A catalyst for preparing ethylene propylene by catalytic cracking and its preparation and application

Abstract

The application discloses a catalyst for preparing ethylene and propylene through catalytic cracking, and the catalyst comprises silicon dioxide, potassium, a molecular sieve and a metal or an oxide thereof attached to the molecular sieve, and the mass ratio of the molecular sieve, the silicon dioxide, the metal oxide and K2O is 30-50:30-65:5-20:0.1-5, and the metal is calculated according to its metal oxide when the catalyst comprises the metal; the potassium in the catalyst is calculated according to potassium oxide. The application further discloses preparation and application of the catalyst. The ZSM-5 molecular sieve modified by the double metal and containing potassium salt is used as the catalyst, the activity of the catalyst is improved, the conversion rate of n-butane is greatly improved, and the ethylene and propylene yield is improved.

Description

Technical Field

[0001] This invention relates to a catalyst for the catalytic cracking of ethylene to propylene, its preparation, and its application. Background Technology

[0002] Ethylene and propylene are important products in the petrochemical industry and also the most important basic organic chemical raw materials in chemical production, occupying a vital position in the national economy. Currently, steam cracking of petroleum hydrocarbons remains the main process for producing dienes. In my country, approximately 90% of ethylene, 35% of propylene, and 20% of butene are produced through naphtha steam cracking. After years of development, the steam cracking process has become quite mature, but it still suffers from inherent drawbacks such as high construction costs, high energy consumption, fixed product composition, and high carbon emissions. Meanwhile, methods for producing dienes, such as catalytic cracking, propane dehydrogenation, and methanol-to-olefins (MTO / MTP), are rapidly emerging. Among these, catalytic cracking offers advantages such as flexible operation, wide availability of raw materials, low energy consumption, and low production costs, and can effectively control the propylene to ethylene ratio, making it of significant practical importance.

[0003] With the rapid development of the oil refining industry, a large amount of C4 alkanes are produced as a byproduct during oil and gas extraction and refining. However, their applications are limited, typically limited to fuel. The demand gap for ethylene and propylene has led to increased attention on producing ethylene and propylene from low-carbon alkanes. Catalytic cracking to produce propylene and ethylene usually occurs at around 550℃. Numerous reports exist on existing olefin catalytic cracking technologies, with the active components of the catalysts primarily being hydrogen-type molecular sieves such as ZSM-5, ZSM-11, and SAPO-34. Due to the relatively low reactivity of alkanes, the reaction typically requires temperatures above 600℃. Furthermore, the stability of molecular sieve catalysts is insufficient, resulting in poor catalyst stability. While some research has made progress using metal oxide catalysts, industrial application remains a significant challenge.

[0004] In existing technologies, hydrocarbon cracking mostly uses easily crackable butene, isobutane, or mixtures thereof as raw materials, employing molecular sieves or modified molecular sieves as catalysts to produce low-carbon olefins. However, n-butane, as a relatively chemically stable raw material, has not been utilized efficiently, and the catalyst preparation processes used in existing technologies are complex and costly. The catalytic cracking of n-butane to produce ethylene and propylene suffers from low diene selectivity and low single-pass propylene yield. Summary of the Invention

[0005] This invention is made to further improve the efficiency of catalytic cracking to produce ethylene and propylene and to increase the selection space of relevant catalysts.

[0006] The term "catalyst" as used in this application refers to catalyst products that include molecular sieves and components such as metals or their oxides, silica, and potassium attached to the molecular sieves. These products are generally sold on a dry basis after calcination.

[0007] As one aspect of the present invention, a catalyst for the catalytic cracking of ethylene to propylene is disclosed. The catalyst comprises silica, potassium, a molecular sieve, and a metal or its oxide attached to the molecular sieve. The mass ratio of the molecular sieve, silica, metal oxide, and K₂O is 30-50:30-65:5-20:0.1-5. When the catalyst includes a metal, the potassium in the catalyst is calculated as potassium oxide, based on the metal oxide. Preferably, the mass ratio of the molecular sieve, silica, metal oxide, and K₂O is 35-45:45-55:5-10:1-3. In a specific embodiment, the molecular sieve accounts for 30-50% of the total weight of the catalyst, the metal oxide accounts for 5-20% of the total weight of the catalyst, and the K₂O accounts for 0.1-5% of the total weight of the catalyst. In a specific embodiment, the metal or its oxide includes M1 and M2, wherein M1 is selected from Ga, In, Bi, or their metal oxides, and M2 is selected from Fe, Zn, or their metal oxides. The mass ratio of M1 to M2 is 1-7:1, preferably 1-2:1.

[0008] As another aspect of the present invention, a method for preparing the above-described catalyst is provided, comprising:

[0009] (1) Dissolve the soluble salts of M1 and M2 in water;

[0010] (2) Add and mix with ZSM-5 molecular sieve and SiO2 powder;

[0011] (3) Add potassium tartrate, adjust the pH value to 7-9, and let it stand for aging and roasting.

[0012] In step (1), the soluble salts of M1 and M2 are nitrates, nitrites or sulfates of M1 and M2.

[0013] In step (3), the static aging temperature is 60-80℃ and the static aging time is 2-24h.

[0014] In step (3), the roasting is first carried out at 450-600℃ for 2-3 hours, and then roasted at 600-750℃ for 1-2 hours.

[0015] As another aspect of the present invention, the application of the above-mentioned catalyst for the catalytic cracking of ethylene and propylene in the catalytic cracking of n-butane is discussed.

[0016] As another aspect of the present invention, a process for the catalytic cracking of n-butane to produce ethylene and propylene is provided, using the above-mentioned catalyst.

[0017] In a specific embodiment, the reaction conditions for the n-butane catalytic cracking process to produce ethylene and propylene include, for example, a temperature of 500–650°C, atmospheric pressure, and a gas hourly space velocity of 1200–1600 h⁻¹. -1 The agent-to-oil ratio is 3 to 10, and the agent-to-oil ratio is a weight ratio.

[0018] The catalyst provided by this invention exhibits good conversion rate, propylene yield, and ethylene-propylene selectivity when applied to the catalytic cracking of butane to produce ethylene-propylene.

[0019] The catalyst of this invention has high catalytic efficiency and the preparation method is simple and easy to implement.

[0020] By utilizing the large amount of n-butane produced as a byproduct in oil and gas extraction and oil refining as raw material, and employing the bimetallic modified ZSM-5 molecular sieve containing potassium salt provided in this invention as a catalyst, the activity of the catalyst and the selectivity of ethylene and propylene are improved, significantly increasing the conversion rate of n-butane and the yield of ethylene and propylene.

[0021] This invention uses ordinary ZSM-5 molecular sieves mixed with metals and other materials, which is simple and low-cost.

[0022] Since the catalytic cracking conditions of butane are often quite harsh, this invention mainly targets the catalytic cracking reaction. By synthesizing a dual-support metal-modified catalyst, it can be made to have high catalytic activity, thereby reducing the harshness of the reaction to a certain extent and improving the selectivity and yield of ethylene and propylene. Detailed Implementation

[0023] Referring to CN103071522A, the inventors prepared a hierarchical porous ZSM-5 molecular sieve as a catalyst using SiO2, Al2O3, TPAOH, and a second template agent. However, this method requires a special preparation process for the hierarchical porous ZSM-5, resulting in a complex and costly process that does not meet the inventors' expectations.

[0024] Ji Dong et al. (Ji Dong, Wang Yi, Liu Tao, Su Yi, Li Ping, Gao Xionghou. Study on catalytic cracking of C4 alkanes to ethylene and propylene by high-silica molecular sieve ZSM-23 [J]. Molecular Catalysis, 2007(03):193-199.) synthesized ZSM-23 molecular sieves with different silica-to-alumina ratios by static hydrothermal crystallization using silica sol as the silicon source and pyrrolidine as the template agent. Among them, the ZSM-23 molecular sieve with a silica-to-alumina ratio of 30 showed the best catalytic performance. Under the conditions of reaction temperature of 600℃ and GHSV: 3000ml / h / g, the yield of ethylene and propylene reached 56.0%, and the conversion rate reached 88.9%. Its raw material composition was 54.5% n-butene, 44.7% isobutene, and 0.8% other hydrocarbons. This high olefin content C4 raw material is more likely to react and obtain a high olefin yield. However, the inventors used it for alkane cracking, and the effect was not as expected.

[0025] CN104557396A discloses a method for catalytic cracking of n-butene to produce propylene, which uses a phosphorus-modified SAPO-11 molecular sieve catalyst and a ZSM-5 molecular sieve catalyst, at a reaction temperature of 500-600℃ and a weight hourly space velocity of 1-10 h⁻¹. -1 Using C4 as a raw material after etherification, the propylene yield can reach 39%. However, the inventors found that its application in alkane cracking did not yield the results they expected.

[0026] Referring to CN1026100C, the inventors prepared a cracking catalyst by impregnating palladium or platinum onto activated alumina using a method. This method uses precious metals as the active component, resulting in high costs. Furthermore, the use of a diluent during the reaction process is not conducive to industrial scale-up; when using n-butane as a raw material, the propylene yield was only 8%, lower than the inventors' expectations.

[0027] The rare earth-containing five-membered ring zeolite ZRP-1 catalyst disclosed by Ma Liqing et al. in the literature Ma Liqing, Weng Huixin. Study on catalytic cracking of n-butane to ethylene and propylene [J]. Natural Gas Chemical Industry (C1 Chemistry and Chemical Engineering), 2010, 35(02):18-21+27. has a good effect on the catalytic cracking of n-butane to ethylene and propylene. However, the synthesis of this catalyst requires the use of rare earth elements and has high process requirements.

[0028] In his paper on the preparation of Co-based HZSM-5 catalyst and its catalytic cracking of n-butane, Ma Xiaobiao synthesized Co@ZSM-5 in situ. At a reaction temperature of 550℃ and a butane to nitrogen flow ratio of 1:19 (2 mL / min: 38 mL / min), the butane conversion was 58.5%, the propylene yield was 15.2%, and the ethylene yield was 13.7%. However, this study suffers from high catalyst preparation costs, the use of a diluent in the reaction process, and low propylene yield, making it unsuitable for industrial applications.

[0029] The inventors, referring to CN101279287A, prepared a catalyst for catalytic cracking to olefins. This was achieved by loading metals onto ZSM-5 / mordenite symbiotic molecular sieves, ZSM-5 / β-zeolite symbiotic molecular sieves, or ZSM-5 / Y symbiotic molecular sieves for naphtha cracking to ethylene and propylene. However, they found that the unsuitable silica content in the symbiotic molecular sieves, and the high silica content (80-99.5%), made catalyst forming difficult, resulting in poor abrasion resistance during use and making it unsuitable for industrial applications, failing to meet the inventors' expectations. Furthermore, symbiotic molecular sieves have a special structure; large-scale use as catalysts requires custom-made products, leading to high costs and making them unsuitable for industrial applications.

[0030] Given that the existing technology could not meet the inventor's expectations, the inventor made this invention after further research and development.

[0031] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0032] Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art.

[0033] The prepared catalyst was evaluated for performance using a microreactor (manufacturer: Qingdao Jietian Technology) at a reaction temperature of 620℃ and a gas hourly space velocity of 1500 h⁻¹. -1 The preparation methods of different catalysts are shown in Examples 1-5, and the evaluation results are shown in Table 1, using 99.5 wt% n-butane as raw material.

[0034] Example 1

[0035] The catalyst was prepared according to the following steps:

[0036] Step (1): At room temperature, dissolve 15g gallium nitrate and 8g ferric nitrate in 80g water, and heat the water bath to 60℃ to completely dissolve them, to obtain a mixed solution of metals;

[0037] Step (2): 35g ZSM-5 molecular sieve and 54.86g SiO2 powder were added to the metal mixed solution obtained in step (1) under continuous stirring, and stirred for 1h to obtain a mixed slurry;

[0038] Step (3): Weigh 5g of potassium tartrate and add it to the slurry obtained in step (2) under continuous stirring. Add ammonia dropwise until the pH value of the solution reaches 7. Continue stirring for 2 hours and let it stand at 60℃ for 3 hours to age.

[0039] Step (4): After static aging, the sample was first dried at 90℃ for 4 hours, then rinsed twice with 0.2mol / L dilute nitric acid, then calcined at 450℃ for 3 hours, and finally calcined at 700℃ for 1 hour. After cooling to room temperature, the bimetallic modified molecular sieve catalyst MC-1 was obtained.

[0040] The catalyst components, by mass ratio, are molecular sieve:SiO2:metal oxide:K2O = 35:54.86:8.14:2. The metal oxide is a mixture of two metal oxides, M1 and M2, where M1 is gallium oxide and M2 is iron oxide, with a ratio of M1:M2 = 2.08:1.

[0041] Catalyst evaluation method: Performance evaluation was conducted on a microreactor (manufacturer: Qingdao Jietian Technology) at a reaction temperature of 620℃ and a gas hourly space velocity of 1500 h⁻¹. -1 The evaluation feedstock was 99.5 wt% n-butane. The catalyst was the MC-1 catalyst prepared in Example 1.

[0042] The catalyst evaluation results showed that the conversion rate of n-butane was 70.48%, the yield of ethylene was 21.73 wt%, and the yield of propylene was 23.64 wt%.

[0043] Example 2

[0044] The catalyst was prepared according to the following steps:

[0045] Step (1): At room temperature, dissolve 15g of indium nitrate and 8g of ferric nitrate in 80g of water, and heat the water bath to 60℃ to completely dissolve them, to obtain a mixed solution of metals;

[0046] Step (2): 35g ZSM-5 molecular sieve and 53.44g SiO2 powder were added to the metal mixed solution obtained in step (1) under continuous stirring, and stirred for 1h to obtain a mixed slurry;

[0047] Step (3): Weigh 5g of potassium tartrate and add it to the slurry obtained in step (2) under continuous stirring. Add ammonia dropwise until the pH value of the solution reaches 9. Continue stirring for 2 hours and let it stand at 60℃ for 3 hours to age.

[0048] Step (4): After static aging, the sample was first dried at 90℃ for 4 hours, then rinsed twice with 0.3mol / L dilute nitric acid, then calcined at 450℃ for 3 hours, and finally calcined at 650℃ for 2 hours. After cooling to room temperature, the bimetallic modified molecular sieve catalyst MC-2 was obtained.

[0049] The catalyst components, by mass ratio, are molecular sieve:SiO2:metal oxide:K2O = 35:53.44:9.56:2. The metal oxide is a mixture of two metal oxides, M1 and M2, where M1 is indium oxide and M2 is iron oxide, with a ratio of M1:M2 = 2.62:1.

[0050] Catalyst evaluation method: Performance evaluation was conducted on a microreactor (manufacturer: Qingdao Jietian Technology) at a reaction temperature of 620℃ and a gas hourly space velocity of 1500 h⁻¹. -1 The evaluation feedstock was 99.5 wt% n-butane. The catalyst was the MC-2 catalyst prepared in Example 2.

[0051] The catalyst evaluation results showed that the conversion rate of n-butane was 65.72%, the yield of ethylene was 17.80 wt%, and the yield of propylene was 22.43 wt%.

[0052] Example 3

[0053] The catalyst was prepared according to the following steps:

[0054] Step (1): At room temperature, dissolve 12g of bismuth nitrate and 8g of ferric nitrate in 60g of water, and heat the water bath to 60℃ to completely dissolve them, to obtain a mixed solution of metals;

[0055] Step (2): 40g ZSM-5 molecular sieve and 50.09g SiO2 powder were added to the metal mixed solution obtained in step (1) under continuous stirring, and stirred for 1h to obtain a mixed slurry;

[0056] Step (3): Weigh 5g of potassium tartrate and add it to the slurry obtained in step (2) under continuous stirring. Add ammonia dropwise until the pH value of the solution reaches 7. Continue stirring for 2 hours and let it stand at 60℃ for 3 hours to age.

[0057] Step (4): After static aging, the sample was first dried at 90℃ for 4 hours, then rinsed twice with 0.2mol / L dilute nitric acid, then calcined at 450℃ for 3 hours, and finally calcined at 700℃ for 1 hour. After cooling to room temperature, the bimetallic modified molecular sieve catalyst MC-3 was obtained.

[0058] The catalyst components, by mass ratio, are molecular sieve:SiO2:metal oxide:K2O = 40:50.09:7.91:0.8. The metal oxide is a mixture of two metal oxides, M1 and M2, where M1 is bismuth oxide and M2 is iron oxide, with a ratio of M1:M2 = 2.00:1.

[0059] Catalyst evaluation method: Performance evaluation was conducted on a microreactor (manufacturer: Qingdao Jietian Technology) at a reaction temperature of 620℃ and a gas hourly space velocity of 1500 h⁻¹.-1 The evaluation feedstock was 99.5 wt% n-butane. The catalyst was the MC-3 catalyst prepared in Example 3.

[0060] The catalyst evaluation results showed that the conversion rate of n-butane was 68.72%, the yield of ethylene was 19.05 wt%, and the yield of propylene was 24.76 wt%.

[0061] Example 4

[0062] The catalyst was prepared according to the following steps:

[0063] Step (1): At room temperature, dissolve 8g gallium nitrate and 8g zinc nitrate in 70g water, and heat the water bath to 60℃ to completely dissolve them, to obtain a mixed solution of metals;

[0064] Step (2): 30g ZSM-5 molecular sieve and 60.31g SiO2 powder were added to the metal mixed solution obtained in step (1) under continuous stirring, and stirred for 1h to obtain a mixed slurry;

[0065] Step (3): Weigh 5g of potassium tartrate and add it to the slurry obtained in step (2) under continuous stirring. Add ammonia dropwise until the pH value of the solution reaches 7-9. Continue stirring for 2 hours and let it stand at 60℃ for 3 hours to age.

[0066] Step (4): After static aging, the sample was first dried at 90℃ for 4 hours, then rinsed once with 0.2mol / L dilute nitric acid, then calcined at 450℃ for 3 hours, and finally calcined at 650℃ for 1.5 hours. After cooling to room temperature, the bimetallic modified molecular sieve catalyst MC-4 was obtained.

[0067] The catalyst components, by mass ratio, are molecular sieve:SiO2:metal oxide:K2O = 30:60.31:7.69:2. The metal oxide is a mixture of two metal oxides, M1 and M2, where M1 is gallium oxide and M2 is zinc oxide, with a ratio of M1:M2 = 6.03:1.

[0068] Catalyst evaluation method: Performance evaluation was conducted on a microreactor (manufacturer: Qingdao Jietian Technology) at a reaction temperature of 620℃ and a gas hourly space velocity of 1500 h⁻¹. -1 The evaluation feedstock was 99.5 wt% n-butane. The catalyst was the MC-4 catalyst prepared in Example 4.

[0069] The catalyst evaluation results showed that the conversion rate of n-butane was 67.58%, the yield of ethylene was 17.51 ​​wt%, and the yield of propylene was 23.56 wt%.

[0070] Example 5

[0071] The catalyst was prepared according to the following steps:

[0072] Step (1): At room temperature, dissolve 15g of bismuth nitrate and 6g of zinc nitrate in 50g of water, and heat the water bath to 60℃ to completely dissolve them, to obtain a mixed solution of metals;

[0073] Step (2): 37g ZSM-5 molecular sieve and 54.63g SiO2 powder were added to the metal mixed solution obtained in step (1) under continuous stirring, and stirred for 0.5h to obtain a mixed slurry;

[0074] Step (3): Weigh 5g of potassium tartrate and add it to the slurry obtained in step (2) under continuous stirring. Add ammonia dropwise until the pH value of the solution reaches 7-9. Continue stirring for 1.5h and let it stand at 60℃ for 3h to age.

[0075] Step (4): After static aging, the sample was first dried at 90℃ for 4 hours, then rinsed twice with 0.1mol / L dilute nitric acid, then calcined at 450℃ for 3 hours, and finally calcined at 650℃ for 2 hours. After cooling to room temperature, the bimetallic modified molecular sieve catalyst MC-5 was obtained.

[0076] The catalyst components, by mass ratio, are molecular sieve:SiO2:metal oxide:K2O = 37:54.63:6.37:2. The metal oxide is a mixture of two metal oxides, M1 and M2, where M1 is bismuth oxide and M2 is zinc oxide, with a ratio of M1:M2 = 4.82:1.

[0077] Catalyst evaluation method: Performance evaluation was conducted on a microreactor (manufacturer: Qingdao Jietian Technology) at a reaction temperature of 620℃ and a gas hourly space velocity of 1500 h⁻¹. -1 The evaluation feedstock was 99.5 wt% n-butane. The catalyst was the MC-5 catalyst prepared in Example 5.

[0078] The catalyst evaluation results showed that the conversion rate of n-butane was 67.9%, the yield of ethylene was 18.71 wt%, and the yield of propylene was 22.52 wt%.

[0079] Example 6

[0080] The catalyst was prepared according to the following steps:

[0081] Step (1): At room temperature, dissolve 15g of bismuth nitrate and 6g of zinc nitrate in 50g of water, and heat the water bath to 60℃ to completely dissolve them, to obtain a mixed solution of metals;

[0082] Step (2): 37g ZSM-5 molecular sieve and 54.63g SiO2 powder were added to the metal mixed solution obtained in step (1) under continuous stirring, and stirred for 0.5h to obtain a mixed slurry;

[0083] Step (3): Weigh 5g of potassium tartrate and add it to the slurry obtained in step (2) under continuous stirring. Add ammonia dropwise until the pH value of the solution reaches 7-9. Continue stirring for 1.5h and let it stand at 70℃ for 10h to age.

[0084] Step (4): After static aging, the sample was first dried at 90℃ for 4 hours, then rinsed twice with 0.1mol / L dilute nitric acid, then calcined at 550℃ for 2 hours, and finally calcined at 700℃ for 2 hours. After cooling to room temperature, the bimetallic modified molecular sieve catalyst MC-6 was obtained.

[0085] The catalyst components, by mass ratio, are molecular sieve:SiO2:metal oxide:K2O = 37:54.63:6.37:2. The metal oxide is a mixture of two metal oxides, M1 and M2, where M1 is bismuth oxide and M2 is zinc oxide, with a ratio of M1:M2 = 4.82:1.

[0086] Catalyst evaluation method: Performance evaluation was conducted on a microreactor (manufacturer: Qingdao Jietian Technology) at a reaction temperature of 650℃ and a gas hourly space velocity of 1500 h⁻¹. -1 The evaluation feedstock was 99.5 wt% n-butane. The catalyst was the MC-6 catalyst prepared in Example 6.

[0087] The catalyst evaluation results showed that the conversion rate of n-butane was 68.12%, the yield of ethylene was 19.71 wt%, and the yield of propylene was 22.83 wt%.

[0088] Example 7

[0089] The catalyst was prepared according to the following steps:

[0090] Step (1): At room temperature, dissolve 15g of indium nitrate and 11g of zinc nitrate in 50g of water, and heat the water bath to 60℃ to completely dissolve them, to obtain a mixed solution of metals;

[0091] Step (2): 35g ZSM-5 molecular sieve and 54.57g SiO2 powder were added to the metal mixed solution obtained in step (1) under continuous stirring, and stirred for 0.5h to obtain a mixed slurry;

[0092] Step (3): Weigh 5g of potassium tartrate and add it to the slurry obtained in step (2) under continuous stirring. Add ammonia dropwise until the pH value of the solution reaches 8. Continue stirring for 1.5h and let it stand at 70℃ for 8h for aging.

[0093] Step (4): After static aging, the sample was first dried at 90℃ for 4 hours, then rinsed twice with 0.1mol / L dilute nitric acid, then calcined at 550℃ for 2 hours, and finally calcined at 700℃ for 2 hours. After cooling to room temperature, the bimetallic modified molecular sieve catalyst MC-6 was obtained.

[0094] The catalyst components, by mass ratio, are molecular sieve:SiO2:metal oxide:K2O = 35:54.57:8.43:2. The metal oxide is a mixture of two metal oxides, M1 and M2, where M1 is indium oxide and M2 is zinc oxide, with a ratio of M1:M2 = 4.6:1.

[0095] Catalyst evaluation method: Performance evaluation was conducted on a microreactor (manufacturer: Qingdao Jietian Technology) at a reaction temperature of 650℃ and a gas hourly space velocity of 1500 h⁻¹. -1 The evaluation feedstock was 99.5 wt% n-butane. The catalyst was the MC-7 catalyst prepared in Example 7.

[0096] The catalyst evaluation results showed that the conversion rate of n-butane was 69.02%, the yield of ethylene was 20.71 wt%, and the yield of propylene was 21.73 wt%.

[0097] Example 8

[0098] The catalyst was prepared according to the following steps:

[0099] Step (1): At room temperature, dissolve 15g of indium nitrate and 11g of zinc nitrate in 50g of water, and heat the water bath to 60℃ to completely dissolve them, to obtain a mixed solution of metals;

[0100] Step (2): 35g ZSM-5 molecular sieve and 54.57g SiO2 powder were added to the metal mixed solution obtained in step (1) under continuous stirring, and stirred for 0.5h to obtain a mixed slurry;

[0101] Step (3): Weigh 5g of potassium tartrate and add it to the slurry obtained in step (2) under continuous stirring. Add ammonia dropwise until the pH value of the solution reaches 9. Continue stirring for 1.5h and let it stand at 63℃ for 24h for aging.

[0102] Step (4): After static aging, the sample was first dried at 90℃ for 4 hours, then rinsed twice with 0.1mol / L dilute nitric acid, then calcined at 450℃ for 1 hour, and finally calcined at 700℃ for 3 hours. After cooling to room temperature, the bimetallic modified molecular sieve catalyst MC-8 was obtained.

[0103] The catalyst components, by mass ratio, are molecular sieve:SiO2:metal oxide:K2O = 35:54.57:6.42:4. The metal oxide is a mixture of two metal oxides, M1 and M2, where M1 is indium oxide and M2 is zinc oxide, with a ratio of M1:M2 = 3.27:1.

[0104] Catalyst evaluation method: Performance evaluation was conducted on a microreactor (manufacturer: Qingdao Jietian Technology) at a reaction temperature of 650℃ and a gas hourly space velocity of 1500 h⁻¹. -1 The evaluation feedstock was 99.5 wt% n-butane. The catalyst was the MC-8 catalyst prepared in Example 8.

[0105] The catalyst evaluation results showed that the conversion rate of n-butane was 68.22%, the yield of ethylene was 19.67 wt%, and the yield of propylene was 22.03 wt%.

[0106] Example 9

[0107] The catalyst was prepared according to the following steps:

[0108] Step (1): At room temperature, dissolve 10.66g of indium nitrate and 20g of zinc nitrate in 80g of water, and heat the water bath to 60℃ to completely dissolve them, to obtain a mixed solution of metals;

[0109] Step (2): 37g ZSM-5 molecular sieve and 54.14g SiO2 powder were added to the metal mixed solution obtained in step (1) under continuous stirring, and stirred for 0.5h to obtain a mixed slurry;

[0110] Step (3): Weigh 3g of potassium tartrate and add it to the slurry obtained in step (2) under continuous stirring. Add ammonia dropwise until the pH value of the solution reaches 9. Continue stirring for 1.5h and let it stand at 66℃ for 14h to age.

[0111] Step (4): After static aging, the sample was first dried at 90℃ for 4 hours, then rinsed twice with 0.1mol / L dilute nitric acid, then calcined at 450℃ for 1 hour, and finally calcined at 700℃ for 3 hours. After cooling to room temperature, the bimetallic modified molecular sieve catalyst MC-9 was obtained.

[0112] The catalyst components, by mass ratio, are molecular sieve:SiO2:metal oxide:K2O = 37:54.14:7.65:1.2. The metal oxide is a mixture of two metal oxides, M1 and M2, where M1 is indium oxide and M2 is zinc oxide, with a ratio of M1:M2 = 1.8:1.

[0113] Catalyst evaluation method: Performance evaluation was conducted on a microreactor (manufacturer: Qingdao Jietian Technology) at a reaction temperature of 650℃ and a gas hourly space velocity of 1500 h⁻¹. -1 The evaluation feedstock was 99.5 wt% n-butane. The catalyst was the MC-9 catalyst prepared in Example 9.

[0114] The catalyst evaluation results showed that the conversion rate of n-butane was 69.32%, the yield of ethylene was 20.83 wt%, and the yield of propylene was 21.36 wt%.

[0115] Example 10

[0116] The catalyst was prepared according to the following steps:

[0117] Step (1): At room temperature, dissolve 10g of indium nitrate and 18g of zinc nitrate in 80g of water, and heat the water bath to 60℃ to completely dissolve them, to obtain a mixed solution of metals;

[0118] Step (2): 36g of ZSM-5 molecular sieve and 54g of SiO2 powder were added to the metal mixed solution obtained in step (1) under continuous stirring, and stirred for 0.5h to obtain a mixed slurry;

[0119] Step (3): Weigh 7.3g of potassium tartrate and add it to the slurry obtained in step (2) under continuous stirring. Add ammonia dropwise until the pH value of the solution reaches 8. Continue stirring for 1.5h and let it stand at 72℃ for 14h to age.

[0120] Step (4): After static aging, the sample was first dried at 90℃ for 4 hours, then rinsed twice with 0.1mol / L dilute nitric acid, then calcined at 450℃ for 1 hour, and finally calcined at 700℃ for 3 hours. After cooling to room temperature, the bimetallic modified molecular sieve catalyst MC-10 was obtained.

[0121] The mass ratio of the catalyst components is as follows: molecular sieve:SiO2:metal oxide:K2O = 36:54:7.08:2.92. The metal oxide is a mixture of two metal oxides, M1 and M2, where M1 is indium oxide and M2 is zinc oxide, with a ratio of M1:M2 = 1.7:1.

[0122] Catalyst evaluation method: Performance evaluation was conducted on a microreactor (manufacturer: Qingdao Jietian Technology) at a reaction temperature of 650℃ and a gas hourly space velocity of 1500 h⁻¹. -1 The evaluation feedstock was 99.5 wt% n-butane. The catalyst was the MC-10 catalyst prepared in Example 10.

[0123] The catalyst evaluation results showed that the conversion rate of n-butane was 68.84%, the yield of ethylene was 21.56 wt%, and the yield of propylene was 20.11 wt%.

[0124] Example 11

[0125] The catalyst was prepared according to the following steps:

[0126] Step (1): At room temperature, dissolve 9g of indium nitrate and 18g of zinc nitrate in 80g of water, and heat the water bath to 60℃ to completely dissolve them, to obtain a mixed solution of metals;

[0127] Step (2): 40g ZSM-5 molecular sieve and 50g SiO2 powder were added to the metal mixed solution obtained in step (1) under continuous stirring, and stirred for 0.5h to obtain a mixed slurry;

[0128] Step (3): Weigh 7.3g of potassium tartrate and add it to the slurry obtained in step (2) under continuous stirring. Add ammonia dropwise until the pH value of the solution reaches 7. Continue stirring for 1.5h and let it stand at 70℃ for 18h to age.

[0129] Step (4): After static aging, the sample was first dried at 90℃ for 4 hours, then rinsed twice with 0.1mol / L dilute nitric acid, then calcined at 450℃ for 1 hour, and finally calcined at 700℃ for 3 hours. After cooling to room temperature, the bimetallic modified molecular sieve catalyst MC-11 was obtained.

[0130] The mass ratio of the catalyst components is as follows: molecular sieve:SiO2:metal oxide:K2O = 40:50:7.08:2.92. The metal oxide is a mixture of two metal oxides, M1 and M2, where M1 is indium oxide and M2 is zinc oxide, with a ratio of M1:M2 = 1.7:1.

[0131] Catalyst evaluation method: Performance evaluation was conducted on a microreactor (manufacturer: Qingdao Jietian Technology) at a reaction temperature of 620℃ and a gas hourly space velocity of 1400 h⁻¹. -1 The evaluation feedstock was 99.5 wt% n-butane. The catalyst was the MC-11 catalyst prepared in Example 11.

[0132] The catalyst evaluation results showed that the conversion rate of n-butane was 68.03%, the yield of ethylene was 20.86 wt%, and the yield of propylene was 20.35 wt%.

[0133] Example 12

[0134] The catalyst was prepared according to the following steps:

[0135] Step (1): At room temperature, dissolve 18g gallium nitrate and 7.8g ferric nitrate in 60g water, and heat the water bath to 60℃ to completely dissolve them, to obtain a mixed solution of metals;

[0136] Step (2): 50g ZSM-5 molecular sieve and 38g SiO2 powder were added to the metal mixed solution obtained in step (1) under continuous stirring, and stirred for 0.5h to obtain a mixed slurry;

[0137] Step (3): Weigh 7.07g of potassium tartrate and add it to the slurry obtained in step (2) under continuous stirring. Add ammonia dropwise until the pH value of the solution reaches 7. Continue stirring for 1.5h and let it stand at 70℃ for 18h to age.

[0138] Step (4): After static aging, the sample was first dried at 90℃ for 4 hours, then rinsed twice with 0.1mol / L dilute nitric acid, then calcined at 450℃ for 1 hour, and finally calcined at 700℃ for 3 hours. After cooling to room temperature, the bimetallic modified molecular sieve catalyst MC-12 was obtained.

[0139] The catalyst components, by mass ratio, are molecular sieve:SiO2:metal oxide:K2O = 50:38:9.17:2.83. The metal oxide is a mixture of two metal oxides, M1 and M2, where M1 is gallium oxide and M2 is iron oxide, with a ratio of M1:M2 = 2.56:1.

[0140] Catalyst evaluation method: Performance evaluation was conducted on a microreactor (manufacturer: Qingdao Jietian Technology) at a reaction temperature of 620℃ and a gas hourly space velocity of 1400 h⁻¹. -1 The evaluation feedstock was 99.5 wt% n-butane. The catalyst was the MC-12 catalyst prepared in Example 12.

[0141] The catalyst evaluation results showed that the conversion rate of n-butane was 70.12%, the yield of ethylene was 21.34 wt%, and the yield of propylene was 19.88 wt%.

[0142] Example 13

[0143] The catalyst was prepared according to the following steps:

[0144] Step (1): At room temperature, dissolve 20g gallium nitrate and 13.85g bismuth nitrate in 60g water, and heat the water bath to 60℃ to completely dissolve them, to obtain a mixed solution of metals;

[0145] Step (2): 47g ZSM-5 molecular sieve and 38g SiO2 powder were added to the metal mixed solution obtained in step (1) under continuous stirring, and stirred for 0.5h to obtain a mixed slurry;

[0146] Step (3): Weigh 7g of potassium tartrate and add it to the slurry obtained in step (2) under continuous stirring. Add ammonia dropwise until the pH value of the solution reaches 8. Continue stirring for 1.5h and let it stand at 65℃ for 20h to age.

[0147] Step (4): After static aging, the sample was first dried at 90℃ for 4 hours, then rinsed twice with 0.1mol / L dilute nitric acid, then calcined at 450℃ for 1 hour, and finally calcined at 700℃ for 3 hours. After cooling to room temperature, the bimetallic modified molecular sieve catalyst MC-13 was obtained.

[0148] The catalyst components, by mass ratio, are molecular sieve:SiO2:metal oxide:K2O = 47:38:12.2:2.8. The metal oxide is a mixture of two metal oxides, M1 and M2, where M1 is gallium oxide and M2 is bismuth oxide, with a ratio of M1:M2 = 1.51:1.

[0149] Catalyst evaluation method: Performance evaluation was conducted on a microreactor (manufacturer: Qingdao Jietian Technology) at a reaction temperature of 620℃ and a gas hourly space velocity of 1400 h⁻¹. -1 The evaluation feedstock was 99.5 wt% n-butane. The catalyst was the MC-13 catalyst prepared in Example 13.

[0150] The catalyst evaluation results showed that the conversion rate of n-butane was 68.88%, the yield of ethylene was 21.05 wt%, and the yield of propylene was 21.03 wt%.

[0151] Example 14

[0152] The catalyst was prepared according to the following steps:

[0153] Step (1): At room temperature, 17.7g of gallium nitrate and 8g of indium nitrate were dissolved in 65g of water, and the water bath was heated to 60℃ to completely dissolve them, resulting in a mixed solution of metals.

[0154] Step (2): 48g of ZSM-5 molecular sieve and 39g of SiO2 powder were added to the metal mixed solution obtained in step (1) under continuous stirring, and stirred for 0.5h to obtain a mixed slurry;

[0155] Step (3): Weigh 7.05g of potassium tartrate and add it to the slurry obtained in step (2) under continuous stirring. Add ammonia dropwise until the pH value of the solution reaches 7. Continue stirring for 1.5h and let it stand at 68℃ for 22h for aging.

[0156] Step (4): After static aging, the sample was first dried at 90℃ for 4 hours, then rinsed twice with 0.1mol / L dilute nitric acid, then calcined at 490℃ for 1 hour, and finally calcined at 700℃ for 3 hours. After cooling to room temperature, the bimetallic modified molecular sieve catalyst MC-14 was obtained.

[0157] The catalyst components, by mass ratio, are molecular sieve:SiO2:metal oxide:K2O = 48:39:10.18:2.82. The metal oxide is a mixture of two metal oxides, M1 and M2, where M1 is gallium oxide and M2 is indium oxide, with a ratio of M1:M2 = 1.75:1.

[0158] Catalyst evaluation method: Performance evaluation was conducted on a microreactor (manufacturer: Qingdao Jietian Technology) at a reaction temperature of 620℃ and a gas hourly space velocity of 1400 h⁻¹. -1 The evaluation feedstock was 99.5 wt% n-butane. The catalyst was the MC-14 catalyst prepared in Example 14.

[0159] The catalyst evaluation results showed that the conversion rate of n-butane was 68.97%, the yield of ethylene was 21.45 wt%, and the yield of propylene was 19.34 wt%.

[0160] Comparative Example 1

[0161] The catalyst was prepared according to the following steps:

[0162] Step (1): At room temperature, dissolve 15g of bismuth nitrate and 6g of zinc nitrate in 50g of water, and heat the water bath to 60℃ to completely dissolve them, to obtain a mixed solution of metals;

[0163] Step (2): 25g ZSM-5 molecular sieve and 66.63g SiO2 powder were added to the metal mixed solution obtained in step (1) under continuous stirring, and stirred for 0.5h to obtain a mixed slurry;

[0164] Step (3): Weigh 10g of potassium tartrate and add it to the slurry obtained in step (2) under continuous stirring. Add ammonia dropwise until the pH value of the solution reaches 7-9. Continue stirring for 1.5h and let it stand at 60℃ for 3h to age.

[0165] In step (4), the sample after static aging is first dried at 90℃ for 4 hours, then rinsed twice with 0.1mol / L dilute nitric acid, then calcined at 450℃ for 3 hours, and finally calcined at 650℃ for 2 hours. After cooling to room temperature, bimetallic modified molecular sieve catalyst D-1 is obtained.

[0166] The catalyst components, by mass ratio, are molecular sieve:SiO2:metal oxide:K2O = 25:66.63:6.37:2. The metal oxide is a mixture of two metal oxides, M1 and M2, where M1 is bismuth oxide and M2 is zinc oxide, with a ratio of M1:M2 = 4.82:1.

[0167] Catalyst evaluation method: Performance evaluation was conducted on a microreactor (manufacturer: Qingdao Jietian Technology) at a reaction temperature of 620℃ and a gas hourly space velocity of 1500 h⁻¹. -1 The evaluation feedstock was 99.5 wt% n-butane. The catalyst was the D-1 catalyst prepared in Comparative Example 1.

[0168] The catalyst evaluation results showed that the conversion rate of n-butane was 63.5%, the yield of ethylene was 16.81 wt%, and the yield of propylene was 20.52 wt%.

[0169] Comparative Example 2

[0170] The catalyst was prepared according to the following steps:

[0171] Step (1): At room temperature, dissolve 15g of bismuth nitrate and 6g of zinc nitrate in 50g of water, and heat the water bath to 60℃ to completely dissolve them, to obtain a mixed solution of metals;

[0172] Step (2): 55g ZSM-5 molecular sieve and 36.63g SiO2 powder were added to the metal mixed solution obtained in step (1) under continuous stirring, and stirred for 0.5h to obtain a mixed slurry;

[0173] Step (3): Weigh 10g of potassium tartrate and add it to the slurry obtained in step (2) under continuous stirring. Add ammonia dropwise until the pH value of the solution reaches 7-9. Continue stirring for 1.5h and let it stand at 60℃ for 3h to age.

[0174] In step (4), the sample after static aging is first dried at 90℃ for 4 hours, then rinsed twice with 0.1mol / L dilute nitric acid, then calcined at 450℃ for 3 hours, and finally calcined at 650℃ for 2 hours. After cooling to room temperature, bimetallic modified molecular sieve catalyst D-2 is obtained.

[0175] The catalyst components, by mass ratio, are molecular sieve:SiO2:metal oxide:K2O = 55:36.63:6.37:2. The metal oxide is a mixture of two metal oxides, M1 and M2, where M1 is bismuth oxide and M2 is zinc oxide, with a ratio of M1:M2 = 4.82:1.

[0176] Catalyst evaluation method: Performance evaluation was conducted on a microreactor (manufacturer: Qingdao Jietian Technology) at a reaction temperature of 620℃ and a gas hourly space velocity of 1500 h⁻¹.-1 The evaluation feedstock was 99.5 wt% n-butane. The catalyst was the D-2 catalyst prepared in Comparative Example 2.

[0177] The catalyst evaluation results showed that the conversion rate of n-butane was 70.5%, the yield of ethylene was 10.81 wt%, and the yield of propylene was 20.52 wt%.

[0178] Comparative Example 3

[0179] The catalyst was prepared according to the following steps:

[0180] Step (1): At room temperature, dissolve 4g of bismuth nitrate and 2g of ferric nitrate in 50g of water, and heat the water bath to 60℃ to completely dissolve them, to obtain a mixed solution of metals;

[0181] Step (2): 40g ZSM-5 molecular sieve and 57.53g SiO2 powder were added to the metal mixed solution obtained in step (1) under continuous stirring, and stirred for 0.5h to obtain a mixed slurry;

[0182] Step (3): Weigh 1g of potassium tartrate and add it to the slurry obtained in step (2) under continuous stirring. Add ammonia dropwise until the pH value of the solution reaches 7-9. Continue stirring for 1.5h and let it stand at 60℃ for 3h to age.

[0183] In step (4), the sample after static aging is first dried at 90℃ for 4 hours, then rinsed twice with 0.1mol / L dilute nitric acid, then calcined at 450℃ for 3 hours, and finally calcined at 650℃ for 2 hours. After cooling to room temperature, bimetallic modified molecular sieve catalyst D-3 is obtained.

[0184] The catalyst components, by mass ratio, are molecular sieve:SiO2:metal oxide:K2O = 40:57.53:2.07:0.4. The metal oxide is a mixture of two metal oxides, M1 and M2, where M1 is bismuth oxide and M2 is zinc oxide, with a ratio of M1:M2 = 2.13:1.

[0185] Catalyst evaluation method: Performance evaluation was conducted on a microreactor (manufacturer: Qingdao Jietian Technology) at a reaction temperature of 620℃ and a gas hourly space velocity of 1500 h⁻¹. -1 The evaluation feedstock was 99.5 wt% n-butane. The catalyst was the D-3 catalyst prepared in Comparative Example 3.

[0186] The catalyst evaluation results showed that the conversion rate of n-butane was 62.5%, the yield of ethylene was 17.1 wt%, and the yield of propylene was 22.02 wt%.

[0187] Comparative Example 4

[0188] The catalyst was prepared according to the following steps:

[0189] Step (1): At room temperature, dissolve 8.45g of bismuth nitrate and 6g of zinc nitrate in 50g of water, and heat the water bath to 60℃ to completely dissolve them, to obtain a mixed solution of metals;

[0190] Step (2): 37g ZSM-5 molecular sieve and 54.01g SiO2 powder were added to the metal mixed solution obtained in step (1) under continuous stirring and stirred for 0.5h to obtain a mixed slurry;

[0191] Step (3): Weigh 13g of potassium tartrate and add it to the slurry obtained in step (2) under continuous stirring. Add ammonia dropwise until the pH value of the solution reaches 10. Continue stirring for 1.5h and let it stand at 90℃ for 30h for aging.

[0192] In step (4), the sample after static aging is first dried at 90℃ for 4 hours, then rinsed twice with 0.1mol / L dilute nitric acid, then calcined at 550℃ for 2 hours, and finally calcined at 700℃ for 2 hours. After cooling to room temperature, the bimetallic modified molecular sieve catalyst D-4 is obtained.

[0193] The catalyst components, by mass ratio, are molecular sieve:SiO2:metal oxide:K2O = 37:54.01:3.79:5.2. The metal oxide is a mixture of two metal oxides, M1 and M2, where M1 is bismuth oxide and M2 is zinc oxide, with a ratio of M1:M2 = 3.62:1.

[0194] Catalyst evaluation method: Performance evaluation was conducted on a microreactor (manufacturer: Qingdao Jietian Technology) at a reaction temperature of 650℃ and a gas hourly space velocity of 1500 h⁻¹. -1 The evaluation feedstock was 99.5 wt% n-butane. The catalyst was the D-4 catalyst prepared in Comparative Example 4.

[0195] The catalyst evaluation results showed that the conversion rate of n-butane was 62.25%, the yield of ethylene was 16.71 wt%, and the yield of propylene was 17.38 wt%.

[0196] Comparing the reaction results: In Comparative Example 1, when the molecular sieve content is too low, there are too few acidic centers, resulting in insufficient number of acidic active centers and a low olefin yield. In Comparative Example 2, when the molecular sieve content is too high, the large number of high-density active centers leads to the formation of a large amount of methane, resulting in a low olefin yield. In Comparative Example 3, when the metal content in the catalyst is too low, there are insufficient metal active centers, resulting in a low olefin yield. In Comparative Example 4, when the K content is too high, the acidity of the molecular sieve is insufficient, resulting in a low olefin yield. Excellent olefin yields require the co-catalysis of acidic centers and metal active centers. Compared with existing technologies, the catalyst prepared in this application is easy to mold, has lower costs, better wear resistance, and the finished catalyst has higher ethylene and propylene yields.

[0197] Table 1. Yield of pure n-butane cracking products (wt%)

[0198]

[0199]

Claims

1. The application of a catalyst for the catalytic cracking of ethylene to propylene in the catalytic cracking of n-butane, characterized in that, The catalyst comprises silica, potassium, molecular sieve, and metal oxides attached to the molecular sieve. The potassium in the catalyst is calculated as potassium oxide, and the mass ratio of molecular sieve, silica, metal oxide, and K2O is 30-50:30-65:5-20:0.1-5. The molecular sieve is ZSM-5 molecular sieve. The metal oxide includes M1 and M2, wherein M1 is selected from gallium oxide, indium oxide or bismuth oxide, and M2 is selected from iron oxide or zinc oxide; the mass ratio of M1 to M2 is 1-7:

1.

2. The application according to claim 1, characterized in that, The mass ratio of molecular sieve, silica, metal oxide and K2O is 35-45:45-55:5-10:1-3.

3. The application according to claim 1, characterized in that, The mass ratio of M1 to M2 is 1-2:

1.

4. The application according to claim 1, characterized in that, The method for preparing the catalyst includes: (1) Dissolve the soluble salts of M1 and M2 in water; (2) Mix with ZSM-5 molecular sieve and SiO2 powder; (3) Add potassium tartrate, adjust the pH value to 7-9 with ammonia water, and let it stand for aging and roasting.

5. The application according to claim 4, characterized in that, In step (1), the soluble salts of M1 and M2 are nitrates, nitrites or sulfates of M1 and M2.

6. The application according to claim 4, characterized in that, In step (3), the static aging temperature is 60-80℃ and the static aging time is 2-24h.

7. The application according to claim 4, characterized in that, In step (3), the roasting is first carried out at 450~600℃ for 2~3 hours, and then roasted at 600-750℃ for 1-2 hours.

8. A process for the catalytic cracking of n-butane to produce ethylene and propylene, characterized in that, A catalyst for the preparation of ethylene and propylene using catalytic cracking; the catalyst comprises silica, potassium, a molecular sieve, and a metal oxide attached to the molecular sieve, wherein the potassium in the catalyst is calculated as potassium oxide, and the mass ratio of molecular sieve, silica, metal oxide, and K2O is 30-50:30-65:5-20:0.1-5; the molecular sieve is ZSM-5 molecular sieve; The metal oxide includes M1 and M2, wherein M1 is selected from gallium oxide, indium oxide or bismuth oxide, and M2 is selected from iron oxide or zinc oxide; the mass ratio of M1 to M2 is 1-7:

1.

9. The process according to claim 8, characterized in that, The reaction conditions for the catalytic cracking of n-butane to ethylene and propylene include: a temperature of 500-650℃, atmospheric pressure, and a gas hourly space velocity of 1200-1600 h⁻¹. -1 The agent-to-oil ratio is 3 to 10, and the agent-to-oil ratio is a weight ratio.

Images