A pyrolysis gasoline selective hydrogenation catalyst, a preparation method and application thereof

Abstract

The application discloses a pyrolysis gasoline selective hydrogenation catalyst, a preparation method and application thereof, and belongs to the field of catalysts. The catalyst comprises a carrier, an active component and an additive. The carrier is alumina, the alumina has a leaf-shaped aggregate structure, the active component comprises palladium, and the additive comprises a Group VI B metal and an alkaline earth metal. The content of the palladium is 0.1-0.5 wt% in terms of metal, the content of the Group VI B element is 0.1-3 wt% in terms of metal, and the content of the alkaline earth metal is 0.2-5 wt% in terms of metal. The catalyst can greatly improve hydrogenation activity and carbon deposition resistance.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of petrochemical industry, and relates to a pyrolysis gasoline selective hydrogenation catalyst, a preparation method and application thereof, in particular to a Pd-based hydrogenation catalyst with leaf-shaped aggregate structure alumina as a carrier and a preparation method and application thereof. BACKGROUND

[0002] Pyrolysis gasoline is an important by-product of a steam cracking ethylene production device, and its yield is 50wt% to 80wt% of the ethylene production capacity. The content of aromatic hydrocarbons in the pyrolysis gasoline is as high as 50% or more, which is an important raw material for extracting aromatic hydrocarbons. The pyrolysis gasoline contains a large amount of unsaturated hydrocarbons which are prone to polymerization, as well as impurities such as sulfur and nitrogen, which can greatly reduce the selectivity of the extractant when extracting aromatic hydrocarbons, and seriously affect the purity and color of the aromatic hydrocarbon product. Therefore, the raw material must be subjected to hydrofining before the extraction of aromatic hydrocarbons, and the first-stage selective hydrogenation is mainly used to remove dienes which are prone to polymerization and cause gumming. Currently, Pd / Al2O3 or Ni / Al2O3 system catalysts are mainly used in industry.

[0003] In recent years, with the rapid expansion of the ethylene production capacity, the cracking raw materials tend to be diversified, which leads to an increase in the feed space velocity and the impurity content of the pyrolysis gasoline device, and a reduction in the operation cycle of the device. At the same time, enterprises are increasingly strict on product control indicators such as aromatic hydrocarbon loss. Therefore, higher requirements are put forward for the hydrogenation activity, selectivity, anti-impurity performance and operation stability of the pyrolysis gasoline catalyst.

[0004] CN85100761A discloses a fibrous carrier catalyst for selective hydrogenation of dienes in pyrolysis gasoline fractions, which uses η-Al2O3 porous fibrous carrier with a specific surface area of 20 to 150 m 2 / g and a pore volume of 0.1 to 0.3 ml / g. The catalyst has high initial activity, but the pore volume is too small. When the content of gum, arsenic and water in the raw material of the pyrolysis gasoline hydrogenation device exceeds the standard, the pores on the catalyst are easily coked and blocked, which affects the hydrogenation stability of the catalyst.

[0005] CN101433841B discloses a selective hydrogenation catalyst and a preparation method thereof. Alumina is used as a carrier, and active component metal palladium is loaded on the alumina carrier. The active component is distributed in the form of an eggshell on the surface of the carrier. The catalyst contains, in 100% by weight, 0.2 to 0.5wt% of active component Pd, 2 to 8wt% of lanthanum and / or cerium as an additive, and 2 to 8wt% of alkaline earth metal elements. The thickness of the shell layer of the catalyst is 0.07 to 0.15 mm, the specific surface area is 70 to 150 m 2 / g, and the pore volume is 0.3 to 0.6 ml / g. The crystal form of the carrier alumina is θ type or a mixed crystal form of θ and α types mainly in θ type. The catalyst has good hydrogenation performance, but the hydrogenation activity of the catalyst needs to be further improved when treating high space velocity raw materials.

[0006] Chinese patent CN104475170B discloses an aluminum-silicon alloy catalyst carrier and a preparation method thereof. The aluminum-silicon alloy powder (silicon content 10-50%) prepared by a spray method is used as a raw material. After hydrothermal treatment, washing, drying and calcination, a porous structure composed of flaky aluminum oxide is formed on the surface of the aluminum-silicon alloy powder, the average diameter is 3-40 nm, the sheet thickness is 10-30 nm, and the specific surface area is 70-500 m 2 / g. After the carrier is applied to a noble metal palladium catalyst, high activity is shown in styrene hydrogenation reaction and low-temperature catalytic combustion of VOCs.

[0007] Chinese patent CN109603850A discloses a pyrolysis gasoline selective hydrogenation catalyst and a preparation method thereof. The catalyst uses an alumina carrier with an expanded pore structure, and is loaded with palladium and nickel oxide. The content of palladium is 0.1-0.15% based on the total weight of the catalyst, and the content of nickel oxide is 8-10% based on the total weight of the catalyst. The alumina carrier is modified with calcium, and the surface of the carrier is further modified by impregnation, which can gelatinize the surface micropores and promote the production of more active site loading centers on the surface of the carrier.

[0008] The above-mentioned prior art mainly changes the micro-pore structure and crystal morphology of the alumina carrier, and adds active additives to improve the hydrogenation performance of the catalyst. However, when the space velocity of pyrolysis gasoline feed increases and the content of olefins and gum is high, the catalyst is easily deactivated. Therefore, in order to further improve the hydrogenation activity and stability of the catalyst, it is necessary to continue to study the catalyst and its preparation method.

[0009] The micro-morphology and surface properties of alumina have a great influence on the performance of supported catalysts, so the controllable synthesis of alumina morphology has attracted the interest of many researchers. At present, researchers have prepared alumina with different morphologies, mainly including flaky, rod-shaped and spherical. Nano-flaky alumina has a large specific surface area and high surface energy, and has high dispersity for active metals of catalysts, as well as a large diffusion rate for reactants, which can significantly reduce diffusion resistance. Therefore, as a carrier, it can greatly improve the activity and anti-carbon performance of the catalyst, and has more excellent performance than traditional alumina. At present, flaky alumina mainly focuses on the synthesis of micron-sized flaky alumina, which is mainly used for the preparation of flaky alumina ceramics. The synthesis route of nano-flaky alumina is mainly based on surfactants as templates, which has high cost and is easy to agglomerate at high temperature calcination, which limits the realization of industrialization to a certain extent.

[0010] Chinese patent CN201710944136.1 discloses a preparation method of a nano-alumina carrier with a surface rich in defect sites, the steps are as follows: (1) dissolve inorganic aluminum salt and precipitant in a water-ethylene glycol mixed solvent according to a molar ratio of 1:5-1:9, stir to obtain a transparent solution, and transfer the solution to a hydrothermal kettle; the hydrothermal reaction temperature is 100-200℃, and the reaction time is 12-48h; (2) after the reaction is completed, the reaction material is filtered, washed, dried, and calcined to obtain a nano-alumina carrier rich in surface defects, the specific surface area of which is 150-400m 2 / g, and the pore volume is 0.34-0.62cm 3 / g. However, ethylene glycol in the mixed solvent is prone to hydrothermal metabolism oxidation to generate toxic oxalic acid, so it cannot be widely used as a solvent and is not conducive to popularization.

[0011] Chinese patent CN201210427889.2 discloses a preparation method of an alumina carrier, which comprises the following contents: measuring an appropriate amount of aluminum salt solution with a concentration of 0.5-2.5mol / L, adding an appropriate amount of urea to the aluminum salt solution and stirring to completely dissolve the urea, the molar ratio of urea to Al 3+ ; after the above solution is placed in a sealed reaction container and reacted at 140℃-200℃ for 2-12 hours, the prepared alumina carrier is directly calcined. The carrier prepared by the method has a high specific surface area and a large pore size, but the alumina carrier obtained by the method has a high content of amorphous alumina and a dispersed pore distribution, which limits its further application.

[0012] Chinese patent CN201110351132.5 provides a method for preparing porous alumina superfine powder by an improved hydrothermal method, which uses aluminum inorganic salt as raw material and urea as coprecipitation agent to generate a precursor under hydrothermal conditions, and centrifugal separation, washing, drying, and calcination are performed to obtain porous alumina superfine powder, which has high purity, narrow particle size distribution, and high porosity.

[0013] Chinese patent CN107540007A discloses a preparation method of nano-sheet-shaped mesoporous alumina: using inorganic aluminum salt as an aluminum source, triethanolamine as an additive, and ethylenediamine as a precipitant, nano-sheet-shaped mesoporous alumina is obtained through hydrothermal aging treatment, the nano-sheet-shaped alumina has a sheet layer thickness of 1-10nm and a width of 0.1-0.5um.

[0014] Chinese patent CN107777713A discloses a gamma-alumina hexagonal nanosheet material and a preparation method thereof, which has a size of 50-500nm and a thickness of 5-10nm. The invention uses an alcohol salt of metallic aluminum as raw material, controls the two-dimensional growth of an intermediate hydroxyl alumina by using an organic amine, and uses chemical precipitation and a hydrothermal method to prepare gamma-alumina hexagonal nanosheets.

[0015] Chinese patent CN104961146A discloses a kind of nanometer sheet-shaped aluminum hydroxide colloid and its preparation method, anhydrous ethanol and anhydrous aluminum chloride are directly hydrothermally obtained nanometer thin sheet gel at 220-300℃, and the thickness is 3-20nm.

[0016] Chinese patent CN106276992A discloses a kind of leaf-shaped nanometer γ-alumina preparation method, inorganic aluminum salt and urea are dissolved in water to obtain a transparent solution, the solution is transferred to a high-pressure reaction kettle, then hydrogen is introduced into the high-pressure reaction kettle, and a certain pressure and temperature are maintained to obtain leaf-shaped nanometer γ-alumina, but the leaves are in a dispersed state, and are not accumulated, and are easy to agglomerate when calcined at high temperature, and when used as a catalyst carrier to load active metals, the dispersion of active metals on the carrier surface will be reduced, and dangerous hydrogen is used in the preparation process, which is not conducive to production safety.

[0017] The article "Controllable synthesis and characterization of γ-Al2O3 nanocrystals with specific morphology" by Li Jinlin et al. in Journal of South-Central University for Nationalities (Natural Science Edition), 2016, 35:1-4 uses acetic acid and isopropyl alcohol as raw materials to hydrothermally prepare aluminum oxide nanosheets with a length of 60-100nm, and the main exposed crystal face is (110) crystal face. The article "Synthesis of AlOOH nanocrystals with different morphologies due to the effect of sulfate ions and the corresponding formation mechanism study" by Yuguo Xia et al. in Phys. Chem. Chem. Phys., 2013, 15, 18290 uses nano AlOOH as raw material, adds sulfuric acid and sulfuric acid, and hydrothermally treats at 200℃ for 24 hours to obtain nanosheet-shaped aluminum oxide with a size of 60-100nm. The specific surface area of the aluminum oxide prepared by this method is small (<100m 2 / g), and the use of dilute acid in the preparation process and the high requirement for the kettle material in the high-temperature hydrothermal process are not conducive to large-scale production.

[0018] Therefore, the cracking gasoline selective hydrogenation catalyst and the carrier used need to be further studied in the art. SUMMARY

[0019] The main purpose of the present application is to provide a kind of cracking gasoline selective hydrogenation catalyst and its preparation method and application, to overcome the defects of low diene hydrogenation activity, poor selectivity and weak carbon deposition resistance of the cracking gasoline selective hydrogenation catalyst in the prior art.

[0020] In order to achieve the above object, the present application provides a pyrolysis gasoline selective hydrogenation catalyst, which comprises a carrier, an active component and an auxiliary agent, the carrier is alumina, the active component comprises palladium, and the auxiliary agent comprises a Group VI B metal and an alkaline earth metal; the content of the palladium is 0.1-0.5 wt% in terms of metal, the content of the Group VI B element is 0.1-3 wt% in terms of metal, and the content of the alkaline earth metal is 0.2-5 wt% in terms of metal.

[0021] In an embodiment of the pyrolysis gasoline selective hydrogenation catalyst, the specific surface area of the catalyst is 60-150 m 2 / g, and the pore volume is 0.4-0.6 cm 3 / g.

[0022] In an embodiment of the pyrolysis gasoline selective hydrogenation catalyst, the Group VI B element is at least one of Cr, Mo and W, and the alkaline earth metal is at least one of Mg, Ca, Sr and Ba.

[0023] In order to achieve the above object, the present application further provides a preparation method of a pyrolysis gasoline selective hydrogenation catalyst, the catalyst comprising a carrier, an active component and an auxiliary agent, the carrier being alumina, the active component comprising palladium, and the auxiliary agent comprising a Group VI B metal and an alkaline earth metal, the preparation method of the alumina comprising:

[0024] Step 1: adding a compound capable of decomposing into NH3 and CO2 into an aqueous inorganic aluminum salt solution, stirring until completely dissolved to form a mixed solution;

[0025] Step 2: introducing CO2 gas with a pressure of 0.1-2 MPa into a closed container in which the mixed solution is located, performing hydrothermal treatment, and calcining to obtain alumina.

[0026] In an embodiment of the preparation method of the pyrolysis gasoline selective hydrogenation catalyst, the compound capable of decomposing into NH3 and CO2 is at least one of the group consisting of ammonium carbonate, ammonium bicarbonate, urea and ammonium oxalate.

[0027] In an embodiment of the preparation method of the pyrolysis gasoline selective hydrogenation catalyst, the molar ratio of the inorganic aluminum salt to the compound capable of decomposing into NH3 and CO2 in the aqueous inorganic aluminum salt solution is 0.1-4.0 in terms of aluminum ions; and the inorganic aluminum salt is at least one of the group consisting of aluminum sulfate, aluminum nitrate and aluminum chloride.

[0028] The preparation method of the pyrolysis gasoline selective hydrogenation catalyst according to the present application, in an embodiment, the temperature of the hydrothermal treatment is 120-200 DEG C, the time of the hydrothermal treatment is 4-24h, the calcination temperature is 800-1050 DEG C, and the calcination time is 3-8h.

[0029] The preparation method of the pyrolysis gasoline selective hydrogenation catalyst according to the present application, in an embodiment, the preparation method of the catalyst comprises: loading the precursor of the active component and the precursor of the auxiliary agent on the alumina.

[0030] The preparation method of the pyrolysis gasoline selective hydrogenation catalyst according to the present application, in an embodiment, the precursor of the active component comprises a soluble compound of palladium, and the precursor of the auxiliary agent comprises a soluble compound of the Group 6B metal and a soluble compound of the alkaline earth metal.

[0031] To achieve the above-mentioned purpose, the present application further provides the application of the catalyst obtained by the above-mentioned preparation method in the selective hydrogenation of pyrolysis gasoline.

[0032] The present application has the following beneficial effects:

[0033] The present application introduces CO2 gas in the preparation process of alumina, which can effectively neutralize the number of surface hydroxyl groups of alumina blades in the crystallization process of alumina, on the one hand, reduce the curling phenomenon of alumina blades in the crystallization process due to the condensation of hydroxyl groups, and effectively control the width of alumina blades, on the other hand, reduce the coordination saturation of hydroxyl groups and aluminum ions, so that the flaky alumina is conducive to chelation with active metals. In addition, the molar ratio of aluminum ions to compounds that can be decomposed into NH3 and CO2 is high, and the high molar ratio is conducive to improving the yield per kettle and effectively reducing the production cost. At the same time, the preparation method has the advantages of low cost and simple operation.

[0034] The alumina used in the catalyst of the present application has a blade-like aggregate structure, which has the characteristics of regular morphology, uniform particles, high crystallinity and high thermal stability. The blade-like aggregate structure overcomes the shortcomings of general nanosheet alumina products, which are difficult to separate and easy to agglomerate at high temperature. The blade-like aggregate structure of the alumina of the present application is simple to separate and does not agglomerate at high temperature, and can continue to maintain the nanosheet morphology. The semi-open "physical confinement" space constructed by the blade-like morphology can effectively prevent the coalescence of active metals, so as to facilitate the high dispersion of active metals as a carrier. At the same time, the carrier has a large pore size and a concentrated pore size distribution, which has a large diffusion rate for reactants and can significantly reduce the diffusion resistance. Therefore, as a carrier, it can greatly improve the hydrogenation activity and anti-carbon deposition performance of the catalyst. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 The SEM image of the alumina carrier obtained in Example 1 of the present application.

[0036] Figure 2 SEM image of the alumina support obtained in Inventive Comparative Example 1. DETAILED DESCRIPTION

[0037] The following detailed description of the embodiments of the present application is made on the premise of the technical solutions of the present application, and detailed implementation manners and processes are given, but the protection scope of the present application is not limited to the following examples. The experimental methods not specified in the following examples are generally carried out according to the conventional conditions.

[0038] The present application provides a pyrolysis gasoline selective hydrogenation catalyst, which comprises a carrier, an active component and an additive, the carrier is alumina, the alumina has a leaf-shaped aggregate structure, the active component comprises palladium, and the additive comprises a Group VI B metal and an alkaline earth metal; the content of the palladium in terms of metal is 0.1-0.5 wt%, the content of the Group VI B element in terms of metal is 0.1-3 wt%, and the content of the alkaline earth metal in terms of metal is 0.2-5 wt%, based on the total weight of the catalyst.

[0039] The alumina used in the catalyst of the present application has a leaf-shaped aggregate structure, that is, the alumina is mainly in the shape of leaves, and the leaves aggregate to form clusters, and has the characteristics of regular morphology, uniform particles, high crystallinity and high thermal stability. The leaf-shaped aggregate structure overcomes the shortcomings of general nanosheet-shaped alumina products, such as difficult separation and easy agglomeration at high temperature. The leaf-shaped aggregate structure alumina of the present application is simple to separate, does not agglomerate after high-temperature calcination, and can continue to maintain the nanosheet-shaped morphology. The semi-open "physical confinement" space constructed by the leaf-shaped morphology can effectively prevent the coalescence of active metals, so that the active metals are beneficial to high dispersion as the carrier. At the same time, the carrier has a large pore size and a concentrated pore size distribution, has a large diffusion rate for reactants, and can significantly reduce the diffusion resistance. Therefore, as the carrier, the catalyst can greatly improve the hydrogenation activity and carbon deposition resistance.

[0040] In an embodiment, the content of Pd in terms of metal is 0.2-0.4 wt%, the content of the Group VI B metal in terms of metal is 0.5-1.5 wt%, and the content of the alkaline earth metal in terms of metal is 0.5-2 wt%, based on the total weight of the pyrolysis gasoline selective hydrogenation catalyst of the present application. The catalyst of the present application has a specific surface area of 60-150 m 2 / g, and a pore volume of 0.4-0.6 cm 3 / g.

[0041] The present application does not particularly limit the existence form of the active component and the additive in the catalyst, which are generally supported on the carrier in the form of oxides. The catalyst is reduced before use, and the active component and the additive can generally be reduced to the metallic state.

[0042] In one embodiment, the Group VI B metal of the present application is at least one of Cr, Mo and W, and the alkaline earth metal is at least one of Mg, Ca, Sr and Ba.

[0043] In one embodiment, the present application also provides a method for preparing the above-mentioned alumina carrier, comprising:

[0044] Step 1, adding a compound capable of decomposing into NH3 and CO2 into an aqueous solution of inorganic aluminum salt, stirring until completely dissolved to form a mixed solution;

[0045] Step 2, introducing CO2 gas with a pressure of 0.1-2 MPa into the closed container where the mixed solution is located, and performing hydrothermal treatment and calcination to obtain alumina.

[0046] In the preparation process of alumina, the present application additionally introduces CO2 gas, which can effectively neutralize the number of surface hydroxyl groups of alumina blades during the crystallization process of alumina. On the one hand, it can reduce the curling phenomenon of alumina blades caused by hydroxyl condensation during the crystallization process, and can effectively control the width of alumina blades, thereby achieving the purpose of controlling the morphology of alumina. On the other hand, it can reduce the coordination saturation of hydroxyl groups with aluminum ions, so that the sheet-shaped alumina is conducive to chelation with active metals.

[0047] In one embodiment, the compound capable of decomposing into NH3 and CO2 of the present application refers to a compound capable of decomposing into NH3 and CO2 under the hydrothermal treatment conditions of step 2. The compound capable of decomposing into NH3 and CO2 of the present application can be one or more of ammonium carbonate, ammonium bicarbonate, urea and ammonium oxalate.

[0048] The aqueous solution of inorganic aluminum salt of the present application refers to a solution formed by dissolving inorganic aluminum salt in water. In one embodiment, the inorganic aluminum salt is a soluble aluminum-containing inorganic salt, and further can be one or more of aluminum sulfate, aluminum nitrate and aluminum chloride.

[0049] In one embodiment, the molar ratio of the inorganic aluminum salt of the present application to the compound capable of decomposing into NH3 and CO2 is 0.1-4.0, preferably 0.5-3, in terms of aluminum ions.

[0050] The hydrothermal treatment of step 2 of the present application is carried out in a closed container, such as a hydrothermal kettle or an autoclave. Step 1 dissolution step can be directly carried out in a closed container, or the mixed solution of step 1 can be introduced into a closed container after being obtained. The present application is not limited thereto.

[0051] After the CO2 gas with the pressure of 0.1-2 MPa is introduced into the closed container, the supply of the CO2 gas is cut off, and the closed container is in a closed state, and the hydrothermal treatment is started. The pressure in the hydrothermal treatment process includes the pressure generated by the decomposition of the compound capable of being decomposed into NH3 and CO2, the pressure generated in the reaction process of the inorganic aluminum salt and the compound capable of being decomposed into NH3 and CO2, and the pressure of the additional CO2 gas. The temperature of the hydrothermal treatment is 120-200 ℃, and the hydrothermal treatment time is 4-24 h. In an embodiment, the introduction of the CO2 gas with the pressure of 0.1-2 MPa into the closed container refers to the introduction of the CO2 gas into the closed container, so that the pressure in the closed container reaches 0.1-2 MPa.

[0052] After the hydrothermal treatment, the obtained product is subjected to solid-liquid separation, and the obtained solid is washed, dried, shaped, and calcined to obtain the leaf-shaped aggregate structure alumina. The solid-liquid separation method is not particularly limited in the present application, for example, filtration. The drying temperature is, for example, 80-120 ℃, and the drying time is 4-20 h.

[0053] Before the leaf-shaped aggregate structure alumina is shaped, one or two of the peptizing agent and the extrusion aid can be added as needed. The specific substances and the addition amount can be determined according to the existing knowledge in the art. For example, the peptizing agent can be nitric acid, and the addition amount is 3-5% of the total weight of the sample to be shaped; the extrusion aid can be sesbania powder, and the amount is generally 2-6% of the total weight of the sample to be shaped.

[0054] The calcination method and conditions are the commonly used method and conditions for the calcination of the catalyst carrier. The vertical furnace, rotary furnace, and mesh belt kiln can be used for calcination. The calcination conditions of the carrier are as follows: the calcination temperature is 800-1050 ℃, and the calcination time is 3-8 h. Preferably, the calcination temperature is 850-1000 ℃, and the calcination time is 4-6 h. The calcination temperature of the carrier is the calcination temperature of the carrier before impregnation of the active component Pd. Before calcination at this temperature, the carrier can be prepared by low-temperature calcination, but it is an intermediate transition calcination step.

[0055] The preparation method of the above-mentioned pyrolysis gasoline selective hydrogenation catalyst is not particularly limited in the present application. For example, the precursors of the active component and the precursors of the auxiliary agent are loaded on the alumina, and the loading method is, for example, impregnation.

[0056] The alkali earth metal in the catalyst is one or more of Mg, Ca, Sr and Ba, preferably one or both of Mg and Sr, and is preferably loaded on the alumina carrier in the form of soluble nitrate by impregnation. When the catalyst is used for selective hydrogenation of pyrolysis gasoline, the unsaturated olefins in the oil are easily polymerized and gelled on the acid centers of the catalyst, covering the active centers of the catalyst, blocking the pores of the catalyst, and causing activity to decrease. The addition of the alkali earth metal can adjust the acidity of the surface of the catalyst, reduce the polymerization of the olefins on the catalyst, and thus prolong the running period of the catalyst.

[0057] The group VI B metal in the catalyst is one or more of Cr, Mo and W, preferably one or both of Mo and W. The group VI B metal is preferably loaded on the alumina carrier in the form of soluble salt by impregnation, and the soluble salt of Cr, Mo and W can be chromium nitrate, ammonium molybdate and ammonium tungstate. Cr, Mo and W, as electron-donating active promoters, interact with the outer electron orbit of the metal palladium during the preparation of the catalyst, regulate the chemical environment of the active metal palladium atom, weaken the adsorption capacity of the active metal palladium atom on mono-olefins and impurities such as sulfur and arsenic with lone pair electrons, and thus improve the hydrogenation selectivity and impurity resistance of the catalyst.

[0058] The present application does not particularly limit the order of loading the active components, the alkali earth metal promoters and the group VI B metal promoters on the carrier. In one embodiment, the catalyst preparation method is as follows: soluble salt of the alkali earth metal element is dissolved in water, impregnated on the carrier, dried and calcined to obtain an alumina carrier containing the alkali earth metal element; a solution containing a salt of the noble metal palladium is used to impregnate the modified alumina carrier, which is washed, dried and calcined at 400-500°C for 3-4 hours to obtain a catalyst precursor containing palladium; then soluble salt of the group VI B metal element is dissolved in water, impregnated on the catalyst precursor loaded with the palladium component, dried and calcined at 400-500°C for 3-4 hours to obtain the catalyst product.

[0059] In another embodiment, the catalyst preparation method is as follows: a solution containing a salt of the noble metal palladium is used to impregnate the alumina carrier, which is washed, dried and calcined at 400-500°C for 3-4 hours to obtain a catalyst precursor containing palladium; then soluble salt of the group VI B metal element is dissolved in water, impregnated on the catalyst precursor loaded with the palladium component, dried and calcined at 400-500°C for 3-4 hours to obtain a catalyst precursor containing palladium and the group VI B element; soluble salt of the alkali earth metal element is dissolved in water, impregnated on the catalyst precursor carrier containing palladium and the group VI B element, and calcined at 400-500°C for 3-4 hours to obtain the catalyst product.

[0060] The catalyst of the present application is not limited to that obtained by the above-mentioned preparation method. Before use, the catalyst of the present application is preferably reduced by hydrogen at 80-100 DEG C for 4-10 hours.

[0061] The pyrolysis gasoline selective hydrogenation catalyst of the present application takes the leaflet-like aggregate structure alumina as the carrier, the leaflet-like aggregate structure alumina takes the cheap aluminum source as the raw material, and the leaflet-like aggregate structure alumina with regular morphology is obtained by hydrothermal treatment without adding a template agent, and the preparation method of the present application has the advantages of low cost, simple operation and simple synthesis conditions. Meanwhile, the leaflet-like aggregate structure alumina prepared by the present application is simple to separate, and does not agglomerate after high-temperature calcination, and can continue to maintain the nanosheet morphology, so that it can be applied to catalytic hydrogenation reaction as an excellent catalyst carrier.

[0062] The pyrolysis gasoline selective hydrogenation catalyst obtained by the method of the present application has excellent di-olefin hydrogenation activity, selectivity and carbon deposition resistance.

[0063] The technical solutions of the present application will be further described in detail below through specific examples.

[0064] Raw material source: The raw materials used in the present application are supplied by the National Pharmaceutical Group Chemical Reagent Co., Ltd.

[0065] Specific surface area and pore distribution analysis method: The pore volume, specific surface area and pore size distribution of the sample are determined on a Tristar 3020 full-automatic physical adsorption instrument of American Micromeritics Company.

[0066] Carrier morphology analysis method: The morphology of the sample is characterized on a scanning electron microscope (SEM) of German Zeiss Company.

[0067] Catalyst metal content analysis method: Measured by atomic absorption method.

[0068] Catalyst metal dispersion analysis method: CO chemical adsorption test, tested on an ASAP2020 automatic chemical adsorption instrument produced by American Micromeritics Company.

[0069] Catalyst carbon deposition content analysis method: The carbon content on the catalyst is determined by X-ray fluorescence method.

[0070] Oil analysis method:

[0071] Oil distillation range: Determined by petroleum product test method SYB-2110-60.

[0072] Bromine value: Determined by SH / T 0236-92 standard.

[0073] Di-olefin value: Determined by UOP326 standard.

[0074] Water content: measured according to GB / T 11133-89 standard.

[0075] Sulfur content: measured by WK-2B micro-coulomb meter.

[0076] Example 1

[0077] (1) Preparation of alumina carrier

[0078] 19.54 g of aluminum sulfate and 3.2 g of urea (molar ratio of aluminum ion to urea is 1.1) were added into 70 ml of deionized water, and after stirring and dissolving, the mixture was transferred into an autoclave, CO2 gas was introduced to 0.8 MPa, and the mixture was reacted in the autoclave at 200°C for 4 h. After cooling to room temperature, the precipitate was separated by filtration, washed, and dried. The prepared product was mixed with nitric acid, sesbania powder, and water to form a plastic body, which was extruded into a strip, then dried at 120°C for 4 h and calcined at 850°C for 4 h to obtain a nano-leaf aggregate alumina carrier. The prepared alumina carrier was determined by scanning electron microscopy, and the results are shown in Figure 1 .

[0079] (2) Preparation of catalyst

[0080] A certain amount of aqueous palladium chloride solution was impregnated onto the carrier prepared in (1) by equal volume impregnation method, dried at 120°C, and calcined at 450°C for 3 h to obtain a palladium-containing catalyst semi-product; a certain amount of ammonium heptamolybdate was dissolved in water to form an impregnation solution, which was used to impregnate the palladium-containing catalyst semi-product by equal volume impregnation method, dried at 120°C, and calcined at 400°C for 4 h to obtain a palladium-molybdenum-containing catalyst semi-product; then a certain amount of magnesium nitrate was dissolved in water to form an impregnation solution, which was used to impregnate the palladium-molybdenum-containing catalyst semi-product by equal volume impregnation method to obtain catalyst C1. The Pd content of C1 catalyst is 0.3 wt%, the Mo content is 1.5 wt%, the Mg content is 1.5 wt%, the metal dispersion is 32.7%, the specific surface area is 125 m 2 / g, and the pore volume is 0.55 cm 3 / g.

[0081] Comparative Example 1

[0082] (1) Preparation of alumina carrier

[0083] Commercially available alumina powder produced by carbonization method was mixed with nitric acid, sesbania powder, and water to form a plastic body, which was extruded into a strip, then dried at 120°C for 4 h and calcined at 980°C for 4 h to obtain an alumina carrier. The prepared alumina carrier was determined by scanning electron microscopy, and the results are shown in Figure 2 .

[0084] (2) Preparation of catalyst

[0085] The catalyst preparation process is the same as that of Example 1. The prepared Comparative Example D1 catalyst has a Pd content of 0.3 wt%, a Mo content of 1.5 wt%, a Mg content of 1.5 wt%, a metal dispersion of 18.2%, a specific surface area of 114 m2 / g, and a pore volume of 0.45 cm3 / g. 2 / g, and a pore volume of 0.45 cm 3 / g.

[0086] Comparative Example 2

[0087] (1) Preparation of an alumina carrier

[0088] The alumina was prepared by the method of existing patent CN201510276063.4: 7.5 g of aluminum nitrate and 6 g of urea were added to 70 mL of deionized water, and the mixture was magnetically stirred for 20 minutes to obtain a colorless transparent solution. Then the solution was transferred to a high-pressure reaction kettle, hydrogen was introduced to remove the air in the reaction kettle, and then the hydrogen pressure of the reaction kettle was set to 0.5 MPa, and the reaction kettle was sealed. The reaction kettle was heated to 120°C, and the reaction was carried out for 24 hours. After the reaction was completed, the reaction slurry was filtered, washed three times, and then dried at 80°C for 10 hours.

[0089] The prepared precipitate was mixed with nitric acid, sesbania powder and water to form a plastic body, which was extruded into a strip, then dried at 120°C for 4 h and calcined at 800°C for 4 h to obtain an alumina carrier.

[0090] (2) Catalyst preparation

[0091] The catalyst preparation process is the same as that of Example 1. The prepared Comparative Example D2 catalyst has a Pd content of 0.3 wt%, a Mo content of 1.5 wt%, a Mg content of 1.5 wt%, a metal dispersion of 20.3%, a specific surface area of 108 m2 / g, and a pore volume of 0.52 cm3 / g. 2 / g, and a pore volume of 0.45 cm 3 / g.

[0092] Example 2

[0093] (1) Preparation of an alumina carrier

[0094] 14.16 g of aluminum chloride and 1.32 g of ammonium bicarbonate (molar ratio of aluminum ions to ammonium bicarbonate is 3.5) were added to 70 mL of deionized water, and after stirring and dissolving, the mixture was transferred into an autoclave, CO2 gas was introduced to 2.0 MPa, and the reaction was carried out at 160°C in the autoclave for 12 h. After cooling to room temperature, the precipitate was separated by filtration, washed, and dried. The prepared product was mixed with nitric acid, sesbania powder and water to form a plastic body, which was extruded into a strip, then dried at 120°C for 4 h and calcined at 550°C for 4 h. A certain amount of calcium nitrate was dissolved in water to prepare an impregnation solution, and the carrier calcined at 550°C was impregnated by the equal volume impregnation method, then dried at 120°C for 4 h and calcined at 800°C for 8 h to prepare a Ca-containing nano-leaf-like aggregate alumina carrier.

[0095] (2) Catalyst preparation

[0096] A certain amount of palladium chloride, ammonium molybdate and ammonium tungstate aqueous solution was impregnated onto the carrier prepared in (1) by equal volume impregnation method, dried at 120°C and calcined at 450°C for 3h to obtain catalyst C2. The Pd content of C2 catalyst was 0.35wt%, Mo content was 0.5wt%, W content was 0.5wt%, Ca content was 0.2wt%, metal dispersion was 34.2%, specific surface area was 135m2 / g, pore volume was 0.60cm3 / g. 2 3

[0097] Example 3

[0098] (1) Preparation of alumina carrier

[0099] 22.0g of aluminum nitrate and 2.56g of ammonium carbonate (molar ratio of aluminum ion to ammonium carbonate was 2.2) were added into 70ml of deionized water, after stirring and dissolving, it was transferred into an autoclave, CO2 gas was introduced to 0.1MPa, and reacted at 120°C in the autoclave for 24h. After cooling to room temperature, the precipitate was separated by filtration, washed and dried. The prepared product was mixed with nitric acid, sesbania powder and water to knead into a plastic body, which was extruded into a strip, then dried at 120°C for 4h and calcined at 950°C for 4h to obtain a nano-leaf aggregate alumina carrier.

[0100] (2) Catalyst preparation

[0101] A certain amount of chromium nitrate was dissolved in water to prepare an impregnation solution, which was impregnated onto the carrier prepared in (1) by equal volume impregnation method, dried at 120°C and calcined at 450°C for 3h to obtain a chromium-containing catalyst semi-product; a certain amount of palladium chloride aqueous solution was impregnated onto the chromium-containing catalyst semi-product by equal volume impregnation method, dried at 120°C and calcined at 450°C for 4h to obtain a chromium and palladium-containing catalyst semi-product; then a certain amount of barium nitrate was dissolved in water to prepare an impregnation solution, which was impregnated onto the chromium and palladium-containing catalyst semi-product by equal volume impregnation method to obtain catalyst C3. The Pd content of C3 catalyst was 0.4wt%, Cr content was 0.1wt%, Ba content was 2.0wt%, metal dispersion was 33.2%, specific surface area was 100m2 / g, pore volume was 0.51cm3 / g. 2 3

[0102] Example 4

[0103] (1) Preparation of alumina carrier

[0104] ​​​​A certain amount of aluminum nitrate, 7.08 g of aluminum chloride and 4.85 g of ammonium oxalate (molar ratio of aluminum ions and ammonium oxalate is 1.5) were added into 70 ml of deionized water, after stirring and dissolving, it was transferred into an autoclave, CO2 gas was introduced to 1.2 MPa, and reacted at 180 ℃ in the autoclave for 8 h. After cooling to room temperature, the precipitate was separated by filtration, washed and dried. The prepared product was mixed with nitric acid, sesbania powder and water to form a plastic body, which was extruded into a strip, then dried at 120 ℃ for 4 h and calcined at 550 ℃ for 4 h. A certain amount of calcium nitrate and strontium nitrate was dissolved in water to prepare an impregnation solution, and the carrier calcined at 550 ℃ was impregnated by the equal volume impregnation method, then dried at 120 ℃ for 4 h and calcined at 900 ℃ for 6 h, to prepare a Ca and Sr containing nano-leaf-like aggregate alumina carrier.

[0105] (2) Catalyst preparation

[0106] A certain amount of aqueous solution of palladium chloride was impregnated into the carrier prepared in (1) by the equal volume impregnation method, dried at 120 ℃ and calcined at 450 ℃ for 4 h to obtain a palladium containing catalyst semi-product; a certain amount of ammonium heptamolybdate and chromium nitrate was dissolved in water to prepare an impregnation solution, which was used to impregnate the palladium containing catalyst semi-product by the equal volume impregnation method, dried at 120 ℃ and calcined at 400 ℃ for 4 h to obtain a catalyst C4 containing palladium, molybdenum and chromium. The Pd content of C4 catalyst is 0.2 wt%, the Mo content is 2.0 wt%, the Cr content is 1.0 wt%, the Ca content is 0.3 wt%, the Sr content is 0.2 wt%, the metal dispersion is 31.8%, the specific surface area is 109 m2 / g and the pore volume is 0.53 cm3 / g. 2 3

[0107] Comparative Example 3

[0108] (1) Preparation of alumina carrier

[0109] The alumina was prepared by the method of existing patent CN201210427889.2: 50 ml of aluminum nitrate solution with a concentration of 0.5 mol / L was measured, 12 g of urea was added to the above solution to make the molar ratio of urea to Al 3+ be 8:1, and the above solution was transferred into a reaction kettle and reacted at 180 ℃ for 9 hours under sealed conditions. The obtained precipitate was dried at 80 ℃ for 35 hours without washing and filtering.

[0110] The prepared precipitate product was mixed with nitric acid, sesbania powder and water to form a plastic body, which was extruded into a strip, then dried at 120 ℃ for 4 h and calcined at 550 ℃ for 4 h. A certain amount of calcium nitrate and strontium nitrate was dissolved in water to prepare an impregnation solution, and the carrier calcined at 550 ℃ was impregnated by the equal volume impregnation method, then dried at 120 ℃ for 4 h and calcined at 950 ℃ for 4 h, to prepare a Ca and Sr containing nano-leaf-like aggregate alumina carrier.

[0111] ​​(2) Catalyst preparation

[0112] The catalyst preparation process was the same as in Example 4. The prepared Comparative Example D3 catalyst had a Pd content of 0.2 wt%, a Mo content of 2.0 wt%, a Cr content of 1.0 wt%, a Ca content of 0.3 wt%, a Sr content of 0.2 wt%, a metal dispersion of 19.6%, a specific surface area of 98 m 2 / g, and a pore volume of 0.49 cm 3 / g.

[0113] Comparative Example 4

[0114] (1) Preparation of the alumina support

[0115] The alumina was prepared by the method of existing patent CN201110351132.5: 0.2 g of urea was dissolved in 6.0 ml of deionized water, and 8.0 ml of an aluminum nitrate nonahydrate aqueous solution (0.2 M) was added. After stirring to uniformity, the solution was transferred into a stainless steel pressure-resistant reaction kettle, and reacted at 150°C for 20 hours. The obtained precipitate was separated by centrifugation, washed with deionized water and anhydrous ethanol three times each, and vacuum dried.

[0116] The obtained precipitate product was mixed with nitric acid, sesbania powder, and water to knead into a plastic body, extruded into a strip, and then dried at 120°C for 4 h and calcined at 550°C for 4 h. A certain amount of calcium nitrate and strontium nitrate was dissolved in water to prepare an impregnation solution, and the support calcined at 550°C was impregnated by the equal volume impregnation method, and then dried at 120°C for 4 h and calcined at 980°C for 4 h to prepare the Ca- and Sr-containing nanosheet aggregate alumina support.

[0117] (2) Catalyst preparation

[0118] The catalyst preparation process was the same as in Example 4. The prepared Comparative Example D4 catalyst had a Pd content of 0.2 wt%, a Mo content of 2.0 wt%, a Cr content of 1.0 wt%, a Ca content of 0.3 wt%, a Sr content of 0.2 wt%, a metal dispersion of 21.3%, a specific surface area of 104 m 2 / g, and a pore volume of 0.48 cm 3 / g.

[0119] Example 5

[0120] (1) Preparation of the alumina support

[0121] A certain amount of aluminum sulfate, 11 g of aluminum nitrate, 0.44 g of urea, 0.91 g of ammonium oxalate (molar ratio of aluminum ion to urea and ammonium oxalate is 4) were added into 70 ml of deionized water, and after stirring and dissolving, the solution was transferred into an autoclave, CO2 gas was introduced to 0.4 MPa, and reaction was carried out at 140°C in the autoclave for 20 h. After cooling to room temperature, the precipitate was separated by filtration, washed and dried. The product was mixed with nitric acid, sesbania powder and water to form a plastic body, which was extruded into a strip, then dried at 120°C for 4 h and calcined at 1050°C for 5 h to obtain a nano-leaf aggregate alumina carrier.

[0122] (2) Catalyst preparation

[0123] A certain amount of palladium chloride and aqueous tungsten acid ammonium solution was impregnated onto the carrier prepared in (1) by equal volume impregnation method, dried at 120°C and calcined at 450°C for 4 h to obtain a palladium and tungsten-containing catalyst semi-product; a certain amount of barium nitrate and calcium nitrate was dissolved in water to form an impregnation solution, which was used to impregnate the palladium and tungsten-containing catalyst semi-product by equal volume impregnation method, dried at 120°C and calcined at 450°C for 4 h to obtain catalyst C5. The Pd content of C5 catalyst is 0.1 wt%, the W content is 2.0 wt%, the Ba content is 2.5 wt%, the Ca content is 2.5 wt%, the metal dispersion is 29.8%, the specific surface area is 72 m 2 / g, and the pore volume is 0.45 cm 3 / g.

[0124] Example 6

[0125] (1) Preparation of an alumina carrier

[0126] A certain amount of aluminum nitrate, 4.71 g of aluminum chloride, 6.5 g of aluminum sulfate and 28.16 g of ammonium carbonate, 17.60 g of urea (molar ratio of aluminum ion to ammonium carbonate and urea is 0.1) were added into 70 ml of deionized water, and after stirring and dissolving, the solution was transferred into an autoclave, CO2 gas was introduced to 1.6 MPa, and reaction was carried out at 150°C in the autoclave for 16 h. After cooling to room temperature, the precipitate was separated by filtration, washed and dried. The product was mixed with nitric acid, sesbania powder and water to form a plastic body, which was extruded into a strip, then dried at 120°C for 4 h and calcined at 1000°C for 3 h to obtain a nano-leaf aggregate alumina carrier.

[0127] (2) Catalyst preparation

[0128] A certain amount of aqueous solution of palladium chloride was impregnated onto the carrier prepared in (1) by equal volume impregnation method, dried at 120°C, and calcined at 450°C for 3h to obtain a catalyst semi-product containing palladium; a certain amount of chromium nitrate and ammonium tungstate were dissolved in water to prepare an impregnation solution, which was used to impregnate the catalyst semi-product containing palladium by equal volume impregnation method, dried at 120°C, and calcined at 400°C for 4h to obtain a catalyst semi-product containing palladium, chromium and tungsten; and then a certain amount of magnesium nitrate and strontium nitrate were dissolved in water to prepare an impregnation solution, which was used to impregnate the catalyst semi-product containing palladium, chromium and tungsten by equal volume impregnation method to obtain catalyst C6. The Pd content of C6 catalyst was 0.5wt%, the Cr content was 0.2wt%, the W content was 0.3wt%, the Sr content was 2.0wt%, the Mg content was 1.0wt%, the metal dispersion was 30.2%, the specific surface area was 95m 2 / g, and the pore volume was 0.50cm 3 / g.

[0129] Table 1 Catalyst composition and physical property indexes of examples and comparative examples

[0130]

[0131]

[0132] The performances of the catalysts C1-C6 of examples and the catalysts D1-D4 of comparative examples in the hydrogenation reaction of pyrolysis gasoline C6-C7 fraction feedstock were as follows:

[0133] The loading amount of the catalyst in the adiabatic fixed bed reactor was 50mL, and the catalyst was reduced at 100°C under hydrogen atmosphere for 8h before use.

[0134] During the hydrogenation process, the fresh oil feedstock of pyrolysis gasoline had a volume space velocity of 2.0h -1 , the reaction pressure was 2.8MPa, the hydrogen / oil volume ratio was 150:1, and the reactor inlet temperature was 40°C. The catalyst evaluation time was 300h.

[0135] The composition of the hydrogenation reaction material was shown in Table 2.

[0136] Table 2 Properties of pyrolysis gasoline C6-C7 fraction feedstock

[0137]

[0138] The results of the catalyst hydrogenation performance evaluation were shown in Table 3.

[0139] Table 3 Catalyst evaluation results of examples and comparative examples

[0140]

[0141] From the evaluation results of the catalysts of the examples and the comparative examples in Table 3, it can be seen that under the same hydrogenation process conditions, the hydrogenation product of the catalyst of the present application has low diene value and high bromine value, and the carbon deposition content on the catalyst is low after 300 hours of operation, which indicates that the catalyst of the present application not only has excellent diene hydrogenation activity and selectivity, but also has excellent anti-coking performance, which is beneficial to the long-period stable operation of the catalyst.

[0142] Of course, the present application can have other various embodiments, and those skilled in the art can make various corresponding changes and modifications according to the present application without departing from the spirit and essence of the present application, but these corresponding changes and modifications shall all belong to the protection scope of the claims of the present application.

Claims

1. A selective hydrotreating catalyst for cracked gasoline, using alumina as a support and palladium as the active component, characterized in that, It also includes auxiliary agents, metal VIB and alkaline earth metals. The alumina support has a leaf-like aggregate structure. Based on the total weight of the catalyst, the palladium content (calculated as metal) is 0.1–0.5 wt%, the metal VIB content (calculated as metal) is 0.1–3 wt%, the alkaline earth metal content (calculated as metal) is 0.2–5 wt%, and the balance is the alumina support. The specific surface area of ​​the catalyst is 60–150 m². 2 / g, pore volume 0.4~0.6cm 3 / g; the carrier alumina is prepared by hydrothermal synthesis.

2. The selective hydrotreating catalyst for cracked gasoline according to claim 1, characterized in that, Based on the total weight of the catalyst, the content of Pd (as metal) is 0.2-0.4 wt%, the content of VIB (as metal) is 0.5-1.5 wt%, and the content of alkaline earth metal (as metal) is 0.5-2 wt%.

3. The selective hydrotreating catalyst for cracked gasoline according to claim 1, characterized in that, The VIB metal is at least one of Cr, Mo, and W; the alkaline earth metal is at least one of Mg, Ca, Sr, and Ba.

4. The selective hydrotreating catalyst for cracked gasoline according to claim 3, characterized in that, The VIB metal is one or both of Mo and W; the alkaline earth metal is one or both of Mg and Sr.

5. A method for preparing a selective hydrogenation catalyst for cracked gasoline as described in any one of claims 1-4, characterized in that, The catalyst comprises a support, an active component, and an auxiliary agent. The support is alumina, the active component includes palladium, and the auxiliary agent includes a VIB metal and an alkaline earth metal. The method for preparing the alumina includes: Step 1: Add a compound that can decompose into NH3 and CO2 to the inorganic aluminum salt aqueous solution, and stir until completely dissolved to form a mixed solution; Step 2: CO2 gas at a pressure of 0.1–2 MPa is introduced into a sealed container containing the mixed solution for hydrothermal treatment and calcination to obtain alumina.

6. The method for preparing the selective hydrogenation catalyst for cracked gasoline according to claim 5, characterized in that, The compound that can decompose into NH3 and CO2 is at least one of the group consisting of ammonium carbonate, ammonium bicarbonate, urea and ammonium oxalate.

7. The method for preparing the selective hydrogenation catalyst for cracked gasoline according to claim 5, characterized in that, The inorganic aluminum salt in the aqueous solution is calculated as aluminum ions, and the molar ratio of the inorganic aluminum salt to the compound that can decompose into NH3 and CO2 is 0.1 to 4.0; the inorganic aluminum salt is at least one of the group consisting of aluminum sulfate, aluminum nitrate and aluminum chloride.

8. The method for preparing the selective hydrogenation catalyst for cracked gasoline according to claim 7, characterized in that, In the aqueous solution of inorganic aluminum salt, the inorganic aluminum salt is expressed as aluminum ions, and the molar ratio of the inorganic aluminum salt to the compound that can decompose into NH3 and CO2 is 0.5 to 3.

9. The method for preparing the selective hydrogenation catalyst for cracked gasoline according to claim 5, characterized in that, The hydrothermal treatment temperature is 120–200℃, the hydrothermal treatment time is 4–24 h, the calcination temperature is 800–1050℃, and the calcination time is 3–8 h.

10. The method for preparing the selective hydrogenation catalyst for cracked gasoline according to claim 9, characterized in that, The roasting temperature is 850~1000℃ and the roasting time is 4~6h.

11. The method for preparing the selective hydrogenation catalyst for cracked gasoline according to claim 5, characterized in that, The method for preparing the catalyst includes: loading the precursor of the active component and the precursor of the auxiliary agent onto the alumina.

12. The method for preparing the selective hydrogenation catalyst for cracked gasoline according to claim 5, characterized in that, The precursor of the active component includes a palladium-soluble compound, and the precursor of the auxiliary includes a VIB metal-soluble compound and an alkaline earth metal-soluble compound, wherein the alkaline earth metal-soluble compound is preferably an alkaline earth metal nitrate.

13. The application of the catalyst obtained by the preparation method according to any one of claims 5 to 12 in the selective hydrogenation of cracked gasoline.

Images