A gasoline prehydrogenation catalyst

Abstract

The application discloses a gasoline pre-hydrogenation catalyst, which comprises a carrier and an active component, and has a meso-meso bimodal pore structure, an average pore diameter of 3-20 nm, a smaller pore of 3-7 nm, a larger pore of 8-20 nm, a specific surface area of 100-250 m 2 / g, and a pore volume of 0.3-0.5 cm 3 / g; the active component is nickel oxide and molybdenum oxide, the active component is loaded on the carrier by impregnation, a nickel-containing compound is impregnated first, and then a molybdenum-containing compound is impregnated after drying and calcination. The meso-meso bimodal pore structure catalyst provided by the application can ensure the diffusion and adsorption of molecules in the pore channel and strengthen the collision between molecules and the pore wall of the catalyst for the catalytic reaction (such as gasoline hydrogenation) of a small-molecule system which does not need to be contained, and is favorable for improving the activity and selectivity of the catalyst.

Description

Technical Field

[0001] This invention belongs to the field of hydrogenation catalyst technology, specifically relating to a gasoline pre-hydrogenation catalyst. Background Technology

[0002] Light hydrocarbons contain small amounts of dienes. Even if the diene mass fraction is less than 2%, it can polymerize at low temperatures to form large molecular colloidal substances. These substances are extremely unstable chemically and readily generate free radicals at higher reaction temperatures, initiating reactions such as self-polymerization, cyclization, dehydrogenation, and condensation. This transforms lower aromatic hydrocarbons into polycyclic aromatic hydrocarbons, then into fused-ring aromatic hydrocarbons, and finally into coke deposits. Small amounts of dienes can even promote the formation of gums from saturated hydrocarbons, causing catalyst coking and affecting catalyst activity. Therefore, before further processing light hydrocarbons, it is necessary to remove dienes and alkynes. Currently, the main solution to these problems is through diene hydrogenation. Light distillate pre-hydrogenation technology plays an indispensable role in the field of diene removal through hydrotreating, but its core function focuses on protecting the main catalyst, essentially acting as a protective agent. Therefore, compared to other technologies, reports on pre-hydrogenation technology, both domestically and internationally, are relatively limited, especially regarding in-depth research and discussion on catalysts; relevant literature is particularly scarce. To further optimize catalyst performance, it is necessary to design a suitable pore size distribution based on the size of reactant molecules and reaction conditions. This typically involves precise control of the physicochemical properties of the catalyst support, including pore size, pore structure, and porosity, to optimize the pore size distribution and achieve catalyst design with high activity and high selectivity.

[0003] The pore structure of a catalyst refers to the channels within the catalyst, categorized into macropores, mesopores, and micropores. Macropores are generally larger than 50 nanometers, mesopores range from 2 to 50 nanometers in size, and micropores are typically smaller than 2 nanometers. In addition, there are mesopores, which fall between mesopores and micropores. The pore structure of a catalyst plays a decisive role in the diffusion of reactant molecules and the emission of reaction products. Specifically, macropores can accommodate large reactant molecules, increasing the mass transport rate; mesopores can increase the surface area and the number of reaction sites on the catalyst, thereby improving the reaction rate and conversion; and micropores can provide more active sites, increasing the stability and selectivity of the catalyst.

[0004] Pore ​​structure is a crucial factor in catalyst design, and its control can improve catalyst activity, selectivity, and stability. For example, preparing high-porosity catalysts can increase reaction rates and selectivity while reducing the amount of active metal used; adjusting pore size distribution can yield highly selective catalysts for selective hydrogenation and heterogeneous catalytic reactions; and preparing porous catalysts can improve their stability and reusability, for example, in catalytic reduction and oxidation reactions. The pore structure of a catalyst is a vital factor in catalytic reactions, significantly impacting catalytic performance, selectivity, stability, and reusability. Pore structure plays a significant role in catalyst design and optimization, and it needs to be adjusted and improved through preparation techniques and pore structure control methods to achieve higher catalytic efficiency and metal utilization.

[0005] The pore structure of supported catalysts mainly originates from the support, therefore, controlling the pore structure of the support is crucial. Patent CN1188216C discloses a method for preparing an alumina support, with the pore diameters of the prepared alumina support concentrated in the ranges of 6nm-35nm and 100nm-2000nm, respectively. The alumina support prepared by this method can be used as a support for the production of heavy oil hydrotreating protective agents, demetallizing catalysts, and diffusion-controlled reaction process catalysts. Patent CN202210804839 discloses a heavy oil support exhibiting a bimodal pore distribution with diameters of 5-20nm and 100-500nm. The pore volume of pores with diameters of 5-20nm accounts for 50-80% of the total pore volume, the pore volume of pores with diameters of 100-500nm accounts for 19-40% of the total pore volume, and the pore volume of pores with diameters below 10nm does not exceed 20% of the total pore volume. Patent CN202110209242 discloses a bimodal porous support, exhibiting characteristic peaks at 25 nm and 480 nm. Pores with diameters between 20-50 nm account for 46.3% of the total pore volume, pores with diameters greater than 100 nm account for 38.2%, and pores with diameters less than 20 nm account for 15.5%. Patent CN202010351478 discloses a hydrogenation catalyst whose bimodal pore structure was determined by mercury intrusion porosimetry. The mesopore volume V, located at 3-100 nm, is 0.7-1.7 mL / g; the macropore volume V, located at 100-5000 nm, is 1.7-4.7 mL / g; and the total macropore volume V is 2.4-6.4 mL / g.

[0006] In summary, existing technologies have produced a series of alumina supports with specific pore distributions. However, the support preparation stage reduces the proportion of small pores, for example, pores below 6 nm, and both pore distributions are 3-100 nm and 100-5000 nm, suitable for catalytic reactions of large molecular systems (such as heavy oil hydrogenation). There is limited research on meso-meso-bimodal alumina supports where both pore sizes are concentrated in the 2-30 nm range. It is well known that during molecular diffusion in porous materials, two types of collisions influence the catalyst's activity and selectivity: collisions between molecules and the catalyst pore walls, and collisions between molecules. Intermolecular collisions tend to hinder molecules from reaching the catalyst pore walls. Therefore, to increase catalyst activity and selectivity, it is necessary to enhance collisions between molecules and the catalyst pore walls. For catalytic reactions of small molecular systems that do not require mixing (such as gasoline hydrogenation), due to the small size of the molecules, when the pore size is greater than 30 nm, collisions between molecules dominate. When the pore size is small (2-30 nm) or the gas concentration is very low, collisions between molecules and the catalyst pore walls dominate.

[0007] Therefore, it is necessary to develop catalysts with meso-meso-bimodal porous alumina supports in which both types of pores are concentrated at 2-30 nm. This can ensure the diffusion and adsorption of molecules in the pores and enhance the collision between molecules and the catalyst pore walls, thereby improving the activity and selectivity of the catalyst. Summary of the Invention

[0008] The purpose of this invention is to provide a gasoline pre-hydrogenation catalyst to solve the problems of wide bimodal pore distribution and unreasonable distribution of active metals in existing catalysts.

[0009] To achieve the above objectives, the present invention provides a gasoline prehydrogenation catalyst, comprising a support and an active component. The catalyst has a meso-meso bimodal pore structure with an average pore size of 3–20 nm, smaller pores of 3–7 nm, larger pores of 8–20 nm, and a specific surface area of ​​100–250 m². 2 / g, pore volume 0.3~0.5cm 3 / g; The active components are nickel oxide and molybdenum oxide. The active components are loaded onto the carrier by impregnation. First, a nickel-containing compound is impregnated, and after drying and calcination, a molybdenum-containing compound is impregnated.

[0010] When the support has only macropores, the distribution of Ni or heptamolybdate ions is relatively uniform, which is conducive to their bonding and enhances the synergistic effect between metals. This synergistic effect can promote the reduction of Mo and enhance the hydrogenation of the catalyst, but may lead to more loss of mono-olefins, thus affecting selectivity. If the support has only micropores, the distribution of heptamolybdate ions will be restricted, weakening the synergistic effect between metals, reducing the hydrogenation of the catalyst, and hindering the hydrogenation of dienes, thus affecting the activity and selectivity of the catalyst. A more suitable bimodal pore size distribution can effectively regulate the hydrogenation of the catalyst. Small channels can provide a high density of active sites, while large channels are conducive to molecular diffusion and reactant transport. This structure can ensure activity while improving the selectivity of the catalyst, especially in reactions that require precise control of the degree of hydrogenation.

[0011] The gasoline pre-hydrogenation catalyst of the present invention is prepared by means of alumina with a meso-meso-bimodal porous structure through the following method:

[0012] S1, Alumina, water, inorganic pore expander and / or organic pore expander are mixed and extruded to obtain an extruded strip; in the XRD pattern of the alumina, the relative intensity of the peak with 2θ of 13 to 16.6° is 100.0%, the relative intensity of the peak with 2θ of 16.6 to 23.2° is 85 to 88%, the peak with 2θ of 23.17 to 53.79° is a diffuse scattering peak, and the relative intensity of the peak with 2θ of 53.79 to 75° is 55 to 60%;

[0013] S2, the extruded strip is matured, dried and calcined to obtain the carrier.

[0014] In the gasoline pre-hydrogenation catalyst of the present invention, the characteristic peak angle of the alumina peak with 2θ of 13-16.6° is 14-15°, the characteristic peak angle of the peak with 2θ of 16.6-23.2° is 19-20°, the peak with 2θ of 23.17-53.79° is a diffuse peak, and the characteristic peak angle of the peak with 2θ of 53.79-75° is 60.5-61.5°.

[0015] In the XRD pattern of the gasoline pre-hydrogenation catalyst of the present invention, after the alumina is calcined at 800°C, the relative intensities of the peaks with 2θ values ​​of 14.69–23.74° are 54–58%, the relative intensities of the peaks with 2θ values ​​of 23.74–34.35° are 76–80%, the relative intensities of the peaks with 2θ values ​​of 34.35–39.04° are 100.0%, the relative intensities of the peaks with 2θ values ​​of 39.04–41.96° are 77–82%, the relative intensities of the peaks with 2θ values ​​of 41.96–52.52° are 62.5–68%, the relative intensities of the peaks with 2θ values ​​of 52.52–63.33° are 38.5–45%, and the relative intensities of the peaks with 2θ values ​​of 63.33–73.95° are 80.0–90%.

[0016] In the XRD pattern of the gasoline pre-hydrogenation catalyst of the present invention, after the alumina is calcined at 800°C, the characteristic peak angles of the peaks with 2θ ranging from 14.69 to 23.74° are 17.8 to 21.8°, the characteristic peak angles of the peaks with 2θ ranging from 23.74 to 34.35° are 30.7 to 34.7°, and the characteristic peak angles of the peaks with 2θ ranging from 34.35 to 39.04° are 35.4 to 39.4°. The characteristic peak angles of the peaks with 2θ values ​​of 39.04–41.96° are 37.7–41.7°, the characteristic peak angles of the peaks with 2θ values ​​of 41.96–52.52° are 43.7–47.7°, the characteristic peak angles of the peaks with 2θ values ​​of 52.52–63.33° are 58.8–62.8°, and the characteristic peak angles of the peaks with 2θ values ​​of 63.33–73.95° are 65.1–69.1°.

[0017] The gasoline pre-hydrogenation catalyst of the present invention further includes step S3, which involves placing the support in a sealed high-pressure container and boiling it in water under autogenous pressure, followed by drying.

[0018] The gasoline pre-hydrogenation catalyst of the present invention comprises one or more of the inorganic pore-expanding agent, namely activated carbon, urea, ammonium carbonate, and ammonia water.

[0019] The gasoline pre-hydrogenation catalyst of the present invention comprises one or more of the following organic pore-expanding agents: hydroxypropyl methylcellulose, starch, polyethylene glycol, polycarboxylic acid water-reducing agent, glycerol, carboxymethyl cellulose, and polyvinylpyrrolidone.

[0020] The gasoline pre-hydrogenation catalyst of the present invention, based on 100% alumina by mass, has an inorganic pore-expanding agent content of 1-20% and an organic pore-expanding agent content of 1-20%.

[0021] The gasoline pre-hydrogenation catalyst of the present invention has the following conditions in step S2: aging conditions are 20-35°C for 24-72 hours; drying temperature is 100-120°C; calcination conditions are 200-900°C for 2-6 hours, preferably calcination temperature is 500-800°C.

[0022] In the gasoline pre-hydrogenation catalyst of the present invention, the water boiling conditions in step S3 are 120-200℃ for 1-6 hours, preferably 130-160℃; the drying temperature is 100-120℃.

[0023] The gasoline pre-hydrogenation catalyst of the present invention comprises an impregnation solution for impregnating nickel-containing compounds, which is composed of nickel-containing compounds and water; and an impregnation solution for impregnating molybdenum-containing compounds, which is composed of molybdenum-containing compounds and water.

[0024] The gasoline pre-hydrogenation catalyst of the present invention is dried dynamically after impregnation. The dynamic drying is one or more of rotary oven drying, converter drying, and vibrating fluidized bed drying, preferably rotary oven drying, and the drying conditions are dynamic drying at 120-160℃ for 2-4 hours.

[0025] The gasoline prehydrogenation catalyst of the present invention, based on 100% catalyst mass, contains 8-12% nickel oxide and 4-8% molybdenum oxide.

[0026] Beneficial effects of this invention:

[0027] The meso-meso bimodal pore structure catalyst provided by this invention can ensure the diffusion and adsorption of molecules in the pores and enhance the collision between molecules and the catalyst pore walls for catalytic reactions of small molecule systems that do not require impurity tolerance (such as gasoline hydrogenation), which is beneficial to improving the activity and selectivity of the catalyst.

[0028] Dynamic drying after impregnation with active metal can improve the migration of metal salts caused by moisture evaporation during the drying process, effectively ensure the uniformity of metal distribution, make the catalyst color more uniform, and improve the utilization rate of active components.

[0029] When impregnating active metals, Ni salt is impregnated first, followed by drying and calcination, and then Mo salt is impregnated. Because Ni ions have a smaller diameter, their diffusion within the pores encounters less resistance, allowing for relatively uniform distribution within pores of different sizes. This facilitates sufficient contact between Ni ions and the support surface, thereby increasing the number of active sites on the catalyst. This impregnation method reduces synergistic effects between metals, weakening the catalyst's hydrogenation performance and thus minimizing olefin loss. Furthermore, a stable solution can be prepared using water, eliminating the need for additional acid-base complexing agents that could cause pollution or increase carbon emissions; solution preparation is simple and environmentally friendly. Detailed Implementation

[0030] The present invention will now be described in detail through embodiments. It should be noted that the following embodiments are only for further illustration of the present invention and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above description.

[0031] Example 1

[0032] Weigh 100g of No. 1 hydrated alumina powder (dry basis content 90wt%), add 10g of hydroxypropyl methylcellulose with a viscosity of 150,000 mPa·s (referring to the viscosity of a 2% aqueous solution), and mix evenly; weigh 60g of deionized water, slowly and evenly add it to the above materials, knead in a kneader to form a plastic body, and then extrude it into a cylindrical shape with a diameter of 2mm on an extruder. After the extruded carrier is placed at 20℃ for 24 hours to mature, it is dried at 120℃ for 4 hours, and then placed in a high-temperature calcination furnace and kept at 600℃ for 3 hours to obtain an intermediate carrier. Weigh 20g of the intermediate carrier into the lining of an autoclave, add 60g of deionized water, boil in water at 100℃ under autogenous pressure for 4 hours, and dry to obtain carrier A.

[0033] 1# Hydrated alumina in dry state: 2θ angle and relative intensity peak

[0034]

[0035] 1# Hydrated alumina under 800°C calcination state: 2θ angle and relative intensity peak

[0036] 2θ angle / ° Characteristic peak angle / ° Relative strength / % 15.5-23 20.5 54.26 24-34 34.0 76.87 35-38 39.0 100.0 39.5-41.0 41.5 79.25 42.5-52 47.0 64.21 54-62 62 39.0 65-72 68.5 83.66

[0037] The catalyst was prepared using a pore saturation impregnation method. Nickel nitrate solution was prepared by mixing nickel nitrate and deionized water, and ammonium heptamolybdate solution was prepared by mixing ammonium heptamolybdate and deionized water. The nickel nitrate solution was first impregnated, followed by standing in air for 6 hours, dynamic drying in a converter at 150°C for 3 hours, and calcination at 500°C for 3 hours. Then, the catalyst was impregnated with ammonium heptamolybdate solution, followed by standing in air for 6 hours, dynamic drying in a converter at 150°C for 3 hours, and calcination at 500°C for 3 hours to obtain catalyst A, with a nickel oxide content of 10% and a molybdenum oxide content of 6%. Its physicochemical properties are shown in Table 1.

[0038] Example 2

[0039] Weigh 100g of the aforementioned No. 1 hydrated alumina powder, add 1.5g of hydroxypropyl methylcellulose with a viscosity of 200,000 mPa·s (referring to the viscosity of a 2% aqueous solution), and 20g of activated carbon powder, and mix evenly; weigh 70g of deionized water, and slowly and evenly add it to the aforementioned materials, kneading it into a plastic body in a kneader, and then extruding it into a cylindrical shape with a diameter of 2mm on a hydraulic extruder. After extrusion, the molded carrier is placed at 25℃ for 24 hours to mature, then dried at 120℃ for 4 hours, and then placed in a high-temperature calcination furnace and kept at 800℃ for 3 hours to obtain an intermediate carrier. Weigh 20g of the intermediate carrier into the lining of an autoclave, add 80g of deionized water, boil it in water at 140℃ under autogenous pressure for 4 hours, and then dry it to obtain carrier B.

[0040] The catalyst was prepared using a pore saturation impregnation method. Nickel nitrate solution was prepared by mixing nickel nitrate and deionized water, and ammonium heptamolybdate solution was prepared by mixing ammonium heptamolybdate and deionized water. The nickel nitrate solution was first impregnated, followed by standing in air for 6 hours, dynamic drying in a converter at 150°C for 3 hours, and calcination at 450°C for 3 hours. Then, the catalyst was impregnated with ammonium heptamolybdate solution, followed by standing in air for 6 hours, dynamic drying in a converter at 150°C for 3 hours, and calcination at 450°C for 3 hours to obtain catalyst B, with a nickel oxide content of 10% and a molybdenum oxide content of 6%. Its physicochemical properties are shown in Table 1.

[0041] Example 3

[0042] Weigh 100g of the aforementioned No. 1 hydrated alumina powder; add 1.5g of hydroxypropyl methylcellulose with a viscosity of 200,000 mPa·s (referring to the viscosity of a 2% aqueous solution) and 20g of activated carbon powder, and mix evenly. Weigh 70g of deionized water and slowly and evenly add it to the aforementioned materials, kneading it into a plastic body in a kneader, and then extruding it into a cylindrical shape with a diameter of 2mm on a hydraulic extruder. After extrusion, the molded carrier is placed at 30℃ for 24 hours to mature, then dried at 120℃ for 4 hours, and then placed in a high-temperature calcination furnace and kept at 800℃ for 3 hours to obtain an intermediate carrier. Weigh 20g of the intermediate carrier into the lining of an autoclave, add 150g of deionized water, boil it under autogenous pressure at 120℃ for 3 hours, and then dry it to obtain carrier C.

[0043] The catalyst was prepared using a pore saturation impregnation method. A nickel nitrate solution was prepared by mixing nickel nitrate and deionized water, and an ammonium heptamolybdate solution was prepared by mixing ammonium heptamolybdate and deionized water. The nickel nitrate solution was first impregnated with the ammonium heptamolybdate solution, followed by standing in air for 6 hours, dynamic drying in a converter at 150°C for 3 hours, and calcination at 500°C for 3 hours. Then, the catalyst was impregnated with the ammonium heptamolybdate solution, followed by standing in air for 3 hours, dynamic drying in a converter at 150°C for 3 hours, and calcination at 500°C for 3 hours to obtain catalyst C, with a nickel oxide content of 10% and a molybdenum oxide content of 6%. Its physicochemical properties are shown in Table 1.

[0044] Example 4

[0045] Weigh 120g of No. 2 hydrated alumina powder, add 1.8g of hydroxypropyl methylcellulose with a viscosity of 150,000 mPa·s (referring to the viscosity of a 2% aqueous solution), and 12g of starch, and mix evenly. Weigh 72g of deionized water and slowly and evenly add it to the above materials, kneading it into a plastic body in a kneader, and then extruding it into a cylindrical shape with a diameter of 2mm on a hydraulic extruder. After extrusion, the molded carrier is placed at 35℃ for 24 hours to mature, then dried at 120℃ for 4 hours, and then placed in a high-temperature calcination furnace and kept at 800℃ for 3 hours to obtain an intermediate carrier. Weigh 20g of the intermediate carrier into the lining of an autoclave, add 80g of deionized water, boil it under autogenous pressure at 120℃ for 4 hours, and then dry it to obtain carrier D.

[0046] 2# Hydrated alumina in dry state: 2θ angle and relative intensity peak

[0047]

[0048] 2θ angle and relative intensity peak of hydrated alumina at 800°C

[0049] 2θ angle / ° Characteristic peak angle / ° Relative strength / % 15-23 19.8 56.35 25-34 32.8 78.68 35-38.5 37.5 100.0 39.5-41.3 39.5 81.39 42-52 45.7 67.01 55-63 61 43.5 64-71 67.2 88.32

[0050] The catalyst was prepared using a pore saturation impregnation method. A nickel nitrate solution was prepared by mixing nickel nitrate and deionized water, and an ammonium heptamolybdate solution was prepared by mixing ammonium heptamolybdate and deionized water. The nickel nitrate solution was first impregnated with the ammonium heptamolybdate solution, followed by standing in air for 4 hours, dynamic drying in a converter at 120°C for 3 hours, and calcination at 500°C for 3 hours. Then, the catalyst was impregnated with the ammonium heptamolybdate solution, followed by standing in air for 6 hours, dynamic drying in a converter at 120°C for 3 hours, and calcination at 500°C for 3 hours to obtain catalyst D, with a nickel oxide content of 10% and a molybdenum oxide content of 6%. Its physicochemical properties are shown in Table 1.

[0051] Example 5

[0052] Weigh 70g of the aforementioned No. 2 hydrated alumina powder, add 3g of hydroxypropyl methylcellulose with a viscosity of 150,000 mPa·s (referring to the viscosity of a 2% aqueous solution), and mix evenly. Weigh 70g of deionized water and slowly and evenly add it to the aforementioned materials, kneading it into a plastic body in a kneader, and then extruding it into a clover shape with a diameter of 2mm on a hydraulic extruder. After the extruded carrier is placed at 30℃ for 72 hours to mature, it is dried at 120℃ for 4 hours, and then placed in a high-temperature calcining furnace and kept at 6800℃ for 3 hours to obtain an intermediate carrier. Weigh 20g of the intermediate carrier into the lining of an autoclave, add 150g of deionized water, boil it under autogenous pressure at 120℃ for 3 hours, and then dry it to obtain carrier E.

[0053] The catalyst was prepared using a pore saturation impregnation method. A nickel nitrate solution was prepared by mixing nickel nitrate and deionized water, and an ammonium heptamolybdate solution was prepared by mixing ammonium heptamolybdate and deionized water. The nickel nitrate solution was first impregnated with the ammonium heptamolybdate solution, followed by standing in air for 5 hours, dynamic drying in a converter at 150°C for 3 hours, and calcination at 500°C for 3 hours. Then, the catalyst was impregnated with the ammonium heptamolybdate solution, followed by standing in air for 3 hours, dynamic drying in a converter at 150°C for 3 hours, and calcination at 500°C for 3 hours to obtain catalyst E, with a nickel oxide content of 9% and a molybdenum oxide content of 5%. Its physicochemical properties are shown in Table 1.

[0054] Example 6

[0055] Weigh 100g of the aforementioned No. 2 hydrated alumina powder, add 1.8g of hydroxypropyl methylcellulose with a viscosity of 100,000 mPa·s (referring to the viscosity of a 2% aqueous solution), and 12g of urea, and mix evenly. Weigh 60g of deionized water and slowly and evenly add it to the aforementioned materials, kneading it into a plastic body in a kneader, and then extruding it into a cylindrical shape with a diameter of 2mm on a hydraulic extruder. After extrusion, the molded carrier is placed at 25℃ for 24 hours to mature, then dried at 120℃ for 4 hours, and then placed in a high-temperature calcination furnace and kept at 800℃ for 3 hours to obtain an intermediate carrier. Weigh 20g of the intermediate carrier into the lining of an autoclave, add 200g of deionized water, boil it under autogenous pressure at 100℃ for 3 hours, and then dry it to obtain carrier F.

[0056] The catalyst was prepared using a pore saturation impregnation method. A nickel nitrate solution was prepared by mixing nickel nitrate and deionized water, and an ammonium heptamolybdate solution was prepared by mixing ammonium heptamolybdate and deionized water. The nickel nitrate solution was first impregnated with the ammonium heptamolybdate solution, followed by standing in air for 6 hours, dynamic drying in a converter at 150°C for 3 hours, and calcination at 450°C for 3 hours. Then, the catalyst was impregnated with the ammonium heptamolybdate solution, followed by standing in air for 6 hours, dynamic drying in a converter at 120°C for 3 hours, and calcination at 500°C for 3 hours to obtain catalyst F, with a nickel oxide content of 10% and a molybdenum oxide content of 6%. Its physicochemical properties are shown in Table 1.

[0057] Example 7

[0058] Weigh 100g of the aforementioned No. 2 hydrated alumina powder, add 1.5g of hydroxypropyl methylcellulose with a viscosity of 200,000 mPa·s (referring to the viscosity of a 2% aqueous solution), and 20g of activated carbon powder, and mix evenly. Weigh 70g of deionized water and slowly and evenly add it to the aforementioned materials, kneading it into a plastic body in a kneader, and then extruding it into a cylindrical shape with a diameter of 2mm on a hydraulic extruder. After extrusion, the molded carrier is placed at 25℃ for 24 hours to mature, then dried at 120℃ for 4 hours, and then placed in a high-temperature calcination furnace and kept at 800℃ for 3 hours to obtain an intermediate carrier. Weigh 20g of the intermediate carrier into the lining of an autoclave, add 60g of deionized water, boil it under autogenous pressure at 110℃ for 4 hours, and then dry it to obtain carrier G.

[0059] The catalyst was prepared using a pore saturation impregnation method. A nickel nitrate solution was prepared by mixing nickel nitrate and deionized water, and an ammonium heptamolybdate solution was prepared by mixing ammonium heptamolybdate and deionized water. The nickel nitrate solution was first impregnated with the ammonium heptamolybdate solution, followed by standing in air for 4 hours, dynamic drying in a converter at 150°C for 3 hours, and calcination at 450°C for 3 hours. Then, the catalyst was impregnated with the ammonium heptamolybdate solution, followed by standing in air for 6 hours, dynamic drying in a converter at 120°C for 3 hours, and calcination at 550°C for 3 hours to obtain catalyst G, with a nickel oxide content of 12% and a molybdenum oxide content of 8%. Its physicochemical properties are shown in Table 1.

[0060] Example 8

[0061] Weigh 100g of the aforementioned No. 2 hydrated alumina powder, add 1.5g of hydroxypropyl methylcellulose with a viscosity of 100,000 mPa·s (referring to the viscosity of a 2% aqueous solution), and 3g of polycarboxylate superplasticizer, and mix evenly; weigh 55g of deionized water, and slowly and evenly add it to the aforementioned materials, kneading it into a plastic body in a kneader, and then extruding it into a cylindrical shape with a diameter of 2mm on a hydraulic extruder. After the extruded carrier is placed at 25℃ for 48 hours to mature, it is dried at 120℃ for 4 hours, and then placed in a high-temperature calcining furnace and kept at 800℃ for 3 hours to obtain an intermediate carrier. Weigh 20g of the intermediate carrier into the lining of an autoclave, add 100g of deionized water, boil it in water at 130℃ under autogenous pressure for 2 hours, and then dry it to obtain carrier H.

[0062] The catalyst was prepared using a pore saturation impregnation method. A nickel nitrate solution was prepared by mixing nickel nitrate and deionized water, and an ammonium heptamolybdate solution was prepared by mixing ammonium heptamolybdate and deionized water. The nickel nitrate solution was first impregnated with the ammonium heptamolybdate solution, followed by standing in air for 4 hours, dynamic drying in a converter at 150°C for 3 hours, and calcination at 500°C for 3 hours. Then, the catalyst was impregnated with the ammonium heptamolybdate solution, followed by standing in air for 3 hours, dynamic drying in a converter at 150°C for 3 hours, and calcination at 500°C for 3 hours to obtain catalyst H, with a nickel oxide content of 10% and a molybdenum oxide content of 6%. Its physicochemical properties are shown in Table 1.

[0063] Example 9

[0064] Weigh 100g of the aforementioned No. 2 hydrated alumina powder, add 1.5g of hydroxypropyl methylcellulose with a viscosity of 200,000 mPa·s (referring to the viscosity of a 2% aqueous solution), and 20g of activated carbon powder, and mix evenly. Weigh 70g of deionized water and slowly and evenly add it to the aforementioned materials, kneading it into a plastic body in a kneader, and then extruding it into a cylindrical shape with a diameter of 2mm on a hydraulic extruder. After extrusion, the molded carrier is placed at 25℃ for 24 hours to mature, then dried at 120℃ for 4 hours, and then placed in a high-temperature calcination furnace and kept at 800℃ for 3 hours to obtain an intermediate carrier. Weigh 20g of the intermediate carrier into the lining of an autoclave, add 100g of deionized water, boil it under autogenous pressure at 150℃ for 2 hours, and then dry it to obtain carrier I.

[0065] The catalyst was prepared using a pore saturation impregnation method. Nickel nitrate solution was prepared by mixing nickel nitrate and deionized water, and ammonium heptamolybdate solution was prepared by mixing ammonium heptamolybdate and deionized water. The nickel nitrate solution was first impregnated, followed by standing in air for 6 hours, dynamic drying in a converter at 150°C for 3 hours, and calcination at 450°C for 3 hours. Then, the catalyst was impregnated with ammonium heptamolybdate solution, followed by standing in air for 4 hours, dynamic drying in a converter at 120°C for 3 hours, and calcination at 450°C for 3 hours to obtain catalyst A, with a nickel oxide content of 10% and a molybdenum oxide content of 6%. Its physicochemical properties are shown in Table 1.

[0066] Comparative Example 1

[0067] Same as Example 4, except that different alumina is used. The XRD characterization results of the alumina used in this comparative example are as follows:

[0068] 3# Hydrated alumina in dry state: 2θ angle and relative intensity peak

[0069] 2θ angle / ° Characteristic peak angle / ° Relative strength / % 10-18 13.88 100.00 23-33 27.99 67.87 35-42 38.57 54.30 45-53 49 58.09 53.5-58 55.39 17.37 62-66 64.82 24.54 70-75 72.04 16.42

[0070] 3# hydrated alumina under 800°C calcination state: 2θ angle and relative intensity peak

[0071]

[0072]

[0073] Catalyst J was prepared.

[0074] Comparative Example 2

[0075] Same as Example 4, except that there is no ripening step in the carrier preparation process.

[0076] Catalyst K was prepared.

[0077] Comparative Example 3

[0078] Similar to Example 4, except that when impregnating the active metal, the carrier is impregnated in an impregnation solution containing both nickel and molybdenum.

[0079] Catalyst L was prepared.

[0080] Table 1 Physicochemical properties of catalysts A to L

[0081] sample <![CDATA[Specific surface area (m 2 / g)]]> <![CDATA[Pore volume (cm 3 / g)]]> Average pore size (nm) Most probable aperture (nm) Catalyst A 220.15 0.45 6.04 3.50、9.02 Catalyst B 110.09 0.48 12.76 7.15、24.05 Catalyst C 155.36 0.50 9.31 5.08、12.41 Catalyst D 127.16 0.32 8.06 5.03、12.12 Catalyst E 248.78 0.53 7.07 3.57、9.09 Catalyst F 160.65 0.50 8.66 5.23、12.57 Catalyst G 130.65 0.40 8.85 7.25、12.85 catalyst H 130.75 0.40 7.35 5.23、15.04 Catalyst I 120.50 0.49 11.25 7.35、18.12 Catalyst J 200.85 0.26 4.80 4.56 catalyst K 155.18 0.46 8.88 8.49 Catalyst L 152.46 0.45 9.09 8.67

[0082] As can be seen from Table 1, the catalysts of Comparative Examples 1, 2, and 3 do not have a bimodal porous structure.

[0083] Model compound evaluation

[0084] In a micro high-pressure hydrogenation reactor, isoprene and n-hexene (dissolved in cyclohexane) and n-octene and nonadiene (dissolved in cyclohexane) were used as simulated feedstocks to investigate the diene removal performance and selectivity of the catalysts. The catalyst loading was 1 g, with a particle size of 20-40 mesh, and the catalyst bed was filled with 20-40 mesh quartz sand at both ends. The reaction pressure was 2 MPa and the mass hourly space velocity was 3.0 h⁻¹. -1 The hydrogen-to-oil volume ratio was 100. The specific evaluation results are shown in Table 2.

[0085] Table 2 Evaluation conditions and results of microreaction of model compounds

[0086]

[0087] Actual oil quality evaluation

[0088] The catalysts described in Examples 4, 5, and 9, as well as Comparative Examples 1 and 2, were each loaded into a 20 ml fixed-bed reactor. The feedstock was FCC gasoline from a certain refinery. The hydrogenation reaction conditions were: reaction temperature, reaction pressure 2.4 MPa, hydrogen-to-oil volume ratio 10:1, and volume hourly space velocity 2.8 h⁻¹. -1 The temperature was 140℃. Specific evaluation results are shown in Table 3.

[0089] Table 3 Properties of Products After Hydrogenation with Raw Materials and Supplemental Refining Catalyst

[0090]

[0091]

[0092] Table 3 shows that the developed bimodal porous catalyst exhibits less olefin loss under the same diene removal performance, and all indicators are superior to the comparative example.

[0093] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.

Claims

1. A gasoline prehydrogenation catalyst characterized by, The catalyst comprises a carrier and an active component, has a bimodal pore structure with an average pore diameter of 3-20 nm, a small pore of 3-7 nm and a large pore of 8-20 nm, a specific surface area of 100-250 m 2 / g, and a pore volume of 0.3-0.5 cm 3 / g; the active component is nickel oxide and molybdenum oxide, and the active component is loaded on the carrier by impregnation, first impregnating a nickel-containing compound, drying and calcining, and then impregnating a molybdenum-containing compound.

2. The gasoline pre-hydrogenation catalyst according to claim 1, characterized in that, The carrier is alumina with a meso-mesobimodal porous structure, and is prepared by the following method: S1, Alumina, water, inorganic pore expander and / or organic pore expander are mixed and extruded to obtain an extruded strip; in the XRD pattern of the alumina, the relative intensity of the peak with 2θ of 13 to 16.6° is 100.0%, the relative intensity of the peak with 2θ of 16.6 to 23.2° is 85 to 88%, the peak with 2θ of 23.17 to 53.79° is a diffuse scattering peak, and the relative intensity of the peak with 2θ of 53.79 to 75° is 55 to 60%; S2, the extruded strip is matured, dried and calcined to obtain the carrier.

3. The gasoline pre-hydrogenation catalyst according to claim 2, characterized in that, In the XRD pattern of the alumina, the characteristic peak angle of the peak with 2θ of 13–16.6° is 14–15°, the characteristic peak angle of the peak with 2θ of 16.6–23.2° is 19–20°, the peak with 2θ of 23.17–53.79° is a diffuse peak, and the characteristic peak angle of the peak with 2θ of 53.79–75° is 60.5–61.5°.

4. The gasoline pre-hydrogenation catalyst according to claim 2, characterized in that, In the XRD pattern of the alumina after calcination at 800℃, the relative intensities of the peaks with 2θ values ​​of 14.69–23.74° are 54–58%, the relative intensities of the peaks with 2θ values ​​of 23.74–34.35° are 76–80%, the relative intensities of the peaks with 2θ values ​​of 34.35–39.04° are 100.0%, the relative intensities of the peaks with 2θ values ​​of 39.04–41.96° are 77–82%, the relative intensities of the peaks with 2θ values ​​of 41.96–52.52° are 62.5–68%, the relative intensities of the peaks with 2θ values ​​of 52.52–63.33° are 38.5–45%, and the relative intensities of the peaks with 2θ values ​​of 63.33–73.95° are 80.0–90%.

5. The gasoline pre-hydrogenation catalyst according to claim 2, characterized in that, In the XRD pattern of the alumina after calcination at 800℃, the characteristic peak angles of the peaks with 2θ values ​​of 14.69–23.74° are 17.8–21.8°, the characteristic peak angles of the peaks with 2θ values ​​of 23.74–34.35° are 30.7–34.7°, the characteristic peak angles of the peaks with 2θ values ​​of 34.35–39.04° are 35.4–39.4°, the characteristic peak angles of the peaks with 2θ values ​​of 39.04–41.96° are 37.7–41.7°, the characteristic peak angles of the peaks with 2θ values ​​of 41.96–52.52° are 43.7–47.7°, the characteristic peak angles of the peaks with 2θ values ​​of 52.52–63.33° are 58.8–62.8°, and the characteristic peak angles of the peaks with 2θ values ​​of 63.33–73.95° are 65.1–69.1°.

6. The gasoline pre-hydrogenation catalyst according to claim 2, characterized in that, It also includes step S3, in which the carrier is placed in a sealed high-pressure container and boiled under autogenous pressure, and then dried.

7. The gasoline pre-hydrogenation catalyst according to claim 2, characterized in that, The inorganic pore-expanding agent is one or more of activated carbon, urea, ammonium carbonate, and ammonia water.

8. The gasoline pre-hydrogenation catalyst according to claim 2, characterized in that, The organic pore expander is one or more of hydroxypropyl methylcellulose, starch, polyethylene glycol, polycarboxylic acid water-reducing agent, glycerin, carboxymethyl cellulose, and polyvinylpyrrolidone.

9. The gasoline pre-hydrogenation catalyst according to claim 2, characterized in that, Based on 100% alumina mass, the inorganic pore expander is added at a rate of 1-20%, and the organic pore expander is added at a rate of 1-20%.

10. The gasoline pre-hydrogenation catalyst according to claim 2, characterized in that, In step S2, the aging conditions are 20-35℃ for 24-72 hours; the drying temperature is 100-120℃; and the calcination conditions are 200-900℃ for 2-6 hours, with the preferred calcination temperature being 500-800℃.

11. The gasoline prehydrogenation catalyst according to claim 2, characterized in that, In step S3, the boiling conditions are 120-200℃ for 1-6 hours, with a preferred boiling temperature of 130-160℃; the drying temperature is 100-120℃.

12. The gasoline prehydrogenation catalyst according to claim 1, characterized in that, The impregnation solution for impregnating nickel-containing compounds consists of nickel-containing compounds and water; the impregnation solution for impregnating molybdenum-containing compounds consists of molybdenum-containing compounds and water.

13. The gasoline prehydrogenation catalyst according to claim 1, characterized in that, The drying after impregnation is dynamic drying, which is one or more of rotary oven drying, converter drying, and vibrating fluidized bed drying, preferably rotary oven drying, and the drying conditions are dynamic drying at 120-160℃ for 2-4 hours.

14. The gasoline pre-hydrogenation catalyst according to claim 1, characterized in that, Based on the catalyst mass of 100%, the content of nickel oxide is 8-12%, and the content of molybdenum oxide is 4-8%.

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