CN117399063A - Catalyst for producing gasoline by hydrocracking and preparation method and application thereof - Google Patents

Abstract

The invention discloses a catalyst for producing gasoline through hydrocracking and its preparation method and application. The properties of the catalyst are as follows: the specific surface area is 350~600 m2/g, the pore volume is 0.4~0.7 mL/g, the pore diameter of the catalyst is 3-6 nm, and the mesopores account for 35~60% of the total pore volume, 6~ The 15 nm mesopores account for 30~55% of the total pore volume. Based on the final catalyst weight, they contain 10wt%~30wt% active metals calculated as oxides and 70wt%~90wt% carriers. The preparation method of the catalyst includes the following steps: first prepare ZSM-23 molecular sieve; then mix and shape the prepared ZSM-23 molecular sieve, Y molecular sieve, amorphous silica aluminum and binder, and then dry and roast to prepare the catalyst. Carrier; finally, active metal is introduced onto the catalyst carrier, and the final catalyst is obtained after drying and roasting. The catalyst is suitable for catalyzing the hydrocracking of diesel to produce gasoline, and has the characteristics of high gasoline yield and high gasoline octane number.

Description

A catalyst for hydrocracking gasoline and its preparation method and application

Technical field

The present invention relates to a catalyst for hydrocracking diesel to produce gasoline and its preparation method and application. Specifically, it relates to a catalyst for catalyzing diesel hydrocracking to produce high-quality gasoline and its preparation method and application.

Background technique

The catalytic cracking process is a major process technology for lightening heavy oil in the oil refining industry, and it occupies a relatively important position among domestic oil refining enterprises. As global oil becomes increasingly heavy, the processing capacity of FCC units continues to increase, producing a large amount of catalytic diesel with high sulfur, nitrogen, and aromatic content, low cetane number or cetane index, and extremely poor stability. In order to improve the utilization rate of petroleum resources, improve the overall quality level of gasoline and diesel fuel, achieve the goals of product blending optimization and product value maximization, and meet the growing domestic demand for clean fuel, it is necessary to find a suitable method for its Processing and processing to meet the requirements for enterprise products to leave the factory, adjusting the structure of gasoline and diesel products, and hydrogenating catalytic diesel to produce high-octane gasoline have emerged in recent years to effectively alleviate the difficulties of catalytic diesel in refineries and improve corporate efficiency. It is an effective way and has good application prospects.

Hydrocracking catalysts are bifunctional catalysts composed of hydrogenation function and cracking function. The hydrogenation function is provided by hydrogenation active metals, which improves the hydrogenation performance of the catalyst and is conducive to the saturation of aromatics; currently, most hydrocracking The cracking center in the catalyst is provided by molecular sieves, and the key components for cracking in such catalysts are usually Y and β molecular sieves.

Beta molecular sieve has insufficient aromatic saturation capacity, resulting in low gasoline octane number. EP20110834653 discloses a method for preparing a polycyclic aromatic hydrocarbon hydrogenation conversion catalyst. The catalyst carrier is composed of beta molecular sieve and pseudo-boehmite. The active metal components of Group VIB and Group VIII are added using conventional methods, but the catalyst is the same It has a strong saturation ability for gasoline components and is not conducive to the process of catalytic diesel hydroconversion to produce high-octane gasoline.

CN109777714 discloses a method for catalytic diesel hydroconversion to produce high-octane gasoline. The Y-type molecular sieve hydrocracking catalyst used has the advantages of high ring-opening performance and high selective cracking performance of components rich in aromatic hydrocarbons, which can effectively Control the depth of hydrogenation saturation of aromatic hydrocarbons in the raw material to convert part of the aromatic hydrocarbons in the raw material and enrich it into the naphtha fraction to produce high-octane gasoline blending components.

US2010116712 discloses a catalytic diesel hydrogenation conversion method. This method uses a conventional cracking catalyst. The feed oil is first pretreated and then contacted with the cracking catalyst to produce clean diesel and high-octane gasoline.

When the above catalyst is used to catalyze the hydrocracking process of diesel to produce gasoline, there are common problems of low gasoline product yield and low octane number to varying degrees.

Contents of the invention

In view of the problems existing in the prior art, the present invention provides a catalyst for hydrocracking to produce gasoline and its preparation method and application. The catalyst is suitable for catalyzing the hydrocracking of diesel to produce gasoline, and has the characteristics of high gasoline yield and high gasoline octane number.

The present invention is a catalyst for hydrocracking to produce gasoline. The properties of the catalyst are as follows: the specific surface area is 350-600 ^m2 /g, the pore volume is 0.4-0.7 mL/g, and the pore diameter of the catalyst is 3-6 nm. Mesopores account for 35~60% of the total pore volume, and 6~15 nm mesopores account for 30~55% of the total pore volume; preferably, 3-6 nm mesopores account for 45~55% of the total pore volume, and 6~15 nm (excluding 6nm) mesopores account for 35~45% of the total pore volume; based on the final catalyst weight, it contains 10wt%~30wt% of active metals calculated as oxides, and the remainder is the carrier.

In the catalyst of the present invention, the active metal includes at least one of Group VIB metal and Group VIII metal. Based on the weight of the catalyst, the content of VIB group metal is 10wt%~20wt% in terms of oxide. The content of Group VIII metal is 2wt%~10wt% in terms of oxide. The Group VIB metal includes W and/or Mo; the Group VIII metal includes Co and/or Ni.

In the catalyst of the present invention, based on the quality of the carrier, the content of ZSM-23 molecular sieve is 3 to 15 wt%, and the content of Y molecular sieve is 30 to 60 wt%; the ZSM-23 molecular sieve has a mesopore volume with a pore diameter of 3 to 6 nm. It accounts for 45-90% of the total pore volume of the molecular sieve, preferably 50-85%, and further preferably 55-81%.

In the catalyst of the present invention, the Y-type molecular sieve is a modified Y-type molecular sieve, and the Y-type molecular sieve SiO ₂ /Al ₂ O ₃ molar ratio is 10 to 25; preferably 15 to 20.

In the catalyst of the present invention, the properties of the ZSM-23 molecular sieve are as follows: specific surface area is 300-430m ² /g, pore volume is 0.31-0.5cm ³ /g, micropore specific surface area is 50-170m ² /g, mesopores The specific surface area is 150-310m ² /g; preferably, the specific surface area is 320-405m ² /g, the pore volume is 0.34-0.45cm ³ /g, the micropore specific surface area is 80-140m ² /g, and the mesopore specific surface area is 261-295m ² /g.

In the catalyst of the present invention, the relative crystallinity of the ZSM-23 molecular sieve is 95 to 120%, and the relative crystallinity retention of the molecular sieve after hydrothermal treatment with water vapor at 600°C for 2 hours is 95 to 100%.

In the catalyst of the present invention, based on the quality of the carrier, the content of macroporous alumina is 20 to 60 wt%, and the content of the binder is 10 to 30 wt%.

In the catalyst of the present invention, the properties of the macroporous alumina are as follows: pore volume is 0.6~1.2mL/g, preferably 0.8~1.0 mL/g, and specific surface area is 300~600 ^m2 /g, preferably 400~500 m ² /g.

In the catalyst of the present invention, the binder can be a binder commonly used in this field, preferably small-pore alumina. The small-pore alumina used has a pore volume of 0.3 to 0.5 mL/g and a specific surface area of 200 to 400 m ² /g.

A method for preparing a catalyst for hydrocracking gasoline production: including the following steps: first prepare ZSM-23 molecular sieve; then mix and shape the prepared ZSM-23 molecular sieve, Y molecular sieve, amorphous silica aluminum and binder, and dry , and then calcined to make a catalyst carrier; finally, active metal is introduced onto the catalyst carrier, and the final catalyst is obtained after drying and calcining. The preparation of ZSM-23 molecular sieve refers to the preparation method of CN202210011767.9.

The preparation of the ZSM-23 molecular sieve includes the following steps:

(1) Preparation or selection of amorphous silica;

(2) Alkali treatment of amorphous silica;

(3) Prepare ZSM-23 molecular sieve using amorphous silica after alkali treatment as the silicon source;

In step (1) of the above method, the amorphous silica has a specific surface area of 600~1300 ^m2 /g, preferably 700~1200 ^m2 /g; and a pore volume of 0.6~1.3 ^cm3 /g, preferably 0.7~1.2 cm ³ /g; the pore diameter is 1~15 nm, preferably 2~10 nm.

In step (1) of the above method, the preparation process of the amorphous silica is as follows: add the silicon source to deionized water to disperse evenly, then add surfactant and stir; adjust the pH of the solution to 1~5, preferably 1.5~ 4, heat treatment in a water bath for a period of time; filter, wash, dry, and roast to obtain amorphous mesoporous silica.

In the above method, during the preparation process of amorphous silica, the silicon source is an inorganic silicon source, preferably one or more of water glass, silica sol or white carbon black.

In the above method, during the preparation process of the amorphous silica, the surfactant is one of cetyltrimethylbromide/ammonium chloride and octadecyltrimethylchloride/ammonium bromide. species or several species.

In the above method, during the preparation process of the amorphous silica, the molar ratio of the silicon source to the surfactant in terms of SiO ₂ is 1: (0.02~0.3), preferably 1: (0.05~0.2).

In the above method, during the preparation process of the amorphous silica, the molar ratio of the silicon source to deionized water in terms of SiO ₂ is 1: (30~300), preferably 1: (50~220);

In the above method, during the preparation process of amorphous silica, the heating temperature is 30~80°C and the heating time is 0.5~8h; preferably, the heating temperature is 40~70°C and the heating time is 3~6h.

In step (2) of the above method, the alkali treatment is to add the amorphous silica prepared in step (1) to an alkaline solution, and heat and stir.

In the above method, the alkali treatment adopts inorganic alkali treatment, and the inorganic alkali is one or more of sodium hydroxide, potassium hydroxide or ammonia water.

In the above method, the alkali treatment heating and stirring time is 0.5~12 h, preferably 2~8 h; the heating temperature is 25~60°C, preferably 30~50°C.

In the above method, the molar ratio of amorphous silica to inorganic base in terms of SiO ₂ is 0.04~0.15, preferably 0.05~0.13.

In step (3) of the above method, amorphous silica after alkali treatment is used as the silicon source, and the silicon source is mixed with an aluminum source, an alkali source (MOH), a template agent (R), and water to form a gel. HZSM-23 molecular sieve is obtained after crystallization, filtration, washing, drying and roasting.

Preferably, the molar ratio of silicon source (calculated as SiO ₂ ): aluminum source (calculated as Al ₂ O ₃ ): alkali source (calculated as hydroxide): template agent: H ₂ O in the gel system is 1: ( 0.003~0.03): (0.03~0.3): (0.05~2): (10~90); Further preferably, the silicon source (calculated as SiO ₂ ) in the gel system: the aluminum source (calculated as Al ₂ O ₃ ) : Alkali source (calculated as hydroxide) : Template: The molar ratio of H ₂ O is 1: (0.005~0.02) : (0.03~0.15) : (0.08~1.6): (20~70);

Preferably, the gel is crystallized at 150~200°C for 24~96h, the preferred crystallization temperature is 170~180°C, and the crystallization time is 36~72h. After filtering, washing, drying and roasting, ZSM-23 molecular sieve is obtained. .

In step (3) of the above method, the drying temperature is 80~120°C, the drying time is 4~12 h, the roasting temperature is 500~600°C, and the roasting time is 2~6 h.

In the preparation process of ZSM-23 molecular sieve of the present invention, mesoporous amorphous silica is initially prepared with the assistance of surfactant, which is used as the silicon source for the later synthesis of ZSM-23 molecular sieve. The amorphous silica generated in this process Silicon oxide has a mesoporous structure and is not highly crystallized into a stable crystal form. After further treatment in a low-concentration alkaline solution for a period of time, some of the -Si-O- bonds are opened, which is helpful for the subsequent -Si in the molecular sieve structure. —O—Al— bonds are generated, but most of the mesoporous structure is retained. Under the action of the microporous template agent in the later stage, in the appropriate ZSM-23 molecular sieve synthesis system, the microporous structure is generated, and at the same time, the mesoporous structure is retained. The pore structure was further crystallized and stabilized, thereby producing a micro-mesoporous composite ZSM-23 molecular sieve. The ZSM-23 molecular sieve synthesized by the method of the present invention not only has acidic properties with adjustable microporous structure, but also has large pore characteristics of mesoporous structure, high specific surface area and pore volume, high crystallinity, thermal stability and hydrothermal stability. Strong sex.

In the preparation method of the catalyst according to the present invention, the shape can be conventionally selected as needed. The shape can be cylindrical bar, clover, etc. During the catalyst molding process, molding aids can also be added, such as peptizing acid, extrusion aids, etc. The peptizing agent can generally be inorganic acids and/or organic acids, and extrusion aids such as sesbania powder. Drying and roasting are carried out using conventional methods. The drying is performed at a temperature of 80 to 120°C for 3 to 10 hours. The roasting is performed at 400-600°C for 3-10 hours.

In the preparation method of the catalyst according to the present invention, the method of loading active metal can adopt a conventional loading method, preferably an impregnation method, which can be saturated impregnation, excess impregnation or complex impregnation. Furthermore, the impregnation method is obtained by impregnating the carrier with a solution containing active metal, drying and roasting. The drying is performed at 100°C to 120°C for 1 to 12 hours. The roasting is performed at 400°C to 600°C for 3 to 10 hours.

A method for producing gasoline by hydrocracking catalytic cracking diesel fuel. After the catalytically cracked diesel fuel is hydrorefined, a hydrocracking reaction is carried out under the action of the above-mentioned hydrocracking catalyst.

In the above method of producing gasoline, the properties of the catalytic cracking diesel are: density is 0.88~0.99g/cm ³ , dry point is 360~400°C, aromatics content is 50~95wt%, and sulfur content of the catalytic cracking diesel is 0.2~ 2wt%, nitrogen content is 500ppm~2000ppm.

In the above method for producing gasoline, the process conditions of the hydrorefining reaction are: reaction temperature is 320-440°C, preferably 340-420°C; reaction pressure is 4.0-15.0MPa, preferably 6.0-12.0MPa; liquid hourly volume void The speed is 0.2 to 6.0 h ^-1 , preferably 0.5 to 3.0 h ^-1 ; the volume ratio of hydrogen to oil is 100 to 2000, preferably 500 to 1500.

In the above method for producing gasoline, the process conditions of the hydrocracking reaction are: reaction temperature is 340-440°C, preferably 360-430°C; reaction pressure is 4.0-15.0MPa, preferably 6.0-12.0MPa; liquid hourly volume void The speed is 0.2 to 6.0 h ^-1 , preferably 0.5 to 3.0 h ^-1 ; the volume ratio of hydrogen to oil is 100 to 2000, preferably 500 to 1500.

The ZSM-23 molecular sieve and Y molecular sieve used in the catalyst of the present invention jointly serve as the cracking center and have a dual port structure, which not only fully exerts their respective performance characteristics, but also enables the synergistic catalytic effect of the two molecular sieves. The Y molecular sieve is beneficial to hydrocarbons. The diffusion of molecules can improve the preferential conversion ability of cyclic hydrocarbons, especially tricyclic aromatic hydrocarbons, and directionally saturate and break the aromatic rings in the middle of tricyclic aromatic hydrocarbons. Secondly, through two-stage ring opening and cracking, the macromolecular cycloalkyl groups of diesel fractions can be saturated and broken. Benzene is cracked into small molecule alkyl benzene and enriched in the gasoline fraction, which can make the product more high-octane gasoline components.

The ZSM-23 molecular sieve of the present invention has highly concentrated pore distribution characteristics of 3-6 nm, which can adsorb and isomerize n-alkanes and small-molecule alkylbenzenes in catalytic diesel very well, increase isomerization products, and further improve the performance of gasoline. The octane rating of the product. The catalyst of the invention is used to catalyze the hydrocracking of diesel to produce gasoline, and has the characteristics of high gasoline yield and gasoline octane number.

Detailed ways

In order to better illustrate the present invention, the present invention will be further described below in conjunction with examples and comparative examples. However, the scope of the present invention is not limited to the scope of these embodiments. The analysis method of the present invention: the specific surface area and pore volume adopt the ASAP2405 low-temperature liquid nitrogen physical adsorption method, and the relative crystallinity of the molecular sieve is measured by X-ray powder diffraction (XRD). Among them, taking the sum of the heights of the diffraction peaks at 2θ of ~11.3 and 19.5-23° in the XRD spectrum of the microporous ZSM-23 molecular sieve as the crystallinity 100%, the crystallinity of NaDZSM-23-1 prepared in Comparative Example 1 of the present invention is 100, and other samples were compared with it to obtain the relative crystallinity. The molar ratio of phase silicon to aluminum adopts chemical method. In the present invention, wt% is the mass fraction and v% is the volume fraction.

In order to better illustrate the present invention, further description will be given below in conjunction with examples and comparative examples. However, the scope of the present invention is not limited to the scope of these embodiments.

Example 1

(1) Preparation of mesoporous silicon source

Add 50 g of water glass (SiO ₂ mass fraction is 27%) to 250 g of deionized water, stir and disperse evenly, then add octadecyltrimethylammonium chloride (C ₁₈ TMACl) and stir for 0.5 hours, in which SiO ₂ and The molar ratio of C ₁₈ TMACl is 1:0.07; after adjusting the pH of the solution to 2 with hydrochloric acid, place it in a 50°C water bath and heat it for 4 hours; after completion, filter, wash, dry, and roast at 550°C for 3 hours to obtain amorphous Silica;

(2) Preparation of micro-mesoporous ZSM-23 molecular sieve:

a) Dissolve 0.35 g NaOH in 35 mL deionized water, add 3.7 g of the mesoporous silicon source prepared in (1), and place it in a 45°C water bath for 3 hours;

b) Dissolve aluminum sulfate and isopropylamine (IPA) into the remaining water in sequence, and then add the silicon source dispersion obtained in a) to obtain a total molar ratio of SiO ₂ in the silicon source: Al ₂ O in the aluminum source. ₃ : NaOH: IPA: H ₂ O=1: 0.01:0.08: 1.0: 50 gel, after crystallization at 180°C for 48 hours, filtered, washed, dried and roasted, the product NaZSM-23-1 was obtained. Its relative crystallinity, specific surface area, pore volume and pore size distribution were measured. After hydrothermal treatment with water vapor at 600°C for 2 hours, its hydrothermal stability was measured. The specific properties are shown in Table 1.

(3) Ammonium exchange

Weigh a certain amount of NaZSM-23-1 molecular sieve sample, place it in an ammonium nitrate solution with a concentration of 2 mol/L, with a liquid-to-solid ratio of 10, stir continuously in a water bath at 80~90°C for 1 hour, then filter and wash . After repeating the above operation process twice, the sample was dried in an oven at 80~100°C for 8 hours and calcined in an air atmosphere at 550°C for 3 hours to obtain HZSM-23-1.

(4) Catalyst preparation

The carrier weight is 13% HZSM-23-1 molecular sieve, 37% Y molecular sieve (SiO ₂ /Al ₂ O ₃ molar ratio is 20), 33% macroporous alumina (pore volume 0.9mL/g, specific surface area 400m ² /g), and a binder composed of 17% small-porous alumina (pore volume 0.30 mL/g, specific surface area 320 m ² /g) and 10% weight concentration dilute nitric acid (HNO ₃ /small-porous Al The molar ratio of ₂ O ₃ is 0.26), put it into a roller compactor, mix it, add water, crush it into a paste, and extrud it into strips. The extruded strips are dried at 110°C for 4 hours, and then roasted at 550°C for 4 hours to obtain the carrier TC -1.

The carrier was immersed in an impregnating solution containing tungsten and nickel at room temperature for 2 hours, dried at 120°C for 4 hours, and roasted at a programmed temperature of 500°C for 4 hours to obtain catalyst C-1. The corresponding catalyst properties are shown in Table 2.

Example 2

(1) Preparation of mesoporous silicon source

Add 50 g of water glass (SiO ₂ mass fraction is 27%) to 250 g of deionized water, stir and disperse evenly, then add octadecyltrimethylammonium chloride (C ₁₈ TMACl) and stir for 0.5 hours, in which SiO ₂ and The molar ratio of C ₁₈ TMACl is 1:0.07; after adjusting the pH of the solution to 2 with hydrochloric acid, place it in a 50°C water bath and heat it for 4 hours; after completion, filter, wash, dry, and roast at 550°C for 3 hours to obtain amorphous Silica;

(2) Preparation of micro-mesoporous ZSM-23 molecular sieve:

a) Dissolve 0.42 g NaOH in 40 mL deionized water, add 3.7 g of the mesoporous silicon source prepared in (1), and place it in a 35°C water bath and stir for 6 hours;

b) Dissolve aluminum sulfate and isopropylamine (IPA) into the remaining water in sequence, and then add the silicon source dispersion obtained in a) to obtain a molar ratio of SiO ₂ in the silicon source: Al ₂ O ₃ in the aluminum source. : NaOH : IPA : H ₂ O=1 : 0.01 : 0.10 :1.0 : 50 gel, after crystallization at 180 ℃ for 48 hours, filtered, washed, dried and roasted, it was named NaZSM-23-2 and measured Its relative crystallinity, specific surface area, pore volume and pore size distribution were obtained. After hydrothermal treatment with water vapor at 600°C for 2 hours, its hydrothermal stability was measured. The specific properties are shown in Table 1.

(3) Ammonium exchange

The preparation process of HZSM-23-2 is the same as in Example 1 (3), except that the NaZSM-23-1 molecular sieve is replaced by NaZSM-23-2.

(4) Catalyst preparation

The carrier weight is 11% HZSM-23-2 molecular sieve, 39% Y molecular sieve (SiO ₂ /Al ₂ O ₃ molar ratio is 20), 33% macroporous alumina (pore volume 0.9mL/g, specific surface area 400m ² /g), and a binder composed of 17% small-porous alumina (pore volume 0.30 mL/g, specific surface area 320 m ² /g) and 10% weight concentration dilute nitric acid (HNO ₃ /small-porous Al The molar ratio of ₂ O ₃ (0.26) is put into a roller compactor, mixed, added with water, rolled into a paste, and extruded into strips. The extruded strips are dried at 110°C for 4 hours, and then roasted at 550°C for 4 hours to obtain the carrier TC- 2.

The carrier was immersed in an impregnating solution containing tungsten and nickel at room temperature for 2 hours, dried at 120°C for 4 hours, and roasted at a programmed temperature of 500°C for 4 hours to obtain catalyst C-2. The corresponding catalyst properties are shown in Table 2.

Example 3

(1) Preparation of mesoporous silicon source

Add 50 g water glass (SiO ₂ mass fraction is 27%) to 1200 g deionized water, stir and disperse evenly, then add octadecyltrimethylammonium chloride (C ₁₈ TMACl) and stir for 2 hours, in which SiO ₂ and The molar ratio of C ₁₈ TMACl is 1:0.2; after adjusting the pH of the solution to 3 with hydrochloric acid, place it in a 50 ℃ water bath and heat it for 4 hours; after completion, filter, wash, dry, and roast at 550 ℃ for 3 hours to obtain amorphous Silica;

(2) Preparation of micro-mesoporous ZSM-23 molecular sieve:

a) Dissolve 0.20 g NaOH in 35 mL deionized water, add 3.7 g of the mesoporous silicon source prepared in (1), and place it in a 45°C water bath for 3 hours;

b) Dissolve aluminum sulfate, isopropylamine (IPA) and sodium hydroxide into the remaining water in sequence, then add the silicon source dispersion obtained in a) to obtain a molar ratio of SiO 2 in the silicon source: SiO ₂ in the aluminum source The gel of Al ₂ O ₃ : NaOH : IPA : H ₂ O=1 :0.01 : 0.08 : 1.0 : 50 was named NaZSM-23 after crystallization at 180°C for 48 hours, filtering, washing, drying and roasting. -3, its relative crystallinity, specific surface area, pore volume and pore size distribution were measured. After hydrothermal treatment with water vapor at 600°C for 2 hours, its hydrothermal stability was measured. The specific properties are shown in Table 1.

(3) Ammonium exchange

The preparation process of HZSM-23-3 is the same as in Example 1 (3), except that the NaZSM-23-1 molecular sieve is replaced by NaZSM-23-3.

(4) Catalyst preparation

The carrier weight is 9% HZSM-23-3 molecular sieve, 41% Y molecular sieve (SiO ₂ /Al ₂ O ₃ molar ratio is 20), 33% macroporous alumina (pore volume 0.9mL/g, specific surface area 400m ² /g), and a binder composed of 17% small-porous alumina (pore volume 0.30 mL/g, specific surface area 320 m ² /g) and 10% weight concentration dilute nitric acid (HNO ₃ /small-porous Al The molar ratio of ₂ O ₃ is 0.26), put it into a roller compactor, mix it, add water, crush it into a paste, and extrud it into strips. The extruded strips are dried at 110°C for 4 hours, and then roasted at 550°C for 4 hours to obtain the carrier TC -3.

The carrier was immersed in an impregnating solution containing tungsten and nickel at room temperature for 2 hours, dried at 120°C for 4 hours, and roasted at a programmed temperature of 500°C for 4 hours to obtain catalyst C-3. The corresponding catalyst properties are shown in Table 2.

Example 4

(1) Preparation of mesoporous silicon source

Add 50 g water glass (SiO ₂ mass fraction is 27%) to 800 g deionized water, stir and disperse evenly, then add octadecyltrimethylammonium chloride (C ₁₈ TMACl) and stir for 2 hours, in which SiO ₂ and The molar ratio of C ₁₈ TMACl is 1:0.2; after adjusting the pH of the solution to 4 with hydrochloric acid, place it in a 50 ℃ water bath and heat it for 4 hours; after completion, filter, wash, dry, and roast at 550 ℃ for 3 hours to obtain amorphous Silica;;

(2) Preparation of micro-mesoporous ZSM-23 molecular sieve:

a) Dissolve 0.42 g NaOH in 40 mL deionized water, add 3.7 g of the mesoporous silicon source prepared in (1), and place it in a 40°C water bath for 3 hours;

b) Dissolve aluminum sulfate and isopropylamine (IPA) into the remaining water in sequence, and then add the silicon source dispersion obtained in a) to obtain a molar ratio of SiO ₂ in the silicon source: Al ₂ O ₃ in the aluminum source. : NaOH : IPA : H ₂ O=1 : 0.005 : 0.10 : 1.0 : 50 gel, after crystallization at 180 ℃ for 48 hours, filtered, washed, dried and roasted, it was named NaZSM-23-4 and measured Its relative crystallinity, specific surface area, pore volume and pore size distribution were obtained. After hydrothermal treatment with water vapor at 600°C for 2 hours, its hydrothermal stability was measured. The specific properties are shown in Table 1.

(3) Ammonium exchange

The preparation process of HZSM-23-4 is the same as in Example 1 (3), except that the NaZSM-23-1 molecular sieve is replaced by NaZSM-23-4.

(4) Catalyst preparation

The carrier weight is 7% HZSM-23-4 molecular sieve, 43% Y molecular sieve (SiO ₂ /Al ₂ O ₃ molar ratio is 20), 33% macroporous alumina (pore volume 0.9mL/g, specific surface area 400m ² /g), and a binder composed of 17% small-porous alumina (pore volume 0.30 mL/g, specific surface area 320 m ² /g) and 10% weight concentration dilute nitric acid (HNO ₃ /small-porous Al The molar ratio of ₂ O ₃ is 0.26), put it into a roller compactor, mix it, add water, crush it into a paste, and extrud it into strips. The extruded strips are dried at 110°C for 4 hours, and then roasted at 550°C for 4 hours to obtain the carrier TC -4.

The carrier was immersed in an impregnating solution containing tungsten and nickel at room temperature for 2 hours, dried at 120°C for 4 hours, and roasted at a programmed temperature of 500°C for 4 hours to obtain catalyst C-4. The corresponding catalyst properties are shown in Table 2.

Comparative Example 1 (refer to CN105540607A)

(1) Molecular sieve preparation

Under stirring at 35°C, 0.51 g of pseudoboehmite and 0.3 g of sodium hydroxide were added to 26 mL of deionized water. After the solution is homogenized, add 0.3 g of isopropylamine, then add 21 g of silica, and homogenize again and mix for 1 hour. Add 24.5 g of grain starch, heat the mixture to 90°C, and stir and age for 6 hours. Finally, the obtained mixture was transferred to a hydrothermal reactor lined with polytetrafluoroethylene, statically crystallized at 160°C for 144 hours, taken out, cooled, filtered, and dried at 80°C to obtain raw molecular sieve powder. After roasting at 500°C for 12 hours in air atmosphere, the micro-mesoporous composite NaDZSM-23-1 molecular sieve was obtained. Its relative crystallinity, specific surface area, pore volume and pore size distribution were measured. After hydrothermal treatment with water vapor at 600°C for 2 hours, the Its hydrothermal stability was obtained, and its specific properties are shown in Table 1.

(2) Ammonium exchange

The preparation process of H-DZSM-23-1 is the same as in Example 1 (3), except that the NaZSM-23-1 molecular sieve is replaced by NaDZSM-23-1.

(3) Catalyst preparation

The preparation method of CC-1 catalyst is the same as in Example 4 (4), except that H-ZSM-23-1 molecular sieve is replaced by H-DZSM-23-1. The specific properties are shown in Table 2.

Comparative example 2

(1) Preparation of mesoporous silicon source

Add 50 g water glass (SiO ₂ mass fraction is 27%) to 1200 g deionized water, stir and disperse evenly, then add octadecyltrimethylammonium chloride (C ₁₈ TMACl) and stir for 2 hours, in which SiO ₂ and The molar ratio of C ₁₈ TMACl is 1:0.2; after adjusting the pH of the solution to 3 with hydrochloric acid, place it in a 50°C water bath and heat it for 4 hours; after completion, filter, wash, dry, and roast at 550°C to obtain amorphous dioxide silicon;

(2) a) Dissolve 0.70 g NaOH in 40 mL deionized water, add 3.7 g of the mesoporous silicon source prepared in (1), and place in a 45°C water bath for 3 hours;

b) Dissolve aluminum sulfate and isopropylamine (IPA) into the remaining water in sequence, and then add the silicon source dispersion obtained in a) to obtain a molar ratio of SiO ₂ in the silicon source: Al ₂ O ₃ in the aluminum source. : NaOH : IPA : H ₂ O=1 : 0.01 :0.16 : 1.0 : 50 gel, after crystallization at 180°C for 48 hours, filtered, washed, dried, and roasted, the sample NaDZSM-23-2 was obtained. Its relative crystallinity, specific surface area, pore volume and pore size distribution were obtained. After hydrothermal treatment with water vapor at 600°C for 2 hours, its hydrothermal stability was measured. The specific properties are shown in Table 1.

(3) Ammonium exchange

The preparation process of H-DZSM-23-2 is the same as in Example 1 (3), except that the NaZSM-23-1 molecular sieve is replaced by NaDZSM-23-2.

(4) Catalyst preparation

The preparation method of the CC-2 catalyst is the same as in Example 4 (4), except that the H-ZSM-23-1 molecular sieve is replaced by H-DZSM-23-2. The specific properties are shown in Table 2.

Comparative example 3

(1) Molecular sieve sample preparation

Mix water glass, aluminum sulfate, isopropylamine (IPA), sodium hydroxide and water to obtain a total molar ratio of SiO ₂ in the silicon source: Al ₂ O ₃ in the aluminum source: NaOH: IPA: H ₂ O=1: The gel of 0.01:0.08:1.0:50 was heated at 180°C for 72 hours, filtered, washed, dried and roasted to obtain a product named NaDZSM-23-3.

(2) Ammonium exchange

The preparation process of H-DZSM-23-3 is the same as in Example 1 (3), except that the NaZSM-23-1 molecular sieve is replaced by NaDZSM-23-3.

(3) Catalyst preparation

The preparation method of CC-3 catalyst is the same as in Example 1 (4), except that H-ZSM-23-1 molecular sieve is replaced by H-DZSM-23-3. The specific properties are shown in Table 2.

Comparative example 4

The carrier weight is 50% Y molecular sieve (SiO ₂ /Al ₂ O ₃ molar ratio is 20), 33% macroporous alumina (pore volume 0.9mL/g, specific surface area 400m ² /g), and 17% small A binder composed of pore alumina (pore volume 0.30 mL/g, specific surface area 320 m ² /g) and 10% weight concentration dilute nitric acid (molar ratio of HNO ₃ /small pore Al ₂ O ₃ 0.26), add water , rolled into a paste, and extruded into strips. The extruded strips were dried at 110°C for 4 hours, and then calcined at 550°C for 4 hours to obtain the carrier TC-4.

The carrier was immersed in an impregnating solution containing tungsten and nickel at room temperature for 2 hours, dried at 120°C for 4 hours, and roasted at a programmed temperature of 500°C for 4 hours to obtain catalyst CC-4. The corresponding catalyst properties are shown in Table 2.

Table 1 Properties of molecular sieves

a The products generated under this condition are mainly other molecular sieves, so this property cannot be analyzed;

d Relative crystallinity retention = crystallinity after hydrothermal treatment/relative crystallinity. Due to the existence of measurement errors, results greater than 100% are recorded as 100%.

Table 2 Physicochemical properties of catalysts

The above catalysts were subjected to activity evaluation tests. The test was conducted on a 200mL small hydrogenation device, using a one-stage series hydrogenation modification process. The properties of the raw oil used are shown in Table 4. The operating conditions are as follows: reaction pressure 6.5MPa, hydrogen-to-oil volume ratio 500:1, liquid hourly volume space velocity 1.0h ^-1 , conversion rate <210°C 70wt%, and refined oil nitrogen content 20ppm. The catalyst activity test results are shown in Table 4.

Table 3 Raw material oil properties

Table 4 Catalyst activity evaluation results

It can be seen from the evaluation results of the catalyst in Table 4 that compared with the comparative example, the catalyst prepared by the present invention has a higher gasoline fraction yield and a higher octane number on the basis of higher activity.

Claims (16)

1. A catalyst for producing gasoline by hydrocracking, characterized in that: the properties of the catalyst are as follows: the specific surface area is 350 to 600 m ² /g, the pore volume is 0.4 to 0.7 mL/g, and the pore diameter of the catalyst is 3-6 nm mesopores account for 35~60% of the total pore volume, and 6~15 nm mesopores account for 30~55% of the total pore volume; based on the weight of the final catalyst, it contains 10wt%~30wt% of active metals calculated as oxides , the remainder is the carrier. 2. The catalyst according to claim 1, characterized in that: in the catalyst, mesopores with a pore diameter of 3-6 nm account for 45-55% of the total pore volume, and mesopores of 6-15 nm account for 35-45% of the total pore volume. . 3. The catalyst according to claim 1, characterized in that the active metal includes at least one of Group VIB metal and Group VIII metal. 4. The catalyst according to claim 1, characterized in that: based on the weight of the catalyst, the content of Group VIB metal is 10wt%~20wt% as oxide, and the content of Group VIII metal is 2wt% as oxide. ~10wt%. 5. The catalyst according to claim 3, characterized in that: the Group VIB metal includes W and/or Mo; the Group VIII metal includes Co and/or Ni. 6. The catalyst according to claim 1, characterized in that: based on the carrier quality, the content of ZSM-23 molecular sieve is 3~15wt%, and the content of Y molecular sieve is 30~60wt%; in the ZSM-23 molecular sieve Mesopores with a pore diameter of 3 to 6 nm account for 45-90% of the total pore volume of the molecular sieve, preferably 50-85%, and further preferably 55-81%. 7. The catalyst according to claim 1, characterized in that: the Y-type molecular sieve SiO ₂ /Al ₂ O ₃ molar ratio is 10 to 25; preferably 15 to 20. 8. The catalyst according to claim 1, characterized in that: the relative crystallinity of the ZSM-23 molecular sieve is 95~120%, and the relative crystallinity retention of the molecular sieve after hydrothermal treatment with water vapor at 600°C for 2 hours. It is 95~100%. 9. The catalyst according to claim 1, characterized in that based on the quality of the carrier, the content of macroporous alumina is 20-60wt%, and the content of the binder is 10-30wt%. 10. The catalyst according to claim 9, characterized in that: the properties of the macroporous alumina are as follows: pore volume is 0.6~1.2mL/g, preferably 0.8~1.0 mL/g, and specific surface area is 300~600 m ² /g, preferably 400 to 500 m ² /g. 11. The catalyst according to claim 9, characterized in that: the binder adopts small pore alumina, the pore volume of the small pore alumina used is 0.3-0.5 mL/g, and the specific surface area is 200-400 m ² /g. 12. The preparation method of any catalyst of claims 1 to 11, characterized in that: it includes the following steps: first prepare ZSM-23 molecular sieve; then mix the prepared ZSM-23 molecular sieve, Y molecular sieve, amorphous silica aluminum and binder , molding, drying and roasting to make a catalyst carrier; finally, active metal is introduced onto the catalyst carrier, and the final catalyst is obtained after drying and roasting; the preparation of the ZSM-23 molecular sieve includes the following steps: (1) Preparation or selection of amorphous silica; (2) Alkali treatment of amorphous silica; (3) Use alkali-treated amorphous silica as the silicon source to prepare ZSM-23 molecular sieve. 13. The method according to claim 12, characterized in that: drying the carrier is at a temperature of 80-120°C for 3-10 hours, and roasting is at 400-600°C for 3-10 hours. 14. The method according to claim 12, characterized in that after introducing the active metal, drying is carried out at 100°C to 120°C for 1 to 12 hours, and roasting is carried out at 400°C to 600°C for 3 to 10 hours. 15. A method for producing gasoline by hydrocracking catalytic cracking diesel, which is characterized in that: after hydrorefining the catalytically cracked diesel, the hydrocracking reaction is carried out under the action of any hydrocracking catalyst of claims 1 to 11. 16. The method according to claim 15, characterized in that: the properties of the catalytically cracked diesel oil: density is 0.88~0.99g/ ^cm3 , dry point is 360~400°C, aromatic hydrocarbon content is 50~95wt%, catalytic The sulfur content of cracked diesel is 0.2 to 2wt%, and the nitrogen content is 500ppm to 2000ppm.