C ₂ H ₆ C ₃ H ₆ C ₃ H ₈ C ₄ C ₅ C ₆ ⁺

0.56 1.08 62.61 6.98 36.90 9.28 3.58 Ethylene conversion rate (%) 19.27

Methanol conversion rate (%) 100

Example 2

Catalyst B was prepared by using SAPO-34 molecular sieve (Dalian Institute of Chemical Physics, Chinese Academy of Sciences, with a micropore diameter of about 0.4 nm and an ammonia adsorption capacity of 1.28 mmol/g at 200 ° C), using silica sol (purchased from Zhejiang Yuda Chemical Co., Ltd.). The company is formed as a binder and calcined at 550 ° C for 4 hours. The content of SAPO-34 in the catalyst after molding is 80%.

The ammonia saturation adsorption amount measurement step of the SAPO-34 molecular sieve at 200 ° C is the same as in the first embodiment.

The reaction is carried out in a fixed bed microreactor. The reaction conditions are as follows: Catalyst A loading is lg, reaction temperature is 400 ° C, and the raw materials are methanol (analytically pure, Shenyang Federal Reagent Factory) and ethylene (purity 98%, Ministry of Chemical Industry Bright Special Gas Research Institute) mixture, the mixing method is Ethylene carries methanol vapor through a bubble saturator. Feed composition was ethylene / methanol = 0.5 (molar ratio), a feed space velocity in terms of methanol 1.0 hr ^"1, o is the reaction pressure O.IMPa. The reaction product was purified using Varian CP-3800 gas chromatograph, the column and hydrogen flame detector Plot Analyzer analysis, sampling time is 6 minutes.

The results of the reaction are shown in Table 2. Under the above reaction conditions, the ethylene conversion was 29.35%, the methanol conversion was 100%, and the yield of propylene in the product was 63.27% (C% by weight, based on methanol).

Table 2: Reaction results of Example 2

Yield %, based on methanol CH ₄ C ₂ H ₆ C _{3 3⁄4} C ₃ H ₈ C ₄ C$ C ₆ +

Ethylene conversion rate (%) 29.35

Methanol conversion rate (%) 100

Comparative example 1 :

Catalyst C was prepared by using SAPO-34 molecular sieve (Dalian Institute of Chemical Physics, Chinese Academy of Sciences, with a micropore diameter of about 0.4 nm and an ammonia adsorption capacity of 2.7 mmol/g at 200 ° C), using silica sol (purchased from Zhejiang Yuda Chemical Co., Ltd.). The company was molded as a binder and calcined at 55 (TC for 4 hours, and the content of SAPO-34 in the catalyst after molding was 80%.

Ammonia-saturated adsorption measurement step, reaction conditions and analytical methods and implementation of SAPO-34 molecular sieve at 200'C Example 2 is the same.

The results of the reaction are shown in Table 3. Under the above reaction conditions, the ethylene conversion was 43.37%, the methanol conversion was 100%, and the yield of propylene in the product was 55.94% (% by number, based on methanol). Table 3: Reaction results of Comparative Example 1

Yield (% by number, based on methanol CH ₄ C ₂ H ₆ C ₃ H ₆ C ₃ H ₈ C ₄ C5 C ₆ + )

0.86 1.70 55.94 20.91 43.07 16.85 7.89 Ethylene conversion rate (%) 43.37

Methanol conversion rate (%) 100

Comparative example 2:

Catalyst D uses ZSM-5 molecular sieve (Fushun Petrochemical Company catalyst plant, micropore diameter 0.53nmX0.56nm, ammonia saturation adsorption capacity of 1.40mmol/g under 200Ό), with clay, aluminum sol and silica sol (all purchased from Zhejiang Yu Da Chemical Co., Ltd.) mixes and disperses into a slurry in water, and is spray-molded into microspheres with a particle size distribution of 20-100 microns. The above microspheres were calcined at 600 ° C for 4 hours to form catalyst D. ZSM-5 content in the catalyst is 30 weight

%.

The ammonia saturation adsorption amount measurement step, reaction conditions and analysis method of the ZSM-5 molecular sieve at 200 ° C are the same as in the first embodiment.

The reaction results are shown in Table 4. Under the above reaction conditions, the olefin conversion rate was 81.6%, the methanol conversion rate was 100%, and the yield of propylene in the product was 95.64% (% by number, based on methanol). And products above C4 are higher. Table 4: Reaction results of Comparative Example 2

Yield (% by number, based on methanol CH4 C ₂ H ₆ C ₃ H ₆ C ₃ H ₈ C ₄ C ₅ C ₆ ⁺ )

2.79 5.16 95.64 49.27 91.58 35.16 112.87 Ethylene conversion rate (%) 81.6

Methanol conversion rate (%) 100

Example 3 Catalyst E was prepared by using SAPO-34 molecular sieve (Dalian Institute of Chemical Physics, Chinese Academy of Sciences, with a micropore diameter of about 0.4 nm and an ammonia adsorption capacity of 1.60 mmol/g at 200 ° C), using silica sol (purchased from Zhejiang Yuda Chemical Co., Ltd.). The company is molded as a binder and calcined at 550 for 4 hours. The amount of SAPO-34 in the catalyst after molding is 80%.

The reaction is carried out in a fixed bed microreactor. The reaction conditions are as follows: Catalyst A loading is lg, reaction temperature is 40 (TC, the raw material is a mixture of dimethyl ether and ethylene (purity 98%, Ministry of Chemical Industry, Guangming Special Gas Research Institute). The raw material composition is ethylene/2 dimethyl ether = 1 (molar ratio), a feed space velocity of dimethyl ether in terms of 0.5 hr ^"1, a reaction pressure of O. lMPao reaction product using Varian CP-3800 gas chromatograph, the column and Plot hydrogen flame detector, sampling time points It is 6 minutes.

The reaction results are shown in Table 5. Under the above reaction conditions, the ethylene conversion was 33.98%, the dimethyl ether conversion was 100%, and the yield of propylene in the product was 61.75% (% by number, based on methanol).

Table 5: Reaction results of Example 3

Yield (% by number, in methanol CH ₄ C ₂ H ₆ C ₃ H ₆ C ₃ H ₈ C ₄ C ₅ C ₆ ⁺

Meter

0.62 1.33 61.75 11.32 41.23 14.02 6.73 Ethylene conversion rate (%) 33.98

Dimethyl ether conversion rate (%) 100

Claims

A method for producing propylene from ethylene and methanol (or/and dimethyl ether), the method comprising: methanol (or/and dimethyl ether) and a gas containing ethylene together with a pore diameter of The catalyst is contacted with a catalyst having an ammonia-saturated adsorption amount of 0.8 mmol/g to 2.5 mmol/g at 200 ° C to form a product containing propylene; wherein the reaction conditions are: ethylene/methanol (or 2 times) The dimethyl ether has a molar ratio of 0.1 to 2, a reaction temperature of 300 to 600 ° C, and a reaction pressure of 0.0I to 0.8 MPa.

2. The method of claim 1 wherein the catalyst comprises at least one microporous pore size of from 0.3 to 0.5 nm and an ammonia saturated adsorption amount of from 0.8 mmol/g to 2.5 mmol/g at 200 ° C. An aluminum molecular sieve or a silicoaluminophosphate molecular sieve, or a product obtained by modifying a molecular sieve having the above characteristics by an element other than a skeleton constituent element, or a mixture of a plurality of molecular sieves satisfying the above characteristics.

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

4. The method of claim 1 wherein the catalyst is bonded and formed using a binder comprising one or more of silica, alumina or clay.

The method according to claim 1, wherein the reaction conditions are: a reaction temperature of 350 to 55 (TC, and a reaction pressure of 0.1 to 0.45 MPa.

6. The method of claim 1 wherein the catalytic conversion process is carried out in a fluidized bed, fixed bed or moving bed reactor.