A straight-run diesel catalytic cracking catalyst and its preparation method

Abstract

This invention discloses a straight-run diesel catalytic cracking catalyst and its preparation method. The catalyst has a core-shell structure, with the core exhibiting catalytic cracking activity and the outer shell exhibiting catalytic dehydrogenation activity. 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%; and metal oxides 0.05-70%. The 10-70% oxide binder refers to the oxides in the oxide binder comprising 10-70% of the total dry-basis amount of the catalyst. The catalyst of this invention has acid catalytic cracking activity in the core and catalytic dehydrogenation activity in the outer shell. When used in the catalytic cracking of straight-run diesel to produce low-carbon olefins, it offers advantages such as high diesel single-pass conversion and high propylene yield.

Description

Technical Field

[0001] This invention relates to the field of straight-run diesel catalytic cracking technology, and particularly to a straight-run diesel catalytic cracking 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. In my country, low-carbon olefins are mainly produced through steam cracking, catalytic cracking, catalytic pyrolysis, alkane dehydrogenation, and methanol-to-olefins (MTO) processes. Catalytic cracking / catalytic pyrolysis industrial units provide approximately one-third of the propylene resources, with processing feedstocks including naphtha, diesel oil, and heavy distillate fuels.

[0003] my country's diesel consumption peak has passed, and the diesel market has entered, and will continue to be, a state of oversupply. Refining and chemical enterprises are competing to reduce diesel production by lowering the diesel-to-gasoline ratio or reducing fuel consumption while increasing chemical production. Straight-run diesel accounts for approximately 50% of my country's diesel fuel mix, and its saturated alkane content is as high as 45-55%, making it a high-quality feedstock for catalytic cracking. Converting straight-run diesel into high-value low-carbon olefins through catalytic cracking would be of great significance for refining and chemical enterprises to reduce the diesel-to-gasoline ratio and optimize their product structure. Since catalysts play a crucial role in the catalytic cracking reaction of straight-run diesel, developing a catalyst with high cracking conversion rate and high low-carbon olefin yield is imperative. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a straight-run diesel catalytic cracking catalyst and its preparation method. The catalyst prepared by this method, when applied to the catalytic cracking reaction of alkane-rich straight-run diesel, exhibits high cracking conversion rate and high propylene yield.

[0005] In a first aspect, the present invention provides a straight-run diesel catalytic cracking catalyst, which is achieved by the following technical solution.

[0006] A straight-run diesel catalytic cracking catalyst, wherein the catalyst has a core-shell structure, the core having catalytic cracking function and the shell having catalytic dehydrogenation function;

[0007] The catalyst, on a dry basis, comprises the following components by weight percentage:

[0008] Molecular sieve 5~65%;

[0009] Oxide binder 10~70%;

[0010] Natural minerals: 10-70%;

[0011] Metal oxides 0.05~70%;

[0012] 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.

[0013] 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.

[0014] Furthermore, the oxide binder includes a first binder and a second binder, and the dry basis ratio of the first binder and the second binder is 1.5:1 to 1:2.5; the first binder is selected from boehmite and / or aluminum sol; the second binder is selected from silica sol and / or sodium silicate.

[0015] 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 1:(1~3); 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.

[0016] Furthermore, the metal oxide is obtained by calcining a macromolecular organometallic salt, wherein the macromolecular organometallic salt is selected from at least one of nickel acetate, zinc acetate, iron acetate, nickel oxalate, zinc oxalate, and iron oxalate.

[0017] Secondly, the present invention provides a method for preparing a straight-run diesel catalytic cracking catalyst, which is achieved by the following technical solution.

[0018] A method for preparing the above-mentioned straight-run diesel catalytic cracking catalyst includes the following steps:

[0019] 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.

[0020] S2. The catalyst semi-finished product obtained in step S1 is mixed evenly with macromolecular organometallic salt, second binder and second natural mineral in deionized water, stirred into a slurry, and the pH of the slurry is adjusted to 2~6 with acidic solution. After secondary spray granulation and calcination, microsphere catalyst finished product of 40~200μm is obtained.

[0021] 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.

[0022] 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%.

[0023] Furthermore, the calcination temperature is 550~650℃, and the time is 2~6h.

[0024] This application has the following beneficial effects.

[0025] Under the action of the core-shell bifunctional catalyst of this invention, the feedstock diesel preferentially contacts the dehydrogenation catalytic active center of the catalyst shell, and the generated active intermediate then contacts the cracking catalytic active center of the catalyst core, thereby maximizing the synergistic catalytic effect of dehydrogenation and cracking, thereby maximizing the single-pass conversion rate, maximizing the inhibition of hydrogen transfer and aromatization reactions, and ultimately achieving the goal of improving propylene selectivity and yield. Detailed Implementation

[0026] The present patent application will be further described below with reference to the embodiments.

[0027] 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.

[0028] Example 1

[0029] A method for preparing a straight-run diesel catalytic cracking catalyst includes the following steps:

[0030] Y molecular sieve, pseudoboehmite, and kaolin were mixed evenly in deionized water and stirred into a slurry. The pH of the slurry was then adjusted to 2.0 with a 6 mol / L formic acid solution, and the solid content of the slurry was controlled to be 10%. Finally, after one spray granulation and calcination at 550℃ for 2 hours, a semi-finished product of microsphere catalyst with a size of 20~100μm was obtained.

[0031] The catalyst semi-finished product was mixed evenly with nickel acetate, silica sol, and halloysite in deionized water and stirred into a slurry. The pH of the slurry was adjusted to 2.0 with an acetic acid solution with a hydrogen ion concentration of 10 mol / L, and the solid content of the slurry was controlled to be 20%. Finally, after secondary spray granulation and calcination at 550℃ for 2 hours, microsphere catalyst products with a size of 40~200μm were obtained and labeled as DDC-1#.

[0032] The DDC-1# catalyst, on a dry basis, comprises the following components by weight percentage:

[0033] A) 5% Y molecular sieve;

[0034] B) 5% alumina (first binder, provided by boehmite) and 5% silica (second binder, provided by silica sol).

[0035] C) 30% kaolin and 40% halloysite;

[0036] D) 15% nickel oxide.

[0037] Using straight-run diesel as feedstock, the reaction performance of the DDC-1# catalyst was evaluated by a 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 single-pass conversion rate of diesel and the yield of propylene were calculated and are shown in Table 1.

[0038] Example 2

[0039] A method for preparing a straight-run diesel catalytic cracking catalyst includes the following steps:

[0040] β molecular sieve, alumina sol, and attapulgite were mixed evenly in deionized water and stirred into a slurry. The pH of the slurry was then adjusted to 6.0 with a hydrochloric acid solution with a hydrogen ion concentration of 0.1 mol / L, and the solid content of the slurry was controlled to be 30%. Finally, after one spray granulation and calcination at 650℃ for 6 hours, a semi-finished product of microsphere catalyst with a size of 20~100μm was obtained.

[0041] The catalyst semi-finished product was mixed evenly with zinc acetate, sodium silicate, and hydrotalcite in deionized water and stirred into a slurry. The pH of the slurry was adjusted to 6.0 with a nitric acid solution with a hydrogen ion concentration of 0.5 mol / L, and the solid content of the slurry was controlled to be 40%. Finally, after secondary spray granulation and calcination at 650℃ for 6 hours, the finished microsphere catalyst product with a size of 40~200μm was obtained and marked as DDC-2#.

[0042] The DDC-2# catalyst, on a dry basis, comprises the following components by weight percentage:

[0043] A) 65% β-zeolite;

[0044] B) 5% alumina (first binder, supplied by alumina sol) and 10% silica (second binder, supplied by sodium silicate).

[0045] C) 5% attapulgite and 5% hydrotalcite;

[0046] D) 10% zinc oxide.

[0047] Using straight-run diesel as feedstock, the reaction performance of the DDC-2# catalyst was evaluated by a 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 single-pass conversion rate of diesel and propylene yield of the catalyst were calculated, as shown in Table 1.

[0048] Example 3

[0049] A method for preparing a straight-run diesel catalytic cracking catalyst includes the following steps:

[0050] MCM-22 molecular sieve, ZSM-5 molecular sieve, boehmite, alumina sol, kaolin, and bentonite were mixed evenly in deionized water and stirred into a slurry. The pH of the slurry was then adjusted to 4.0 with a sulfuric acid solution with a hydrogen ion concentration of 2 mol / L, and the solid content of the slurry was controlled to be 20%. Finally, after one spray granulation and calcination at 600℃ for 4 hours, a semi-finished product of microsphere catalyst with a size of 20~100μm was obtained.

[0051] The catalyst semi-finished product was mixed evenly with ferric acetate, silica sol, sodium silicate, hydrotalcite, and magnesium aluminum spinel in deionized water and stirred into a slurry. The pH of the slurry was adjusted to 3.0 with a 3 mol / L formic acid solution, and the solid content of the slurry was controlled to be 35%. Finally, after secondary spray granulation and calcination at 620℃ for 5 h, the finished microsphere catalyst product with a size of 40~200 μm was obtained and marked as DDC-3#.

[0052] The DDC-3# catalyst, on a dry basis, comprises the following components by weight percentage:

[0053] A) 3% MCM-22 molecular sieve and 7% ZSM-5 molecular sieve;

[0054] B) 20% alumina (first binder, of which 15% is provided by boehmite and 5% by alumina sol), and 50% silica (second binder, of which 40% is provided by silica sol and 10% by sodium silicate).

[0055] C) 3% kaolin, 2% bentonite, 9.95% hydrotalcite, and 5% magnesium aluminum spinel;

[0056] D) 0.05% iron oxide (provided with ferric acetate).

[0057] Using straight-run diesel as feedstock, the reaction performance of DDC-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 single-pass conversion rate of diesel and propylene yield of the catalyst were calculated, as shown in Table 1.

[0058] Example 4

[0059] A method for preparing a straight-run diesel catalytic cracking catalyst includes the following steps:

[0060] IM-5 molecular sieve, alumina sol, and attapulgite were mixed evenly in deionized water and stirred into a slurry. The pH of the slurry was then adjusted to 3.0 with an acetic acid solution with a hydrogen ion concentration of 1 mol / L, and the solid content of the slurry was controlled to be 12%. Finally, after one spray granulation and calcination at 630℃ for 3 hours, a semi-finished product of microsphere catalyst with a size of 20~100μm was obtained.

[0061] The catalyst semi-finished product was mixed evenly with nickel oxalate, zinc oxalate, silica sol, and hydrotalcite in deionized water and stirred into a slurry. The pH of the slurry was adjusted to 5.0 with a nitric acid solution with a hydrogen ion concentration of 0.7 mol / L, and the solid content of the slurry was controlled to be 38%. Finally, after secondary spray granulation and calcination at 640℃ for 5 h, the finished microsphere catalyst product with a size of 40~200 μm was obtained and marked as DDC-4#.

[0062] The DDC-4# catalyst, on a dry basis, comprises the following components by weight percentage:

[0063] A) 6% IM-5 molecular sieve;

[0064] B) 3% aluminum oxide (first binder, supplied by aluminum sol) and 7% silicon oxide (second binder, supplied by silica sol).

[0065] C) 4% attapulgite and 10% hydrotalcite;

[0066] D) 40% nickel oxide, 30% zinc oxide.

[0067] Using straight-run diesel as feedstock, the reaction performance of DDC-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 single-pass conversion rate of diesel and propylene yield of the catalyst were calculated, as shown in Table 1.

[0068] Example 5

[0069] A method for preparing a straight-run diesel catalytic cracking catalyst includes the following steps:

[0070] MOR molecular sieve, SAPO-34 molecular sieve, pseudoboehmite, and kaolin were mixed evenly in deionized water and stirred into a slurry. The pH of the slurry was then adjusted to 3.5 with a 5 mol / L hydrochloric acid solution, and the solid content of the slurry was controlled to be 18%. Finally, after one spray granulation and calcination at 580℃ for 3 hours, a semi-finished product of microsphere catalyst with a size of 20~100μm was obtained.

[0071] The catalyst semi-finished product was mixed evenly with ferric oxalate, sodium silicate, and halloysite in deionized water and stirred into a slurry. The pH of the slurry was adjusted to 4.5 with a sulfuric acid solution with a hydrogen ion concentration of 1.2 mol / L, and the solid content of the slurry was controlled to be 32%. Finally, after secondary spray granulation and calcination at 610℃ for 3 hours, the finished microsphere catalyst product with a size of 40~200μm was obtained and marked as DDC-5#.

[0072] The DDC-5# catalyst, on a dry basis, comprises the following components by weight percentage:

[0073] A) 16% MOR molecular sieve, 19% SAPO-34 molecular sieve;

[0074] B) 18% alumina (first binder, provided by boehmite) and 12% silica (second binder, provided by sodium silicate).

[0075] C) 3% kaolin and 7% halloysite;

[0076] D) 25% iron oxide (provided with ferric oxalate).

[0077] Using straight-run diesel as feedstock, the reaction performance of DDC-5# 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 single-pass conversion rate of diesel and propylene yield of the catalyst were calculated, as shown in Table 1.

[0078] Table 1

[0079]

[0080] The reference catalyst is a commercially available heavy oil catalytic cracking catalyst, comprising the following components by weight percentage:

[0081] A) 10% Y molecular sieve, 30% ZSM-5 molecular sieve;

[0082] B) 22% alumina (provided by boehmite);

[0083] C) 35% kaolin;

[0084] D) 3% phosphorus oxide.

[0085] Compared to the reference reagent, the samples prepared by the method of this invention have higher diesel single-pass conversion rate and propylene yield, among which sample DCC-2# has the best reaction performance.

[0086] 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. A straight-run diesel catalytic cracking catalyst, characterized in that: The catalyst has a core-shell structure, with the core having catalytic cracking function and the shell having catalytic dehydrogenation function; 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%; Metal oxides 0.05~70%; 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 oxide binder includes a first binder and a second binder; the natural mineral includes a first natural mineral and a second natural mineral; The preparation method of the catalyst for straight-run diesel catalytic cracking 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 catalyst semi-finished product obtained in step S1 is mixed evenly with macromolecular organometallic salt, second binder and second natural mineral in deionized water, stirred into a slurry, and the pH of the slurry is adjusted to 2~6 with acidic solution. After secondary spray granulation and calcination, microsphere catalyst finished product of 40~200μm is obtained. The molecular screening uses at least one of Y, β, MCM-22, ZSM-5, IM-5, MOR, and SAPO-34; The metal oxide is obtained by calcining a macromolecular organometallic salt, wherein the macromolecular organometallic salt is selected from at least one of nickel acetate, zinc acetate, iron acetate, nickel oxalate, zinc oxalate, and iron oxalate.

2. The straight-run diesel catalytic cracking catalyst according to claim 1, characterized in that: The dry basis ratio of the first binder and the second binder is 1.5:1 to 1:2.5; 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 straight-run diesel catalytic cracking catalyst according to claim 1, characterized in that: The dry basis ratio of the first natural mineral and the second natural mineral is 1:(1~3); 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 straight-run diesel catalytic cracking 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 catalyst semi-finished product obtained in step S1 is mixed evenly with macromolecular organometallic salt, second binder and second natural mineral in deionized water, stirred into a slurry, and the pH of the slurry is adjusted to 2~6 with acidic solution. After secondary spray granulation and calcination, microsphere catalyst finished product of 40~200μm is obtained.

5. The method for preparing a straight-run diesel catalytic cracking 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 straight-run diesel catalytic cracking 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 straight-run diesel catalytic cracking catalyst according to claim 4, characterized in that: In steps S1 and S2, the calcination temperature is 550~650℃ and the time is 2~6h.

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