High-performance catalyst for naphtha catalytic cracking as well as preparation method and application of high-performance catalyst

Abstract

The invention provides a catalyst for catalytic cracking of naphtha, which is prepared from the following raw materials in parts by mole: 1 part of calcined and activated kaolin, 4 to 13 parts of silicon source, 3 to 11 parts of alkaline substance, 1.5 to 4.5 parts of template agent and 60 to 200 parts of water. The high-performance catalyst for naphtha catalytic cracking contains the micro-crystalline ZSM-5 molecular sieve, and the micro-crystalline molecular sieve contains an incomplete crystal structure, is high in specific surface area and high in diffusion rate, and shows high catalytic activity, excellent diene selectivity and low coke yield in a light hydrocarbon cracking reaction. The light hydrocarbon catalytic cracking catalyst prepared by the invention can improve the diffusion rate of a reaction substrate, the reaction conversion rate and the diene selectivity, and is especially suitable for the field of high yield of diene through light hydrocarbon cracking in a refinery plant.

Description

Technical Field

[0001] The present invention belongs to the technical field of naphtha catalytic cracking catalyst preparation, and relates to a catalyst for naphtha catalytic cracking and a preparation method and application thereof, and in particular to a high-performance catalyst for naphtha catalytic cracking and a preparation method and application thereof. Background Art

[0002] Naphtha, also known as chemical light oil, is a petroleum product produced from crude oil or other raw materials. It is a light oil used as a chemical feedstock, primarily used as a raw material in chemical processes such as catalytic reforming and cracking. It has various distillation ranges depending on its intended use, with the domestic standard being a final distillation point of approximately 220°C. When used as a cracking feedstock for ethylene production, the fraction between 70°C and 145°C is called light naphtha. When used to produce aromatics or high-octane gasoline, the fraction between 70°C and 180°C is called heavy naphtha. When used as a solvent, it is called solvent naphtha. Aromatic solvents derived from coal tar are also called heavy naphtha or solvent naphtha.

[0003] Naphtha cracking uses naphtha as a feedstock, breaking down the various hydrocarbon molecules in the naphtha under air-tight conditions and high temperatures. The primary products of naphtha cracking are ethylene, propylene, and butadiene, along with considerable by-products such as pyrolysis gasoline (which contains significant amounts of pyrolysis aromatics), pyrolysis diesel, methane hydrogen, and pyrolysis fuel oil. Therefore, naphtha cracking is primarily used to produce ethylene, propylene, butadiene, and pyrolysis aromatics.

[0004] Kaolin is a natural non-metallic mineral with the chemical formula Al2O3-2SiO2-2H2O. Its theoretical chemical composition is 46.54% SiO2 and 39.5% Al2O3. Due to its abundant reserves and low price, it is an ideal natural raw material for synthesizing molecular sieves.

[0005] The researchers used calcined kaolin as a silicon and aluminum source and a hydrothermal method to synthesize a highly crystalline ZSM-5 molecular sieve. Using kaolin as a raw material and without the use of an organic template, they rapidly synthesized micron-sized ZSM-5 with the assistance of seed crystals.

[0006] There are two common methods for synthesizing molecular sieves: chemical synthesis and natural mineral synthesis. Compared with chemical synthesis, synthesizing molecular sieves from natural minerals can effectively conserve resources and reduce production costs. Molecular sieves synthesized from kaolin also have the characteristics of small particles and high mesopore content.

[0007] Currently, naphtha cracking catalysts are typically prepared by combining molecular sieve crystals and a kaolin matrix with a binder. The resulting molecular sieve crystals are expensive and have large grains. The large molecular sieve crystals restrict the diffusion of naphtha cracking substrates and products, resulting in reduced reaction efficiency and the occurrence of side reactions, coke formation, and reduced diene yields.

[0008] Therefore, how to design a more suitable catalyst to solve the above-mentioned problems of existing naphtha cracking catalysts has become one of the focuses of widespread attention of many researchers in the industry. Summary of the Invention

[0009] In light of this, the present invention aims to provide a catalyst for catalytic cracking of naphtha, its preparation method, and its application, specifically a high-performance catalyst for catalytic cracking of naphtha. The light hydrocarbon catalytic cracking catalyst prepared by the present invention can improve substrate diffusion rate, reaction conversion rate, and diene selectivity, making it particularly suitable for the production of dienes in light hydrocarbon cracking in refineries. Furthermore, the preparation method is simple, the conditions are mild, and the controllability is strong, making it more suitable for promotion and application in industrial production.

[0010] The present invention provides a catalyst for catalytic cracking of naphtha, which comprises, calculated by molar fraction of raw materials:

[0011] 1 mol part of calcined activated kaolin;

[0012] Silicon source, calculated as SiO2: 4 to 13 parts by mole;

[0013] Alkaline substance: 3 to 11 parts by mole;

[0014] Template: 1.5 to 4.5 molar parts;

[0015] Water: 60 to 200 parts by mole.

[0016] Preferably, in the raw materials, the molar ratio of SiO2 and Al2O3 is (10-30):1;

[0017] The silicon source is one or more of silica gel, ethyl orthosilicate and silica sol;

[0018] The alkaline substance is one or more of tetrapropylammonium hydroxide, tetraethylammonium hydroxide, urea and ammonia water;

[0019] The template agent is one or more of tetrapropylammonium hydroxide, n-butylamine, ethylamine and tetrapropylammonium bromide.

[0020] Preferably, the calcination activation temperature is 600-800°C;

[0021] The calcination activation time is 2 to 4 hours;

[0022] The catalyst is specifically catalyst microspheres;

[0023] The particle size of the catalyst microsphere particles is 20 to 80 μm.

[0024] The present invention provides a method for preparing a catalyst for catalytic cracking of naphtha, comprising the following steps:

[0025] 1) calcining and activating kaolin to obtain activated kaolin;

[0026] 2) mixing the activated kaolin obtained in the above step, a silicon source, an alkaline substance, a template and water to obtain a slurry, and then pre-crystallizing the slurry to obtain a pre-crystallized mixed solution;

[0027] 3) The pre-crystallization mixed solution obtained in the above step, the acid and the binder are mixed again, shaped and then calcined to obtain a catalyst.

[0028] Preferably, the calcination activation temperature is 600-800°C;

[0029] The calcination activation time is 2 to 4 hours;

[0030] In the slurry, the molar ratio of SiO2 to Al2O3 is (10-30):1.

[0031] Preferably, the silicon source is one or more of silica gel, ethyl orthosilicate and silica sol;

[0032] The alkaline substance is one or more of tetrapropylammonium hydroxide, tetraethylammonium hydroxide, urea and ammonia water;

[0033] The template agent is one or more of tetrapropylammonium hydroxide, n-butylamine, ethylamine and tetrapropylammonium bromide.

[0034] Preferably, the pre-crystallization temperature is 90-130°C;

[0035] The pre-crystallization time is 48 to 72 hours;

[0036] The acid is one or more of hydrochloric acid, phosphoric acid and sulfuric acid.

[0037] Preferably, the binder is one or more of silica sol, alumina sol, acidified pseudo-boehmite, water glass and aluminum phosphate;

[0038] The mass ratio of dry basis to acid in the pre-crystallization mixture is 1:(0.5-1.7);

[0039] The mass ratio of dry basis to binder in the pre-crystallization mixed solution is 1:(7-10).

[0040] Preferably, before the forming, a grinding step is also included;

[0041] The forming method includes spray forming;

[0042] The calcination temperature is 550-700°C;

[0043] The calcination time is 4-6 hours.

[0044] The present invention also provides the use of the catalyst described in any one of the above technical solutions or the catalyst prepared by the preparation method described in any one of the above technical solutions in catalytic cracking of light hydrocarbons.

[0045] The present invention provides a catalyst for catalytic cracking of naphtha. The catalyst comprises, by molar proportion of raw materials, 1 mole of calcined activated kaolin, 4 to 13 moles of a silicon source, 3 to 11 moles of an alkaline substance, 1.5 to 4.5 moles of a template, and 60 to 200 moles of water. Compared to the prior art, the present invention innovatively designs a high-performance catalyst for catalytic cracking of naphtha with a specific composition and structure. The catalyst microspheres contain microcrystalline ZSM-5 molecular sieves. This microcrystalline molecular sieve has an incomplete crystal structure, a high specific surface area, and a high diffusion rate. It exhibits high catalytic activity, excellent diene selectivity, and low coke yield in light hydrocarbon cracking reactions.

[0046] The present invention also provides a specific preparation method for the catalyst, comprising activating kaolin; mixing the activated kaolin with a silicon source, an alkali, a template, and water; pre-crystallizing the mixture at low temperature; and molding the pre-crystallized mixture with an acid and a binder to produce catalyst microspheres. The present invention utilizes calcined activated kaolin as the primary aluminum source and a partial silicon source. Pre-crystallization is performed in an alkaline environment by introducing another silicon source to form a mixture of kaolin with a partial MFI crystal structure and ZSM-5 molecular sieve. Due to the low crystallization temperature, the synthesized molecular sieve is incompletely crystallized, resulting in small, uniformly dispersed crystals in the uncrystallized kaolin. This alkaline mixture is neutralized with acid and then spray-molded with a binder to produce a catalyst with high catalytic performance.

[0047] The naphtha catalytic cracking catalyst prepared by the invention can improve the diffusion rate of reaction substrates, the reaction conversion rate and the diene selectivity, and is particularly suitable for the field of cracking light hydrocarbons in refineries to produce more dienes. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 The X-ray diffraction spectra of the catalyst powders prepared in Example 1 and Comparative Example 1 of the present invention;

[0049] Figure 2 These are scanning electron microscope photos of the catalyst particles prepared in Example 1 of the present invention and Comparative Example 1. DETAILED DESCRIPTION

[0050] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention rather than limiting the patent claims of the present invention.

[0051] All raw materials of the present invention are not particularly limited in their sources and can be purchased from the market or prepared according to conventional methods well known to those skilled in the art.

[0052] There is no particular limitation on the purity of all raw materials in the present invention. The present invention preferably uses analytically pure materials or materials with conventional purities in the field of naphtha catalytic cracking catalyst preparation.

[0053] The present invention provides a catalyst for catalytic cracking of naphtha, which comprises, calculated by molar fraction of raw materials:

[0054] 1 mol part of calcined activated kaolin;

[0055] Silicon source, calculated as SiO2: 4 to 13 parts by mole;

[0056] Alkaline substance: 3 to 11 parts by mole;

[0057] Template: 1.5 to 4.5 molar parts;

[0058] Water: 60 to 200 parts by mole.

[0059] In the present invention, the silicon source is added in an amount of 4 to 13 parts by mole, 6 to 11 parts by mole, or 8 to 9 parts by mole, calculated as SiO2.

[0060] In the present invention, the amount of the alkaline substance added is 3 to 11 parts by mole, 4 to 10 parts by mole, 5 to 9 parts by mole, or 6 to 8 parts by mole.

[0061] In the present invention, the amount of the template added is 1.5 to 4.5 parts by mole, can be 2 to 4 parts by mole, and can be 2.5 to 3.5 parts by mole.

[0062] In the present invention, the amount of water added is 60 to 200 parts by mole, can be 90 to 170 parts by mole, and can be 120 to 140 parts by mole.

[0063] In the present invention, in the raw materials, the molar ratio of SiO2 and Al2O3 is preferably (10-30):1, more preferably (14-26):1, and more preferably (18-22):1.

[0064] In the present invention, the silicon source is preferably one or more of silica gel, ethyl orthosilicate and silica sol, more preferably silica gel, ethyl orthosilicate or silica sol.

[0065] In the present invention, the alkaline substance is preferably one or more of tetrapropylammonium hydroxide, tetraethylammonium hydroxide, urea and ammonia water, more preferably tetrapropylammonium hydroxide, tetraethylammonium hydroxide, urea or ammonia water.

[0066] In the present invention, the template is preferably one or more of tetrapropylammonium hydroxide, n-butylamine, ethylamine and tetrapropylammonium bromide, more preferably tetrapropylammonium hydroxide, n-butylamine, ethylamine or tetrapropylammonium bromide.

[0067] In the present invention, the temperature of the calcination activation is preferably 600-800°C, more preferably 640-760°C, and even more preferably 680-720°C.

[0068] In the present invention, the calcination activation time is preferably 2 to 4 hours, more preferably 2.4 to 3.6 hours, and even more preferably 2.8 to 3.2 hours.

[0069] In the present invention, the catalyst is preferably catalyst microspheres.

[0070] In the present invention, the particle size of the catalyst microsphere particles is preferably 20 to 80 μm, more preferably 30 to 70 μm, and even more preferably 40 to 60 μm.

[0071] The present invention provides a method for preparing a catalyst for catalytic cracking of naphtha, comprising the following steps:

[0072] 1) calcining and activating kaolin to obtain activated kaolin;

[0073] 2) mixing the activated kaolin obtained in the above step, a silicon source, an alkaline substance, a template and water to obtain a slurry, and then pre-crystallizing the slurry to obtain a pre-crystallized mixed solution;

[0074] 3) The pre-crystallization mixed solution obtained in the above step, the acid and the binder are mixed again, shaped and then calcined to obtain a catalyst.

[0075] The present invention first calcines and activates kaolin to obtain activated kaolin.

[0076] In the present invention, the temperature of the calcination activation is preferably 600-800°C, more preferably 640-760°C, and even more preferably 680-720°C.

[0077] In the present invention, the calcination activation time is preferably 2 to 4 hours, more preferably 2.4 to 3.6 hours, and even more preferably 2.8 to 3.2 hours.

[0078] The present invention further mixes the activated kaolin obtained in the above steps, a silicon source, an alkaline substance, a template agent and water to obtain a slurry, and then pre-crystallizes the slurry to obtain a pre-crystallized mixed solution.

[0079] In the present invention, in the slurry, the molar ratio of SiO2 to Al2O3 is preferably (10-30):1, more preferably (14-26):1, and even more preferably (18-22):1.

[0080] In the present invention, the silicon source is preferably one or more of silica gel, ethyl orthosilicate and silica sol, more preferably silica gel, ethyl orthosilicate or silica sol.

[0081] In the present invention, the alkaline substance is preferably one or more of tetrapropylammonium hydroxide, tetraethylammonium hydroxide, urea and ammonia water, more preferably tetrapropylammonium hydroxide, tetraethylammonium hydroxide, urea or ammonia water.

[0082] In the present invention, the template is preferably one or more of tetrapropylammonium hydroxide, n-butylamine, ethylamine and tetrapropylammonium bromide, more preferably tetrapropylammonium hydroxide, n-butylamine, ethylamine or tetrapropylammonium bromide.

[0083] In the present invention, the temperature of the pre-crystallization is preferably 90-130°C, more preferably 95-125°C, more preferably 100-120°C, and even more preferably 105-115°C.

[0084] In the present invention, the pre-crystallization time is preferably 48 to 72 hours, more preferably 52 to 68 hours, and even more preferably 56 to 64 hours.

[0085] Finally, the present invention mixes the pre-crystallization mixed solution obtained in the above steps, the acid and the binder again, forms the mixture and then calcines the mixture to obtain the catalyst.

[0086] In the present invention, the acid is preferably one or more of hydrochloric acid, phosphoric acid and sulfuric acid, more preferably hydrochloric acid, phosphoric acid or sulfuric acid.

[0087] In the present invention, the binder is preferably one or more of silica sol, alumina sol, acidified pseudo-boehmite, water glass and aluminum phosphate, more preferably silica sol, alumina sol, acidified pseudo-boehmite, water glass or aluminum phosphate.

[0088] In the present invention, the mass ratio of dry basis to acid in the pre-crystallization mixed solution is preferably 1:(0.5-1.7), more preferably 1:(0.7-1.5), and even more preferably 1:(0.9-1.3).

[0089] In the present invention, the mass ratio of the dry basis to the binder in the pre-crystallization mixed solution is preferably 1:(7-10), more preferably 1:(7.5-9.5), and even more preferably 1:(8-9).

[0090] In the present invention, the step of grinding is preferably included before the molding.

[0091] In the present invention, the molding method preferably includes spray molding.

[0092] In the present invention, the calcination temperature is preferably 550-700°C, more preferably 580-670°C, and even more preferably 610-640°C.

[0093] In the present invention, the calcination time is preferably 4 to 6 hours, more preferably 4.4 to 5.6 hours, and even more preferably 4.8 to 5.2 hours.

[0094] The present invention provides the use of the catalyst described in any one of the above technical solutions or the catalyst prepared by the preparation method described in any one of the above technical solutions in catalytic cracking of light hydrocarbons.

[0095] In the present invention, the light hydrocarbons preferably include naphtha.

[0096] The present invention is a complete and detailed overall technical solution, which better ensures the composition and structure of the naphtha catalytic cracking catalyst, further improves the effect of catalyst preparation and the catalytic effect for naphtha catalytic cracking. The high-performance catalyst for naphtha catalytic cracking and its preparation method and application can specifically include the following contents:

[0097] A method for preparing a high-performance catalyst for catalytic cracking of naphtha comprises the following steps:

[0098] (1) The preparation method of the molecular sieve comprises: activating kaolin at a certain temperature for a period of time;

[0099] (2) Activated kaolin is mixed with a certain amount of silicon source, alkali, template and water;

[0100] (3) pre-crystallizing the mixture at a certain temperature for a period of time;

[0101] (4) The pre-crystallization mixture is molded with a certain amount of acid and binder to obtain catalyst microspheres.

[0102] Specifically, the activation temperature of kaolin is 600-800° C., and the activation time is 2-4 hours.

[0103] Specifically, the silicon source is one or more of silica gel, ethyl orthosilicate, and silica sol.

[0104] Specifically, the alkaline substance is one or more of tetrapropylammonium hydroxide, tetraethylammonium hydroxide, urea, and ammonia water.

[0105] Specifically, the template agent is one or more of tetrapropylammonium hydroxide, n-butylamine, ethylamine, and tetrapropylammonium bromide.

[0106] Specifically, the molar ratio of SiO2:Al2O3 in the mixture is 10-30.

[0107] Specifically, the molar ratio of kaolin: silicon source (SiO2): alkali: template: water is 1:4-13:3-11:1.5-4.5:60-200.

[0108] Specifically, the pre-crystallization temperature is 90-130° C.; and the pre-crystallization time is 48-72 hours.

[0109] Specifically, the acid is one or more of hydrochloric acid, phosphoric acid, and sulfuric acid.

[0110] Specifically, the binder is one or more of silica sol, alumina sol, acidified pseudo-boehmite, water glass, and aluminum phosphate.

[0111] Specifically, the mass ratio of dry basis to acid and binder in the mixed liquid is 1:0.5-1.7:7-10.

[0112] Specifically, the catalyst microspheres are calcined at a temperature of 550-700° C. for 4-6 hours.

[0113] Further,

[0114] (1) Activating kaolin at a certain temperature for a period of time;

[0115] (2) Activated kaolin is mixed with a certain amount of silicon source, alkali, template and water to obtain slurry A.

[0116] (3) Slurry A is transferred to a crystallization kettle and crystallized at a certain temperature for a certain time to obtain slurry B.

[0117] (4) Slurry B is mixed evenly with a certain amount of acid and binder, and then ball milled and atomized to obtain catalyst microspheres.

[0118] (5) The catalyst was calcined and the obtained sample was evaluated for naphtha cracking reaction using a fixed fluidized bed reactor.

[0119] Specifically, the catalytic cracking light hydrocarbon in step (5) is one of C5-C8 alkanes, olefins, aromatic hydrocarbons or a mixture thereof, and can be specifically naphtha.

[0120] The present invention provides a high-performance catalyst for catalytic cracking of naphtha, its preparation method, and its application. The high-performance catalyst microspheres designed by the present invention for catalytic cracking of naphtha, having a specific composition and structure, contain microcrystalline ZSM-5 molecular sieve. This microcrystalline molecular sieve has an incomplete crystal structure, a high specific surface area, and a high diffusion rate. It exhibits high catalytic activity, excellent diene selectivity, and low coke yield in light hydrocarbon cracking reactions.

[0121] The present invention also provides a specific preparation method for the catalyst, comprising activating kaolin; mixing the activated kaolin with a silicon source, an alkali, a template, and water; pre-crystallizing the mixture at low temperature; and molding the pre-crystallized mixture with an acid and a binder to produce catalyst microspheres. The present invention utilizes calcined activated kaolin as the primary aluminum source and a partial silicon source. Pre-crystallization is performed in an alkaline environment by introducing another silicon source to form a mixture of kaolin with a partial MFI crystal structure and ZSM-5 molecular sieve. Due to the low crystallization temperature, the synthesized molecular sieve is incompletely crystallized, resulting in small, uniformly dispersed crystals in the uncrystallized kaolin. This alkaline mixture is neutralized with acid and then spray-molded with a binder to produce a catalyst with high catalytic performance.

[0122] The naphtha catalytic cracking catalyst prepared by the invention can improve the diffusion rate of reaction substrates, the reaction conversion rate and the diene selectivity, and is particularly suitable for the field of cracking light hydrocarbons in refineries to produce more dienes.

[0123] To further illustrate the present invention, a catalyst for catalytic cracking of naphtha provided by the present invention, its preparation method, and application are described in detail below in conjunction with examples. However, it should be understood that these examples are implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operating processes are provided only to further illustrate the features and advantages of the present invention, rather than to limit the claims of the present invention. The scope of protection of the present invention is not limited to the following examples.

[0124] Example 1

[0125] (1) 1 mol of kaolin (SiO2 about 54%, Al2O3 about 46%) was activated at 600℃ for 4h to obtain activated kaolin.

[0126] (2) Activated kaolin was mixed with 13 mol of ethyl orthosilicate, 10.7 mol of aqueous ammonia, 4.7 mol of n-butylamine and 200 mol of water to obtain slurry A.

[0127] (3) Slurry A was transferred to a crystallization kettle and crystallized at 90°C for 72 hours to obtain slurry B.

[0128] (4) Slurry B was mixed with 1.7 mol of sulfuric acid and 7 mol of aluminum sol to form a slurry. The slurry was ball-milled and then spray-formed in a spray dryer.

[0129] (5) The prepared microsphere particles were calcined at 550 °C for 6 h, and the obtained samples were evaluated using a fixed fluidized bed reactor.

[0130] Example 2

[0131] (1) 1 mol of kaolin (SiO2 about 54%, Al2O3 about 46%) was activated at 600℃ for 4h to obtain activated kaolin.

[0132] (2) Activated kaolin was mixed with 20 mol of silica sol, 6.4 mol of urea, 2.8 mol of ethylamine and 188 mol of water to obtain slurry A.

[0133] (3) Slurry A was transferred to a crystallization kettle and crystallized at 90°C for 72 hours to obtain slurry B.

[0134] (4) Slurry B was mixed with 1.1 mol of sulfuric acid and 7 mol of aluminum sol to form a slurry. The slurry was ball-milled and then spray-formed in a spray dryer.

[0135] (5) The prepared microsphere particles were calcined at 550 °C for 6 h, and the obtained samples were evaluated using a fixed fluidized bed reactor.

[0136] Example 3

[0137] (1) 1 mol of kaolin (SiO2 about 54%, Al2O3 about 46%) was activated at 600℃ for 4h to obtain activated kaolin.

[0138] (2) Activated kaolin was mixed with 4 mol of silica gel, 18.4 mol of tetrapropylammonium hydroxide and 186.5 mol of water to obtain slurry A.

[0139] (3) Slurry A was transferred to a crystallization kettle and crystallized at 90°C for 72 hours to obtain slurry B.

[0140] (4) Slurry B is mixed with 0.5 mol of sulfuric acid and 7 mol of aluminum sol to form a slurry. The slurry is ball-milled and then spray-formed in a spray dryer.

[0141] (5) The prepared microsphere particles were calcined at 550 °C for 6 h, and the obtained samples were evaluated using a fixed fluidized bed reactor.

[0142] Example 4

[0143] (1) 2 mol of kaolin (SiO2 about 54%, Al2O3 about 46%) was activated at 600℃ for 4h to obtain activated kaolin.

[0144] (2) Activated kaolin was mixed with 4 mol of silica gel, 18.4 mol of tetrapropylammonium hydroxide and 186.5 mol of water to obtain slurry A.

[0145] (3) Slurry A was transferred to a crystallization kettle and crystallized at 90°C for 72 hours to obtain slurry B.

[0146] (4) Slurry B is mixed with 0.5 mol of sulfuric acid and 7 mol of aluminum sol to form a slurry. The slurry is ball-milled and then spray-formed in a spray dryer.

[0147] (5) The prepared microsphere particles were calcined at 550 °C for 6 h, and the obtained samples were evaluated using a fixed fluidized bed reactor.

[0148] Example 5

[0149] (1) 3 mol of kaolin (SiO2 about 54%, Al2O3 about 46%) was activated at 600℃ for 4 hours to obtain activated kaolin.

[0150] (2) Activated kaolin was mixed with 4 mol of silica gel, 18.4 mol of tetrapropylammonium hydroxide and 186.5 mol of water to obtain slurry A.

[0151] (3) Slurry A was transferred to a crystallization kettle and crystallized at 90°C for 72 hours to obtain slurry B.

[0152] (4) Slurry B is mixed with 0.5 mol of sulfuric acid and 7 mol of aluminum sol to form a slurry. The slurry is ball-milled and then spray-formed in a spray dryer.

[0153] (5) The prepared microsphere particles were calcined at 550 °C for 6 h, and the obtained samples were evaluated using a fixed fluidized bed reactor.

[0154] Comparative Example 1

[0155] (1) 1 mol of kaolin, 4 mol of ZSM-5 molecular sieve, 200 mol of water, 0.5 mol of sulfuric acid, and 7 mol of aluminum sol were mixed and stirred to form a slurry. The slurry was ball-milled and then spray-formed in a spray dryer.

[0156] (2) The prepared microsphere particles were calcined at 550 °C for 6 h, and the obtained samples were evaluated using a fixed fluidized bed reactor.

[0157] The catalysts prepared in the examples of the present invention and the comparative examples were characterized.

[0158] See also Figure 1 , Figure 1 The X-ray diffraction spectra of the catalyst powders prepared in Example 1 and Comparative Example 1 of the present invention are shown.

[0159] See also Figure 2 , Figure 2 These are scanning electron microscope photos of the catalyst particles prepared in Example 1 of the present invention and Comparative Example 1.

[0160] from Figure 1 The XRD patterns in Figure 1 show that, compared to a standard MFI diffraction peak spectrum, both Example 1 and Comparative Example 1 exhibit characteristic diffraction peaks of the MFI phase, indicating that the catalysts prepared by both methods contain ZSM-5 molecular sieve. Comparing the diffraction peak heights of the two methods reveals that the MFI crystalline phase is more pronounced in Comparative Example 1, indicating that the preparation method of the present invention facilitates the introduction of a greater amount of the MFI crystalline phase into the catalyst.

[0161] from Figure 2 It can be seen from the SEM photos in that the morphology of the catalyst prepared by the present invention is basically similar to that of the catalyst obtained by directly introducing ZSM-5 molecular sieve in Comparative Example 1, with no obvious difference.

[0162] The catalytic performance of the catalysts prepared in the examples of the present invention and the comparative examples was evaluated.

[0163] See Table 1, which shows the physical properties of the cracking feedstock oil evaluated in the Examples and Comparative Examples of the present invention.

[0164] Table 1

[0165]

[0166]

[0167] See Table 2, which shows the physical properties and catalytic performance data of the catalyst samples prepared in the examples of the present invention and the comparative examples.

[0168] Table 2

[0169]

[0170] As can be seen from Table 2, Examples 1-5 prepared according to the present invention exhibit higher conversion rates and diene yields, and lower coke yields, compared to Comparative Example 1. The molecular sieve obtained by kaolin crystallization is uniformly dispersed in the kaolin. Its crystals are incomplete, resulting in more numerous crystallites, which helps increase the specific surface area and the mass transfer rate between the reaction substrate and product, improving catalytic efficiency while suppressing secondary reactions. This helps improve reaction conversion and diene selectivity while suppressing coke formation.

[0171] The above describes in detail a high-performance catalyst for catalytic cracking of naphtha, its preparation method, and its application provided by the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above examples is intended only to facilitate understanding of the methods and core concepts of the present invention, including the best mode, and to enable any person skilled in the art to practice the present invention, including the manufacture and use of any device or system, and the implementation of any combined method. It should be noted that, without departing from the principles of the present invention, a person skilled in the art may make several improvements and modifications to the present invention, and such improvements and modifications fall within the scope of protection of the claims of the present invention. The scope of patent protection for the present invention is defined by the claims and may include other embodiments that can be conceived by those skilled in the art. If these other embodiments have structural elements that are not different from the literal language of the claims, or if they include equivalent structural elements that are not substantially different from the literal language of the claims, then these other embodiments are also intended to be included within the scope of the claims.

Claims

1. A catalyst for catalytic cracking of naphtha, characterized in that: Calculated by molar fraction of raw materials, including: 1 mol part of calcined activated kaolin; Silicon source, calculated as SiO2: 4 to 13 parts by mole; Alkaline substance: 3 to 11 parts by mole; Template: 1.5 to 4.5 molar parts; Water: 60 to 200 parts by mole.

2. The catalyst according to claim 1, characterized in that In the raw materials, the molar ratio of SiO2 and Al2O3 is (10-30):1; The silicon source is one or more of silica gel, ethyl orthosilicate and silica sol; The alkaline substance is one or more of tetrapropylammonium hydroxide, tetraethylammonium hydroxide, urea and ammonia water; The template agent is one or more of tetrapropylammonium hydroxide, n-butylamine, ethylamine and tetrapropylammonium bromide.

3. The catalyst according to claim 1, characterized in that The calcination activation temperature is 600-800°C; The calcination activation time is 2 to 4 hours; The catalyst is specifically catalyst microspheres; The particle size of the catalyst microsphere particles is 20 to 80 μm.

4. A method for preparing a catalyst for catalytic cracking of naphtha, characterized in that: The following steps are involved: 1) calcining and activating kaolin to obtain activated kaolin; 2) mixing the activated kaolin obtained in the above step, a silicon source, an alkaline substance, a template and water to obtain a slurry, and then pre-crystallizing the slurry to obtain a pre-crystallized mixed solution; 3) The pre-crystallization mixed solution obtained in the above step, the acid and the binder are mixed again, shaped and then calcined to obtain a catalyst.

5. The preparation method according to claim 4, characterized in that The calcination activation temperature is 600-800°C; The calcination activation time is 2 to 4 hours; In the slurry, the molar ratio of SiO2 to Al2O3 is (10-30):

1.

6. The preparation method according to claim 4, characterized in that The silicon source is one or more of silica gel, ethyl orthosilicate and silica sol; The alkaline substance is one or more of tetrapropylammonium hydroxide, tetraethylammonium hydroxide, urea and ammonia water; The template agent is one or more of tetrapropylammonium hydroxide, n-butylamine, ethylamine and tetrapropylammonium bromide.

7. The preparation method according to claim 4, characterized in that The pre-crystallization temperature is 90-130°C; The pre-crystallization time is 48 to 72 hours; The acid is one or more of hydrochloric acid, phosphoric acid and sulfuric acid.

8. The preparation method according to claim 4, characterized in that The binder is one or more of silica sol, alumina sol, acidified pseudo-boehmite, water glass and aluminum phosphate; The mass ratio of dry basis to acid in the pre-crystallization mixture is 1:(0.5-1.7); The mass ratio of dry basis to binder in the pre-crystallization mixed solution is 1:(7-10).

9. The preparation method according to claim 4, characterized in that Before the forming, the step of grinding is also included; The forming method includes spray forming; The calcination temperature is 550-700°C; The calcination time is 4-6 hours.

10. Use of the catalyst according to any one of claims 1 to 3 or the catalyst prepared by the preparation method according to any one of claims 4 to 9 in catalytic cracking of light hydrocarbons.

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