Isomerization catalyst, preparation method thereof and application thereof in catalytic diesel hydrocracking

Abstract

The present invention discloses an isomerization catalyst, a preparation method thereof, and an application thereof in catalytic diesel hydrocracking. Based on the weight of the catalyst, the mass content of HZSM-23 molecular sieve is 30-70 wt%, the mass content of macroporous alumina is 20-40 wt%, the mass content of Group VIB metal as oxide is 10-30 wt%, and the mass content of Group VIII metal as oxide is 4-10 wt%. The specific surface area of ​​the isomerization catalyst is 250-500 m 2 / g, pore volume of 0.30~0.70 cm 3 / g; the weak acid content in the catalyst accounts for 75-90% of the total acid content. The preparation method of the catalyst includes preparing a catalyst support and loading a hydrogenation-active metal, wherein the preparation method of the catalyst support comprises mixing and shaping an HZSM-23 molecular sieve, macroporous alumina, and a binder, followed by drying and calcining to form the catalyst support. The catalyst is suitable for catalytic diesel hydrocracking to produce gasoline, and has the characteristics of high gasoline yield and high gasoline octane number.

Description

Technical Field

[0001] The present invention relates to an isomerization catalyst, a preparation method thereof and application thereof in catalytic diesel hydrocracking. Specifically, it relates to an isomerization catalyst, a preparation method thereof and application thereof in catalytic diesel hydrocracking to produce high-octane gasoline. Background Art

[0002] With the rapid development of the economy, the demand structure of gasoline and diesel has undergone great changes. my country's apparent diesel-to-gasoline ratio has dropped from 2.31 in 2005 to 1.25 in 2018. It is predicted that it will drop to around 0.8 by 2023. The decline in the diesel-to-gasoline ratio will bring huge challenges to the structural adjustment of China's refining equipment.

[0003] As global oil becomes increasingly heavier, the processing capacity of FCC units continues to increase, and the quality of catalytic diesel fuel deteriorates. To improve the utilization of oil resources, achieve the goals of optimizing product blending and maximizing product value, and meet the growing domestic demand for clean fuels, the hydrocracking process technology for hydroconverting high-aromatic diesel to produce high-octane gasoline blending components has great application prospects.

[0004] EP20110834653 discloses a method for preparing a catalyst for the hydroconversion of polycyclic aromatic hydrocarbons. The catalyst carrier is composed of β molecular sieve and pseudo-boehmite, and Group VIB and Group VIII active metal components are added by conventional methods. However, the catalyst also has a strong ability to saturate gasoline components, which is not conducive to the catalytic hydroconversion of diesel to produce high-octane gasoline.

[0005] CN109777714 discloses a method for catalytically converting diesel into high-octane gasoline by hydrocracking. The method uses a Y-type molecular sieve hydrocracking catalyst, which has the advantages of high ring-opening performance and high selective cracking performance for components rich in aromatics. It can effectively control the depth of hydrogenation saturation of aromatics in the feedstock, convert and enrich part of the aromatics in the feedstock into the naphtha fraction to produce high-octane gasoline blending components.

[0006] US2010116712 discloses a catalytic diesel hydroconversion method, which uses a conventional cracking catalyst. The crude oil is first pretreated and then contacted with the cracking catalyst to produce clean diesel and high-octane gasoline.

[0007] When the above method is used in the catalytic diesel production gasoline hydrocracking process, there are generally problems such as low gasoline product yield to varying degrees and the octane number needs to be further improved. Summary of the Invention

[0008] In response to the problems existing in the prior art, the present invention provides an isomerization catalyst, a preparation method thereof, and its application in catalytic diesel hydrocracking. The catalyst is suitable for catalytic diesel hydrocracking to produce gasoline, and has the characteristics of high gasoline yield and high gasoline octane number.

[0009] An isomerization catalyst comprises, based on the weight of the catalyst, 30-70 wt% of HZSM-23 molecular sieve, 20-40 wt% of macroporous alumina, 10-30 wt% of Group VIB metal oxide, and 4-10 wt% of Group VIII metal oxide. The specific surface area of ​​the isomerization catalyst is 250-500 m 2 / g, pore volume of 0.30~0.70 cm 3 / g; the specific surface area is preferably 300~450 m 2 / g, and the pore volume is preferably 0.37~0.60 cm 3 / g; the weak acid content in the catalyst accounts for 75-90% of the total acid content; preferably, the weak acid content accounts for 80-90% of the total acid content.

[0010] In the isomerization catalyst of the present invention, the properties of the HZSM-23 molecular sieve are as follows: a total acid content of 0.1 to 0.25 mmol / g, a strong acid content of 10 to 25%; a relative crystallinity of 95 to 120%, and a relative crystallinity of 93 to 115% after steam hydrothermal treatment; preferably, the total acid content is 0.15 to 0.25 mmol / g, the strong acid content is 10 to 20%; the relative crystallinity is 98 to 116%, and the relative crystallinity after steam hydrothermal treatment is 95 to 114%.

[0011] In the isomerization catalyst of the present invention, the properties of the HZSM-23 molecular sieve are as follows: a crystallite size of 300-600 nm, a SiO2 / Al2O3 molar ratio of 80-130, a specific surface area of ​​300-400 m 2 / g, pore volume 0.30~0.45 cm 3 / g.

[0012] In the isomerization catalyst of the present invention, the metal of Group VIB is molybdenum and / or tungsten, and the metal of Group VIII is cobalt and / or nickel.

[0013] In the isomerization catalyst of the present invention, the macroporous alumina has the following properties: pore volume of 0.6-1.2 mL / g, preferably 0.8-1.0 mL / g, specific surface area of ​​300-600 m 2 / g, preferably 400 to 500 m 2 / g.

[0014] The preparation method of the isomerization catalyst of the present invention includes the preparation of a catalyst carrier and the loading of a hydrogenation active metal. The preparation method of the catalyst carrier includes: mixing and shaping HZSM-23 molecular sieve, macroporous alumina and a binder, and then drying and calcining to prepare the catalyst carrier.

[0015] In the method of the present invention, the hydrogenation active metal is a Group VIB metal and / or a Group VIII metal, the Group VIB metal is molybdenum and / or tungsten, and the Group VIII metal is cobalt and / or nickel.

[0016] In the method of the present invention, the molding process can be conventionally selected as needed. The shape can be cylindrical, clover-shaped, etc. During the catalyst molding process, molding aids such as peptizing acid and extrusion aids can also be added. Peptizers can generally be inorganic acids and / or organic acids, and extrusion aids can be sesbania powder. Conventional methods are used for drying and calcining. Drying is performed at a temperature of 80-120°C for 3-10 hours. Calcination is performed at a temperature of 400-600°C for 3-10 hours.

[0017] In the method of the present invention, the active metal loading method can be conventional loading methods, preferably impregnation, which can be saturation impregnation, excess impregnation, or complex impregnation. Furthermore, the impregnation method comprises impregnating the support with a solution containing the active metal, drying, and calcining the support. The drying step is performed at 100°C to 120°C for 1 to 12 hours. The calcination step is performed at 400°C to 600°C for 3 to 10 hours.

[0018] A method for producing gasoline by catalytic diesel hydrocracking comprises the following steps: catalytically cracked diesel is sequentially reacted in a hydrorefining reaction zone, a hydrocracking reaction zone, and an isomerization reaction zone; the isomerization reaction zone is loaded with an isomerization catalyst containing HZSM-23 molecular sieve, preferably the isomerization catalyst prepared in the present invention.

[0019] In the above method, the properties of the catalytic cracking diesel are as follows: density of 0.88 to 0.99 g / cm 3 The distillation range is 280-400℃, the aromatic content is 50-95wt%, the sulfur content of catalytic cracking diesel is 0.2-2wt%, and the nitrogen content is 500ppm-1800ppm.

[0020] In the above method, the catalyst loaded into the hydrorefining reaction zone is a conventional hydrocracking pretreatment catalyst, generally using an alumina support, and the hydrogenation-active metal components are Group VIB and Group VIII metals. The Group VIB metals are preferably molybdenum and / or tungsten, and the content of the catalyst as oxides is 15.0% to 25.0% by weight. The Group VIII metals are preferably cobalt and / or nickel, and the content of the catalyst as oxides is 4.0% to 7.0% by weight.

[0021] The reaction conditions are as follows: reaction temperature is 320-440°C, preferably 340-420°C; reaction pressure is 4.0-12.0 MPa, preferably 6.0-10.0 MPa; liquid hourly volume space velocity is 0.2-6.0 h -1 , preferably 0.5~3.0h -1 ; The volume ratio of hydrogen to oil is 100 to 2000, preferably 500 to 1500.

[0022] In the above method, the catalyst loaded into the hydrocracking reaction zone comprises, based on their weight, 20-60 wt% of Y molecular sieve, 30-70 wt% of macroporous alumina, 10-25 wt% of Group VIB metal (calculated as oxide), and 3-8 wt% of Group VIII metal (calculated as oxide). The Group VIB metal is preferably molybdenum and / or tungsten, and the Group VIII metal is preferably cobalt and / or nickel. The Y molecular sieve has the following properties: a Na2O weight content of less than 0.3%; a silicon-aluminum molar ratio of SiO2 / Al2O3 of 10-25, preferably 14-20; and a specific surface area of ​​600-900 m2. 2 / g; pore volume is 0.3~0.6mL / g; particle size is 500~1000nm.

[0023] In the above method, the preparation of the catalyst loaded in the hydrocracking reaction zone includes the preparation of the carrier and the loading of the hydrogenation active metal. The preparation method of the catalyst A carrier includes: mixing Y molecular sieve and macroporous alumina uniformly, adding dilute nitric acid and then shaping, and then drying and calcining to prepare the catalyst carrier.

[0024] In the above method, the process conditions of the hydrocracking reaction are: reaction temperature of 340-440°C, preferably 360-430°C; reaction pressure of 6.0-12.0 MPa; liquid hourly volume space velocity of 0.5-3.0 h -1 ; The volume ratio of hydrogen to oil is 500~1500.

[0025] In the above method, the volume ratio of the catalysts loaded in the hydrocracking reaction zone and the isomerization reaction zone is 20:1-3:1, preferably 15:1-4:1.

[0026] The method of the present invention catalyzes the hydrorefining of diesel raw materials before they enter the hydrocracking reaction zone. The hydrocracking reaction zone is conducive to the diffusion of hydrocarbon molecules, which can improve the preferential conversion capacity of cyclic hydrocarbons, especially tricyclic aromatic hydrocarbons, and directionally saturate and break the aromatic rings in the middle of the tricyclic aromatic hydrocarbons. Secondly, through two-stage ring opening and cracking, large molecular cycloalkylbenzenes in the diesel fraction are cracked into small molecular alkylbenzenes, which are enriched in the gasoline fraction, thereby increasing the high-octane gasoline components in the product. The hydrocracked material enters the isomerization reaction zone, where normal alkanes and cracked small molecular alkylbenzenes are well adsorbed on the HZSM-23 molecular sieve, especially at the strong acid content and rich in weak acid sites, and isomerize to form pairs, thereby increasing the isomerized products and further improving the octane number of the gasoline product. The catalyst of the present invention is used to catalyze diesel hydrocracking to produce gasoline, and has the characteristics of high gasoline yield and gasoline octane number. DETAILED DESCRIPTION

[0027] The preparation of the ZSM-23 molecular sieve of the present invention refers to the preparation method of CN202210011752.2.

[0028] The HZSM-23 molecular sieve comprises the following preparation steps:

[0029] (1) preparing a mixed solution containing a structure directing agent, amorphous silicon aluminum or an amorphous silicon aluminum precursor;

[0030] (2) adding a supplementary silicon source to the material of step (1);

[0031] (3) The material of step (2) is crystallized, filtered, washed, dried and calcined to obtain ZSM-23 molecular sieve.

[0032] (4) The molecular sieve obtained in (3) is subjected to ammonium exchange to obtain HZSM-23 molecular sieve.

[0033] In step (1) of the above method, the structure directing agent is one or more of isopropylamine, pyrrolidine, N,N-dimethylformamide, and dimethylamine.

[0034] In step (1) of the above method, the molar ratio of silicon (calculated as silicon oxide) to aluminum (calculated as aluminum oxide) in the mixed solution is 1: (0.10-0.85), preferably 1: (0.20-0.79), and more preferably 1: (0.24-0.78); the molar ratio of aluminum (calculated as aluminum oxide) to structure directing agent is 1: (10-100), preferably 1: (15-85), and more preferably 1: (20-65).

[0035] In step (1) of the above method, a carbonization method is used to prepare an amorphous silicon-aluminum precursor mixture, and then a structure directing agent is added to the amorphous silicon-aluminum precursor mixture.

[0036] A non-limiting process for preparing an amorphous silicon-aluminum precursor mixture in an embodiment of the present invention is as follows: prepare an aluminum source (preferably sodium aluminate) solution and a silicon-containing compound solution separately; mix the sodium aluminate solution with part of the silicon-containing compound solution, and introduce CO2 gas to form a gel; when the volume of the introduced CO2 gas accounts for 50~100% of the total volume introduced, preferably 70~90%, add the remaining part of the silicon-containing compound solution, and then introduce the remaining CO2 gas, and optionally age it to obtain an amorphous silicon-aluminum precursor mixture.

[0037] During the preparation of the amorphous silicon-aluminum precursor mixed solution, the remaining portion of the silicon-containing compound solution, calculated as silicon dioxide, accounts for 20-90 wt %, preferably 30-80 wt %, of the total amount of the added silicon-containing compound solution, calculated as silicon dioxide.

[0038] During the preparation of the amorphous silicon-aluminum precursor mixture, the reaction temperature for gelation is 10-40° C., preferably 15-35° C., and the pH value after gelation is controlled to be 9-12.

[0039] During the preparation of the amorphous silicon-aluminum precursor mixed solution, the silicon-containing compound solution is water glass and / or sodium silicate solution.

[0040] During the preparation of the above-mentioned amorphous silicon-aluminum precursor mixture, the concentration of the aluminum source solution is 15~60 g Al2O3 / L based on the mass of Al2O3, the concentration of the silicon-containing compound solution is 40~260 g SiO2 / L based on the mass of SiO2, and the concentration of the CO2 gas is 30~60 v%.

[0041] During the preparation of the amorphous silicon-aluminum precursor mixture, the aging time is 5 to 60 minutes, preferably 10 to 30 minutes; and the aging temperature is 10 to 40°C, preferably 15 to 35°C.

[0042] In step (1) of the above method, the mixed solution is stirred at 10-35°C for 0.2-1.5 hours, preferably at 10-25°C for 0.5-1 hour.

[0043] In step (2) of the above method, based on the aluminum (calculated as alumina) in the mixed solution of step (1), a supplementary silicon source is added to the material of step (1) at a total feed molar ratio of SiO2:Al2O3:H2O=1:(0.005~0.0125):(30~60) and SDA (structure directing agent) / SiO2=0.10~1.8.

[0044] In step (2) of the above method, the silicon source is one or more of fumed silica, silica sol and water glass.

[0045] In step (3) of the above method, the crystallization conditions are: crystallization at 160-180°C for 10-48 hours; drying temperature at 80-120°C for 4-8 hours; and calcination temperature at 500-600°C for 2-8 hours.

[0046] In step (4) of the above method, ammonium exchange is carried out by conventional methods, such as one or more ammonium exchanges, and the Na2O content in the HZSM-23 molecular sieve after ammonium exchange is less than 0.1%; washing, drying and calcination can then be carried out, wherein the drying temperature is 60~130℃ and the time is 2~12 hours, preferably drying at 80~120℃ for 4~8 hours; the calcination temperature is 500~600℃ and the time is 2~8 hours, preferably calcining at 530~570℃ for 3~6 hours.

[0047] In the preparation process of the HZSM-23 molecular sieve of the present invention, mesoporous amorphous silica is initially prepared with the assistance of a surfactant and used as a silicon source for the subsequent synthesis of the ZSM-23 molecular sieve. The amorphous silica generated in this process has a mesoporous structure but is not highly crystallized into a stable crystalline form. After further treatment in a low-concentration alkaline solution for a period of time, some of the -Si-O- bonds are opened, which facilitates the subsequent formation of -Si-O-Al- bonds in the molecular sieve structure, but most of the mesoporous structure is retained. Under the action of a microporous template agent in the later stage, a microporous structure is generated in a suitable ZSM-23 molecular sieve synthesis system, and the mesoporous structure is 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 has both the acidic properties of the microporous structure that can be adjusted and the large pore characteristics of the mesoporous structure, high specific surface area and pore volume, high crystallinity, and strong thermal stability and hydrothermal stability.

[0048] In order to better illustrate the present invention, the present invention is further illustrated below in conjunction with Examples and Comparative Examples. However, the scope of the present invention is not limited to the scope of these Examples.

[0049] In the present invention, the specific surface area and pore volume are measured by using a low-temperature liquid nitrogen physical adsorption method using an ASAP 2405 physical adsorption instrument produced by Micromeritics, USA.

[0050] The silicon to aluminum molar ratio was determined by chemical analysis.

[0051] XRD patterns of the samples were collected using a Dmax2500 X-ray diffractometer manufactured by Rigaku Corporation. The relative crystallinity of the molecular sieves was determined by X-ray powder diffraction (XRD). Specifically, the sum of the heights of the diffraction peaks at approximately 11.3 and 19.5-23° 2θ in the XRD spectrum of a conventional ZSM-23 molecular sieve was taken as 100% crystallinity. The crystallinity of H-DZSM-23-1 prepared in Comparative Example 1 of the present invention was 100, and the relative crystallinity of the other samples was compared with this.

[0052] The grain size was obtained by a JSM-7500F field emission scanning electron microscope from JEOL, Japan.

[0053] The acid distribution (including total acid content and strong acid content) was measured by NH3 temperature-programmed desorption (NH3-TPD), where the acid content corresponding to a desorption temperature above 350 ºC was considered strong acid, and that below 350 ºC was considered weak acid. The total acid content is Acid content corresponding to adsorption temperature of 150°C 。

[0054] In the present invention, wt% refers to mass fraction and v% refers to volume fraction.

[0055] Example 1

[0056] (1) Preparation of amorphous silicon aluminum precursor

[0057] Prepare a sodium aluminate working solution with a concentration of 40 g Al₂O₃ / L. Take a sodium silicate solution containing 28 wt% SiO₂ and dilute it to a sodium silicate working solution with a concentration of 100 g SiO₂ / L. Place 150 mL of the sodium aluminate working solution in a gelling tank, then add 60 mL of the sodium silicate working solution. Maintain the reaction temperature at 20°C and introduce 50 vol% CO₂ gas. When the pH reaches 10.0, stop the CO₂ flow and add 80 mL of the sodium silicate working solution. Continue bubbling with the remaining CO₂ gas to stabilize the mixture. After aging at 25°C for 30 minutes, an amorphous silicon-alumina precursor is obtained. The amorphous silicon-alumina precursor contains 70 wt% silicon dioxide, based on the total weight of silicon dioxide and aluminum oxide.

[0058] (2) Preparation of gel

[0059] According to the total feed molar ratio of SiO2: Al2O3: IPA: H2O = 1: 0.01: 0.04: 0.7: 45 (IPA is the structure-directing agent isopropylamine), isopropylamine is added to the amorphous silica-alumina precursor obtained in step (1), and stirred at 15 ° C for 0.8 hours; then, a mixture consisting of silica sol and water is added thereto and stirred evenly to obtain silica-alumina gel.

[0060] (3) Crystallization

[0061] The gel obtained in step (2) was poured into a stainless steel reactor and statically crystallized at 160°C for 20 hours. After the crystallization, it was filtered, washed to neutrality, dried at 120°C, and calcined in air at 550°C for 3 hours to obtain the molecular sieve raw powder NaZSM-23-1.

[0062] (4) Ammonium exchange

[0063] A certain amount of NaZSM-23-1 molecular sieve was weighed and placed in a 2 mol / L ammonium nitrate solution with a liquid-to-solid ratio of 10. After continuous stirring in an 80–90°C water bath for 1 hour, the solution was filtered and washed. This process was repeated twice. The sample was then dried in an oven at 80–100°C for 8 hours and calcined in air at 550°C for 3 hours to obtain HZSM-23-1. The relative crystallinity of the HZSM-23-1 was determined by XRD. The relative crystallinity of the HZSM-23-1 was also measured after hydrothermal treatment with steam at 600°C for 2 hours. Specific properties are shown in Table 1.

[0064] (5) Catalyst preparation

[0065] The catalyst weight was 45% HZSM-23-1 molecular sieve and 37% macroporous alumina (pore volume 0.8 mL / g, specific surface area 360 m 2 / g) was put into a roller compactor for mixing and grinding, 100 g of 15% mass concentration dilute nitric acid and an appropriate amount of water were added, and the mixture was rolled into a paste, extruded into strips, and the extruded strips were dried at 110°C for 4 hours and then calcined at 550°C for 4 hours to obtain carrier TB-1.

[0066] The support was impregnated with an impregnation solution containing tungsten and nickel at room temperature for 2 hours, dried at 120°C for 4 hours, and calcined at 500°C for 4 hours to obtain catalyst B-1. The corresponding catalyst properties are shown in Table 2.

[0067] Example 2

[0068] 1) Preparation of amorphous silicon aluminum precursor

[0069] A sodium aluminate working solution with a concentration of 40 g Al2O3 / L was prepared. A sodium silicate solution containing 28 wt% SiO2 was diluted to a sodium silicate working solution with a concentration of 120 g SiO2 / L. 200 mL of the sodium aluminate working solution was placed in a gelling tank, followed by the addition of 40 mL of the sodium silicate working solution. The reaction temperature was controlled at 25°C, and 50% CO2 gas was introduced. When the pH reached 10.5, the CO2 flow was stopped, and 60 mL of the sodium silicate working solution was added. The remaining CO2 gas was then introduced for stabilization. After aging at 20°C for 20 minutes, an amorphous silicon-alumina precursor was obtained. The amorphous silicon-alumina precursor contained 40 wt% silicon dioxide, based on the total weight of silicon dioxide and aluminum oxide.

[0070] (2) Preparation of gel

[0071] Isopropylamine was added to the amorphous silica-alumina precursor obtained in step (1) at a total feed molar ratio of SiO2: Al2O3: IPA: H2O = 1: 0.01: 0.04: 0.15: 60, and the mixture was stirred at 20°C for 1 hour; thereafter, a mixture consisting of silica sol and water was added thereto and stirred uniformly to obtain silica-alumina gel.

[0072] (3) Crystallization

[0073] The gel obtained in step (2) was poured into a stainless steel reactor and statically crystallized at 180°C for 22 hours. After the crystallization, the gel was filtered, washed to neutrality, dried at 120°C, and calcined in air at 550°C for 3 hours to obtain the molecular sieve raw powder NaZSM-23-2.

[0074] (4) Ammonium exchange

[0075] The preparation process of HZSM-23-2 is the same as that of Example 1 (4), except that NaZSM-23-1 molecular sieve is replaced by HZSM-23-2. The specific properties are shown in Table 1.

[0076] (5) Catalyst preparation

[0077] The catalyst weight was 50% HZSM-23-2 molecular sieve and 30% macroporous alumina (pore volume 0.9 mL / g, specific surface area 430 m 2 / g) was put into a roller compactor for mixing and grinding, 100 g of 15% mass concentration dilute nitric acid and an appropriate amount of water were added, and the mixture was rolled into a paste, extruded into strips, and the extruded strips were dried at 110°C for 4 hours and then calcined at 550°C for 4 hours to obtain carrier TB-2.

[0078] The support was impregnated with an impregnation solution containing tungsten and nickel at room temperature for 2 hours, dried at 120°C for 4 hours, and calcined at 500°C for 4 hours to obtain catalyst B-2. The corresponding catalyst properties are shown in Table 2.

[0079] Example 3

[0080] (1) Preparation of amorphous silicon aluminum precursor

[0081] Prepare a sodium aluminate working solution with a concentration of 35 g Al₂O₃ / L. Take a sodium silicate solution containing 28 wt% SiO₂ and dilute it to a sodium silicate working solution with a concentration of 65 g SiO₂ / L. Place 100 mL of the sodium aluminate working solution in a gelling tank, then add 40 mL of the sodium silicate working solution. Control the reaction temperature at 30°C and introduce 50 vol% CO₂ gas. Stop the CO₂ flow when the pH reaches 11.0, then add 60 mL of the sodium silicate working solution. Continue bubbling with the remaining CO₂ gas to stabilize the mixture. After aging at 20°C for 30 minutes, an amorphous silicon-alumina precursor is obtained. The amorphous silicon-alumina precursor contains 35 wt% silicon dioxide, based on the total weight of silicon dioxide and aluminum oxide.

[0082] (2) Preparation of gel

[0083] Isopropylamine was added to the amorphous silica-alumina precursor obtained in step (1) at a total feed molar ratio of SiO2: Al2O3: IPA: H2O = 1: 0.008: 0.3: 45, and the mixture was stirred at 15°C for 1 hour; thereafter, a mixture consisting of silica sol and water was added thereto and stirred uniformly to obtain silica-alumina gel.

[0084] (3) Crystallization

[0085] The gel obtained in step (2) was poured into a stainless steel reactor and statically crystallized at 160°C for 25 hours. After the crystallization, the gel was filtered, washed to neutrality, dried at 120°C, and calcined in air at 550°C for 3 hours to obtain the molecular sieve raw powder NaZSM-23-3.

[0086] (4) Ammonium exchange and template removal agent

[0087] The preparation process of HZSM-23-3 is the same as that of Example 1 (4), except that NaZSM-23-1 molecular sieve is replaced by HZSM-23-3. The specific properties are shown in Table 1.

[0088] (5) Catalyst preparation

[0089] The catalyst weight was 55% HZSM-23-3 molecular sieve and 24% macroporous alumina (pore volume 0.95 mL / g, specific surface area 450 m 2 / g) was put into a roller compactor for mixing and grinding, and 100 g of 15% mass concentration dilute nitric acid and an appropriate amount of water were added, and the mixture was rolled into a paste, extruded into strips, dried at 110°C for 4 hours, and then calcined at 550°C for 4 hours to obtain carrier TB-3.

[0090] The support was impregnated with an impregnation solution containing tungsten and nickel at room temperature for 2 hours, dried at 120°C for 4 hours, and calcined at 500°C for 4 hours to obtain catalyst B-3. The corresponding catalyst properties are shown in Table 2.

[0091] Example 4

[0092] (1) Preparation of amorphous silicon aluminum precursor

[0093] Prepare a sodium aluminate working solution with a concentration of 40 g Al₂O₃ / L. Take a sodium silicate solution containing 28 wt% SiO₂ and dilute it to a sodium silicate working solution with a concentration of 60 g SiO₂ / L. Place 150 mL of the sodium aluminate working solution in a gelling tank, then add 500 mL of the sodium silicate working solution. Control the reaction temperature at 20°C and introduce 50% CO₂ gas. When the pH reaches 10.0, stop the CO₂ flow and add another 50 mL of the sodium silicate working solution. Continue bubbling with the remaining CO₂ gas to stabilize the mixture. After aging at 25°C for 20 minutes, an amorphous silicon-alumina precursor is obtained. The amorphous silicon-alumina precursor contains 50 wt% silicon dioxide, based on the total weight of silicon dioxide and aluminum oxide.

[0094] (2) Preparation of gel

[0095] Isopropylamine was added to the amorphous alumina-silica precursor obtained in step (1) at a total feed molar ratio of Al2O3: SiO2: IPA: H2O = 1: 0.01: 0.4: 45, and the mixture was stirred at 15°C for 1 hour; thereafter, a mixture of fumed silica and water was added thereto, and the mixture was stirred evenly to obtain alumina-silica gel.

[0096] (3) Crystallization

[0097] The gel obtained in step (2) was poured into a stainless steel reactor and statically crystallized at 180°C for 24 hours. After the crystallization, it was filtered, washed to neutrality, dried at 120°C, and calcined in air at 550°C for 3 hours to obtain the molecular sieve raw powder NaZSM-23-4.

[0098] (4) Ammonium exchange

[0099] The preparation process of HZSM-23-4 is the same as that of Example 1 (4), except that NaZSM-23-1 molecular sieve is replaced by HZSM-23-4. The specific properties are shown in Table 1.

[0100] (5) Catalyst preparation

[0101] The catalyst weight was 60% HZSM-23-4 molecular sieve and 17% macroporous alumina (pore volume 1.0 mL / g, specific surface area 480 m 2 / g) was put into a roller compactor for mixing and grinding, 100 g of 15% mass concentration dilute nitric acid and an appropriate amount of water were added, and the mixture was rolled into a paste, extruded into strips, and the extruded strips were dried at 110°C for 4 hours and then calcined at 550°C for 4 hours to obtain the carrier TB-4.

[0102] The support was impregnated with an impregnation solution containing tungsten and nickel at room temperature for 2 hours, dried at 120°C for 4 hours, and calcined at 500°C for 4 hours to obtain catalyst B-4. The corresponding catalyst properties are shown in Table 2.

[0103] Example 5

[0104] Y molecular sieve (particle size 800 nm, Na2O content 0.25 wt%, specific surface area 720 m2) containing 50% of the catalyst weight 2 / g, pore volume 0.47mL / g, SiO2 / Al2O3 molar ratio of 18) and 31% macroporous alumina (pore volume 0.8mL / g, specific surface area 360m 2 / g) was put into a roller and mixed and ground, 100 g of 12% mass concentration dilute nitric acid and an appropriate amount of water were added, and the mixture was rolled into a paste, extruded into strips, and the extruded strips were dried at 110°C for 4 hours and then calcined at 550°C for 4 hours to obtain the carrier TA.

[0105] The support was impregnated with an impregnation solution containing tungsten and nickel at room temperature for 2 hours, dried at 120°C for 4 hours, and calcined at 500°C for 4 hours to obtain catalyst A. The corresponding catalyst properties are shown in Table 2.

[0106] Comparative Example 1 (Refer to CN101214971A)

[0107] A reaction mixture was prepared using a molar ratio of Al2O3 from the aluminum source: SiO2 from the silicon source: NaOH from the alkali source: isopropylamine: H2O of 0.01:1:0.06:0.8:12. The aluminum source was sodium metaaluminate, the silicon source was silica sol, and the alkali source was sodium hydroxide. The aluminum source was first added to an aqueous sodium hydroxide solution and stirred uniformly. The silicon source was then added and stirred uniformly. Finally, isopropylamine was added and stirred uniformly to obtain a reaction mixture. The resulting reaction mixture was transferred to an autoclave and hydrothermally crystallized at 170°C for 3 days. The mixture was then filtered, washed until neutral, and dried at 120°C to obtain NaDZSM-23-1 molecular sieve.

[0108] (2) Ammonium exchange

[0109] The preparation process of H-DZSM-23-1 is the same as that of Example 1 (4), except that NaZSM-23-1 molecular sieve is replaced by NaDZSM-23-1. The specific properties are shown in Table 1.

[0110] (3) Catalyst preparation

[0111] The preparation method of CB-1 catalyst is the same as that of Example 1 (5), except that H-ZSM-23-1 molecular sieve is replaced by H-DZSM-23-1. The specific properties are shown in Table 2.

[0112] Comparative Example 2

[0113] Comparative Example 2 (refer to CN102992346A)

[0114] 8.12 g of H₂O and 0.092 g of aluminum sulfate were mixed uniformly, followed by the addition of 0.38 g of NaOH. Then, 3.32 g of silica sol with a silica content of 30.5 wt% was added with stirring. Stirring was continued until the solution became homogeneous, and 10 wt% ZSM-23 molecular sieve was added as seed crystals (the seed amount was calculated as a percentage of the mass of the SiO₂ input). The raw materials were added to a Teflon-coated stainless steel reactor and subjected to dynamic crystallization at 160°C for 10 hours. The product was then filtered and dried to obtain NaDZSM-23-2 molecular sieve. The raw material ratio was SiO₂: 0.0083% Al₂O₃: 0.27% Na₂O: 35% H₂O.

[0115] (2) Ammonium exchange

[0116] The preparation process of H-DZSM-23-2 is the same as that of Example 1 (4), except that NaZSM-23-1 molecular sieve is replaced by NaDZSM-23-2. The specific properties are shown in Table 1.

[0117] (3) Catalyst preparation

[0118] The preparation method of CB-2 catalyst is the same as that of Example 1 (5), except that H-ZSM-23-1 molecular sieve is replaced by H-DZSM-23-2. The specific properties are shown in Table 2.

[0119] Comparative Example 3

[0120] (1) Preparation of amorphous silicon aluminum precursor

[0121] Prepare a sodium aluminate working solution with a concentration of 50 g Al2O3 / L. Take a sodium silicate solution containing 28 wt% SiO2 and dilute it to a sodium silicate working solution with a concentration of 100 g SiO2 / L. Place 200 mL of the sodium aluminate working solution in a gelling tank, then add 60 mL of the sodium silicate working solution. Control the reaction temperature at 30°C and introduce 50% CO2 gas. When the pH reaches 10.0, stop the CO2 flow and add 40 mL of the sodium silicate working solution. Aerate the mixture until the remaining CO2 gas is stable. After aging at 25°C for 30 minutes, an amorphous silicon-alumina precursor is obtained. The amorphous silicon-alumina precursor contains 50 wt% silicon dioxide, based on the total weight of silicon dioxide and aluminum oxide.

[0122] (2) Preparation of gel

[0123] A mixture of silica sol, isopropylamine and water was added to the amorphous silica-alumina precursor obtained in step (1) at a total feed molar ratio of SiO2: Al2O3: IPA: H2O = 1: 0.01: 0.4: 30, and the mixture was stirred evenly to obtain silica-alumina gel.

[0124] (3) Crystallization

[0125] The gel obtained in step (2) was poured into a stainless steel reactor and statically crystallized at 160°C for 24 hours. After crystallization, the mixture was filtered, washed to neutrality, and dried at 120°C to obtain the molecular sieve raw powder. After drying, the NaDZSM-23-2 molecular sieve product was obtained. The reaction raw material ratio was SiO2: 0.0083Al2O3: 0.27Na2O: 35H2O.

[0126] (4) Ammonium exchange

[0127] The preparation process of H-DZSM-23-2 is the same as that of Example 1 (4), except that NaZSM-23-1 molecular sieve is replaced by NaDZSM-23-2. The specific properties are shown in Table 1.

[0128] (5) Catalyst preparation

[0129] The preparation method of CB-3 catalyst is the same as that of Example 1 (5), except that H-ZSM-23-1 molecular sieve is replaced by H-DZSM-23-3. The specific properties are shown in Table 2.

[0130] Table 1 Properties of molecular sieves

[0131]

[0132] Table 2 Physicochemical properties of catalysts

[0133]

[0134] The above catalysts were tested for activity evaluation. The tests were conducted on a small 200mL hydrogenation unit using a one-stage cascade hydrogenation conversion process. The properties of the feedstock oil used are shown in Table 4. The refined catalyst composition was as follows: 20 wt% molybdenum oxide, 5 wt% nickel oxide, and the balance alumina. The refined catalyst operating conditions were as follows: reaction pressure 7.0 MPa, hydrogen-to-oil volume ratio 800:1, and liquid hourly space velocity 1.0 h-1. -1 , reaction temperature 370 ° C. The operating conditions of the cracking section and isomerization section are as follows: reaction pressure 7.0 MPa, hydrogen oil volume ratio 700:1, liquid hourly volume space velocity 0.8h -1 , <210℃ conversion rate ~75wt%, catalyst activity test results are shown in Table 4.

[0135] Table 3 Properties of crude oil

[0136]

[0137] Table 4 Catalyst activity evaluation results

[0138]

[0139] It can be seen from the evaluation results of the catalysts in Table 4 that, compared with the comparative examples, 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

1. A method for producing gasoline by catalytic diesel hydrocracking, characterized in that: The invention comprises the following contents: catalytic diesel is reacted in sequence through a hydrorefining reaction zone, a hydrocracking reaction zone and an isomerization reaction zone; the isomerization reaction zone is filled with an isomerization catalyst; based on the weight of the isomerization catalyst, the mass content of HZSM-23 molecular sieve is 30-70wt%, the mass content of macroporous alumina is 20-40wt%, the mass content of Group VIB metal in terms of oxide is 10wt%-30wt% and the mass content of Group VIII metal in terms of oxide is 4wt%-10wt%, and the sum of the contents of the components in the isomerization catalyst is 100wt%; the specific surface area of ​​the isomerization catalyst is 250-500m 2 / g, pore volume is 0.30~0.70cm 3 / g; the weak acid content in the catalyst accounts for 75-90% of the total acid content; the properties of the HZSM-23 molecular sieve are as follows: the total acid content is 0.1-0.25 mmol / g, the strong acid content is 10-25%; the relative crystallinity is 95-120%, and the relative crystallinity after water vapor hydrothermal treatment is 93-115%; the acid distribution is measured by NH3 temperature-programmed desorption, wherein the acid content corresponding to the desorption temperature above 350°C is strong acid content, and the acid content corresponding to the desorption temperature below 350°C is weak acid content; The aromatic content of the catalytic diesel is 50-95 wt %.

2. The method according to claim 1, wherein: The specific surface area of ​​the isomerization catalyst is 300-450 m 2 / g, pore volume is 0.37~0.60cm 3 / g; the weak acid content in the catalyst accounts for 80~90% of the total acid content.

3. The method according to claim 1, wherein: The properties of the HZSM-23 molecular sieve are as follows: a total acid content of 0.15-0.25 mmol / g, a strong acid content of 10-20%; a relative crystallinity of 98-116%, and a relative crystallinity of 95-114% after steam hydrothermal treatment.

4. The method according to claim 1, wherein: The preparation method of the isomerization catalyst includes the preparation of a catalyst carrier and the loading of a hydrogenation active metal, wherein the preparation of the catalyst carrier includes: mixing and shaping HZSM-23 molecular sieve, macroporous alumina and a binder, and then drying and calcining to prepare the catalyst carrier.

5. The method according to claim 4, characterized in that: The drying step is performed at 100° C. to 120° C. for 1 to 12 hours, and the calcining step is performed at 400° C. to 600° C. for 3 to 10 hours.

6. The method according to claim 1, wherein: The properties of the catalytic diesel are as follows: density 0.88-0.99 g / cm 3 , the distillation range is 280-400℃, the sulfur content is 0.2-2wt%, and the nitrogen content is 500ppm-1800ppm.

7. The method according to claim 1, wherein: The catalyst loaded in the hydrofining reaction zone adopts an alumina carrier, and the hydrogenation active metal components are Group VIB and Group VIII metals.

8. The method according to claim 1, wherein: The reaction conditions of the hydrofining reaction zone are as follows: reaction temperature is 320-440°C; reaction pressure is 4.0-12.0 MPa; liquid hourly volume space velocity is 0.2-6.0 h -1 ; The volume ratio of hydrogen to oil is 100~2000.

9. The method according to claim 8, characterized in that: The reaction conditions of the hydrofining reaction zone are as follows: reaction temperature is 340-420°C; reaction pressure is 6.0-10.0 MPa; liquid hourly volume space velocity is 0.5-3.0 h -1 ; The volume ratio of hydrogen to oil is 500~1500.

10. The method according to claim 1, wherein: The catalyst loaded in the hydrocracking reaction zone has a Y molecular sieve content of 20-60 wt%, a macroporous alumina content of 30-70 wt%, a Group VIB metal content of 10 wt%-25 wt% and a Group VIII metal content of 3 wt%-8 wt% calculated as oxide, based on its weight; the sum of the contents of each component in the catalyst loaded in the hydrocracking reaction zone is 100 wt%.

11. The method according to claim 10, characterized in that: The catalyst loaded in the hydrocracking reaction zone contains molybdenum and / or tungsten as Group VIB metals, and cobalt and / or nickel as Group VIII metals. The Y molecular sieve has the following properties: a Na2O weight content of less than 0.3%; and a silicon-aluminum molar ratio of SiO2 / Al2O3 of 10-25.

12. The method according to claim 11, wherein: The properties of the Y molecular sieve are as follows: the silicon-aluminum molar ratio SiO2 / Al2O3 is 14-20.

13. The method according to claim 10, wherein: Preparation of catalyst loaded in hydrocracking reaction zone: The method includes the preparation of a carrier and the loading of hydrogenation active metals, wherein the preparation of the carrier includes: uniformly mixing Y molecular sieve and macroporous alumina, adding dilute nitric acid to form the mixture, and then drying and calcining the mixture to prepare a catalyst carrier.

14. The method according to claim 1, wherein: The process conditions of the hydrocracking reaction zone are: reaction temperature of 340-440°C; reaction pressure of 6.0-12.0 MPa; liquid hourly volume space velocity of 0.5-3.0 h -1 ; The volume ratio of hydrogen to oil is 500~1500.

15. The method according to claim 14, characterized in that: The process conditions of the hydrocracking reaction zone are: reaction temperature is 360-430°C.

16. The method according to claim 1, wherein: The volume ratio of the catalysts loaded in the hydrocracking reaction zone and the isomerization reaction zone is 20:1-3:

1.

17. The method according to claim 16, wherein: The volume ratio of the catalysts loaded in the hydrocracking reaction zone and the isomerization reaction zone is 15:1 to 4:1.

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