A gradient-loaded oil hydrogenation dearsenic catalyst and a preparation method thereof

Abstract

The application discloses a gradient-loaded oil hydrogenation dearsenification catalyst and a preparation method thereof. The preparation method comprises the following steps: preparing stable dispersion impregnation component A-1 by mixing organic complexing agent I, hole expansion aid II, active component IV containing group ⅥB metal and deionized water; preparing stable dispersion impregnation component A-2 by mixing organic complexing agent I, hole expansion aid III and deionized water; dissolving component X1 containing group Ⅷ metal in the stable dispersion impregnation component A-1 to form stable complex impregnation liquid B-1; dissolving component X2 containing group Ⅷ metal in the stable dispersion impregnation component A-2 to form stable complex impregnation liquid B-2; impregnating porous carrier Z with the stable complex impregnation liquid B-1 to obtain catalyst C1; impregnating the catalyst C1 with the stable complex impregnation liquid B-2 to obtain catalyst C2; dissolving organic aid V and hole expansion aid VI in deionized water, and then impregnating the catalyst C2 to obtain the hydrogenation dearsenification catalyst C3. The preparation method can increase arsenic poisoning sites of the catalyst.

Description

Technical Field

[0001] This invention relates to a catalyst, specifically a hydrodearsenic removal catalyst for oil processing and its preparation method, and more particularly to a hydrodearsenic removal catalyst used in petroleum processing of olefin-containing feedstocks and its preparation method. Background Technology

[0002] Hydrogenation technology is one of the main methods for improving the quality of oil products in my country. The refining industry routinely uses hydrogenation to reduce the content of impurities such as sulfur, nitrogen, and aromatics in oil products, thereby improving their quality. Arsenic compounds in the feedstock are poisons during the hydrogenation process, especially in reforming units using precious metal catalysts. Even trace amounts of arsenic compounds can cause permanent catalyst poisoning and deactivation, shortening the long-term operation of the unit and resulting in economic losses for the refinery. Therefore, arsenic compounds need to be removed beforehand to ensure the stable operation of subsequent units.

[0003] Common methods for removing arsenic from oil products include adsorption, oxidation, and hydrotreating. Hydrotreating offers high arsenic capacity, excellent removal efficiency, and long operating cycles, making it more suitable for production conditions with high arsenic content in feedstocks, low arsenic content requirements in products, and long operating cycles. Unlike desulfurization, trace amounts of organic arsenic compounds readily combine with the d orbitals of Group VIII metals (such as Ni) on the surface of conventional hydrotreating catalysts, forming coordinate bonds. Simultaneously, as temperature increases, a large number of arsenic atoms migrate from the surface to the catalyst interior, forming arsenide alloys. Therefore, hydrotreating catalysts need to provide more arsenic poisoning sites (generally expressed as total arsenic capacity) and a suitable diffusion environment to meet long-term operating requirements. Unlike hydrodesulfurization, hydrotreating permanently sacrifices a large number of arsenic poisoning sites; the utilized sites cannot be reused. Therefore, improving the effective utilization rate of arsenic poisoning sites is crucial.

[0004] Currently, to address the diffusion problem of large molecular arsenide in arsenic removal catalysts, pore-expanding treatment is typically performed. However, this inevitably reduces the number of arsenic poisoning sites on the catalyst surface, affecting the fast reaction characteristics of the arsenic removal catalyst under high space velocities. Furthermore, impregnating the same concentration of active metal in different pore structures can affect the arsenic removal selectivity of the catalyst when processing olefin-containing feedstocks, and it also cannot guarantee the uniform dispersion of the active metal within the pores, resulting in a waste of arsenic poisoning sites.

[0005] Patent CN 1043151C discloses a single-nickel catalyst prepared on a macroporous alumina support with a dual-channel distribution. It requires reduction under H2 and N2 atmospheres during use and can reduce arsenic content to below 5 ppb. CN 102140C relates to an arsenic removal catalyst for hydrocarbons, with a single-nickel system as the active center and a macroporous alumina support. It requires at least 50% of the nickel-hydrogen gas to be reduced before use and can also reduce arsenic content to below 5 ppb. However, both of these existing technologies use reduction as a pretreatment method for the catalyst. Currently, most mainstream catalysts in conventional oil refining hydrotreating processes are in a sulfide state. Reduction activation increases start-up complexity. Furthermore, although this patent uses macroporous alumina, it does not consider the dispersion of active metals within the pores, affecting the utilization rate of arsenic poisoning sites.

[0006] Patent CN 108246242B proposes a catalytic gasoline hydrodearsenic removal catalyst and its application. This technology uses hydrothermal treatment to modify the TiO2-Al2O3 composite support and uses a single nickel system to prepare the hydrodearsenic removal catalyst. The catalyst has good arsenic removal selectivity, and the arsenic removal selectivity can reach more than 99% when processing raw materials with an arsenic content of about 200 ppb. Patent CN 108246302B proposes a catalyst and its application for the hydrodearsenic removal of gasoline. This technology also uses a hydrothermal method to modify the TiO2-Al2O3 composite support and employs a bimetallic arsenic removal catalyst, which can reduce the arsenic content of the raw material from 200 ppb to below 20 ppb. Its arsenic capacity is improved compared with the single nickel system. However, in the catalyst preparation methods involved in the above two inventions, the average pore size of the catalyst is increased after the support is modified. Although this is beneficial to the diffusion of large molecular arsenides, the same concentration of metal impregnation on the support with a single pore size distribution will affect the selectivity of hydrodearsenic removal, especially in the bimetallic catalyst system, which will cause more octane number loss. In addition, this patent does not address the issue of metal dispersion in the pore channels after pore expansion.

[0007] Patent CN 106833731B proposes a catalyst for the hydrodearsenic removal of naphtha and its application method. The catalyst support is prepared by alternating titration with non-constant pH to obtain a zinc oxide layered structure containing zinc aluminum spinel. The preparation process is complex and the industrial production cost is high, making it difficult to achieve in actual production. At the same time, the existing technology does not involve the selectivity of dearsenic removal, nor does it address the issue of the dispersion and utilization of active metals within the pores.

[0008] Patent CN 100388980C proposes a pseudoboehmite composition containing an organic pore expander. By adding an organic pore expander to the pseudoboehmite, macroporous alumina can be obtained after calcination. However, the catalyst preparation method involved in this invention will also affect the fast reaction characteristics of the catalyst for arsenic removal, and it does not address the issues of dispersion and utilization of active metals within the pores.

[0009] Patent CN 102284295B proposes a method for preparing a hydrogenation catalyst impregnation solution and a method for preparing the catalyst. This invention uses water-soluble organic additives to reduce the surface tension of the impregnation solution, without calcination, and reduces the aggregation of metal particles, thereby effectively improving the hydrogenation activity of the hydrogenation catalyst for heavy aromatics. However, this method does not address the utilization of metals in the pores, nor does it address the diffusion of macromolecular raw materials in the catalyst pores.

[0010] Patent CN 107812525A discloses a hydrogenation catalyst composition comprising hydrogenation catalyst I and hydrogenation catalyst II. The hydrogenation catalyst I, by volume and based on the hydrogenation catalyst composition, comprises 5-95% hydrogenation catalyst I. Hydrogenation catalyst I comprises a support, a hydrogenation-active metal element, and a non-metallic auxiliary element, wherein the hydrogenation-active metal element contains Group VIB and Group VIII metal elements. The preparation method of hydrogenation catalyst I includes: subjecting a support loaded with a compound containing a hydrogenation-active metal element, a first organic complexing agent, and a non-metallic auxiliary element to a first drying and calcination to obtain a semi-finished catalyst; wherein, by dry basis and based on the dry weight of the semi-finished catalyst, the carbon content of the semi-finished catalyst is 0.01-0.5% by weight; loading a second organic complexing agent onto the semi-finished catalyst, and subjecting it to a second drying without calcination to obtain hydrogenation catalyst I. This technology is applied in the field of desulfurization and denitrification. The active metal and complex components are added together to the impregnation solution before the impregnation of the carrier. The poor dispersion of the active metal will cause the active metal to stack. In the field of hydrodearsenic removal, the stacking of active metal will cause the loss of arsenic poisoning sites. Therefore, the dispersion of the active metal needs to be further improved. In addition, the preparation method of the hydrogenation catalyst involved in this technology does not involve the utilization of metal in the pores. Summary of the Invention

[0011] To address the aforementioned problems, this invention provides a gradient-loaded hydroarsenic removal catalyst for oil products and its preparation method. During the catalyst impregnation process, a multi-stage pore-expansion gradient impregnation method is employed. This ensures both the flowability of large arsenic molecules within the catalyst and stable arsenic removal activity under high space velocities. Furthermore, different concentrations of metal are impregnated with pores of varying sizes to balance arsenic removal selectivity. Additionally, this invention employs a pre-dispersion impregnation method. The pre-dispersion solution is prepared before being dispersed and complexed with the main active metal. This ensures that the main active metal is fully complexed with the pore-expansion and dispersion components, allowing it to enter the pore channels for high-dispersion loading during pore expansion. This increases the number of arsenic poisoning sites on the catalyst, ensuring that these sites are fully utilized, thereby improving the arsenic capacity of the catalyst and reducing refinery investment costs.

[0012] To achieve the above objectives, the present invention provides a method for preparing a gradient-supported hydroarsenic removal catalyst for oil products, the method comprising the following steps:

[0013] (1) Organic complexing agent I, pore-expanding aid II, auxiliary active component IV containing group VIB metal and deionized water are formulated into stable dispersion impregnation component A-1; organic complexing agent I, pore-expanding aid III and deionized water are formulated into stable dispersion impregnation component A-2;

[0014] (2) Dissolve component X1 containing Group VIII metal in stable dispersion impregnation component A-1 to form stable complex impregnation solution B-1; dissolve component X2 containing Group VIII metal in stable dispersion impregnation component A-2 to form stable complex impregnation solution B-2.

[0015] (3) The porous support Z was impregnated with stable complex impregnation solution B-1, and then dried and calcined to obtain catalyst C1;

[0016] (4) Catalyst C1 was impregnated with stable complex impregnation solution B-2, and then dried and calcined to obtain catalyst C2;

[0017] (5) Dissolve organic auxiliary agent V in deionized water, then impregnate catalyst C2, and after drying and calcination, obtain the final hydrogen arsenic removal catalyst C3;

[0018] Wherein, the Group VIB metal is at least one of molybdenum and tungsten;

[0019] In step (1), the molecular weight of the pore-expanding agent III is less than that of the pore-expanding agent II.

[0020] Preferably, in step (1), the organic complexing agent I is ammonia or a hydroxy acid compound, and the hydroxy acid compound includes at least one of ethylene glycol, glyceric acid, malic acid, citric acid, tartaric acid, gluconic acid, acetic acid, oxalic acid, malonic acid, trichloroacetic acid, and monochloroacetic acid, more preferably citric acid or ammonia.

[0021] Preferably, in step (1), the pore-expanding agent II and pore-expanding agent III are respectively one of glycerol, propylene glycol, 1,4-butanediol, pentaerythritol, ethylene glycol, polyethylene glycol, diethylene glycol, polyvinyl alcohol, sodium stearate, carboxymethyl cellulose, and soluble starch, more preferably one of glycerol, ethylene glycol, polyethylene glycol, sodium carboxymethyl cellulose, and soluble starch.

[0022] Preferably, in step (1), the amount of the pore-expanding agent II added accounts for 1 to 18 wt% of the porous carrier Z, more preferably 2 to 15 wt%.

[0023] Preferably, in step (1), the amount of the pore-expanding agent III added accounts for 1 to 18 wt% of the catalyst C1, more preferably 2 to 13 wt%.

[0024] Preferably, the auxiliary active component IV containing Group VIB metal is a soluble salt, soluble acid solution or oxide of molybdenum or tungsten; more preferably, the auxiliary active component IV containing Group VIB metal is molybdate or molybdenum trioxide.

[0025] Preferably, the component X1 containing a Group VIII metal and the component X2 containing a Group VIII metal are nickel salts, including at least one of nickel nitrate, nickel acetate, nickel sulfate, and nickel basic carbonate, more preferably nickel nitrate or nickel basic carbonate.

[0026] Preferably, in step (2), the content of component X1 containing Group VIII metal in stable dispersion impregnation component A-1 is greater than the content of component X2 containing Group VIII metal in stable dispersion impregnation component A-2.

[0027] Preferably, the hydrodearsenic removal catalyst C3 contains 6-23 wt% NiO, 1-23 wt% MoO3 and / or WO3, and 54-93 wt% support; more preferably, it contains 7-21 wt% NiO, 2-16 wt% MoO3 or WO3, and 63-91 wt% support.

[0028] Preferably, the porous carrier Z is one or more composite carriers of alumina, titanium dioxide, silicon dioxide, and magnesium oxide, and more preferably alumina.

[0029] Preferably, the temperature during the preparation of the stable dispersion impregnation component A-1 in step (1) is 10 to 100°C, the temperature does not exceed the boiling point of the pore-expanding agent II, and the mixing time is 10 min to 120 min.

[0030] Preferably, in step (1), the temperature during the preparation of the stable dispersion impregnation component A-2 is 10 to 100°C, the temperature does not exceed the boiling point of the pore-expanding agent III, and the mixing time is 10 min to 120 min.

[0031] Preferably, in step (2), the temperature during the preparation of the stable complex impregnation solution B-1 is 10 to 100°C, the temperature does not exceed the boiling point of the pore-expanding agent II, and the mixing time is 10 min to 120 min.

[0032] Preferably, in step (2), the temperature during the preparation of the stable complex impregnation solution B-2 is 10 to 100°C, the temperature does not exceed the boiling point of the pore-expanding agent III, and the mixing time is 10 min to 120 min.

[0033] Preferably, in step (5), the organic additive V is an alcohol, including one of ethanol, glycerol, ethylene glycol, and polyethylene glycol.

[0034] Preferably, in step (5), the molecular weight of the alcohol in the organic auxiliary agent V is smaller than the molecular weight of the pore-expanding auxiliary agent III.

[0035] Preferably, in step (5), the amount of organic auxiliary agent V added is 1 to 15 wt% of catalyst C2, more preferably 2 to 10 wt%.

[0036] Preferably, in steps (3), (4), or (5), after impregnation, the mixture needs to stand for 1 to 7 hours before drying and roasting, more preferably 1 to 6 hours.

[0037] Preferably, in steps (3), (4), or (5), the drying temperature is 50–150°C and the drying time is 3–6 hours; more preferably, the drying temperature is 50–120°C; and the calcination temperature is 300°C–600°C and the calcination time is 3–6 hours.

[0038] Preferably, in step (3), step (4) or step (5), the impregnation process is saturated impregnation or supersaturated impregnation, more preferably saturated impregnation.

[0039] Preferably, the hydrodearsenic removal catalyst C3 is in a sulfided form when used in the dearsenic removal process of oil processing.

[0040] The present invention also provides a gradient-supported oil hydrodearsenic removal catalyst, which is obtained by the above preparation method.

[0041] Compared with the prior art, the present invention has at least the following advantages:

[0042] (1) During the catalyst impregnation process, by controlling different molecular weight pore-expanding aids II and III, different concentrations of the main arsenic removal active metal nickel are impregnated in pores of different sizes to achieve gradient impregnation. This allows for the impregnation of more Group VIII main active metal containing metal aids in the macropores, ensuring that large molecular weight arsenides enter the pores and are deeply removed. In the medium-sized pores, a low content of Group VIII main active metal is complexed and impregnated to improve the arsenic removal selectivity. In the arsenic removal process of gasoline feedstock containing olefins, this can reduce octane number loss.

[0043] (2) The catalyst preparation process adopts a multi-stage pore expansion gradient impregnation method. While ensuring the flowability of arsenic macromolecules in the catalyst, the catalyst can also achieve stable arsenic removal activity under high space velocity conditions through multi-stage pore expansion.

[0044] (3) In a single impregnation, a pre-dispersion impregnation method is adopted, in which the dispersing aid (organic complexing agent I), pore-expanding aid (II or III) and co-active component IV are uniformly complexed and then complexed with the Group VIII main active metal. This can ensure the uniform dispersion of the pore-expanding aid (II or III) and co-active component IV with the Group VIII main active metal, improve the uniform dispersion of active metals in the catalyst loading process, increase the number of arsenic poisoning sites, and thus improve the arsenic capacity.

[0045] (4) Pore-expanding aids II and III are pre-dispersed and then complexed with active metals. During the calcination process, active metals can be uniformly loaded at the same time during pore expansion. Pore expansion can not only improve the diffusion of macromolecular arsenides into the pores and improve the utilization rate of active sites in the pores, but also improve the dispersion and number of arsenic poisoning sites in the expanded pores.

[0046] (5) By using a small molecule organic additive V with a molecular weight less than that of the two pore-expanding additives II and III to perform secondary dispersion of the active metal through post-treatment, it is possible to ensure that the secondary activation impregnation solution enters the pores, prevent metal agglomeration caused by heating during the calcination process after metal impregnation, and further improve the dispersion and effective utilization rate of arsenic poisoning sites on the surface and in the pores, thereby increasing the arsenic capacity.

[0047] (6) Increasing the arsenic capacity can improve the service life of the catalyst, ensure long-term ultra-deep stable arsenic removal, ensure the stable operation of long-term refinery units, and save investment costs. Detailed Implementation

[0048] The technical solutions of the present invention are further described below through embodiments, but the technical solutions of the present invention are not limited to the following embodiments.

[0049] The catalyst supports used in the examples and comparative examples can be obtained by the following preparation methods. However, it should be noted that the following preparation methods are only intended to provide a feasible method for preparing the support and are not intended to limit the present invention. The supports and preparation methods of the present invention are not limited thereto:

[0050] 600g of boehmite was mixed with 12g of guar gum powder, and then a solution consisting of 27g of citric acid, 17mL of concentrated nitric acid, and 500g of water was added. D3.0 clover-shaped wet strips were prepared using a conventional laboratory extruder, dried at 120℃, and then calcined at 830℃ for 6 hours to obtain carrier L1. The properties of carrier L1 are shown in Table 1.

[0051] Table 1 Physicochemical properties of the carrier

[0052] <![CDATA[Specific surface area, m 2 / g]]> 275 Pore ​​diameter, nm 11.3 Bulk density, g / 100L 61 Water absorption rate, mL / 100g 83

[0053] Example 1

[0054] 1) Dissolve 9g glycerol and 19.32g ammonium molybdate in 30mL of 25% ammonia water, mix at 20℃ for 20min until a homogeneous and clear solution is obtained, then add 9.13g nickel acetate to make up to 42mL, mix for 20min until a homogeneous and clear solution is obtained, weigh 50g of support L1 and impregnate it with an equal volume, let it stand for 6 hours, dry at 80℃ for 3h, and then calcine at 550℃ for 3h to obtain catalyst C1-1.

[0055] 2) Dissolve 0.5g of ethylene glycol in 25% ammonia water, mix at 20℃ for 20min until a homogeneous and clear solution is obtained, then add 3.4g of nickel acetate, mix for 10min until a homogeneous and clear solution is obtained, saturate 50g of catalyst C1-1, let stand for 1 hour, dry at 50℃ for 3h, and then calcine at 550℃ for 3h to obtain catalyst C2-1.

[0056] 3) Dissolve 0.5g of ethanol in deionized water and make up to a final volume. Impregnate 50g of catalyst C2-1 with an equal volume. Dry at 80℃ for 3h and calcine at 500℃ for 3h to obtain the hydrogen arsenic removal catalyst C3-1.

[0057] Example 2

[0058] 1) Dissolve 7.5g polyethylene glycol (4000), 2.8g ammonium molybdate, and 1.5g citric acid in deionized water. Mix at 25°C for 30 min until a homogeneous and clear solution is obtained. Then add 17.7g nickel nitrate to make up to 42mL. Mix for 25 min until a homogeneous and clear solution is obtained. Weigh 50g of support L1 and impregnate it with an equal volume. Let it stand for 6 hours, dry at 110°C for 6 hours, and then calcine at 500°C for 6 hours to obtain catalyst C1-2.

[0059] 2) Dissolve 5g polyethylene glycol (2000) and 1g citric acid in deionized water, mix at 25℃ for 30min until a homogeneous and clear solution is obtained, then add 8.1g nickel nitrate, mix for 25min until a homogeneous and clear solution is obtained, saturate 50g catalyst C1-2, let stand for 6 hours, dry at 110℃ for 5h, and then calcine at 500℃ for 6h to obtain catalyst C2-2.

[0060] 3) Dissolve 4g of polyethylene glycol (800) in deionized water and make up to a final volume. Impregnate 50g of catalyst C2-2 with an equal volume. Dry at 110℃ for 6h and calcine at 500℃ for 6h to obtain the hydrodearsenic removal catalyst C3-2.

[0061] Example 3

[0062] 1) Dissolve 0.5g polyethylene glycol (800), 0.8g ammonium molybdate, and 0.5g citric acid in deionized water. Mix at 25°C for 40 min until a homogeneous and clear solution is obtained. Then add 34.8g nickel nitrate to make up to 42mL. Mix for 30 min until a homogeneous and clear solution is obtained. Weigh 50g of support L1 and impregnate it with an equal volume. Let it stand for 4 hours, dry at 120°C for 4 hours, and then calcine at 600°C for 4 hours to obtain catalyst C1-3.

[0063] 2) Dissolve 9g sodium carboxymethyl cellulose and 1g citric acid in deionized water, mix at 25℃ for 40min until a homogeneous and clear solution is obtained, then add 17g nickel nitrate and mix for 30min until a homogeneous and clear solution is obtained. Saturate impregnate 50g catalyst C1-3, let stand for 4 hours, dry at 120℃ for 5h, and then calcine at 600℃ for 4h to obtain catalyst C2-3.

[0064] 3) Dissolve 7.5g of glycerol in deionized water and make up to a final volume. Impregnate 50g of catalyst C2-3 with an equal volume. Dry at 120℃ for 4h and calcine at 350℃ for 4h to obtain the hydrodearsenic removal catalyst C3-3.

[0065] Example 4

[0066] 1) Dissolve 1g of soluble starch, 4.1g of ammonium molybdate, and 2.2g of citric acid in deionized water. Mix at 50℃ for 50min until a homogeneous and clear solution is obtained. Then add 15.5g of nickel nitrate and bring the volume to 42mL. Mix for 20min until a homogeneous and clear solution is obtained. Weigh 50g of support L1 and impregnate it with an equal volume. Let it stand for 5 hours, dry at 100℃ for 5h, and then calcine at 500℃ for 5h to obtain catalyst C1-4.

[0067] 2) Dissolve 1g glycerol and 1.5g citric acid in deionized water, mix at 50℃ for 50min until a homogeneous and clear solution is obtained, then add 6g nickel nitrate, mix for 20min until a homogeneous and clear solution is obtained, saturate 50g catalyst C1-4, let stand for 5 hours, dry at 100℃ for 5h, and then calcine at 500℃ for 5h to obtain catalyst C2-4.

[0068] 3) Dissolve 5g of ethylene glycol in deionized water and make up to a final volume. Impregnate 50g of catalyst C2-4 with an equal volume. Dry at 100℃ for 5h and calcine at 400℃ for 5h to obtain the hydrodearsenic removal catalyst C3-4.

[0069] Example 5

[0070] 1) Dissolve 5g polyethylene glycol (4000), 2g phosphoric acid, 1.2g molybdenum oxide and 2g citric acid in deionized water, mix at 90℃ for 60min until a homogeneous and clear solution is obtained, then add 14g basic nickel carbonate, reflux at 90℃ for 120min and make up to 42mL, weigh 50g of carrier L1 and impregnate it with an equal volume, let stand for 6 hours, dry at 100℃ for 6h and calcine at 500℃ for 6h to obtain arsenic removal catalyst C1-5.

[0071] 2) Dissolve 6.5g polyethylene glycol (800), 1.2g phosphoric acid and 1.5g citric acid in deionized water, mix at 90℃ for 60min until a homogeneous and clear solution is obtained, then add 6.3g basic nickel carbonate, reflux at 90℃ for 60min until a homogeneous and clear solution is obtained, saturate impregnate 50g catalyst C1-5, let stand for 6 hours, dry at 100℃ for 5h, and then calcine at 500℃ for 6h to obtain catalyst C2-5.

[0072] 3) Dissolve 1g of ethanol in deionized water and make up to a final volume. Impregnate 50g of catalyst C2-5 with an equal volume. Dry at 100℃ for 6h and calcine at 350℃ for 6h to obtain the hydrogen arsenic removal catalyst C3-5.

[0073] Comparative Example 1

[0074] 1) Dissolve 9g glycerol, 19.32g ammonium molybdate, and 9.13g nickel acetate in 30mL of 25% ammonia water. Mix at 20℃ for 20min until a homogeneous and clear solution is obtained, and then bring the volume up to 42mL. Mix for 20min until a homogeneous and clear solution is obtained. Weigh 50g of support L1 and impregnate it with an equal volume. Let it stand for 6 hours, dry at 80℃ for 3h, and then calcine at 550℃ for 3h to obtain catalyst D1-1.

[0075] 2) Dissolve 0.5g ethylene glycol and 3.4g nickel acetate in 25% ammonia water, mix at 20℃ for 20min until a homogeneous and clear solution is obtained, then mix for 10min until a homogeneous and clear solution is obtained. 50g catalyst D1-1 is saturated and impregnated, allowed to stand for 1 hour, dried at 50℃ for 3h, and then calcined at 550℃ for 3h to obtain catalyst D1-2.

[0076] 3) Dissolve 0.5g of ethanol in deionized water and make up to a final volume. Impregnate 50g of catalyst D1-2 with an equal volume. Dry at 80℃ for 3h and calcine at 500℃ for 3h to obtain the hydrogen arsenic removal catalyst D1.

[0077] Comparative Example 2

[0078] 1) Dissolve 0.5g ethylene glycol, 19.32g ammonium molybdate, and 9.13g nickel acetate in 30mL of 25% ammonia water. Mix at 20℃ for 20min until a homogeneous and clear solution is obtained, and then bring the volume up to 42mL. Mix for 20min until a homogeneous and clear solution is obtained. Weigh 50g of support L1 and impregnate it with an equal volume. Let it stand for 6 hours, dry at 80℃ for 3h, and then calcine at 550℃ for 3h to obtain catalyst D2-1.

[0079] 2) Dissolve 9g of glycerol and 3.4g of nickel acetate in 25% ammonia water, mix at 20°C for 20min until a homogeneous and clear solution is obtained, then mix for 10min until a homogeneous and clear solution is obtained. Saturate impregnate 50g of catalyst D2-1, let stand for 1 hour, dry at 50°C for 3h, and then calcine at 550°C for 3h to obtain catalyst D2-2.

[0080] 3) Dissolve 0.5g of ethanol in deionized water and make up to a final volume. Impregnate 50g of catalyst D2-2 with an equal volume. Dry at 80℃ for 3h and calcine at 500℃ for 3h to obtain the hydrogen arsenic removal catalyst D2.

[0081] Comparative Example 3

[0082] 1) Dissolve 9g glycerol and 19.32g ammonium molybdate in 30mL of 25% ammonia water, mix at 20℃ for 20min until a homogeneous and clear solution is obtained, then add 9.13g nickel acetate to make up to 42mL, mix for 20min until a homogeneous and clear solution is obtained, weigh 50g of support L1 and impregnate it with an equal volume, let it stand for 6 hours, dry at 80℃ for 3h, and then calcine at 550℃ for 3h to obtain catalyst D3-1.

[0083] 2) Dissolve 0.5g of polyethylene glycol (800) in 25% ammonia water, mix at 20°C for 20 min until a homogeneous and clear solution is obtained, then add 3.4g of nickel acetate, mix for 10 min until a homogeneous and clear solution is obtained, saturate 50g of catalyst D3-1, let stand for 1 hour, dry at 50°C for 3 h, and then calcine at 550°C for 3 h to obtain catalyst D3-2.

[0084] 3) Dissolve 0.5g of ethanol in deionized water and make up to a final volume. Impregnate 50g of catalyst D3-2 with an equal volume. Dry at 80℃ for 3h and calcine at 500℃ for 3h to obtain the hydrogen arsenic removal catalyst D3.

[0085] Example 6

[0086] This embodiment relates to the catalyst evaluation of Examples 1 to 5 and Comparative Examples 1 to 3.

[0087] The catalyst evaluations for the above embodiments and comparative examples were conducted in a 30mL microreactor evaluation device using wet sulfidation. Carbon disulfide was used as the sulfiding agent at a dosage of 3wt%, and refined naphtha was used as the sulfiding oil. Hydrogen was passed through once. The sulfidation conditions were 230℃ and 320℃ for 8 hours each, with a sulfidation pressure of 2.0 MPa and a hydrogen-to-oil ratio of 300:1. After sulfidation, feedstock oil was introduced. A summary table of feedstock oil properties is shown in Table 2, and a summary table of reaction process parameters and products for each embodiment is shown in Table 3.

[0088] Arsenic content was analyzed using an Agilent ICP-MS 7850. Group composition analysis of the oil was performed using an Agilent PONA chromatographic analyzer.

[0089] The arsenic content test used the arsenic-containing raw materials listed in Table 2. The arsenic-containing raw materials were prepared by adding triethylarsenic (20 ppm) to the catalytic gasoline product oil and conducting the test at a temperature of 260℃, a pressure of 2 MPa, and a space velocity of 8 h⁻¹. -1The arsenic removal reaction was carried out under the reaction conditions of hydrogen / oil = 300. When the arsenic removal rate of the product was <90%, the arsenic capacity experiment was stopped, and the As content was determined by X-ray diffraction spectroscopy (XRF analysis) to obtain the arsenic capacity of the catalyst.

[0090] Table 2 Properties of Crude Oil

[0091]

[0092]

[0093] Table 3 Summary of Evaluation Results

[0094]

[0095]

[0096] Comparative analysis revealed that the hydroarsenic removal catalyst prepared according to this invention exhibits significantly better arsenic capacity and removal efficiency than the catalyst prepared in the comparative example. When processing olefin-containing gasoline feedstocks, the catalyst prepared according to this invention, while meeting the requirement of an arsenic content of less than 20 ppb in the product, also maintains arsenic removal selectivity, resulting in less octane number loss than existing technologies. Under high space velocity reaction conditions (17 h⁻¹), [further details are needed]. -1 Even at high space velocities, the arsenic content of the de-arsenic product can be guaranteed to be less than 20 ppb, meeting the arsenic content requirements for gasoline and ensuring the fast reaction performance of the catalyst for arsenic removal. This demonstrates that the preparation method of this invention, while ensuring the flowability of macromolecular arsenic in the catalyst, achieves the goal of maintaining arsenic removal selectivity by impregnating substrates with different concentrations of metal at different pore sizes through multi-stage pore expansion gradient impregnation, thereby reducing octane number loss and meeting the arsenic content requirements for gasoline even at high space velocities.

[0097] Of course, the present invention may have other embodiments and variations. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and variations according to the present invention, but these corresponding changes and variations should all fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing a gradient-supported hydroarsenic removal catalyst for oil products, characterized in that, Includes the following steps: (1) Complexing agent I, pore-expanding aid II, auxiliary active component IV containing group VIB metal and deionized water are prepared into stable dispersion impregnation component A-1; complexing agent I, pore-expanding aid III and deionized water are prepared into stable dispersion impregnation component A-2; (2) Dissolve component X1 containing Group VIII metal in stable dispersion impregnation component A-1 to form stable complex impregnation solution B-1; dissolve component X2 containing Group VIII metal in stable dispersion impregnation component A-2 to form stable complex impregnation solution B-2. (3) The porous support Z was impregnated with stable complex impregnation solution B-1, and then dried and calcined to obtain catalyst C1; (4) Catalyst C1 was impregnated with stable complex impregnation solution B-2, and then dried and calcined to obtain catalyst C2; (5) Dissolve organic auxiliary agent V in deionized water, then impregnate catalyst C2, and after drying and calcination, obtain the final hydrogen arsenic removal catalyst C3; Wherein, the Group VIB metal is at least one of molybdenum and tungsten; In step (1), the molecular weight of the pore-expanding agent III is smaller than that of the pore-expanding agent II; In step (1), the complexing agent I is ammonia or a hydroxy acid compound; In step (1), the pore-expanding agent II and pore-expanding agent III are respectively one of glycerol, propylene glycol, 1,4-butanediol, pentaerythritol, ethylene glycol, polyethylene glycol, diethylene glycol, polyvinyl alcohol, sodium stearate, carboxymethyl cellulose, and soluble starch. The components X1 and X2 containing Group VIII metals are nickel salts; The porous carrier Z is one or more composite carriers of alumina, titanium dioxide, silicon dioxide, and magnesium oxide. In step (5), the organic auxiliary agent V is an alcohol; The content of component X1 containing Group VIII metal in stable dispersion impregnation component A-1 is greater than the content of component X2 containing Group VIII metal in stable dispersion impregnation component A-2. In step (5), the molecular weight of the alcohol in the organic additive V is smaller than the molecular weight of the pore-expanding additive III.

2. The preparation method according to claim 1, characterized in that, The hydroxy acid compounds include at least one of ethylene glycol, glyceric acid, malic acid, citric acid, tartaric acid, gluconic acid, and lactic acid.

3. The preparation method according to claim 2, characterized in that, In step (1), the complexing agent I is citric acid or ammonia.

4. The preparation method according to claim 1, characterized in that, In step (1), the pore-expanding agent II and pore-expanding agent III are respectively one of glycerol, ethylene glycol, polyethylene glycol, sodium carboxymethyl cellulose, and soluble starch.

5. The preparation method according to claim 1, characterized in that, In step (1), the amount of pore-expanding agent II added accounts for 1 to 18 wt% of the porous carrier Z.

6. The preparation method according to claim 5, characterized in that, In step (1), the amount of the pore-expanding agent II added accounts for 2 to 15 wt% of the porous carrier Z.

7. The preparation method according to claim 1, characterized in that, In step (1), the amount of the pore-expanding agent III added accounts for 1 to 18 wt% of the catalyst C1.

8. The preparation method according to claim 7, characterized in that, In step (1), the amount of pore-expanding agent III added accounts for 2 to 13 wt% of catalyst C1.

9. The preparation method according to claim 1, characterized in that, The auxiliary active component IV containing Group VIB metals is a soluble salt, soluble acid solution, or oxide of molybdenum or tungsten.

10. The preparation method according to claim 9, characterized in that, The auxiliary active component IV containing Group VIB metals is molybdate or molybdenum trioxide.

11. The preparation method according to claim 1, characterized in that, The nickel salt includes at least one of nickel nitrate, nickel acetate, nickel sulfate, and nickel basic carbonate.

12. The preparation method according to claim 11, characterized in that, The nickel salts include nickel nitrates or nickel basic carbonates.

13. The preparation method according to claim 1, characterized in that, The hydrodearsenic removal catalyst C3 contains 6-23 wt% NiO, 1-23 wt% MoO3 and / or WO3, and 54-93 wt% support.

14. The preparation method according to claim 13, characterized in that, The hydrogenated arsenic removal catalyst C3 contains 7-21 wt% NiO, 2-16 wt% MoO3 or WO3, and 63-91 wt% support.

15. The preparation method according to claim 1, characterized in that, The porous carrier Z is alumina.

16. The preparation method according to claim 1, characterized in that, In step (1), the temperature during the preparation of the stable dispersion impregnation component A-1 is 10~100℃, the temperature does not exceed the boiling point of the pore-expanding aid II, and the mixing time is 10min~120min; in step (1), the temperature during the preparation of the stable dispersion impregnation component A-2 is 10~100℃, the temperature does not exceed the boiling point of the pore-expanding aid III, and the mixing time is 10min~120min; in step (2), the temperature during the preparation of the stable complex impregnation liquid B-1 is 10~100℃, the temperature does not exceed the boiling point of the pore-expanding aid II, and the mixing time is 10min~120min; in step (2), the temperature during the preparation of the stable complex impregnation liquid B-2 is 10~100℃, the temperature does not exceed the boiling point of the pore-expanding aid III, and the mixing time is 10min~120min.

17. The preparation method according to claim 1, characterized in that, In step (5), the organic additive V includes one of ethanol, glycerol, ethylene glycol, and polyethylene glycol.

18. The preparation method according to claim 1, characterized in that, In step (5), the amount of organic additive V added is 1 to 15 wt% of catalyst C2.

19. The preparation method according to claim 18, characterized in that, In step (5), the amount of organic additive V added is 2 to 10 wt% of catalyst C2.

20. The preparation method according to claim 1, characterized in that, In steps (3), (4) or (5), after the impregnation is completed, it is necessary to let it stand for 1 to 7 hours before drying and roasting.

21. The preparation method according to claim 1, characterized in that, In steps (3), (4), or (5), the drying temperature is 50~150℃ and the drying time is 3~6h; the calcination temperature is 300℃~600℃ and the calcination time is 3~6h.

22. The preparation method according to claim 1, characterized in that, In step (3), step (4) or step (5), the impregnation process is saturated impregnation or supersaturated impregnation.

23. The preparation method according to claim 1, characterized in that, The hydro-dearsenic removal catalyst C3 is used in a sulfided form during the dearsenic removal process in oil processing.

24. A gradient-supported catalyst for the hydrodearsenic removal of oil products, characterized in that, It is obtained by the preparation method according to any one of claims 1-23.

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