A bifunctional acid-base synergistic catalyst and its preparation method

Abstract

This invention discloses an acid-base synergistic bifunctional catalyst and its preparation method. The catalyst has a core-shell structure, with the core exhibiting acid catalysis and the active component being a molecular sieve; the outer shell exhibits base catalysis and the active component is a silicon-containing composite oxide. The catalyst, on a dry basis, comprises the following components by weight percentage: 5-65% molecular sieve; 10-70% oxide binder; 10-70% natural minerals; and 5-65% silicon-containing composite oxide. The 10-70% oxide binder refers to the oxides in the oxide binder comprising 10-70% of the total dry-basis volume of the catalyst. This catalyst, with its core-shell structure, acid catalysis in the core, and base catalysis in the outer shell, exhibits characteristics of low coke yield, high heavy oil conversion rate, and high propylene yield in heavy oil catalytic cracking reactions.

Description

Technical Field

[0001] This invention relates to the field of heavy oil catalytic cracking technology, and in particular to an acid-base synergistic bifunctional catalyst and its preparation method. Background Technology

[0002] Low-carbon olefins such as ethylene, propylene, and butene are important basic chemical raw materials, widely used in the production of the three major synthetic materials—resins, fibers, and rubber. With the increasing demand for these three synthetic materials, my country's demand for low-carbon olefins continues to rise, leading to widespread attention on technologies for increasing low-carbon olefin production.

[0003] In my country, ethylene, propylene, and butene are mainly produced through steam cracking, catalytic cracking, catalytic pyrolysis, alkane dehydrogenation, and methanol-to-olefins processes. Among these, catalytic cracking / catalytic pyrolysis industrial units provide about one-third of the propylene resources. The raw materials for production include naphtha, diesel oil, and heavy distillate oil.

[0004] Given my country's fossil energy structure and the fact that its crude oil resources are primarily heavy crude oil, research on technologies to increase the production of low-carbon olefins from heavy oils such as atmospheric residue and vacuum residue is of great strategic significance. Since catalysts play a crucial role in the catalytic cracking reaction of heavy oil, it is imperative to develop a catalyst with high heavy oil conversion rate and high low-carbon olefin yield. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides an acid-base synergistic bifunctional catalyst and its preparation method. The catalyst prepared by this method, when applied to the catalytic cracking process of heavy oil, exhibits characteristics such as low coke yield, high heavy oil conversion rate, and high propylene yield.

[0006] In a first aspect, the present invention provides an acid-base synergistic bifunctional catalyst, which is achieved by the following technical solution.

[0007] A bifunctional acid-base synergistic catalyst has a core-shell structure, wherein the core has acid catalysis function and the active component is a molecular sieve; the outer shell has base catalysis function and the active component is a silicon-containing composite oxide.

[0008] The catalyst, on a dry basis, comprises the following components by weight percentage:

[0009] Molecular sieve 5~65%;

[0010] Oxide binder 10~70%;

[0011] Natural minerals: 10-70%;

[0012] Silicon-containing composite oxides 5-65%;

[0013] Among them, 10-70% oxide binder means that the oxides in the oxide binder account for 10-70% of the total dry base of the catalyst.

[0014] Furthermore, the molecular screening uses at least one of Y, β, MCM-22, ZSM-5, IM-5, MOR, and SAPO-34. Preferably, the molecular screening uses Y, β, ZSM-5, and IM-5.

[0015] Furthermore, the oxide binder includes a first binder and a second binder, with a dry basis ratio of 1:(1~2) for the first binder and the second binder; the first binder is selected from boehmite and / or aluminum sol; the second binder is selected from silica sol and / or sodium silicate.

[0016] Furthermore, the natural minerals include a first natural mineral and a second natural mineral, and the dry basis ratio of the first natural mineral and the second natural mineral is 2:1 to 1:2.5; the first natural mineral is selected from at least one of kaolin, attapulgite, and bentonite; the second natural mineral is selected from at least one of halloysite, hydrotalcite, and magnesium aluminum spinel.

[0017] Furthermore, the preparation method of the silicon-containing composite oxide is as follows: using mesoporous silica powder as a carrier, the silicon-containing composite oxide is prepared by impregnating it in the impregnation component by an equal volume impregnation method. After impregnation, the powder is dried and calcined to obtain the silicon-containing composite oxide. The oxide of the metal component in the silicon-containing composite oxide accounts for 0.05~80wt% of the total amount of the silicon-containing composite oxide.

[0018] Furthermore, the specific surface area of ​​the mesoporous silica powder is greater than 200 m². 2 / g, pore volume greater than 0.2cm 3 / g; the impregnation component is selected from at least one of Group 1 metal oxides, Group 2 metal oxides, Group 1 metal salts, and Group 2 metal salts. Preferably, the impregnation component is selected from potassium oxide, magnesium oxide, calcium oxide, barium oxide, potassium nitrate, magnesium nitrate, calcium nitrate, and barium nitrate.

[0019] Furthermore, the drying temperature of the impregnated powder is 100~200℃ for 2~6h, and the calcination temperature is 550~650℃ for 2~6h.

[0020] Secondly, the present invention provides a method for preparing an acid-base synergistic bifunctional catalyst, which is achieved by the following technical solution.

[0021] A method for preparing the above-mentioned acid-base synergistic bifunctional catalyst includes the following steps:

[0022] S1. Molecular sieve, first binder, and first natural mineral are mixed evenly in deionized water and stirred into a slurry. Then, the pH of the slurry is adjusted to 2-6 with an acidic solution. After one spray granulation and calcination, a semi-finished product of microsphere catalyst with a size of 20-100 μm is obtained.

[0023] S2. The silicon-containing composite oxide, the second binder, and the second natural mineral are mixed evenly in deionized water and stirred into a slurry. Then, the catalyst semi-finished product obtained in step S1 is added to the slurry and stirred evenly. The pH of the slurry is adjusted to 2-6 with an acidic solution. After secondary spray granulation and calcination, a 40-200 μm microsphere acid-base synergistic bifunctional catalyst is obtained.

[0024] Furthermore, the acidic solution is selected from formic acid solution, acetic acid solution, hydrochloric acid solution, nitric acid solution or sulfuric acid solution, and the hydrogen ion concentration is 0.1~10 mol / L.

[0025] Furthermore, the slurry solid content of the primary spray granulation is 10-30%, and the slurry solid content of the secondary spray granulation is 20-40 wt%.

[0026] Furthermore, the calcination temperature is 550~650℃, and the time is 2~6h.

[0027] This application has the following beneficial effects.

[0028] The catalyst of this invention has a core-shell structure, with the core having acid catalytic function and the outer shell having base catalytic function. Under the action of the core-shell, acid-base dual-function catalyst, the feedstock heavy oil preferentially contacts the base catalytic active center of the catalyst shell, and then contacts the acid catalytic active center of the catalyst core. This can maximize the acid-base synergistic catalytic effect, thereby maximizing the single-pass conversion rate, maximizing the inhibition of hydrogen transfer and aromatization reactions, and ultimately achieving the goal of improving the selectivity and yield of low-carbon olefins and reducing the coke yield. Detailed Implementation

[0029] The present patent application will be further described below with reference to the embodiments.

[0030] Unless otherwise specified, the experimental methods used in the following preparation examples and embodiments are conventional methods; the materials and reagents used in the following preparation examples and embodiments are commercially available unless otherwise specified.

[0031] Example 1

[0032] A method for preparing an acid-base synergistic bifunctional catalyst includes the following steps:

[0033] (1) ZSM-5 molecular sieve, pseudoboehmite and kaolin are mixed evenly in deionized water and stirred into a slurry. The pH of the slurry is adjusted to 2.0 with a formic acid solution with a hydrogen ion concentration of 0.1 mol / L, and the solid content of the slurry is adjusted to 10% with deionized water. Finally, after spray granulation and calcination at 550℃ for 2 hours, a microsphere catalyst semi-finished product of 20~100μm is obtained.

[0034] (2) Using mesoporous silica powder as a carrier, silicon-containing composite oxides were prepared by an equal-volume impregnation method. First, a hydrochloric acid solution of potassium oxide and magnesium oxide was added to the mesoporous silica powder and allowed to stand for 3 hours. Then, the impregnated powder was dried at 100°C for 2 hours and calcined at 550°C for 2 hours to obtain silicon-containing composite oxides. In the silicon-containing composite oxides, potassium oxide accounted for 0.05 wt% of the total amount of silicon-containing composite oxides and magnesium oxide accounted for 0.5 wt% of the total amount of silicon-containing composite oxides.

[0035] (3) Mix the silicon-containing composite oxide, silica sol and halloysite evenly in deionized water and stir to form a slurry. Then add the catalyst semi-finished product obtained in step (1) into the slurry and stir evenly. Adjust the pH of the slurry to 6.0 with acetic acid solution with a hydrogen ion concentration of 0.2 mol / L and adjust the solid content of the slurry to 30% with deionized water. Finally, after secondary spray granulation and calcination at 560℃ for 3h, the finished microsphere catalyst product with a diameter of 40~200μm is obtained and marked as ABC-1#.

[0036] (4) The ABC-1# catalyst, on a dry basis, comprises the following components by weight percentage:

[0037] A) 65% ZSM-5 molecular sieve;

[0038] B) 5% Al2O3 (provided by boehmite), 5% SiO2 (provided by silica sol).

[0039] C) 5% kaolin, 5% halloysite;

[0040] D) 15% silicon-containing composite oxides.

[0041] (5) Using atmospheric residue oil as raw material, under the conditions of reaction temperature 600℃, catalyst-to-oil ratio 10, water-to-oil ratio 20% and regeneration temperature 670℃, the reaction performance of ABC-1# catalyst was evaluated by fixed fluidized bed, and the coke yield, heavy oil conversion rate and propylene yield of the catalyst were calculated, as shown in Table 1.

[0042] Example 2

[0043] A method for preparing an acid-base synergistic bifunctional catalyst includes the following steps:

[0044] (1) Mix Y molecular sieve, IM-5 molecular sieve, alumina sol and attapulgite in deionized water and stir to form a slurry. Adjust the pH of the slurry to 4.0 with hydrochloric acid solution with a hydrogen ion concentration of 1.0 mol / L and adjust the solid content of the slurry to 20% with deionized water. Finally, after spray granulation and calcination at 600℃ for 4 hours, a semi-finished product of microsphere catalyst with a diameter of 20~100μm is obtained.

[0045] (2) Using mesoporous silica powder as a carrier, silicon-containing composite oxides were prepared by an equal-volume impregnation method. First, a hydrochloric acid solution of calcium oxide and barium oxide was added to the mesoporous silica powder and allowed to stand for 5 hours. Then, the impregnated powder was dried at 150°C for 4 hours and calcined at 600°C for 4 hours to obtain silicon-containing composite oxides. In the silicon-containing composite oxides, calcium oxide accounted for 5.0 wt% of the total amount of silicon-containing composite oxides, and barium oxide accounted for 10 wt% of the total amount of silicon-containing composite oxides.

[0046] (3) Mix silicon-containing composite oxide, sodium silicate and hydrotalcite evenly in deionized water and stir to form a slurry. Then add the catalyst semi-finished product obtained in step (1) into the slurry and stir evenly. Adjust the pH of the slurry to 5.0 with nitric acid solution with a hydrogen ion concentration of 5.0 mol / L and adjust the solid content of the slurry to 25% with deionized water. Finally, after secondary spray granulation and calcination at 650℃ for 6 hours, the finished microsphere catalyst product with a diameter of 40~200μm is obtained and marked as ABC-2#.

[0047] (4) The ABC-2# catalyst, on a dry basis, comprises the following components by weight percentage:

[0048] A) 5% Y molecular sieve, 5% IM-5 molecular sieve;

[0049] B) 5% Al2O3 (provided by aluminum sol), 5% SiO2 (provided by sodium silicate).

[0050] C) 10% attapulgite, 5% hydrotalcite;

[0051] D) 65% silicon-containing composite oxides.

[0052] (5) Using atmospheric residue oil as raw material, the reaction performance of ABC-2# catalyst was evaluated by fixed fluidized bed under the conditions of reaction temperature 600℃, catalyst-to-oil ratio 10, water-to-oil ratio 20% and regeneration temperature 670℃. The coke yield, heavy oil conversion rate and propylene yield of the catalyst were calculated and are shown in Table 1.

[0053] Example 3

[0054] A method for preparing an acid-base synergistic bifunctional catalyst includes the following steps:

[0055] (1) Mix β molecular sieve, MCM-22 molecular sieve, pseudoboehmite, alumina sol, kaolin, and bentonite in deionized water and stir to form a slurry. Adjust the pH of the slurry to 6.0 with sulfuric acid solution with a hydrogen ion concentration of 10 mol / L and adjust the solid content of the slurry to 30% with deionized water. Finally, after spray granulation and calcination at 650℃ for 6 hours, a microsphere catalyst semi-finished product of 20~100μm is obtained.

[0056] (2) Using mesoporous silica powder as a carrier, silicon-containing composite oxides were prepared by an equal-volume impregnation method. First, an aqueous solution of magnesium nitrate and barium nitrate was added to the mesoporous silica powder and allowed to stand for 3 hours. Then, the impregnated powder was dried at 200°C for 6 hours and calcined at 650°C for 6 hours to obtain silicon-containing composite oxides. In the silicon-containing composite oxides, magnesium oxide accounted for 50 wt% of the total amount of silicon-containing composite oxides and barium oxide accounted for 10 wt% of the total amount of silicon-containing composite oxides.

[0057] (3) The silicon-containing composite oxide, silica sol, sodium silicate, halloysite, and magnesium aluminum spinel are mixed evenly in deionized water and stirred into a slurry. Then, the catalyst semi-finished product obtained in step (1) is added to the slurry and stirred evenly. The pH of the slurry is adjusted to 5.0 with a formic acid solution with a hydrogen ion concentration of 10 mol / L, and the solid content of the slurry is adjusted to 40% with deionized water. Finally, after secondary spray granulation and calcination at 650℃ for 6 hours, a microsphere catalyst product of 40~200μm is obtained and marked as ABC-3#.

[0058] (4) The ABC-3# catalyst, on a dry basis, comprises the following components by weight percentage:

[0059] A) 2% β molecular sieve, 3% MCM-22 molecular sieve;

[0060] B) 15% Al2O3 (provided by boehmite), 10% Al2O3 (provided by aluminum sol), 35% SiO2 (provided by silica sol), 10% SiO2 (provided by sodium silicate).

[0061] C) 5% kaolin, 5% bentonite, 5% halloysite, 5% magnesium aluminum spinel;

[0062] D) 5% silicon-containing composite oxides.

[0063] (5) Using atmospheric residue oil as raw material, the reaction performance of ABC-3# catalyst was evaluated by fixed fluidized bed under the conditions of reaction temperature 600℃, catalyst-to-oil ratio 10, water-to-oil ratio 20% and regeneration temperature 670℃. The coke yield, heavy oil conversion rate and propylene yield of the catalyst were calculated and are shown in Table 1.

[0064] Example 4

[0065] A method for preparing an acid-base synergistic bifunctional catalyst includes the following steps:

[0066] (1) MOR molecular sieve, SAPO-34 molecular sieve, pseudoboehmite and bentonite are mixed evenly in deionized water and stirred into a slurry. The pH of the slurry is adjusted to 5.0 with acetic acid solution with a hydrogen ion concentration of 8.0 mol / L, and the solid content of the slurry is adjusted to 15% with deionized water. Finally, after one spray granulation and calcination at 630℃ for 5 h, a microsphere catalyst semi-finished product of 20~100μm is obtained.

[0067] (2) Using mesoporous silica powder as a carrier, silicon-containing composite oxides were prepared by an equal-volume impregnation method. First, an aqueous solution of potassium nitrate and calcium nitrate was added to the mesoporous silica powder and allowed to stand for 3 hours. Then, the impregnated powder was dried at 200°C for 6 hours and calcined at 650°C for 6 hours to obtain silicon-containing composite oxides. In the silicon-containing composite oxides, potassium oxide accounted for 5.0 wt% of the total amount of silicon-containing composite oxides and calcium oxide accounted for 75 wt% of the total amount of silicon-containing composite oxides.

[0068] (3) Mix the silicon-containing composite oxide, silica sol, and magnesium aluminum spinel evenly in deionized water and stir to form a slurry. Then add the catalyst semi-finished product obtained in step (1) into the slurry and stir evenly. Adjust the pH of the slurry to 4.5 with hydrochloric acid solution with a hydrogen ion concentration of 7.5 mol / L and adjust the solid content of the slurry to 38% with deionized water. Finally, after secondary spray granulation and calcination at 640℃ for 5 hours, the finished microsphere catalyst product with a diameter of 40~200μm is obtained and marked as ABC-4#.

[0069] (4) The ABC-4# catalyst, on a dry basis, comprises the following components by weight percentage:

[0070] A) 5% MOR molecular sieve, 5% SAPO-34 molecular sieve;

[0071] B) 5% Al2O3 (provided by boehmite), 5% SiO2 (provided by silica sol).

[0072] C) 20% bentonite, 50% magnesium aluminum spinel;

[0073] D) 10% silicon-containing composite oxides.

[0074] (5) Using atmospheric residue oil as raw material, the reaction performance of ABC-4# catalyst was evaluated by fixed fluidized bed under the conditions of reaction temperature 600℃, catalyst-to-oil ratio 10, water-to-oil ratio 20% and regeneration temperature 670℃. The coke yield, heavy oil conversion rate and propylene yield of the catalyst were calculated and are shown in Table 1.

[0075] Table 1

[0076]

[0077] The reference catalyst is a commercially available heavy oil catalytic cracking catalyst, comprising the following components by weight percentage:

[0078] A) 10% Y molecular sieve, 30% ZSM-5 molecular sieve;

[0079] B) 22% alumina (provided by boehmite);

[0080] C) 35% kaolin;

[0081] D) 3% phosphorus oxide.

[0082] Compared to the reference agent, the samples prepared by the method of this invention have higher heavy oil conversion rate and propylene yield. Among them, sample ABC-2# has the highest heavy oil conversion rate, and sample ABC-1# has the highest propylene yield.

[0083] The embodiments described herein are preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape, and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. An acid-base synergistic bifunctional catalyst, characterized in that: The catalyst has a core-shell structure, with the core having acid catalysis function and the active component being a molecular sieve; the outer shell has base catalysis function and the active component being a silicon-containing composite oxide. The catalyst, on a dry basis, comprises the following components by weight percentage: Molecular sieve 5~65%; Oxide binder 10~70%; Natural minerals: 10-70%; Silicon-containing composite oxides 5-65%; Among them, 10-70% oxide binder means that the oxides in the oxide binder account for 10-70% of the total dry base of the catalyst; The molecular screening uses at least one of Y, β, MCM-22, ZSM-5, IM-5, MOR, and SAPO-34; The method for preparing the silicon-containing composite oxide is as follows: using mesoporous silica powder as a carrier, the silicon-containing composite oxide is prepared by impregnating the powder in an impregnation component using an equal-volume impregnation method. The impregnated powder is then dried and calcined to obtain the silicon-containing composite oxide. The metal component oxide in the silicon-containing composite oxide accounts for 0.05~80 wt% of the total silicon-containing composite oxide. The specific surface area of ​​the mesoporous silica powder is greater than 200 m² / g. 2 / g, pore volume greater than 0.2cm 3 / g; the impregnation component is selected from at least one of the following: a first group metal oxide, a second group metal oxide, a first group metal salt, and a second group metal salt.

2. The acid-base synergistic bifunctional catalyst according to claim 1, characterized in that: The oxide binder includes a first binder and a second binder, with a dry basis ratio of 1:(1~2) for the first binder and the second binder; the first binder is selected from boehmite and / or aluminum sol; the second binder is selected from silica sol and / or sodium silicate.

3. The acid-base synergistic bifunctional catalyst according to claim 1, characterized in that: The natural minerals include a first natural mineral and a second natural mineral, and the dry basis ratio of the first natural mineral and the second natural mineral is 2:1 to 1:2.5; the first natural mineral is selected from at least one of kaolin, attapulgite, and bentonite; the second natural mineral is selected from at least one of halloysite, hydrotalcite, and magnesium aluminum spinel.

4. A method for preparing the acid-base synergistic bifunctional catalyst according to any one of claims 1-3, characterized in that: Includes the following steps: S1. Molecular sieve, first binder, and first natural mineral are mixed evenly in deionized water and stirred into a slurry. Then, the pH of the slurry is adjusted to 2-6 with an acidic solution. After one spray granulation and calcination, a semi-finished product of microsphere catalyst with a size of 20-100 μm is obtained. S2. The silicon-containing composite oxide, the second binder, and the second natural mineral are mixed evenly in deionized water and stirred into a slurry. Then, the catalyst semi-finished product obtained in step S1 is added to the slurry and stirred evenly. The pH of the slurry is adjusted to 2-6 with an acidic solution. After secondary spray granulation and calcination, a 40-200 μm microsphere acid-base synergistic bifunctional catalyst is obtained.

5. The method for preparing a base-synergistic bifunctional catalyst according to claim 4, characterized in that: The acidic solution is selected from formic acid solution, acetic acid solution, hydrochloric acid solution, nitric acid solution or sulfuric acid solution, and the hydrogen ion concentration is 0.1~10 mol / L.

6. The method for preparing a base-synergistic bifunctional catalyst according to claim 4, characterized in that: The solid content of the slurry in the primary spray granulation is 10-30%, and the solid content of the slurry in the secondary spray granulation is 20-40 wt%.

7. The method for preparing a base-synergistic bifunctional catalyst according to claim 4, characterized in that: The roasting temperature is 550~650℃, and the time is 2~6h.

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