A method for hydro-upgrading of diesel rich in aromatic hydrocarbons

Abstract

The present invention discloses a method for hydrogenation reforming of aromatic-rich diesel. The method uses aromatic-rich diesel as raw material and carries out a reaction under the action of hydrogen and a hydrogenation reforming catalyst. The reaction conditions are as follows: reaction temperature 350-390°C, total reaction pressure 5-12 MPa, liquid hourly volume space velocity 0.5-3 h ‑1 , the hydrogen-to-oil volume ratio is 400: 1 to 1200: 1, the hydroreforming catalyst contains HZSM-23 molecular sieve and modified Y molecular sieve, the total acid amount of the catalyst is 0.131 to 0.196 mmol / g, preferably 0.135 to 0.181 mmol / g; the weak acid content is 34 to 55%, preferably 36 to 52%. The method can ensure the diesel yield while catalyzing the hydroreforming of aromatic-rich diesel, and can also increase the cetane number of diesel, effectively lowering its pour point.

Description

Technical Field

[0001] The present invention relates to a method for hydrogenating and reforming aromatics-rich diesel, in particular to a method for hydrogenating and reforming aromatics-rich catalytic cracking diesel. Background Art

[0002] Currently, one-third of my country's automotive diesel is catalytically cracked diesel. In recent years, as refineries have increased the proportion of residual oil blended into their fuels, the quality of catalytically cracked diesel has steadily declined. Consequently, the development and upgrading of diesel hydro-reforming technologies to produce high-quality diesel has garnered significant attention, with the development of diesel hydro-reforming catalysts being a crucial component.

[0003] Due to the high aromatic content in catalytic diesel, diesel hydroconversion catalysts typically use molecular sieves or amorphous silica-alumina with cracking properties as the acidic component, and support VIB and Group VII metals as the hydrogenation active component. Y molecular sieve and β molecular sieve are the most commonly used due to their excellent acidity and stability. CN1184843A discloses a diesel hydroconversion catalyst using a mixture of Y molecular sieve with a SiO2 / Al2O3 molar ratio of 7-15, alumina, and amorphous silica-alumina as the support. Patent 111097487A discloses a catalytic diesel hydroconversion catalyst with a modified Y molecular sieve as the primary acidic component, with a total pyridine infrared acid content of 0.1-1.2 mmol / L and a ratio of pyridine infrared acid to n-butylpyridine infrared acid content of 1-1.2. The low-quality diesel fuel hydroreforming catalyst carrier disclosed in CN107233913B includes a modified β molecular sieve with a Si / Al molar ratio of 50-70, amorphous Si / Al, macroporous alumina, and SB powder. The β molecular sieve requires a series of modification processes, including dealumination, siliconization, and hydrothermal treatment, followed by treatment with an aluminum salt and acid mixed solution, to achieve the desired acidic properties and pore structure. This process is complex and results in a high product loss rate. The hydroreforming catalyst carrier disclosed in CN111318312 uses a Y-β composite molecular sieve loaded with an organosilane as the primary acidic component, with the Y molecular sieve having a SiO / AlO molar ratio of 8-55 and the β molecular sieve having a SiO / AlO molar ratio of 35-155. When Y molecular sieve and β molecular sieve are the primary active components of the catalyst carrier, both have high strong acid content and outstanding cracking performance. Although the catalyst has good desulfurization and denitrification activity and can effectively improve the cetane number of the diesel product, it often leads to problems such as low diesel product yield and high pour point.

[0004] Isomerization pour point depressant technology is a common technique for improving the low-temperature fluidity of oil products. This technology primarily utilizes precious metals loaded onto ten-membered ring, one-dimensional pore-channel molecular sieves, such as SAPO-11, ZSM-22, and ZSM-23, in a two-stage process to isomerize long-chain normal alkanes into branched alkanes, thereby lowering the pour point of the oil. However, due to issues with acid strength and acid site distribution, these molecular sieves synthesized using conventional technology have limited effectiveness in improving the cetane number of diesel. Furthermore, the high price and cost of precious metals limit their application. Summary of the Invention

[0005] To overcome the deficiencies in the prior art, the present invention provides a method for hydro-modifying aromatic-rich diesel. The method ensures diesel yield during the hydro-modifying of aromatic-rich diesel, while also increasing the cetane number of the diesel and effectively lowering its pour point.

[0006] A method for hydro-reforming of aromatic-rich diesel, wherein the method uses aromatic-rich diesel as raw material, reacts under the action of hydrogen and a hydro-reforming catalyst, and the reaction conditions are as follows: reaction temperature 350-390 °C, total reaction pressure 5-12 MPa, liquid hourly volume space velocity 0.5-3 h -1 , the hydrogen-to-oil volume ratio is 400: 1 to 1200: 1, the hydro-reforming catalyst contains HZSM-23 molecular sieve and modified Y molecular sieve, the total acid content of the catalyst is 0.131 to 0.196 mmol / g, preferably 0.135 to 0.181 mmol / g; the weak acid content is 34 to 55%, preferably 36 to 52%.

[0007] In the method of the present invention, the aromatics-rich diesel can be catalytically cracked diesel, in which the mass content of aromatics is 72-90%, and the mass content of dicyclic and / or tricyclic aromatics is 40-60%; preferably, the mass content of aromatics is 75-88%, and the mass content of dicyclic and / or tricyclic aromatics is 43-58%.

[0008] In the method of the present invention, the properties of the aromatics-rich diesel are as follows: density of 0.905-0.930 g / cm 3 , preferably 0.910~0.928 g / cm 3 ; Distillation range is 165~390 ℃, the mass content of S is 0.5~1.5%, the mass content of N is 300~1300 μg / g, and the cetane number is 15~25.

[0009] In the method of the present invention, the hydro-reforming catalyst is based on its weight.

[0010] a) HZSM-23 molecular sieve, with a content of 3 to 20 wt%, preferably 5 to 18 wt%;

[0011] b) modified Y molecular sieve, with a content of 5 to 35 wt%, preferably 7 to 28 wt%;

[0012] c) macroporous alumina, with a content of 15 to 65 wt%, preferably 18 to 60 wt%;

[0013] d) The active component is one or more metal oxides of Group VIB and Group VIII, wherein the content of the Group VIB metal as oxide is 10-30 wt%, and the content of the Group VIII metal as oxide is 3-15 wt%.

[0014] In the method of the present invention, the specific surface area of the hydro-reforming catalyst is 225-400 m 2 / g, pore volume is 0.23~0.62 cm 3 / g; preferably 250~375 m 2 / g, and the pore volume is preferably 0.26~0.60 cm 3 / g.

[0015] In the catalyst of the present invention, the HZSM-23 molecular sieve has the following properties: a total acid content of 0.05 to 0.16 mmol / g, a weak acid content of 53 to 80%; 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 0.06 to 0.15 mmol / g, the weak acid content is 60 to 75%; the relative crystallinity is 98 to 116%, and the relative crystallinity after steam hydrothermal treatment is 95 to 114%.

[0016] In the catalyst of the present invention, the properties of the HZSM-23 molecular sieve are as follows: the crystal size is 100-700 nm, the SiO2 / Al2O3 molar ratio is 80-200, the specific surface area is 200-400 m 2 / g, pore volume of 0.25~0.50 cm 3 / g; Preferably, the properties of the HZSM-23 molecular sieve are as follows: a grain size of 200-500 nm, a SiO2 / Al2O3 molar ratio of 85-120, a specific surface area of 280-370 m 2 / g, pore volume 0.28~0.46 cm 3 / g.

[0017] In the catalyst of the present invention, the properties of the modified Y molecular sieve are as follows: SiO2 / Al2O3 molar ratio is 20-40, unit cell parameters are 2.464-2.469, specific surface area is 750-850 m 2 / g, pore volume is 0.40~0.56 cm 3 / g.

[0018] In the catalyst of the present invention, the properties of the macroporous alumina are: specific surface area 375~450 m 2 / g, pore volume 0.74~1.15 cm 3 / g; preferably a specific surface area of 390~430 m 2 / g, pore volume 0.78~1.10 cm 3 / g.

[0019] In the catalyst of the present invention, the active component is preferably tungsten and / or molybdenum, and the Group VIII metal is preferably nickel and / or cobalt.

[0020] Compared with the prior art, the method for hydro-reforming of aromatics-rich diesel fuel of the present invention has the following beneficial technical effects:

[0021] (1) In the method of the present invention, HZSM-23 molecular sieve and modified Y molecular sieve are used as the main acidic components for diesel hydro-reforming. The weak acid content of the catalyst is higher than that of conventional catalysts, the strong acid content is appropriate, and the degree of matching between the acid properties and the pore structure is better. When treating low-quality diesel with high cycloalkane and aromatic content, the cycloalkane, aromatic and other components in the raw material undergo ring opening and cracking reactions on the modified Y molecular sieve, while the paraffin undergoes hydrogenation isomerization reaction in the HZSM-23 molecular sieve rich in weak acid and medium-strong acid sites without secondary cracking, thereby ensuring the diesel yield while improving the cetane number of the product, reducing the diesel pour point, and improving the quality of the diesel product;

[0022] (2) When the catalyst of the present invention is used for hydro-modification of low-quality diesel fuel, it can significantly improve product quality while ensuring the yield of the target product. The yield of the target product, modified diesel fuel, can reach 97.4%, the cetane number can reach 53.5, and the pour point can be as low as -29°C. DETAILED DESCRIPTION

[0023] The preparation method of the aromatics-rich diesel hydro-reforming catalyst of the present invention includes carrier preparation and active metal loading. The carrier is prepared by mixing HZSM-23 molecular sieve, modified Y molecular sieve, macroporous alumina, and a binder, forming the mixture, and then drying and calcining the mixture. The ZSM-23 molecular sieve is prepared according to the preparation method of CN202210011752.2.

[0024] In the preparation method of the catalyst support of the present invention, the preparation steps of the HZSM-23 molecular sieve are as follows:

[0025] (1) preparing a mixed solution containing a structure directing agent, amorphous silicon aluminum or an amorphous silicon aluminum precursor;

[0026] (2) adding a supplementary silicon source to the material of step (1);

[0027] (3) The material of step (2) is crystallized, filtered, washed, dried and calcined to obtain sodium ZSM-23 molecular sieve.

[0028] (4) The molecular sieve obtained in (3) is subjected to ammonium exchange to obtain HZSM-23 molecular sieve.

[0029] In step (1) of the above method, the structure directing agent is one or more of isopropylamine, pyrrolidine, N,N-dimethylformamide, and dimethylamine.

[0030] 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).

[0031] 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.

[0032] 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.

[0033] 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 5 to 85 wt %, preferably 30 to 70 wt %, of the total amount of the added silicon-containing compound solution, calculated as silicon dioxide.

[0034] 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.

[0035] During the preparation of the amorphous silicon-aluminum precursor mixed solution, the silicon-containing compound solution is water glass and / or sodium silicate solution.

[0036] 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%.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] In step (2) of the above method, the silicon source is one or more of fumed silica, silica sol and water glass.

[0041] 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.

[0042] 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.

[0043] The catalyst support of the present invention is dried and calcined by conventional methods, specifically as follows: the calcination temperature is 500-600°C for 2-8 hours, preferably 530-570°C for 3-6 hours.

[0044] The active metal loading method of the present invention can adopt conventional loading methods in the prior art, preferably the impregnation method. After impregnation, the catalyst is dried at 80-120°C for 4-10 hours and then calcined at 400-600°C for 3-6 hours to obtain the final catalyst.

[0045] In the catalyst preparation method of the present invention, especially in the preparation method of the sodium ZSM-23 molecular sieve, all the aluminum sources required for synthesis are added when preparing the amorphous silicon-aluminum precursor, which promotes the generation of the primary structural unit of the molecular sieve; when the structure directing agent is added, the structure directing agent preferentially chelates with the Al species and then adsorbs on the surface of the formed primary structural unit to achieve the pre-assembly of the molecular sieve structure and generate a large number of crystal nuclei; at the same time, it can better control the binding sites of the Al atoms, which is conducive to the later crystallization to obtain sodium ZSM-23 with more weak acid sites. After the additional silicon source is added to form the final gel, after static crystallization, a large number of crystal nuclei can quickly grow into a sodium ZSM-23 molecular sieve with high crystallinity and small grain size. The sodium ZSM-23 molecular sieve synthesized by the method of the present invention has a high weak acid content and good thermal stability and hydrothermal stability, and is an excellent catalytic material.

[0046] 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.

[0047] 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 Corporation of the United States.

[0048] The silicon to aluminum molar ratio was determined by chemical analysis.

[0049] 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 2θ of approximately 11.3 and 19.5-23° in the XRD spectrum of the HZSM-23 molecular sieve prepared in Comparative Example 1 was taken as 100% crystallinity. The relative crystallinity of the other samples was then compared with this value.

[0050] The grain size was obtained by a JSM-7500F field emission scanning electron microscope from JEOL, Japan.

[0051] The acid distribution was measured by NH3 temperature-programmed desorption (NH3-TPD), in which the acid sites corresponding to the desorption temperature between 120 and 500 °C were regarded as the total acid content, the acid sites corresponding to the desorption temperature below 350 °C were regarded as weak acid sites, and the acid sites corresponding to the desorption temperature above 350 °C were regarded as strong acid sites.

[0052] In the present invention, wt% refers to mass fraction and v% refers to volume fraction.

[0053] Example 1

[0054] (1) Preparation of amorphous silicon aluminum precursor

[0055] 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 50 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 90 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.

[0056] (2) Preparation of gel

[0057] 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.

[0058] (3) Crystallization

[0059] 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, the gel was filtered, washed to neutrality, dried at 120°C, and calcined in air at 550°C for 3 hours to obtain molecular sieve raw powder.

[0060] (4) Ammonium exchange

[0061] A certain amount of molecular sieve powder 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 at 550°C in air for 3 hours to obtain HZSM-23-1. The relative crystallinity of the HZSM-23-1 was measured 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.

[0062] (2) Catalyst preparation

[0063] Macroporous alumina (specific surface area 412 m 2 / g, pore volume 0.94 cm 3 / g), 8 wt% HZSM-23-1 molecular sieve, 17 wt% modified Y molecular sieve (SiO2 / Al2O3 molar ratio of 25, unit cell parameter of 2.468, specific surface area of 788 m 2 / g, pore volume 0.54 cm 3 / g), sesbania powder (1 wt% of the total weight of alumina and molecular sieve), and a 1 wt% nitric acid aqueous solution were mixed and ground. Water was added, and the mixture was rolled into a paste, which was then extruded into strips. The extruded strips were dried at 120°C for 4 hours and then calcined at 550°C for 3 hours to obtain carrier strips. The carrier strips were loaded with 20 wt% WO3 and 5 wt% NiO by the conventional equal volume impregnation method. A pre-prepared impregnation solution equal to the carrier's water absorption capacity was added to the carrier strips, allowed to stand for 12 hours, dried at 120°C in air for 8 hours, and calcined at 450°C for 4 hours to obtain Catalyst C-1. Specific properties are shown in Table 2.

[0064] Example 2

[0065] (1) Preparation of amorphous silicon aluminum precursor

[0066] 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 150 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 40 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 had a silicon dioxide content of 60 wt%, based on the total weight of silicon dioxide and aluminum oxide.

[0067] (2) Preparation of gel

[0068] 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: 0.011: 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.

[0069] (3) Crystallization

[0070] The gel obtained in step (2) was poured into a stainless steel reactor and statically crystallized at 180°C for 18 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 molecular sieve raw powder.

[0071] (4) Ammonium exchange

[0072] A certain amount of molecular sieve powder 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-23-2. The relative crystallinity of the HZSM-23-2 was measured by XRD. The relative crystallinity of the HZSM-23-2 was also measured after hydrothermal treatment with steam at 600°C for 2 hours. Specific properties are shown in Table 1.

[0073] (5) Catalyst preparation

[0074] Macroporous alumina (specific surface area 404 m 2 / g, pore volume 0.93 cm 3 / g), 10wt% HZSM-23-2 molecular sieve, 15wt% modified Y molecular sieve (SiO2 / Al2O3 molar ratio is 20, unit cell parameter is 2.469, specific surface area is 789 m 2 / g, and a pore volume of 0.53 cm 3 / g), sesbania powder (1 wt% of the total weight of alumina and molecular sieve), and a 1 wt% nitric acid aqueous solution were mixed and ground. Water was added, and the mixture was rolled into a paste, which was then extruded into strips. The extruded strips were dried at 120°C for 4 hours and then calcined at 550°C for 3 hours to obtain carrier strips. The carrier strips were loaded with 20 wt% WO3 and 5 wt% NiO by weight using a conventional equal volume impregnation method. The carrier strips were added to a pre-prepared impregnation solution equal to the carrier's water absorption capacity, allowed to stand for 12 hours, dried at 120°C in air for 8 hours, and calcined at 450°C for 4 hours to obtain Catalyst C-2. Specific properties are shown in Table 2.

[0075] Example 3

[0076] (1) Preparation of amorphous silicon aluminum precursor

[0077] Prepare a sodium aluminate working solution with a concentration of 20 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 150 g SiO2 / L. Place 300 mL of the sodium aluminate working solution in a gelling tank, then add 20 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 another 20 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 50 wt% silicon dioxide, based on the total weight of silicon dioxide and aluminum oxide.

[0078] (2) Preparation of gel

[0079] 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.

[0080] (3) Crystallization

[0081] 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, the gel was filtered, washed until neutral, dried at 120°C, and calcined in air at 550°C for 3 hours to obtain the molecular sieve raw powder.

[0082] (4) Ammonium exchange and template removal agent

[0083] A certain amount of molecular sieve powder 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-23-3. The relative crystallinity of the HZSM-23-3 was measured by XRD. The relative crystallinity of the HZSM-23-3 was also measured after hydrothermal treatment with steam at 600°C for 2 hours. Specific properties are shown in Table 1.

[0084] (5) Catalyst preparation

[0085] Macroporous alumina (specific surface area 412 m 2 / g, pore volume 0.94 cm 3 / g), 12wt% HZSM-23-3 molecular sieve, 28wt% modified Y molecular sieve (SiO2 / Al2O3 molar ratio of 40, unit cell parameter of 2.466, specific surface area of 771m 2 / g, pore volume 0.52 cm 3 / g), sesbania powder (1 wt% by weight of the total weight of alumina and molecular sieve), and a 1 wt% nitric acid aqueous solution were mixed and ground. Water was added, and the mixture was rolled into a paste, which was then extruded into strips. The extruded strips were dried at 120°C for 4 hours and then calcined at 550°C for 3 hours to obtain carrier strips. The carrier strips were loaded with 17 wt% WO3 and 5 wt% NiO using a conventional equal volume impregnation method. The impregnation conditions were as follows: a pre-prepared impregnation solution equal in volume to the carrier's water absorption capacity was added, the mixture was allowed to stand for 12 hours, dried at 120°C in air for 8 hours, and then calcined at 450°C for 4 hours to obtain Catalyst C-3. Specific properties are shown in Table 2.

[0086] Example 4

[0087] (1) Preparation of amorphous silicon aluminum precursor

[0088] 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 50 g SiO₂ / L. Place 150 mL of the sodium aluminate working solution in a gelling tank, then add 140 mL of the sodium silicate working solution. Control the reaction temperature at 20°C and introduce 50 vol% CO₂ gas. When the pH reaches 10.0, stop the CO₂ flow and add another 140 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 alumina-silica precursor is obtained. The amorphous alumina-silica precursor contains 70 wt% silica, based on the total weight of silica and alumina.

[0089] (2) Preparation of gel

[0090] 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.

[0091] (3) Crystallization

[0092] The gel obtained in step (2) was poured into a stainless steel reactor and statically crystallized at 180°C for 12 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.

[0093] (4) Ammonium exchange

[0094] A certain amount of molecular sieve powder 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-23-4. The relative crystallinity of the HZSM-23-4 was measured by XRD. The relative crystallinity of the HZSM-23-4 was also measured after hydrothermal treatment with steam at 600°C for 2 hours. Specific properties are shown in Table 1.

[0095] (5) Catalyst preparation

[0096] Macroporous alumina (specific surface area 398 m 2 / g, pore volume 0.92 cm 3 / g), 18 wt% HZSM-23-4 molecular sieve, 7 wt% modified Y molecular sieve (SiO2 / Al2O3 molar ratio of 20, unit cell parameter of 2.469, specific surface area of 789 m 2 / g, pore volume 0.53 cm 3 / g), sesbania powder (1 wt% by weight of the total weight of alumina and molecular sieve), and a 1 wt% nitric acid aqueous solution were mixed and ground. Water was added, and the mixture was rolled into a paste, which was then extruded into strips. The extruded strips were dried at 120°C for 4 hours and then calcined at 550°C for 3 hours to obtain carrier strips. The carrier strips were loaded with 20 wt% WO3 and 5 wt% NiO by conventional equal volume impregnation. The carrier strips were added to a pre-prepared impregnation solution equal to the carrier's water absorption capacity, allowed to stand for 12 hours, dried at 120°C in air for 8 hours, and calcined at 450°C for 4 hours to obtain catalyst C-4. Specific properties are shown in Table 2.

[0097] Comparative Example 1 (Refer to CN101214971A)

[0098] 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. First, the aluminum source was added to an aqueous sodium hydroxide solution and stirred evenly. The silicon source was added and stirred evenly. Finally, isopropylamine was added and stirred evenly 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 the raw molecular sieve powder.

[0099] A certain amount of molecular sieve powder 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 at 550°C in air for 3 hours to obtain H-CNZSM-23-1. Its relative crystallinity was determined by XRD. The relative crystallinity of H-CNZSM-23-1 after hydrothermal treatment with steam at 600°C for 2 hours was also measured. Specific properties are shown in Table 1.

[0100] Macroporous alumina (specific surface area 412 m 2 / g, pore volume 0.94 cm 3 / g), 8 wt% HZSM-23-3 molecular sieve, 17 wt% modified Y molecular sieve (SiO2 / Al2O3 molar ratio of 25, unit cell parameter of 2.468, specific surface area of 788 m 2 / g, pore volume 0.54 cm 3 / g), sesbania powder (1 wt% of the total weight of alumina and molecular sieve), and a 1 wt% nitric acid aqueous solution were mixed and ground. Water was added, and the mixture was rolled into a paste, which was then extruded into strips. The extruded strips were dried at 120°C for 4 hours and then calcined at 550°C for 3 hours to obtain carrier strips. The carrier strips were loaded with 20 wt% WO3 and 5 wt% NiO using a conventional equal volume impregnation method. The impregnation conditions were as follows: a pre-prepared impregnation solution equal to the water absorption capacity of the carrier was added, the mixture was allowed to stand for 12 hours, dried at 120°C in air for 8 hours, and then calcined at 450°C for 4 hours to obtain catalyst DC-1. Specific properties are shown in Table 2.

[0101] Comparative Example 2 (refer to CN102992346A)

[0102] 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, while stirring, 3.32 g of silica sol with a silica content of 30.5 wt% was added. Stirring was continued until the solution became homogeneous, and 10 wt% of 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-lined stainless steel reactor and subjected to dynamic crystallization at 160°C for 10 hours. The product was then filtered and dried to obtain the product. The raw material ratio was SiO₂: 0.0083% Al₂O₃: 0.27% Na₂O: 35% H₂O.

[0103] A certain amount of the above molecular sieve sample 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 80-100°C oven for 8 hours and calcined in air at 550°C for 3 hours to obtain H-CNZSM-23-2. Its relative crystallinity was measured by XRD. The relative crystallinity of H-CNZSM-23-1 after hydrothermal treatment with steam at 600°C for 2 hours was also measured. Specific properties are shown in Table 1.

[0104] Macroporous alumina (specific surface area 412 m 2 / g, pore volume 0.94 cm 3 / g), 12 wt% H-CNZSM-23-2 molecular sieve, 28 wt% modified Y molecular sieve (SiO2 / Al2O3 molar ratio of 25, unit cell parameter of 2.468, specific surface area of 788 m 2 / g, pore volume 0.54 cm 3 / g), sesbania powder (1 wt% by weight of the total weight of alumina and molecular sieve), and a 1 wt% nitric acid aqueous solution were mixed and ground. Water was added, and the mixture was rolled into a paste, which was then extruded into strips. The extruded strips were dried at 120°C for 4 hours and then calcined at 550°C for 3 hours to obtain carrier strips. The carrier strips were loaded with 17 wt% WO3 and 5 wt% NiO using a conventional equal volume impregnation method. The impregnation conditions were as follows: a pre-prepared impregnation solution equal in volume to the carrier's water absorption capacity was added, the mixture was allowed to stand for 12 hours, dried at 120°C in air for 8 hours, and then calcined at 450°C for 4 hours to obtain catalyst DC-2. Specific properties are shown in Table 3.

[0105] Comparative Example 3

[0106] (1) Preparation of amorphous silicon aluminum precursor

[0107] 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.

[0108] (2) Preparation of gel

[0109] 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.

[0110] (3) Crystallization

[0111] The gel obtained in step (2) was poured into a stainless steel reactor and statically crystallized at 160°C for 24 hours. After the crystallization, the gel was filtered, washed to neutrality, and dried at 120°C to obtain molecular sieve raw powder.

[0112] (4) Ammonium exchange

[0113] A certain amount of molecular sieve sample 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 at 550°C in air for 3 hours to obtain H-CNZSM-23-3. Its relative crystallinity was determined by XRD. The relative crystallinity of H-CNZSM-23-3 after hydrothermal treatment with steam at 600°C for 2 hours was also measured. Specific properties are shown in Table 1.

[0114] (5) Catalyst preparation

[0115] Macroporous alumina (specific surface area 412 m 2 / g, pore volume 0.94 cm 3 / g), 8 wt% H-CNZSM-23-3 molecular sieve, 17 wt% modified Y molecular sieve (SiO2 / Al2O3 molar ratio of 25, unit cell parameter of 2.468, specific surface area of 788 m2 / g, pore volume 0.54 cm 3 / g), sesbania powder (1% by weight of the total weight of alumina and molecular sieve), and a 1% nitric acid aqueous solution were mixed and ground. Water was added, and the mixture was rolled into a paste, which was then extruded into strips. The extruded strips were dried at 120°C for 4 hours and then calcined at 550°C for 3 hours to obtain carrier strips. The carrier strips were loaded with 20 wt% WO3 and 5 wt% NiO using a conventional equal volume impregnation method. The impregnation conditions were as follows: a pre-prepared impregnation solution equal in volume to the carrier's water absorption capacity was added, the mixture was allowed to stand for 12 hours, dried at 120°C in air for 8 hours, and then calcined at 450°C for 4 hours to obtain catalyst DC-3. Specific properties are shown in Table 2.

[0116] Table 1

[0117]

[0118] aThe actual SiO2 / Al2O3 molar ratio was measured by XRF.

[0119] Table 2

[0120]

[0121] The catalytic performance of the above-mentioned catalysts C-1, C-2, C-3, and C-4 of the present invention and the comparative catalysts DC-1, DC-2, and DC-3 were evaluated. The reactions were carried out in a fixed-bed reactor under the following conditions: pressure of 10.0 MPa, light oil volume ratio of 800, liquid volume space velocity of 1.5 h -1 Catalytic diesel was used as the raw oil, the properties of which are shown in Table 3, and the reaction results are shown in Table 4.

[0122] Analysis of the reaction results in Table 4 shows that, under the same process conditions, the catalyst of the present invention has better diesel yield and quality than the reference catalyst.

[0123] Table 3

[0124]

[0125] Table 4

[0126]

Claims

1. A method for hydro-reforming of aromatics-rich diesel, characterized by: The method uses aromatics-rich diesel as raw material and reacts under the action of hydrogen and a hydrogenation catalyst. The reaction conditions are as follows: reaction temperature 350-390 °C, total reaction pressure 5-12 MPa, liquid hourly volume space velocity 0.5-3 h -1 , the hydrogen-oil volume ratio is 400: 1 to 1200: 1, the hydro-reforming catalyst contains HZSM-23 molecular sieve and modified Y molecular sieve, the total acid content of the hydro-reforming catalyst is 0.131 to 0.196 mmol / g, and the weak acid content is 34 to 55%; The properties of the HZSM-23 molecular sieve are as follows: total acid content of 0.05-0.16 mmol / g, weak acid content of 53-80%; relative crystallinity of 95-120%, and relative crystallinity of 93-115% after steam hydrothermal treatment; The acid distribution was measured by NH3 temperature-programmed desorption, where the acid sites corresponding to the desorption temperature between 120 and 500 °C were regarded as the total acid content, and the acid sites corresponding to the desorption temperature below 350 °C were regarded as the weak acid content. The properties of the modified Y molecular sieve are as follows: SiO2 / Al2O3 molar ratio is 20-40, unit cell parameters are 2.464-2.469, specific surface area is 750-850 m 2 / g, pore volume is 0.40~0.56 cm 3 / g; The aromatics-rich diesel is catalytically cracked diesel, and the mass content of aromatics in the catalytically cracked diesel is 72-90%.

2. The method according to claim 1, wherein: The total acid content of the hydro-reforming catalyst is 0.135-0.181 mmol / g; and the weak acid content is 36-52%.

3. The method according to claim 1, wherein: The catalytic cracking diesel oil contains 40-60% by mass of di-ring and / or tri-ring aromatic hydrocarbons.

4. The method according to claim 3, wherein: The catalytic cracking diesel has an aromatic content of 75-88% by mass, and a di-ring and / or tri-ring aromatic content of 43-58% by mass.

5. The method according to claim 1, wherein: The properties of the aromatics-rich diesel are as follows: density 0.905-0.930 g / cm 3 ; Distillation range is 165~390 ℃, the mass content of S is 0.5~1.5%, the mass content of N is 300~1300μg / g, and the cetane number is 15~25.

6. The method according to claim 5, wherein: The properties of the aromatics-rich diesel are as follows: density 0.910~0.928 g / cm 3 .

7. The method according to claim 1, wherein: The hydro-reforming catalyst contains the following components based on its weight: a) HZSM-23 molecular sieve, content of 3~20 wt%; b) modified Y molecular sieve, with a content of 5 to 35 wt%; c) macroporous alumina, with a content of 15-65 wt%; d) The active component is one or more metal oxides of Group VIB and Group VIII, wherein the content of the Group VIB metal as oxide is 10-30 wt%, and the content of the Group VIII metal as oxide is 3-15 wt%.

8. The method according to claim 7, wherein: The hydro-reforming catalyst contains the following components based on its weight: a) HZSM-23 molecular sieve, content of 5~18 wt%; b) modified Y molecular sieve, with a content of 7 to 28 wt%; c) Macroporous alumina, content of 18~60 wt%.

9. The method according to claim 1, wherein: The specific surface area of the hydro-reforming catalyst is 225~400 m 2 / g, pore volume is 0.23~0.62 cm 3 / g.

10. The method according to claim 9, wherein: The specific surface area of the hydro-reforming catalyst is 250-375 m 2 / g, pore volume of 0.26~0.60 cm 3 / g.

11. The method according to claim 1 or 7, wherein: The HZSM-23 molecular sieve has the following properties: a total acid content of 0.06-0.15 mmol / g, a weak acid content of 60-75%; a relative crystallinity of 98-116%, and a relative crystallinity of 95-114% after steam hydrothermal treatment.

12. The method according to claim 1 or 7, wherein: The properties of the HZSM-23 molecular sieve are as follows: grain size of 100-700 nm, SiO2 / Al2O3 molar ratio of 80-200, specific surface area of 200-400 m 2 / g, pore volume of 0.25~0.50 cm 3 / g.

13. The method according to claim 12, wherein: The properties of the HZSM-23 molecular sieve are as follows: a grain size of 200-500 nm, a SiO2 / Al2O3 molar ratio of 85-120, and a specific surface area of 280-370 m 2 / g, pore volume 0.28~0.46cm 3 / g.

14. The method according to claim 7, wherein: The properties of the macroporous alumina are: specific surface area 375~450 m 2 / g, pore volume 0.74~1.15 cm 3 / g.

15. The method according to claim 14, wherein: The properties of the macroporous alumina are: specific surface area 390~430 m 2 / g, pore volume 0.78~1.10 cm 3 / g.

16. The method according to claim 7, wherein: In the active components, the Group VIB metal is tungsten and / or molybdenum, and the Group VIII metal is nickel and / or cobalt.

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