Hydrofining catalyst and preparation method thereof

Abstract

The invention relates to the field of hydrogenation catalysts, and particularly discloses a hydrofining catalyst and a preparation method thereof. The preparation method of the hydrofining catalyst comprises the following steps: (a) adding an acid solution into an ethanol water solution of cetyltrimethylammonium bromide, adjusting the pH value to be acidic, stirring, adding polyethylene glycol, and uniformly mixing to prepare a blended solution; (b) adding a tetrabutyl titanate solution into the blended solution, stirring, adding an ethanol solution of aluminum chloride, uniformly stirring, standing, aging, carrying out supercritical drying, and calcining to obtain a carrier material, with the molar ratio of tetrabutyl titanate to cetyltrimethylammonium bromide being 1: 0.1-0.3; and (c) putting the carrier material into a solution containing at least one of molybdenum, tungsten, cobalt, nickel, copper and zinc compounds, and carrying out ultrasonic dispersion, drying and roasting. The hydrofining catalyst prepared by the invention has the advantages of large carrier material pore volume, pore diameter and specific surface area and high catalytic activity.

Description

Technical Field

[0001] This application relates to the field of hydrogenation catalyst technology, and more specifically, to a hydrogenation refining catalyst and a method for preparing the same. Background Technology

[0002] With increasingly stringent environmental regulations, the quality standards for gasoline and diesel products are becoming higher and higher. Among these, diesel hydrodesulfurization is an important means of improving diesel quality. Therefore, the demand for various types of hydrorefining catalysts in the petrochemical industry is gradually increasing. The conventional production process of hydrorefining catalysts includes carrier molding, carrier drying and calcination, active component impregnation, and drying and calcination of the impregnated material to obtain the finished catalyst. Currently, the main approach is to optimize the various performance parameters of the catalyst by adjusting the raw materials, thereby producing hydrorefining catalysts with high pore volume, high strength, and good particle size distribution.

[0003] Deep hydrodesulfurization of diesel fuel requires the removal of large molecular weight sulfides such as 4,6-DMDBT. The steric hindrance effect of these methyl groups hinders the contact between sulfur atoms and the catalyst, primarily achieved through hydrogenation to saturate aromatic rings before desulfurization. Furthermore, organic nitrogen compounds compete with sulfides for adsorption sites on the catalyst, inhibiting the desulfurization reaction and causing activity to decrease with increasing feed nitrogen content. These two characteristics necessitate increasing the catalyst pore size to allow large molecular weight sulfides and nitrogen compounds to freely enter the pores and undergo hydrodenitrification and desulfurization reactions. While existing bulk catalysts possess numerous hydrogenation active centers, most are supported by alumina. Due to the small specific surface area, pore volume, and pore size of alumina, the pore structure is disordered, with pores mainly concentrated in micropores. Large molecular compounds containing S and N cannot access the hydrogenation active centers, reducing their utilization and hindering the improvement of the bulk catalyst's hydrogenation activity. Meanwhile, smaller pore volume and specific surface area can cause excessive accumulation of high-content active metals on the catalyst surface in bulk catalysts, reducing the formation of active phase, lowering catalyst activity, affecting the utilization rate of active metals in the catalyst, and increasing the cost of catalyst use. Summary of the Invention

[0004] In order to increase the pore volume and pore size of the catalyst and thus improve the hydrogenation catalytic ability, this application provides a hydrogenation refining catalyst and its preparation method.

[0005] In a first aspect, this application provides a method for preparing a hydrorefining catalyst, employing the following technical solution: A method for preparing a hydrorefining catalyst includes the following steps: (a) Add acid to an ethanol aqueous solution of hexadecyltrimethylammonium bromide with a concentration of 0.6-0.65wt%, adjust the pH to acidic, stir at 35-40℃ until clear, add polyethylene glycol, mix evenly, and obtain a blended solution. The mass ratio of hexadecyltrimethylammonium bromide to polyethylene glycol is 1:1-2. (b) Add tetrabutyl titanate solution to the blend, stir at 35-40℃ for 0.5-1h, add aluminum chloride ethanol solution, stir evenly, allow to stand for aging, supercritical drying, and calcination to obtain the carrier material. The molar ratio of tetrabutyl titanate to hexadecyltrimethylammonium bromide is 1:0.1-0.3, and the mass ratio of hexadecyltrimethylammonium bromide to aluminum chloride is 1:0.1-0.2. (c) The carrier material is placed in a solution containing the active component, ultrasonically dispersed, dried at 80-90°C, and calcined at 500-550°C for 5-6 hours to obtain the catalyst, wherein the active component is at least one of molybdenum, tungsten, cobalt, nickel, copper, and zinc compounds.

[0006] By adopting the above technical solution, under acidic conditions, tetrabutyl titanate undergoes a hydrolysis reaction to form titanium hydroxy compounds. The titanium hydroxy compounds generated by hydrolysis undergo a condensation reaction to form Ti-O-Ti bonds, thereby forming a sol with a three-dimensional network structure. As hydrolysis and condensation proceed, the solution gradually transforms into a sol and further forms a gel. After aging, the network structure of the gel becomes more stable and perfect.

[0007] Supercritical drying slowly removes the solvent, avoiding cracks and shrinkage. Compared with traditional drying, supercritical drying allows ethanol and water to reach a supercritical state, which can completely eliminate capillary forces, thus preserving the original porous structure of the carrier and preventing pore collapse. Moreover, materials after supercritical drying usually have a higher specific surface area and larger pore volume. In addition, supercritical drying can obtain a more uniform dispersion state, improving the dispersion of active metals loaded on the carrier.

[0008] After supercritical drying, calcination removes hexadecyltrimethylammonium bromide, polyethylene glycol, and residual organic matter, and induces a crystal phase transformation in titanium oxides, forming a carrier material with certain crystallinity and thermal stability. Hexadecyltrimethylammonium bromide (CTAB) is a cationic surfactant that forms micelles in solution. Under acidic conditions, CTAB micelles are positively charged and can be electrostatically adsorbed onto negatively charged titanium hydroxyl compounds. As the sol-gel process proceeds, titanium hydroxyl compounds deposit and grow around CTAB, forming a gel with specific channels. CTAB serves as a template and is removed after calcination. In addition, PEG leaves channels in the carrier corresponding to the size and shape of the micelles. PEG is a nonionic surfactant that interacts with tetrabutyl titanate and its hydrolysis products. PEG molecular chains can act as separators and supports in the gel network, preventing excessive shrinkage and collapse of the gel during drying and calcination. This helps to form carrier materials with larger pore volume and pore size. Moreover, PEG can reduce the interaction forces between CTAB micelles, making the micelles more uniformly dispersed in the solution, which is beneficial for forming carriers with larger pore sizes. Therefore, PEG and CATB can have a synergistic effect, jointly regulating the pore structure of the carrier.

[0009] Adding aluminum chloride during the preparation of the carrier material allows aluminum ions to form acidic sites on the surface of titanium dioxide, promoting the breaking of CS bonds in reactions such as hydrodesulfurization. The acidic sites work synergistically with the active ingredients to improve the efficiency of hydrodesulfurization. Moreover, the generation of aluminum ions can also improve thermal stability, delay the anatase to rutile phase transformation, and prevent pore collapse during high-temperature calcination. In addition, aluminum ions form Al-O-Ti bonds with titanium dioxide, enhancing the mechanical strength of the carrier material and better anchoring the active metal precursor, thus improving dispersibility. Appropriate addition of aluminum chloride can synergistically expand pores with CTAB micelles, increasing pore volume and pore size, while also preventing pore blockage.

[0010] CATB can form a pore structure, and polyethylene glycol can prevent pore shrinkage and collapse. The carrier material made by combining the two has a regular pore structure, high specific surface area, large pore size and large volume. It can reduce the diffusion resistance of reactants, make reactants more accessible to the active sites in the pores, which is conducive to the reaction of macromolecules and improves the catalytic activity of the catalyst.

[0011] Optionally, the active component solution comprises the following raw materials by weight percentage: 7.5-15 wt% ammonium molybdate, 5-8 wt% ammonium metatungstate, 3-5 wt% nickel silicate, with the balance being deionized water.

[0012] By adopting the above technical solutions, when nickel silicate decomposes on the support, nickel ions are partially exposed as silicate structures, which delays Ni agglomeration, improves metal dispersibility, and reduces the risk of high-temperature sintering. Ammonium metatungstate is more likely to generate active WS2 during sulfidation than pure WO3, which is more conducive to the diffusion and adsorption of macromolecular sulfides. Ammonium molybdate provides sufficient MoS2 active phase to form electronic synergy with WS2. MoS2 nanosheets are more easily dispersed in the mesopores of the support, making up for the possible large interparticle gaps of WS2. Therefore, the combination of ammonium molybdate, ammonium metatungstate, and nickel silicate, through the synergistic cooperation of the Ni-W-Mo-S composite active phase, can improve the CS bond breaking ability, promote aromatic ring hydrogenation, enhance sulfur vacancy concentration, improve overall activity, and significantly improve hydrodesulfurization efficiency.

[0013] Optionally, the mass ratio of ammonium molybdate to ammonium metatungstate in the active component solution is 1:1, and the mass ratio of nickel silicate to the total amount of nickel silicate and ammonium molybdate is 0.4:1.

[0014] By adopting the above technical solution, the combination of ammonium molybdate, ammonium metatungstate, and nickel silicate in the above amounts can produce a catalyst with better catalytic effect.

[0015] Optionally, citric acid is also added to the aluminum chloride ethanol solution, and the mass ratio of citric acid to aluminum chloride is 1:1-1.5.

[0016] By employing the above-mentioned technical solution, adding aluminum chloride during the sol-gel stage may affect the orderly assembly of the template, leading to disordered mesoporous structures. Therefore, to avoid destroying the mesoporous order, citric acid is added. This citric acid forms a complex with aluminum ions, slowing down their hydrolysis rate, preventing local deposition, and inhibiting the electrostatic interaction between aluminum ions and hexadecyltrimethylammonium bromide. This allows the hexadecyltrimethylammonium bromide micelles to arrange themselves more orderly, forming a mesoporous structure. Furthermore, the carboxyl groups of citric acid chelate with chloride ions, preventing hydrolysis and the formation of aluminum hydroxide clusters that block the pores, maintaining mesoporous connectivity, promoting uniform aluminum doping into the titanium dioxide lattice, and preventing localized alumina aggregation that damages the structure during high-temperature calcination. Additionally, citric acid generates additional voids during calcination, increasing pore volume. The synergistic effect of citric acid and polyethylene glycol in expanding pores improves specific surface area, increases high-temperature stability, reduces carrier fragmentation, and enhances hydrodesulfurization and denitrification efficiency. Optionally, the polyethylene glycol comprises polyethylene glycol 10000-20000 and polyethylene glycol 1000-4000 in a mass ratio of 1:0.2-0.5.

[0017] By adopting the above technical solutions, low molecular weight polyethylene glycol can form smaller mesopores, while high molecular weight polyethylene glycol has a more significant pore-expanding effect, forming a mesoporous structure with a larger pore size, obtaining a larger pore volume and specific surface area, and also taking into account the density of active sites and macromolecular diffusion. The high specific surface area provided by low molecular weight polyethylene glycol can provide more anchoring sites, while high molecular weight polyethylene glycol can promote the penetration of the active ingredient solution, thereby increasing the dispersion of the active metal, making its loading more uniform and the loading capacity greater. Therefore, by adjusting the molecular weight and dosage of the two polyethylene glycols, the pore structure of the carrier can be precisely controlled, the loading capacity of the active metal can be increased, and the catalytic effect can be enhanced.

[0018] Optionally, in step (b), the supercritical drying product is kept at 80-120℃ in a steam environment for 1-3 hours before calcination.

[0019] By adopting the above technical solution, the introduction of aluminum chloride in the sol-gel stage may interfere with template assembly and affect the mesoporous structure. Therefore, the supercritical dried material is steam-treated. The surface of the dried support is still rich in hydroxyl groups, and water vapor can react with it to reorganize the pore walls, partially dissolve or rearrange the pore walls, thereby repairing the collapsed micropores / mesopores, increasing the pore volume of the support material, increasing the loading of active ingredients, and improving catalytic activity.

[0020] Optionally, the supercritical drying process is as follows: under nitrogen protection, the temperature is increased to 250-260℃ at 1-5℃ / min, and the pressure is simultaneously increased to 7-10MPa. The temperature and pressure are maintained for 1-3 hours, and then the pressure is reduced to atmospheric pressure at 0.1-0.5MPa / min and cooled to room temperature.

[0021] By adopting the above technical solution, the supercritical drying temperature is greater than the critical temperature and critical pressure of ethanol, so that the ethanol solution reaches the critical state, eliminating capillary forces and retaining the porous structure. The supercritical drying rate ensures that the solvent completely reaches the supercritical state and diffuses out of the gel network, and the pressure is reduced slowly to avoid structural damage caused by rapid pressure reduction.

[0022] Optionally, in step (b), the calcination process is as follows: first, the temperature is raised to 200℃ at 1-3℃ / min and held for 2 hours, then the temperature is raised to 400℃ at 5-10℃ / min and held for 2 hours, and finally the temperature is raised to 500℃ at 5-10℃ / min and held for 10-20 minutes.

[0023] By adopting the above technical solution, a stepwise calcination method is used to protect the mesoporous structure. First, CTAB and PEG are slowly removed at low temperature, which can retain more porosity and avoid the anatase to rutile phase transition. Then, chloride ions are partially migrated to the titanium dioxide lattice at medium temperature. Finally, a short-time high-temperature treatment is performed to complete the anatase crystallization, avoiding over-sintering. While gradually removing the template, aluminum sites are fixed, promoting the adsorption of nitrogen-containing compounds and the breaking of CN bonds, thereby increasing the catalytic effect.

[0024] Optionally, the acid solution is 1M dilute nitric acid or acetic acid, and the pH value of the acid solution is adjusted to 1.5-3.

[0025] By employing the above technical solution, acidic conditions can slow down the hydrolysis rate of tetrabutyl titanate, prevent local precipitation, form a uniform sol, and stabilize CTAB / PEG micelles. This results in a carrier material with high porosity and specific surface area after calcination. If the pH value is too low, hydrolysis is slow, leading to instability of the CTAB micelles and resulting in a carrier material with disordered pores and a low specific surface area. Conversely, if the pH value is too high, it will accelerate the hydrolysis of tetrabutyl titanate, destroying the template structure and causing uneven pore size and decreased pore volume in the carrier material. Secondly, this application provides a hydrorefining catalyst, which adopts the following technical solution: A hydrorefining catalyst, prepared using the aforementioned method for preparing a hydrorefining catalyst.

[0026] By adopting the above technical solution, the synergistic effect of CTAB and PEG is utilized to regulate the pore structure of the support material, thereby preparing a support material with a large pore volume and pore size, thus avoiding excessive accumulation of active components that would affect catalyst activity.

[0027] In summary, this application has the following beneficial effects: 1. Because this application uses tetrabutyl titanate, CTAB and PEG to prepare the support material through sol-gel, supercritical drying and calcination, and incorporates aluminum chloride during the sol-gel process, the synergistic effect of CTAB and PEG can obtain a support material with specific channels, pore volume and large specific surface area. This ensures the hydrogenation demetallization activity per unit surface area of ​​the catalyst while increasing the proportion of macropores in the prepared catalyst, resulting in high desulfurization rate, good protection effect and greatly improved catalyst lifespan.

[0028] 2. In this application, ammonium molybdate, ammonium metatungstate, and nickel silicate are preferably used as active ingredients. After impregnation and ultrasonication, they are dispersed in the carrier material. Nickel silicate can increase high-temperature stability and increase metal dispersion, while ammonium metatungstate and ammonium molybdate can cooperate with nickel silicate to promote hydrodesulfurization efficiency through the Ni-W-Mo-S composite active phase.

[0029] 3. This application uses a combination of high molecular weight and low molecular weight polyethylene glycol. High molecular weight PEG can increase the pore volume of the support material and improve the penetration of active ingredients, while low molecular weight PEG can form smaller mesopores and increase the specific surface area. The two work synergistically to improve the loading of active metals and increase the catalytic effect. Detailed Implementation

[0030] The following embodiments provide a further detailed description of this application. Example

[0031] Example 1: A method for preparing a hydrorefining catalyst, comprising the following steps: (a) 20g of hexadecyltrimethylammonium bromide was added to an ethanol aqueous solution (ethanol to water volume ratio of 4:1) to prepare an ethanol aqueous solution of hexadecyltrimethylammonium bromide with a concentration of 0.65%. Dilute nitric acid with a concentration of 1M was added to adjust the pH to 2. The solution was stirred at 35°C until clear. 30g of polyethylene glycol was added and stirred to mix evenly to obtain a blend. The polyethylene glycol contained polyethylene glycol 20000 and polyethylene glycol 4000 in a mass ratio of 1:0.5. (b) Add a 25% tetrabutyl titanate solution (tetrabutyl orthosilicate dissolved in ethanol) to the blend, stir at 35°C for 1 h, add 20 g of aluminum chloride ethanol solution (prepared by mixing 4 g of aluminum chloride and 16 g of ethanol), stir evenly, let stand for aging for 24 h, and then supercritically dry under nitrogen protection. The specific method is as follows: first, heat up to 250°C at 5°C / min, simultaneously pressurize to 7 MPa, hold for 3 h, then cool down to atmospheric pressure at 0.5 MPa / min, cool to room temperature, and then calcine. The calcine process is as follows: heat up to 200°C at 3°C / min, hold for 2 h, then heat up to 400°C at 10°C / min, hold for 2 h, and finally heat up to 500°C at 10°C / min, hold for 10 min to obtain the carrier material. The molar ratio of tetrabutyl titanate to hexadecyltrimethylammonium bromide is 1:0.3. (c) Take 100g of the support material and put it into 180mL of solution containing the active component. After ultrasonic dispersion for 30min, dry it at 90℃ for 10h and calcine it at 550℃ for 5h to obtain the hydrogenation refining catalyst. The active component solution contains the following raw materials by weight percentage: 7.5wt% ammonium molybdate, 7.5wt% ammonium metatungstate, 5wt% nickel silicate, and the balance is deionized water.

[0032] Example 2: A method for preparing a hydrorefining catalyst, comprising the following steps: (a) 20g of hexadecyltrimethylammonium bromide was added to an aqueous ethanol solution (ethanol to water volume ratio of 4:1) to prepare an aqueous ethanol solution of hexadecyltrimethylammonium bromide with a concentration of 0.6%. Dilute nitric acid with a concentration of 1M was added to adjust the pH to 3. The solution was stirred at 40°C until clear. 20g of polyethylene glycol was added and stirred to mix evenly to obtain a blend. The polyethylene glycol contained polyethylene glycol 20000 and polyethylene glycol 4000 in a mass ratio of 1:0.2. (b) Add a 25% tetrabutyl titanate solution (tetrabutyl orthosilicate dissolved in ethanol) to the blend, stir at 40°C for 0.5 h, add 2 g of aluminum chloride (prepared by mixing 2 g of aluminum chloride and 8 g of ethanol), stir evenly, let stand for aging for 24 h, and then supercritically dry under nitrogen protection. The specific method is as follows: first, heat up to 260°C at 3°C / min, simultaneously pressurize to 10 MPa, hold for 1 h, then cool down to atmospheric pressure at 0.3 MPa / min, cool to room temperature, and then calcine. The calcine process is as follows: heat up to 200°C at 1°C / min, hold for 2 h, then heat up to 400°C at 5°C / min, hold for 2 h, and finally heat up to 500°C at 5°C / min, hold for 20 min to obtain the carrier material. The molar ratio of tetrabutyl titanate to hexadecyltrimethylammonium bromide is 1:0.1. (c) Take 100g of carrier material and put it into 180mL of solution containing active components. After ultrasonic dispersion for 30min, dry it at 80℃ for 12h and calcine it at 500℃ for 6h to obtain the hydrogenation refining catalyst. The active component solution contains the following raw materials by weight percentage: 11wt% ammonium molybdate, 7wt% ammonium metatungstate, 3wt% nickel silicate, and the balance is deionized water.

[0033] Example 3: A method for preparing a hydrorefining catalyst, comprising the following steps: (a) 20g of hexadecyltrimethylammonium bromide was added to an ethanol aqueous solution (ethanol to water volume ratio of 4:1) to prepare an ethanol aqueous solution of hexadecyltrimethylammonium bromide with a concentration of 0.63%. Dilute nitric acid with a concentration of 1M was added to adjust the pH to 1.5. The solution was stirred at 35°C until clear. 40g of polyethylene glycol was added and stirred to mix evenly to obtain a blend. The polyethylene glycol contained polyethylene glycol 20000 and polyethylene glycol 4000 in a mass ratio of 1:0.4. (b) Add a 25% tetrabutyl titanate solution (tetrabutyl orthosilicate dissolved in ethanol) to the blend, stir at 35°C for 0.5 h, add 15 g of aluminum chloride in ethanol (prepared by mixing 3 g of aluminum chloride and 12 g of ethanol), stir evenly, let stand for aging for 24 h, and then supercritically dry under nitrogen protection. The specific method is as follows: first, heat up to 250°C at 1°C / min, simultaneously pressurize to 8 MPa, hold for 2 h, then cool down to atmospheric pressure at 0.1 MPa / min, cool to room temperature, and then calcine. The calcine process is as follows: heat up to 200°C at 3°C / min, hold for 2 h, then heat up to 400°C at 8°C / min, hold for 2 h, and finally heat up to 500°C at 8°C / min, hold for 15 min to obtain the carrier material. The molar ratio of tetrabutyl titanate to hexadecyltrimethylammonium bromide is 1:0.2. (c) Take 100g of carrier material and put it into 180mL of solution containing active components. After ultrasonic dispersion for 30min, dry it at 90℃ for 12h and calcine it at 550℃ for 6h to obtain the hydrogenation refining catalyst. The active component solution contains the following raw materials by weight percentage: 15wt% ammonium molybdate, 8wt% ammonium metatungstate, 4wt% nickel silicate, and the balance is deionized water.

[0034] Example 4: A method for preparing a hydrorefining catalyst, which differs from Example 1 in that the active component contains the following raw materials by weight percentage: 7.5 wt% ammonium molybdate, 5 wt% ammonium metatungstate and 5 wt% nickel silicate, with the balance being deionized water.

[0035] Example 5: A method for preparing a hydrorefining catalyst, which differs from Example 1 in that the active component contains the following raw materials by weight percentage: 8 wt% ammonium molybdate, 8 wt% ammonium metatungstate, 5 wt% nickel silicate, and the balance being deionized water.

[0036] Example 6: A method for preparing a hydrogenation refining catalyst, which differs from Example 1 in that Ni(NO3)2 is used to replace nickel silicate in an equal amount.

[0037] Example 7: A method for preparing a hydrogenation refining catalyst, the difference from Example 1 is that the polyethylene glycol used is polyethylene glycol 4000.

[0038] Example 8: A method for preparing a hydrogenation refining catalyst, the difference from Example 1 is that the polyethylene glycol used is polyethylene glycol 20000.

[0039] Example 9: A method for preparing a hydrogenation refining catalyst, which differs from Example 1 in that citric acid is added to the ethanol solution of aluminum chloride, and the mass ratio of citric acid to aluminum chloride is 1:1.5.

[0040] Example 10: A method for preparing a hydrogenation refining catalyst, which differs from Example 1 in that citric acid is added to the ethanol solution of aluminum chloride, and the mass ratio of citric acid to aluminum chloride is 1:1.

[0041] Example 11: A method for preparing a hydrogenation refining catalyst, which differs from Example 9 in that the supercritical drying product is first kept at 120°C in a steam environment for 1 hour before calcination.

[0042] Example 12: A method for preparing a hydrogenation refining catalyst, which differs from Example 9 in that the supercritical drying product is first kept at 80°C in a steam environment for 3 hours before calcination.

[0043] Comparative Example Comparative Example 1: A method for preparing a hydrogenation refining catalyst, which differs from Example 1 in that, in step (b), an ethanol solution of aluminum chloride is not added.

[0044] Comparative Example 2: A method for preparing a hydrogenation refining catalyst, which differs from Example 1 in that, in step (b), drying in a 60°C oven for 12 hours is used instead of supercritical drying.

[0045] Comparative Example 3: A method for preparing a hydrogenation refining catalyst, which differs from Example 1 in that, in step (b), freeze drying at -40°C for 10 hours is used instead of supercritical drying.

[0046] Comparative Example 4: A method for preparing a hydrogenation refining catalyst, which differs from Example 1 in that PEG is not added.

[0047] Performance testing Hydrogenation refining catalysts were prepared according to the methods in the examples and comparative examples, and their performance was tested according to the following methods. The test results are recorded in Table 2.

[0048] 1. Pore volume: The pore volume was determined by the method described in Q / SH 361 913 "Determination of pore volume and pore crystal of catalysts for catalytic hydrogenation and reforming by low-temperature nitrogen adsorption method". The sample was pressed into tablets, sieved, and treated at 90℃ for 1 h and 350℃ for 4 h under vacuum conditions to remove the adsorbate on the sample surface. Finally, the nitrogen adsorption-desorption isotherm was obtained at -196℃.

[0049] 2. Specific surface area: Measured by the method described in GB / T5816-1995 "Determination of surface area of ​​catalysts and adsorbents".

[0050] 3. Crushing strength: The crushing strength of the catalyst was determined using a ZQJ-2 intelligent particle strength tester.

[0051] 4. Catalytic Hydrogenation Capacity: A blended diesel fuel, consisting of 35% and 65% by mass of catalytic cracking diesel and coking diesel (both produced by a petrochemical company of China National Petroleum Corporation), was used as feedstock. The properties of the blended diesel fuel are shown in Table 1. The catalyst was loaded into the reactor and then pre-sulfurized to convert the oxidized catalyst into a sulfidized catalyst. The pre-sulfurization conditions were as follows: catalyst loading 50 mL, pressure 6.5 MPa, and volumetric hourly space velocity (VHSV) 1.5 h⁻¹. -1 The feed rate was 75 ml / h, the hydrogen-to-oil volume ratio was 300:1, the fresh hydrogen flow rate was 22.5 L / h, and a 3% CS2 cyclohexane solution was introduced. Sulfation was carried out at 300℃ for 6 h, followed by hydrodesulfurization and denitrogenation of the feed oil at a reaction pressure of 6.5 MPa, a hydrogen-to-oil volume ratio of 1000:1, and a volume hourly space velocity (VHSV) of 1 h⁻¹. -1 .

[0052] Table 1 Performance of blended diesel fuel

[0053] Table 2 Performance testing of hydrorefining catalysts

[0054] As can be seen from the data in Table 2 and the methods in Examples 1-3, the catalysts prepared in Examples 1-3 not only have a high specific surface area and pore volume, but also improve catalytic activity, increase the generation of active phase, and improve catalytic effect.

[0055] In Examples 4 and 5, different active component ratios were used compared to Example 1. It can be seen that the catalysts prepared in Examples 4 and 5 have higher desulfurization and denitrification rates, indicating that appropriate amounts of ammonium molybdate, ammonium metatungstate, and nickel silicate as active components can effectively improve catalytic activity.

[0056] Compared with Example 1, Example 6 uses nickel nitrate instead of nickel silicate. It can be seen that the specific surface area and pore volume of the prepared catalyst are reduced, the crushing strength is decreased, and the catalytic activity is weakened. This shows that using nickel silicate as the active ingredient, in combination with molybdenum and tungsten, can increase the high-temperature structural stability of the support material, reduce collapse, and thus improve catalytic activity.

[0057] Compared with Example 1, in Example 7, the polyethylene glycol was only PEG4000, and in Example 8, the polyethylene glycol was only PEG20000. The data comparison in Table 2 shows that using only low molecular weight polyethylene glycol increases the specific surface area of ​​the catalyst, but reduces the pore volume and weakens the catalytic activity. Using only high molecular weight polyethylene glycol increases the pore volume of the catalyst, reduces the specific surface area, and has higher catalytic activity than Example 7 which only used low molecular weight polyethylene glycol.

[0058] Compared with Example 1, Examples 9 and 10 also added citric acid to the aluminum chloride ethanol solution. The data in Table 2 show that the catalysts prepared in Examples 9 and 10 have increased pore volume and specific surface area, and improved catalytic activity. This indicates that citric acid can maintain the mesopore connectivity and integrity, thereby improving pore volume and specific surface area and increasing catalytic activity.

[0059] Compared with Example 9, Examples 11 and 12 involved supercritical drying followed by steam treatment. As can be seen, the catalysts prepared in Examples 11 and 12 had increased pore volume, specific surface area, and crushing strength, resulting in enhanced catalytic activity.

[0060] In Comparative Example 1, the ethanol solution without aluminum chloride showed that the catalyst prepared from it had reduced pore volume and specific surface area, decreased crushing strength, and weakened catalytic ability.

[0061] Compared with Example 1, Comparative Examples 2 and 3 used oven drying and freeze drying instead of supercritical drying, respectively. It can be seen that the catalysts prepared in Comparative Examples 2 and 3 have significantly reduced pore volume and specific surface area, and reduced catalytic ability.

[0062] In Comparative Example 4, no PEG was added. Compared with Example 1, the pore volume and specific surface area of ​​the material decreased significantly, and the catalytic ability also decreased.

[0063] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for preparing a hydrorefining catalyst, characterized in that, Includes the following steps: (a) Add acid to an ethanol aqueous solution of hexadecyltrimethylammonium bromide with a concentration of 0.6-0.65wt%, adjust the pH to acidic, stir at 35-40℃ until clear, add polyethylene glycol, mix evenly, and obtain a blended solution. The mass ratio of hexadecyltrimethylammonium bromide to polyethylene glycol is 1:1-2. (b) Add tetrabutyl titanate solution to the blend, stir at 35-40℃ for 0.5-1h, add aluminum chloride ethanol solution, stir evenly, allow to stand for aging, supercritical drying, and calcination to obtain the carrier material. The molar ratio of tetrabutyl titanate to hexadecyltrimethylammonium bromide is 1:0.1-0.3, and the mass ratio of hexadecyltrimethylammonium bromide to aluminum chloride is 1:0.1-0.

2. (c) The carrier material is placed in a solution containing the active component, ultrasonically dispersed, dried at 80-90°C, and calcined at 500-550°C for 5-6 hours to obtain the catalyst, wherein the active component is at least one of molybdenum, tungsten, cobalt, nickel, copper, and zinc compounds.

2. The method for preparing the hydrorefining catalyst according to claim 1, characterized in that: The active component solution contains the following raw materials by weight percentage: 7.5-15 wt% ammonium molybdate, 5-8 wt% ammonium metatungstate, 3-5 wt% nickel silicate, and the balance being deionized water.

3. The method for preparing the hydrorefining catalyst according to claim 2, characterized in that: The mass ratio of ammonium molybdate to ammonium metatungstate in the active component solution is 1:1, and the mass ratio of nickel silicate to the total amount of nickel silicate and ammonium molybdate is 0.4:

1.

4. The method for preparing the hydrorefining catalyst according to claim 1, characterized in that: Citric acid is also added to the ethanol solution of aluminum chloride, and the mass ratio of citric acid to aluminum chloride is 1:1-1.

5.

5. The method for preparing the hydrorefining catalyst according to claim 1, characterized in that: The polyethylene glycol comprises polyethylene glycol 10000-20000 and polyethylene glycol 1000-4000 in a mass ratio of 1:0.2-0.

5.

6. The method for preparing the hydrorefining catalyst according to claim 1, characterized in that: In step (b), the supercritical drying product is kept at 80-120℃ in a steam environment for 1-3 hours before calcination.

7. The method for preparing the hydrorefining catalyst according to claim 1, characterized in that: The supercritical drying process is as follows: under nitrogen protection, the temperature is increased to 250-260℃ at 1-5℃ / min, and the pressure is simultaneously increased to 7-10MPa. The temperature and pressure are maintained for 1-3 hours, and then the pressure is reduced to atmospheric pressure at 0.1-0.5MPa / min and cooled to room temperature.

8. The method for preparing the hydrorefining catalyst according to claim 1, characterized in that: In step (b), the calcination process is as follows: first, the temperature is raised to 200℃ at 1-3℃ / min and held for 2 hours, then the temperature is raised to 400℃ at 5-10℃ / min and held for 2 hours, and finally the temperature is raised to 500℃ at 5-10℃ / min and held for 10-20 minutes.

9. The method for preparing the hydrorefining catalyst according to claim 1, characterized in that: The acid solution is 1M dilute nitric acid or acetic acid, and the pH value of the acid solution is adjusted to 1.5-3.

10. A hydrorefining catalyst, characterized in that, It is prepared by the method described in any one of claims 1-9 for the preparation of the hydrorefining catalyst.

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