A hydro-upgrading catalyst, its preparation method and use

Abstract

This invention discloses a hydroretrograding catalyst, its preparation method, and its application. The preparation method includes: (1) preparing an appropriate amount of active metal solution and impregnating the active metal onto a molecular sieve using an impregnation method, and then drying to obtain an impregnated molecular sieve for later use; (2) weighing an appropriate amount of alumina powder, guar gum powder, citric acid, and nitric acid solution and mixing them evenly to obtain a mixture; (3) mixing the impregnated molecular sieve from step (1) with the mixture from step (2) evenly to obtain a mixture, and then molding it on an extruder, and then drying and calcining to obtain a support; (4) preparing a certain amount of active metal solution again and impregnating the active metal onto the support from step (3) using an impregnation method, and then drying and calcining to obtain the hydroretrograding catalyst. This invention can improve the ring-opening conversion efficiency of aromatics and cycloalkanes in oil products, reduce the occurrence of secondary cracking reactions, and improve the selectivity of hydrocracking reaction products.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, and more particularly to the field of hydrotreating catalysts for oils rich in cycloalkanes, specifically to a hydrotreating catalyst, its preparation method, and its application. Background Technology

[0002] Diesel fractions rich in high-cycloalkane hydrocarbons exhibit excellent low-temperature performance, making them high-quality low-pour-point diesel fuels. However, their cetane number is low, failing to meet national standards and impacting their performance. Research has revealed that after hydrosaturation of polycyclic aromatic hydrocarbons (PAHs), PAH molecules can undergo selective ring-opening reactions on suitable hydroreforming catalysts without secondary cracking or isomerization, generating cycloalkanes with long side chains. This significantly improves the cetane number of diesel fuel. Due to the large molecular weight of PAHs, high pore size and specific surface area are required for hydroreforming catalysts. Mesoporous pores effectively reduce diffusion resistance of large aromatic molecules, allowing for smooth contact with active centers within the pores. After the ring-opening reaction, these molecules diffuse promptly to the catalyst surface, reducing the possibility of secondary cracking. Hydroreforming catalysts are bifunctional catalysts, possessing both a metal component for activating hydrogenation and an acidic support component for cracking. The selection and combination of these components significantly influence the catalyst's activity, selectivity, mechanical strength, thermal stability, and service life. Excellent hydrotreating catalysts need to have suitable acid centers, pore structures and metal active centers. Under the action of high-performance hydrotreating metal catalysts, ring-opening products can react with active hydrogen as soon as possible, effectively hindering the secondary cracking of ring-opening products and improving diesel yield and product performance.

[0003] CN102746894B discloses a method for selective ring-opening reaction of aromatics, in which the hydrogenation reaction is carried out in two reactors connected in series; the material enters the first reactor for deep desulfurization and denitrification reactions, and after passing through H2... SAfter desulfurization and nitrogen removal in the NH3 separation unit, when the S content in the material is below 50 ppm and the N content is below 10 ppm, the material enters the second reactor for a selective ring-opening reaction. This reactor has two reaction beds. The first reaction bed carries out a hydrogenation saturated isomerization reaction, and the second reaction bed carries out a selective ring-opening reaction. The first reactor uses a conventional hydrodesulfurization metal sulfide catalyst, with CoMo / Al2O3 catalyst packed at the bottom and NiMo / Al2O3 catalyst packed at the top. In the first bed of the second reactor, a noble metal / molecular sieve catalyst is used to achieve the hydroisomerization reaction. The reactants then enter the second bed with a noble metal / alumina catalyst to achieve a five-membered ring-opening reaction. This catalyst is preferably an Ir / Al2O3 catalyst with strong hydrogenolysis capability. The avoidance of acidic supports limits further cracking reactions of the reactants, thereby maximizing the selective ring-opening reaction products. This method has achieved shape-selective ring-opening cracking reactions of polycyclic aromatic hydrocarbons and cycloalkanes to a limited extent, improving the cetane number and performance of diesel fuel. However, the process is complex, the requirements for raw materials are high, and the precious metal catalysts required for the reaction are difficult to prepare and expensive, making it difficult to meet the needs of large-scale industrial development.

[0004] CN111097487 A provides a catalyst for catalytic diesel hydrotreating, its preparation method, and its application. The preparation of the catalyst includes the following steps: (1) The acidic centers of Y molecular sieve are first impregnated with benzyl quaternary ammonium salt solution. The benzyl quaternary ammonium salt is selectively distributed in the macropores. Then, after oxygen-free carbonization, the benzyl quaternary ammonium salt is carbonized in situ in the macropores, blocking the macropore channels. The subsequent sodium ion exchange treatment selectively shields the acidic centers distributed in the micropores of Y molecular sieve. Finally, calcination treatment is performed to obtain the acidic center sites concentrated in the macropore channels; (2) The modified Y molecular sieve and oxygen At least one of alumina, silica, or amorphous alumina is mixed evenly, and then 20 wt% nitric acid aqueous solution is added to the carrier mixture to form a slurry. After extrusion molding, it is dried and calcined; (3) The alumina carrier is saturated with a solution containing active metal, and the resulting product is dried and calcined to obtain a hydrogenation-modified catalyst; The modified Y-type molecular sieve provided by the present invention has acid centers mainly distributed in the macropores, while the micropores have a small number or even no acid centers, which can reduce the secondary cracking reaction of hydrocarbon oil molecules entering the micropores and occurring on the acid centers. However, the process of this method is complicated, and sodium in the catalyst may react with other elements under high temperature and high pressure conditions to generate salts such as NaCl. These substances will block the microporous structure of the catalyst, thereby reducing the catalytic efficiency.

[0005] Patent CN108452839 A discloses a method for preparing a mesoporous composite molecular sieve catalyst. This method involves uniformly mixing molecular sieves (Beta or ZSM-5 / SAPO-5 composite molecular sieves) and MCM-48 mesoporous composite molecular sieves with alumina, extruding the mixture to form a catalyst support, using Group VIB and VIII metals as active metals, and loading the active components onto the support using equal-volume impregnation or stepwise impregnation methods. The catalyst is then impregnated with an alcohol solution to redisperse the active components, followed by drying and calcination to obtain the catalyst product. This method controls the ratio of microporous to mesoporous phases in the mesoporous support by adding different masses of microporous molecular sieves, thereby adjusting the acidity distribution of the composite support and achieving selective aromatic ring-opening in diesel fuel. However, this method suffers from problems such as poor hydrothermal properties of the mesoporous MCM-48 molecular sieve, making it unsuitable for processing low-quality products. Furthermore, the use of template agents is uneconomical and causes significant pollution.

[0006] CN200810104303.2 discloses a modified molecular sieve-based noble metal diesel deep hydrodearomatization catalyst and its preparation method. The method includes the following steps: (1) preparing HY molecular sieves by ion exchange; (2) modifying the HY molecular sieves by dealumination and silicon supplementation to prepare a support; (3) impregnating the catalyst with a Group VIII noble metal salt solution, followed by drying, calcination, and activation. This catalyst uses a noble metal and additive active component system, which exhibits good ring-opening activity, but its resistance to heteroatoms such as S and N in the raw materials is weak.

[0007] Current hydroretrogradation catalysts primarily utilize molecular sieves, including USY, Beta, or ZSM-5 / SAPO-5, or composite molecular sieves, mixed uniformly with traditional γ-Al₂O₃. A certain amount of nitric acid is then added as a binder, and the powder is kneaded, dried, and calcined to serve as the catalyst support. The addition of inorganic acids significantly impacts the molecular sieves during this process. Inorganic acids react with the aluminum elements in the molecular sieves, disrupting their pore structure and crystallinity, thus affecting their acidity and hydrothermal stability. Furthermore, the acid added during extrusion causes NOx generation during the calcination process, contributing to air pollution and failing to meet green production requirements. Currently, the γ-Al₂O₃ used in industrial production is mainly SB powder, which is expensive and has small pore volumes, hindering the diffusion of large molecules within the pores. Catalysts prepared using SB powder have high bulk density, requiring larger quantities in the same reactor, resulting in lower economic efficiency.

[0008] Furthermore, current hydrotreating catalysts on the market are mainly designed and prepared for petroleum-based oils, with fewer catalysts for coal-based oils, especially those for direct coal liquefaction. Developing hydrotreating catalysts specifically for coal-based oils, achieving selective ring-opening of aromatics and cycloalkanes to generate cycloalkanes with long side chains, can effectively improve the cetane number of coal-based diesel and the viscosity-temperature properties of cycloalkaned oils. Summary of the Invention

[0009] The purpose of this invention is to provide a hydrotreating catalyst, its preparation method, and its application, so as to improve the ring-opening conversion efficiency of aromatics and cycloalkanes, especially cycloalkanes with two or more rings, in direct coal liquefaction diesel, and reduce the occurrence of secondary cracking reactions.

[0010] To achieve one aspect of the above-mentioned objectives, the present invention adopts the following technical solution: A method for preparing a hydrogenation-modified catalyst, comprising the following steps: (1) Prepare an appropriate amount of active metal solution and impregnate the active metal onto the molecular sieve using the impregnation method, and then dry it to obtain the impregnated molecular sieve for later use; (2) Mix the ingredients, including boehmite, guar gum powder, citric acid and nitric acid solution, evenly to obtain a mixture; (3) Mix the impregnated molecular sieve in step (1) with the kneading material in step (2) to obtain a mixture, knead it on an extruder, and then dry and calcin it to obtain a carrier; (4) Prepare a certain amount of active metal solution again, and use the impregnation method to impregnate the active metal onto the support in step (3), and then dry and calcine to obtain the hydrogenation catalyst.

[0011] In step (1) of the present invention, an active metal solution is impregnated onto a molecular sieve so that a certain amount of active metal can be pre-adsorbed onto the molecular sieve. The molecular sieve used can be a commonly used molecular sieve in the art for preparing supported hydrogenation catalysts. In some embodiments, the molecular sieve is selected from one or more of USY, HY, REY, Beta, SAPO-5 and ZSM-5 molecular sieves.

[0012] In a preferred embodiment, the active metal impregnated in step (1) accounts for less than 50 wt% of the total active metal in the hydrogenation catalyst, such as 10%, 20 wt%, 30 wt% or 40 wt%, preferably 10-30 wt%.

[0013] In this invention, the active metal used to prepare the active metal solution can be an active metal commonly used in oil hydrotreating catalysts well known in the art, such as elements selected from Group VIII and / or Group VI of the periodic table; preferably, the Group VIII active metal is Ni and / or Co, and the Group VI active metal is W and / or Mo.

[0014] In step (2) of the present invention, boehmite, which is a precursor of alumina as a partial carrier, is mixed with guar gum powder, citric acid and nitric acid solution to obtain a mixture, thereby avoiding direct contact between the molecular sieve, which is another partial carrier, and nitric acid, so as to maintain the crystal structure, pore properties and acid properties of the molecular sieve.

[0015] In a preferred embodiment, the mixture further contains an additive element, which is one or more of Si, B, Zr, Ti, La, and Ce; preferably, the additive element, calculated as its oxide, is used in an amount of 0.1-8 wt% of the total amount of the molecular sieve and pseudoboehmite, such as 0.5 wt%, 1 wt%, 3 wt%, 5 wt%, or 7 wt%; studies have found that the added additive element can subsequently react with alumina, which can reduce Li acid, increase some B acid, reduce the amount of carbon deposited on the catalyst, and extend the service life of the catalyst.

[0016] In step (3) of the present invention, the impregnated molecular sieve is mixed with the kneading material, kneaded and shaped on an extruder, and then dried and calcined to obtain a carrier. It is understood in the art that after calcination, the pseudoboehmite is converted into alumina to serve as a carrier; in a preferred embodiment, the mass ratio of the molecular sieve to the alumina obtained from the calcination and decomposition of the pseudoboehmite in the carrier is 1:9-3:2, for example 1:8, 1:6, 1:5, 1:3, 1:2 or 1:1, preferably 1:4-2:3.

[0017] In some embodiments, to ensure good kneading and extrusion performance of the mixture, the amount of guar gum powder is 0.5%-10 wt%, preferably 1-5 wt%, such as 2 wt%, 3 wt%, or 4 wt%, based on the total amount of the molecular sieve and boehmite. That is, when the total amount of the molecular sieve and boehmite is 100 parts by weight, the amount of guar gum powder can be 0.5-10 parts by weight. This is readily understood in the art and will not be elaborated further here. The amount of citric acid is 0.5%-10 wt%, preferably 1-5 wt%, such as 2 wt%, 3 wt%, or 4 wt%. The concentration of the nitric acid solution is 0.2-1 mol / L, and the amount is 0.5-2 wt%, preferably 1-1.5 wt%, such as 1.2 wt%, 1.3 wt%, or 1.4 wt%. wt%; when an additive is added, the precursor of the additive element (such as boric acid) is dissolved in the nitric acid solution to mix evenly with the remaining ingredients, and the amount of the additive element, calculated as its oxide, is 0.5-5 wt% of the total amount of the USY molecular sieve and pseudoboehmite.

[0018] In step (4) of the present invention, a certain amount of active metal solution is prepared again, and the active metal is impregnated onto the support by impregnation method, and then dried and calcined to obtain the hydrogenation-modified catalyst; through two impregnations, the amount of active metal in the molecular sieve and alumina has different concentration gradients.

[0019] Of course, it is understood in the art that the active metal solution can also be prepared once and used in steps (1) and (4) respectively, which should be considered equivalent to the present invention.

[0020] In a preferred embodiment, in step (4) above, the active metal, in the form of its oxide, accounts for 1-10 wt% (preferably 3-5 wt%) of the group VIII active metal and 10-40 wt% (preferably 15-30 wt%) of the group VI active metal in the hydrogenation catalyst.

[0021] In a preferred embodiment, the Group VIII active metal impregnated in step (4) accounts for 50-90 wt% of the total Group VIII active metal in the hydrotreating catalyst, for example, 60 wt%, 70 wt% or 80 wt%, and the Group VI active metal impregnated in step (4) accounts for 50-90 wt% of the total Group VI active metal in the hydrotreating catalyst, for example, 60 wt%, 70 wt% or 80 wt%.

[0022] In a preferred embodiment, the active metal of Group VIII is Ni and the active metal of Group VI is W. The active metal solution in steps (1) and (4) is prepared as follows: about 70% of deionized water is added to a beaker, the temperature is raised to 40-50°C, citric acid and phosphoric acid are added, the mixture is stirred evenly, basic nickel carbonate is added, and after the basic nickel carbonate is dissolved, ammonium metatungstate is added. After the ammonium metatungstate is completely dissolved, the volume is adjusted to the required volume. Preferably, when preparing the active metal solution, the amount of citric acid added is (0.1-5.0):1 in mass ratio with nickel oxide, preferably (0.5-2.0):1, for example, 1:1. The amount of phosphoric acid added, calculated as phosphorus oxide, is 0.5%-5.0% of the mass of the hydrogenation catalyst, preferably 1.0%-3.0%.

[0023] In this invention, the impregnation method can be an equal-volume impregnation method to facilitate control of the impregnation load. Of course, it is understood in the art that other impregnation methods can also be used, all of which are well known in the art and will not be described in detail here.

[0024] In addition, the present invention also involves drying and calcining of the relevant materials, which are conventional processing methods in the preparation of supported hydrogenation catalysts and are well known in the art. For example, the drying can be carried out at 80-120°C for 6-12 hours; the calcination can be carried out at 500-550°C for 3-6 hours.

[0025] In another aspect of achieving the above-described objective, the present invention also provides a hydrogenation-modified catalyst prepared according to the above-described preparation method.

[0026] In some embodiments, the specific surface area of ​​the hydrotreating catalyst is 200-400 m². 2 / g, pore volume 0.2-0.5 cm³ 3 / g, with an average pore size of 5-15 nm; it is understood in the art that good porous properties are beneficial for reducing the diffusion resistance of molecules in the pores, reducing the density of the catalyst, and lowering the manufacturing cost.

[0027] In another aspect to achieve the above-mentioned objective, the present invention also provides the application of the hydrotreating catalyst in the hydrotreating of oil products, wherein the oil products are oil products containing aromatics and cycloalkanes, preferably aromatic compounds containing benzene, naphthalene, and phenanthrene, coal tar, direct coal liquefaction oil, and cycloalkyl oil.

[0028] In this invention, unless otherwise specified, all percentages or percentages mentioned are mass percentages or mass percentages.

[0029] Compared with the prior art, the present invention has the following advantages: This invention innovatively changes the feeding sequence, avoiding contact between the molecular sieve and the acidic solution. This helps maintain the acidic properties and crystal structure of the molecular sieve, and while improving the hydrogenation performance of the catalyst, it also extends the catalyst's lifespan. It is a novel technology for preparing hydrogenation support. Furthermore, this invention employs different concentration gradients for the active metal content in the molecular sieve and alumina, resulting in a higher density of active metal near the acid centers of the catalyst. Before mixing, the molecular sieve is first impregnated with a portion of the active metal solution, dried, and then mixed uniformly with alumina. Citric acid, guar gum powder, etc., are added and kneaded into shape. After drying and calcination, a partial active metal support is obtained. The remaining metal solution is then impregnated onto the support to obtain catalysts with different metal concentration gradients. This facilitates the rapid contact of cracked molecules with the metal centers for hydrogenation and stabilization, preventing further cracking and reducing secondary cracking reactions, thereby significantly improving catalyst selectivity. The hydrogenation-modified catalyst of this invention should have the characteristic that the acidity of the support itself matches the strength of the hydrogenation / dehydrogenation centers of the catalyst, with the distance between the two centers being maximized. In addition, through the interaction of auxiliary elements with alumina, the amount of L acid can be reduced and the amount of Brønsted acid can be increased, which can reduce the amount of carbon deposited on the catalyst and extend its service life.

[0030] The catalyst prepared by the method of this invention has excellent selective ring-opening conversion ability of polycyclic cycloalkanes, which can significantly improve the cetane number of direct coal liquefaction diesel products. At the same time, the diesel yield is high, and it has broad application prospects in the hydrotreating reaction of coal-based oil products. Detailed Implementation

[0031] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0032] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and should be understood to include values ​​close to these ranges or values, such as values ​​±10% of the endpoint values. For numerical ranges, endpoint values ​​of various ranges, endpoint values ​​of various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. Without conflict, the embodiments and features described in this application can be combined with each other.

[0033] It should be noted that the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, for example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or device.

[0034] Unless otherwise specified, all reagents used in the following examples / comparative examples are of analytical grade.

[0035] Example 1 This embodiment provides a method for preparing a catalyst for hydrogenation reforming, which includes the following steps: (1) Take an appropriate amount of deionized water, heat it to 50°C, weigh citric acid and phosphoric acid, add them to the deionized water, stir for 0.5 h, add basic nickel carbonate solid, add ammonium metatungstate after the basic nickel carbonate is dissolved, and after the ammonium metatungstate is completely dissolved, adjust the volume to the required volume of active metal solution for later use; wherein the mass ratio of citric acid to nickel oxide is 0.5:1, and the amount of phosphoric acid added is 1% of the mass of the hydrogenation catalyst based on phosphorus oxide; weigh an appropriate amount of USY molecular sieve powder, pour the above prepared solution into the molecular sieve and impregnate it evenly, and dry it at 80°C for 6 h; (2) Weigh appropriate amounts of boehmite powder (hereinafter referred to as PB powder), guar gum powder and citric acid, mix them evenly, and then add appropriate amounts of nitric acid solution with a concentration of 0.3 mol / L. Boric acid is also added to this nitric acid solution. After complete dissolution, mix evenly. The mass ratio of alumina obtained from the decomposition of boehmite to USY molecular sieve is 4:1. Based on the total amount of USY molecular sieve and boehmite, the amount of guar gum powder is 1%, the amount of citric acid is 1%, the amount of nitric acid solution is 1%, and the amount of boron additive (calculated as boron oxide) is 1%. (3) The molecular sieve after the metal impregnation and drying in step (1) is mixed evenly with the kneaded material in step (2), and kneaded into shape on an extruder. After drying and calcination, a carrier is obtained, named Z-1, in which the amount of nickel oxide and tungsten oxide accounts for 10% of the total amount of nickel oxide in the catalyst and the amount of tungsten oxide accounts for 10% of the total amount of tungsten oxide in the catalyst. The drying temperature is 80℃ and the time is 6h, and the calcination temperature is 500℃ and the time is 6h. (4) Prepare the remaining active metal solution in the same way as in step (1), and impregnate it in the above-mentioned carrier. After drying and calcining, obtain the catalyst, named C-1. The drying temperature is 80℃ and the time is 6h, and the calcination temperature is 500℃ and the time is 6h. In the catalyst, the mass fraction of nickel oxide is 3% and the mass fraction of tungsten oxide is 22.5%.

[0036] Example 2 (1) Take an appropriate amount of deionized water, heat it to 50°C, weigh citric acid and phosphoric acid, add them to the deionized water, stir for 0.5 h, add basic nickel carbonate solid, add ammonium metatungstate after the basic nickel carbonate is dissolved, and after the ammonium metatungstate is completely dissolved, adjust the volume to the required volume of active metal solution for later use; wherein the mass ratio of citric acid to nickel oxide is 1:1, and the amount of phosphoric acid added is 1.2% of the mass of the hydrogenation catalyst based on phosphorus oxide; weigh an appropriate amount of USY molecular sieve powder, pour the above prepared solution into the molecular sieve and impregnate it evenly, and dry it at 100°C for 4 h; (2) Weigh appropriate amounts of PB powder, guar gum powder, and citric acid, mix them evenly, and then add appropriate amounts of nitric acid solution with a concentration of 0.5 mol / L. Boric acid is also added to this nitric acid solution. After complete dissolution, mix evenly. The mass ratio of alumina obtained from the decomposition of boehmite to USY molecular sieve is 7:3. Based on the total amount of USY molecular sieve and boehmite, the amount of guar gum powder is 2%, the amount of citric acid is 2%, the amount of nitric acid solution is 1.1%, and the amount of boron additive (calculated as boron oxide) is 2%. (3) The molecular sieve after the metal impregnation and drying in step (1) is mixed evenly with the kneaded material in step (2), and kneaded into shape on an extruder. After drying and calcination, a carrier is obtained, named Z-2, in which the amount of nickel oxide and tungsten oxide accounts for 20% of the total amount of nickel oxide in the catalyst and the amount of tungsten oxide accounts for 20% of the total amount of tungsten oxide in the catalyst. The drying temperature is 100℃ and the time is 4h, and the calcination temperature is 550℃ and the time is 4h. (4) Prepare the remaining active metal solution in the same way as in step (1), and impregnate it in the above-mentioned carrier. After drying and calcining, obtain the catalyst, named C-2. The drying temperature is 100℃ and the time is 4h, and the calcination temperature is 550℃ and the time is 4h. In the catalyst, the mass fraction of nickel oxide is 3% and the mass fraction of tungsten oxide is 22.5%.

[0037] Example 3 (1) Take an appropriate amount of deionized water, heat it to 50°C, weigh citric acid and phosphoric acid, add them to the deionized water, stir for 0.5 h, add basic nickel carbonate solid, add ammonium metatungstate after the basic nickel carbonate is dissolved, and after the ammonium metatungstate is completely dissolved, adjust the volume to the required volume of active metal solution for later use; wherein the mass ratio of citric acid to nickel oxide is 1.5:1, and the amount of phosphoric acid added is 1.2% of the mass of the hydrogenation catalyst based on phosphorus oxide; weigh an appropriate amount of USY molecular sieve powder, pour the above prepared solution into the molecular sieve and impregnate it evenly, and dry it at 120°C for 3 h; (2) Weigh appropriate amounts of PB powder, guar gum powder, and citric acid, mix them evenly, and then add appropriate amounts of nitric acid solution with a concentration of 0.5 mol / L. Boric acid is also added to this nitric acid solution. After complete dissolution, mix evenly. The mass ratio of alumina obtained from the decomposition of boehmite to USY molecular sieve is 3:2. Based on the total amount of USY molecular sieve and boehmite, the amount of guar gum powder is 3%, the amount of citric acid is 3%, the amount of nitric acid solution is 1.2%, and the amount of boron additive (calculated as boron oxide) is 3%. (3) The molecular sieve after the metal impregnation in step (1) is dried is mixed evenly with the kneaded material in step (2), and kneaded into shape on an extruder. After drying and calcination, a carrier is obtained, named Z-3, in which the amount of nickel oxide and tungsten oxide accounts for 20% of the total amount of nickel oxide in the catalyst and the amount of tungsten oxide accounts for 20% of the total amount of tungsten oxide in the catalyst. The drying temperature is 120℃ and the time is 3h, and the calcination temperature is 550℃ and the time is 3h. (4) Prepare the remaining active metal solution in the same way as in step (1), and impregnate it in the above-mentioned carrier. After drying and calcining, obtain the catalyst, named C-3. The drying temperature is 120°C and the time is 3h, and the calcination temperature is 550°C and the time is 3h. In the catalyst, the mass fraction of nickel oxide is 3% and the mass fraction of tungsten oxide is 22.5%.

[0038] Example 4 (1) Take an appropriate amount of deionized water, heat it to 50°C, weigh citric acid and phosphoric acid, add them to the deionized water, stir for 0.5 h, add basic nickel carbonate solid, add ammonium metatungstate after the basic nickel carbonate is dissolved, and after the ammonium metatungstate is completely dissolved, adjust the volume to the required volume of active metal solution for later use; wherein the mass ratio of citric acid to nickel oxide is 1.5:1, and the amount of phosphoric acid added is 1.2% of the mass of the hydrogenation catalyst based on phosphorus oxide; weigh an appropriate amount of USY molecular sieve powder, pour the above prepared solution into the molecular sieve and impregnate it evenly, and dry it at 120°C for 3 h; (2) Weigh appropriate amounts of PB powder, guar gum powder, and citric acid, mix them evenly, and then add appropriate amounts of nitric acid solution with a concentration of 0.6 mol / L. Boric acid is also added to this nitric acid solution. After complete dissolution, mix evenly. The mass ratio of alumina obtained from the decomposition of boehmite to USY molecular sieve is 3:2. Based on the total amount of USY molecular sieve and boehmite used, the amount of guar gum powder is 3%, the amount of citric acid is 3%, the amount of nitric acid solution is 1.1%, and the amount of boron additive (calculated as boron oxide) is 3%. (3) The molecular sieve after the metal impregnation and drying in step (1) is mixed evenly with the kneaded material in step (2), and kneaded into shape on an extruder. After drying and calcination, a carrier is obtained, named Z-4, in which the amount of nickel oxide and tungsten oxide accounts for 30% of the total amount of nickel oxide in the catalyst and the amount of tungsten oxide accounts for 30% of the total amount of tungsten oxide in the catalyst. The drying temperature is 120℃ and the time is 3h, and the calcination temperature is 550℃ and the time is 3h. (4) Prepare the remaining active metal solution in the same way as in step (1), and impregnate it in the above-mentioned carrier. After drying and calcining, obtain the catalyst, named C-4. The drying temperature is 120°C and the time is 3h, and the calcination temperature is 550°C and the time is 3h. In the catalyst, the mass fraction of nickel oxide is 3% and the mass fraction of tungsten oxide is 22.5%.

[0039] Example 5 The difference from Example 3 is that in step (1), the molecular sieve used is changed to a mixed molecular sieve of USY and β, wherein the mass ratio of USY to β molecular sieve is 7:3. The rest is the same as in Example 3. The resulting catalyst is named C-5.

[0040] Example 6 The difference between Example 6 and Example 5 is that no boron additive was added in step (2). The resulting catalyst was named C-6.

[0041] Comparative Example 1: The difference from Example 2 is that in step (2), the impregnated and dried molecular sieve from step (1) is directly mixed with PB powder, guar gum powder and citric acid, and then an appropriate amount of 0.5 mol / L nitric acid solution is added to prepare a kneaded material; in step (3), the above kneaded material is directly kneaded and shaped on an extruder. The rest is the same as in Example 2. The obtained catalyst is named D-1.

[0042] Comparative Example 2: The difference from Comparative Example 1 is as follows: In step (1), the USY molecular sieve is no longer impregnated with the active metal solution prepared in step (1); in step (2), the unimpregnated USY molecular sieve is directly mixed with PB powder, guar gum powder, and citric acid; in step (3), the resulting support is further impregnated with the active metal solution prepared in step (1) and dried. The rest is the same as Comparative Example 1. The resulting catalyst is named D-2.

[0043] Comparative Example 3 The difference from Example 5 is as follows: In step (1), the USY and β molecular sieves are no longer impregnated with the active metal solution prepared in step (1); in step (2), the unimpregnated USY molecular sieve is directly mixed with PB powder, guar gum powder and citric acid, and then an appropriate amount of nitric acid solution with a concentration of XX is added to prepare a kneaded material; in step (3), the above kneaded material is directly kneaded and shaped on an extruder; and in step (3), the obtained support is further impregnated with the active metal solution prepared in step (1) and dried. The rest is the same as in Example 5. The obtained catalyst is named D-3.

[0044] Table 1. Comparison of composition and physicochemical properties between the examples and comparative examples.

[0045] Note: NiO-1 and WO3-1 represent the percentage of active metal mass in the molecular sieve relative to the total metal mass; NiO-2 and WO3-2 represent the percentage of active metal mass in the catalyst.

[0046] Table 2 Comparison of acid properties of catalysts in the examples and comparative examples.

[0047] As shown in Table 2, by changing the order of nitric acid addition and avoiding direct contact between the molecular sieve and nitric acid, the amount of medium-strong acid in the catalyst increases, the amount of strong acid decreases, and the ratio of medium-strong acid to strong acid increases, which can improve the effect of ring-opening without breaking the catalyst.

[0048] The above catalyst was used for oil hydrotreating reaction (reaction temperature 350℃, reaction pressure 13MPa, reaction space velocity 2.5 h⁻¹). -1 Under the condition of a hydrogen-to-oil ratio of 800, the relevant oil properties are shown in Table 3.

[0049] Table 3 Results of the hydroretrogradation reaction of coal liquefaction oil under reaction condition 1 with different catalysts

[0050] As can be seen from the comparison of the above examples / comparative examples, the hydrogenation performance of the catalyst can be improved by avoiding direct contact between the molecular sieve and the acidic solution and by changing the active metal concentration of the molecular sieve and PB powder. In addition, the C-5 catalyst with PB (wt%):(USY+β) (wt%)=3:2, which is first impregnated with 20% active metal solution, exhibits the best reaction performance, can achieve ring-opening without chain breaking, and significantly improves the cetane number of the feedstock.

Claims

1. A method for preparing a hydrotreating catalyst, comprising the following steps: (1) Prepare an appropriate amount of active metal solution and impregnate the active metal onto the molecular sieve using the impregnation method, and then dry it to obtain the impregnated molecular sieve for later use; (2) Mix the ingredients, including boehmite, guar gum powder, citric acid and nitric acid solution, evenly to obtain a mixture; (3) Mix the impregnated molecular sieve in step (1) with the kneading material in step (2) to obtain a mixture, knead it on an extruder, and then dry and calcin it to obtain a carrier; (4) Prepare a certain amount of active metal solution again, and use the impregnation method to impregnate the active metal onto the carrier in step (3), and then dry and calcine to obtain the hydrogenation catalyst.

2. The preparation method according to claim 1, characterized in that, The active metal impregnated in step (1) accounts for less than 50% of the total active metal in the hydrogenation catalyst.

3. The preparation method according to claim 2, characterized in that, The active metal impregnated in step (1) accounts for 10-30% of the total active metal in the hydrogenation catalyst.

4. The preparation method according to claim 2 or 3, characterized in that, The mixture also contains additive elements, which are one or more of Si, B, Zr, Ti, La and Ce.

5. The preparation method according to claim 4, characterized in that, The amount of the auxiliary element, calculated as its oxide, is 0.1-8 wt% of the total amount of the molecular sieve and pseudoboehmite.

6. The preparation method according to claim 4, characterized in that, In step (1) above, the molecular sieve is selected from one or more of USY, HY, REY, Beta, SAPO-5 and ZSM-5 molecular sieves; the active metals in steps (1) and (4) are selected from elements of group VIII and / or group VI of the periodic table, wherein the active metal of group VIII is Ni and / or Co, and the active metal of group VI is W and / or Mo.

7. The preparation method according to claim 6, characterized in that, In the hydrotreating catalyst, the active metal, in its oxide form, comprises 1-10 wt% of Group VIII active metal and 10-40 wt% of Group VI active metal. In step (4), the Group VIII active metal impregnated accounts for 50-90% of the total Group VIII active metal in the hydrogenation catalyst, and the Group VI active metal impregnated in step (4) accounts for 50-90% of the total Group VI active metal in the hydrogenation catalyst.

8. The preparation method according to claim 7, characterized in that, In the hydrogenation catalyst, the active metal is in oxide form, and the group VIII active metal accounts for 3-5 wt% and the group VI active metal accounts for 15-30%.

9. The preparation method according to claim 7 or 8, characterized in that, In the carrier of step (3) above, the mass ratio of the molecular sieve to the alumina obtained by roasting and decomposing pseudoboehmite is 1:9-3:2; and based on the total amount of the molecular sieve and pseudoboehmite, the amount of guar gum powder is 0.5%-10wt%, the amount of citric acid is 0.5%-10wt%, the nitric acid concentration of the nitric acid solution is 0.2-1 mol / L, and the amount is 0.5-2wt%; the precursor of the auxiliary element is dissolved in the nitric acid solution to mix evenly with the other ingredients, and the amount of the auxiliary element, based on its oxide, is 0.5-5 wt% of the total amount of the USY molecular sieve and pseudoboehmite.

10. The preparation method according to claim 9, characterized in that, In the carrier of step (3) above, the mass ratio of the molecular sieve to the alumina obtained by roasting and decomposing pseudoboehmite is 1:4-2:3; and based on the total amount of the molecular sieve and pseudoboehmite, the amount of guar gum powder is 1-5wt%, the amount of citric acid is 1-5wt%, and the amount of nitric acid solution is 1-1.5wt%.

11. The preparation method according to claim 9, characterized in that, In the active metal solutions in steps (1) and (4) above, the active metal of group VIII is Ni and the active metal of group VI is W. The preparation method is as follows: add deionized water to a beaker, heat to 40-50℃ and then add citric acid and phosphoric acid. After stirring evenly, add basic nickel carbonate. After the basic nickel carbonate is dissolved, add ammonium metatungstate. After the ammonium metatungstate is completely dissolved, adjust the volume to the required volume.

12. The preparation method according to claim 11, characterized in that, When preparing the active metal solution, the amount of citric acid added is in a mass ratio of (0.1-5.0):1 with nickel oxide; the amount of phosphoric acid added, calculated as phosphorus oxide, is 0.5%-5.0% of the mass of the hydrogenation catalyst.

13. The preparation method according to claim 12, characterized in that, When preparing the active metal solution, the amount of citric acid added is in a mass ratio of (0.5-2.0):1 with nickel oxide; the amount of phosphoric acid added, calculated as phosphorus oxide, is 1.0%-3.0% of the mass of the hydrogenation catalyst.

14. The preparation method according to claim 12 or 13, characterized in that, The impregnation method is an equal-volume impregnation method; the drying is carried out at 80-120℃ for 6-12 hours; the calcination is carried out at 500-550℃ for 3-6 hours.

15. The hydrogenation-modified catalyst prepared by any one of claims 1-14.

16. The hydrotreating catalyst according to claim 15, characterized in that, The specific surface area of ​​the hydrogenation catalyst is 200-400 m². 2 / g, pore volume 0.2-0.5 cm³ 3 / g, with an average pore size of 5-15 nm.

17. The application of the hydrotreating catalyst according to claim 15 or 16 in the hydrotreating of oil products, wherein, The oil product is an oil product containing aromatics and cycloalkanes.

18. The application of the hydrotreating catalyst according to claim 17 in the hydrotreating of oil products, characterized in that, The oil products are aromatic compounds containing benzene, naphthalene, and phenanthrene, coal tar, direct coal liquefaction oil, and naphthenic oil.

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