CN107096552B - A kind of catalyst and preparation method for FCC gasoline removal of mercaptans - Google Patents

Abstract

The invention relates to a catalyst for FCC gasoline desulfurization. The catalyst comprises an alumina carrier with a macroporous structure and metal active components nickel and molybdenum supported on the carrier. The alumina with a macroporous structure is based on weight percent. The carrier is 66-91wt%, the carrier contains auxiliary components phosphorus and magnesium, the pore size distribution is 60-180nm, the macropore ratio is 2-75%, the pore volume is 0.8-2.0ml/g, and the specific surface area is 250-300m ² /g. The nickel oxide content is 5-19wt%, and the molybdenum oxide content is 2-15wt%. The catalyst has high desulfurization activity, high diolefin hydrogenation selectivity and low octane loss.

Description

A kind of catalyst for FCC gasoline desulfurization and preparation method

technical field

The invention relates to a catalyst for FCC gasoline desulfurization and a preparation method.

Background technique

With the increasingly strict environmental regulations, countries around the world have put forward more and more stringent requirements for the quality of petroleum processing products, especially the restrictions on the sulfur content of petroleum processing products are becoming more and more strict. The sulfides contained in light petroleum products are mainly mercaptans (RSH), sulfides (RSR), etc. Among them, mercaptans have the greatest impact on product quality. product stability.

CN1229838A discloses a method for converting hydrocarbon oil. The method is to desulfurize raw oil and a hydrorefining catalyst under the process conditions of hydrodesthiol, and the hydrorefining catalyst contains a Tungsten oxide (molybdenum), nickel oxide and cobalt oxide, wherein the content of tungsten oxide (molybdenum) is 4-10wt%, the content of nickel oxide is 1-5wt%, the content of cobalt oxide is 0.01-0.1wt%, nickel and cobalt The ratio of the total atomic number to that of nickel, cobalt, and tungsten (molybdenum) is 0.3-0.9. CN102451694A discloses a hydrodesthiol catalyst and a preparation method and application thereof. The catalyst uses alumina or silicon-containing alumina as the carrier, phosphorus as the auxiliary component, copper and zinc as the active components, and the content of the auxiliary phosphorus is 0.5-3.0 wt% based on the quality of the catalyst. The content of copper oxide is 3-15wt%, and the content of copper oxide is 5-30wt%. Due to the strong hydrogenation activity of the catalyst, the mercaptan content was reduced from 38μg/g to 3μg/g, and the olefin content was also reduced from 25v% to 20v%, and the RON loss was as high as 1.3 when used in the treatment of full-cut FCC gasoline. units. CN00136870.2 provides a selective desulfurization catalyst for removing mercaptan sulfur in aviation fuel and a preparation method thereof. The catalyst comprises the following components by weight: 1. molybdenum oxide 7-20; 2. cobalt oxide 0.1-5; 3. nickel oxide 0-5; 4. silicon dioxide 0-10; 5. phosphorus or boron or fluorine 0-4; 6. oxidation Aluminum 0-40; ⑦ Titanium dioxide 60-100. The preparation method of the catalyst is as follows: the catalyst carrier is impregnated with the impregnating liquid for 1-2 hours, then dried at 100-130 DEG C, and finally calcined at 400-550 DEG C for 2-6 hours to obtain the catalyst. The catalyst has good removal effect and good low temperature activity for mercaptan sulfur in jet fuel. CN201210393263.4 relates to a preparation method and application of a novel gasoline desulfurizer adsorbent. The preparation method of the gasoline sweetening alcohol adsorbent comprises the following steps: uniformly mixing a solvent, a metal ion precursor and a mesoporous material, aging, adding an organic ligand, and performing a hydrothermal crystallization treatment; then, performing a hydrothermal crystallization treatment on The obtained product is filtered, washed and dried to obtain a zeolite imidazole framework material/mesoporous material composite; the zeolite imidazole framework material/mesoporous material composite is subjected to tablet molding, crushing and screening to obtain gasoline sweetener adsorbent. In the zeolite imidazole framework material/mesoporous material composite provided by the present invention, the zeolite imidazole framework material has a high specific surface area and is in a highly dispersed state on the mesoporous material, effectively solving the diffusion limitation caused by agglomeration. The solvent is one or a combination of deionized water, methanol, ethanol and N,N-dimethylformamide; the metal ion is one of Zn ²⁺ , Cu ²⁺ and Co ²⁺ . One or more combinations; the metal ion precursor is one or more combinations of metal ion nitrate and/or acetate; the organic ligands are imidazole, 2-methylimidazole, 2 - One or more of nitroimidazole and benzimidazole; the mesoporous material is a modified ordered mesoporous molecular sieve. CN200910082945.1 relates to a catalytic cracking gasoline selective hydrogenation catalyst and a preparation method thereof. The catalyst of the invention is composed of Al ₂ O ₃ -TiO ₂ composite oxide carrier and active metal oxide. According to the weight percentage of the catalyst, the content of NiO in the active metal oxide is 10-20w%, and the content of MoO ₃ is 5%. -12w%; wherein the weight ratio of the carrier Al ₂ O ₃ -TiO ₂ oxide TiO ₂ : Al ₂ O ₃ is 0.01-1:1. Under the conditions of low temperature (100-200° C.), low pressure (1-3.0 MPa) and low hydrogen-to-oil ratio (hydrogen-oil volume ratio of 5:1-100:1), the catalyst of the present invention treats catalytically cracked gasoline, and shows high performance. The activity, selectivity and stability of the dediolefine and thiol desulfurizers. CN200910187903.4 discloses a hydrodesthiol catalyst and its preparation method and application. The catalyst uses HZSM-5 molecular sieve as the main carrier component, and copper and zinc as the active components. The active components are based on the weight of oxides, the content of copper oxide is 5%-27%, and the content of zinc oxide is 3%-15%, which is prepared by saturated co-dipping technology. The catalyst of the invention is suitable for the selective hydrodesulfurization reaction of light oil products, and has the characteristics of high desulfurization activity and low olefin hydrogenation activity, high liquid yield after the reaction, and little loss of octane number. CN201610187374.8 provides a light hydrocarbon desulfurization catalyst based on the control of alumina crystal plane and a preparation method thereof. The catalyst uses the γ-alumina regulated by the hydrothermal treatment of the present invention as a carrier, and uses nickel and molybdenum as active metals . The light hydrocarbon desulfurization catalyst of the present invention is a catalyst with high activity and high selectivity, which can be used to catalyze the action of mercaptans and diolefins in light hydrocarbons to generate macromolecular sulfides, and can also catalyze the selectivity of diolefins Hydrogenation is saturated, compared with the existing catalysts, the catalyst provided by the invention has high desulfurization activity, high diolefin hydrogenation selectivity, and no loss of active components and is not easy to be deactivated, so the catalyst has a long operating period and has good performance. prospects for industrial applications. The γ-alumina regulated by the hydrothermal treatment of the present invention, as mentioned above, the γ-alumina is characterized in that it has highly exposed (111) and (110) crystal planes, so that the active metal nickel in the catalyst of the present invention is (Ni) and molybdenum (Mo) can achieve preferential loading on this γ-alumina crystal plane, with metallic Ni preferentially loaded on the newly exposed (111) plane, and metallic Mo preferentially loaded on the newly exposed (111) plane. 110) crystal plane. At the same time, the two active metals also form two different active crystal planes through the interaction with the modified γ-alumina (111) and (110) crystal planes, thereby obtaining high activity and high selectivity. High quality hydrocarbon desulfanization catalyst. The catalyst can efficiently remove mercaptans and/or diolefins in light fractions such as liquefied petroleum gas, FCC gasoline, catalytic pyrolysis gasoline, and coker gasoline, while retaining the olefins in the feedstock, and the octane RON of gasoline is only reduced by 0.3 It can realize high value-added utilization of light hydrocarbons.

The composition and content of the above-mentioned catalyst are relatively large, the preparation process is complicated, and the quality of the mass-produced catalyst product is difficult to control.

Macroporous oxides are widely used in heterogeneous catalysts, catalyst supports, adsorption and separation materials, chromatography fillers, electrode materials, acoustic resistance and thermal resistance materials due to their large pore structure, high specific surface area and good thermal stability. and other fields.

There are many supports of alumina with macroporous structure. CN03126434.4 discloses a macroporous alumina carrier, containing alumina and a halogen, based on the total amount of the carrier, the carrier contains 95-99% by weight of alumina, based on the element, 0.1-5% by weight The halogen, its acid content is less than 0.2 mmol/g. The preparation method of the macroporous alumina carrier comprises forming and calcining a precursor of alumina, and before forming and calcining, mixing the precursor of alumina with a pore-enlarging agent, the pore-enhancing agent comprising an organic Pore-enlarging agent and a halide, the calcination temperature is 600-850 ℃, the calcination time is 1-10 hours, the amount of each component is such that the final alumina carrier contains, based on the total amount of the carrier, 95-99% by weight Alumina, calculated as element, 0.1-5 wt% halogen. The organic pore expander is selected from one or more of starch, synthetic cellulose, polyalcohol, and surfactant. The synthetic cellulose is selected from one or more of carboxymethyl cellulose, methyl cellulose, ethyl cellulose and hydroxy cellulose. The polyalcohol is selected from one or more of polyethylene glycol, polypropanol and polyvinyl alcohol, and the surfactant is selected from fatty alcohol polyoxyethylene ether, fatty alcohol amide, acrylic copolymer with molecular weight of 200-10000, cis One or more of crotonic acid copolymers. CN201110410339.5 provides a high temperature resistant active alumina material and a preparation method thereof. The alumina material is prepared by the following steps: mixing macroporous pseudo-boehmite, high-viscosity pseudo-boehmite and additives with water Then, stir evenly at a rotating speed of 100-1000 r/min, and then add dilute nitric acid with a concentration of 30% to react until the pH is 2.0-5.5. 6h, adding pore-forming agent at room temperature, stirring evenly, slurrying, spraying, drying, and calcining at 900 °C to obtain alumina. The alumina material has the advantages of easy mass production and high specific surface area. At a temperature of 1000-1100° C., the specific surface can be kept above 110 m ² /g for a long time; the process for preparing the alumina material is simple and the cost is low. The air-forming agent is selected from one of polyvinyl alcohol, polyethylene glycol, polyacrylamide or methyl cellulose, and the amount thereof is 0-40% of the total weight of oxides in the alumina material. The method introduced in "Journal of Sun Yat-sen University" (2002, 41(2): 121-122) is as follows: polystyrene colloidal microspheres with a diameter of 600 nm are placed on a Buchner funnel, and then aluminum nitrate and citric acid in ethanol The solution was added dropwise to the colloidal crystals under suction filtration to allow it to fully penetrate into the gaps of the microspheres. After drying and calcination, the polystyrene template was removed to obtain macroporous alumina. "Acta Physical Chemistry" (2006, 22(7): 831-835) introduced a method for preparing three-dimensional ordered macroporous alumina by particle template method. The method is as follows: Firstly, polystyrene microspheres are obtained by emulsion polymerization, and then Aluminum nitrate is added with dilute ammonia water to obtain alumina sol, and then the two are stirred and mixed in a certain proportion, ultrasonically treated, and then dried and calcined to obtain macroporous alumina. CN201010221302.3 (CN102311134A) discloses a spherical integral macroporous alumina and a preparation method thereof. The method includes the following steps: mixing the polymer microsphere emulsion, the alumina sol and the coagulant uniformly in a certain proportion, dispersing the mixture in the oil phase to form W/O type droplets, and then heating the above mixed-phase system, The alumina sol in the water phase is gelled into spheres, then the formed gel microspheres are separated from the oil phase, and the spherical integral macroporous oxidation is obtained after aging, drying and roasting in an aqueous ammonia medium aluminum. The macropore diameter of the alumina is uniform and controllable within the range of less than 1 μm, the size of the spherical particles is controllable, the mechanical strength is high, the forming process is simple and easy, and it is convenient for mass production. The diameter of the polymer microspheres is 50-1000nm, and the types of the polymer microspheres are polystyrene microspheres, poly(n-butyl phenylacrylate) microspheres, polyacrylate and other ester microspheres. The coagulant is hexamethylenetetramine and urea. The oil phase is organic hydrocarbons. The invention mainly prepares monolithic macroporous alumina, and the macropore diameter is uniform and controllable. The preparation process used lipid microspheres and coagulants. The preparation process is complicated, and the reagents and raw materials used are relatively large. Due to the polymer microspheres used, the internal pore structure of the alumina carrier is closed pores, that is to say, the internal pores of the alumina carrier do not have continuity. CN201010221297.6 discloses a preparation method of monolithic macroporous alumina. The method includes the following steps: after uniformly mixing aluminum source, polyethylene glycol and at least one selected from low-carbon alcohol and water, adding low-carbon alkylene oxide to the mixture, and obtaining the obtained by aging, soaking, drying and roasting Monolithic macroporous alumina. The preparation method of the invention is simple and feasible, and has little environmental pollution, and the obtained monolithic macroporous alumina has a controllable pore diameter of 0.05-10 μm. The monolithic macroporous oxide provided by the invention can be applied to the fields of macromolecular heterogeneous catalysis, adsorption separation materials, chromatographic fillers, electrode materials, acoustic resistance and thermal resistance materials and the like. CN201410347665.X discloses a preparation method of alumina with large pore volume and high strength. By adding pore-enlarging agents such as polyacrylamide, polyvinyl alcohol, alkyl cellulose, succulent powder, starch, etc., an oxide containing macropores is obtained. For the aluminum support, the amount of the pore expander accounts for 10-30% of the alumina, but the specific pore size range is not disclosed. Although the hard templating agent method can obtain better macroporous alumina carrier, the amount of templating agent is preferably greater than 20%, which leads to a substantial increase in processing cost, and the decomposition of a large amount of templating agent does not meet the development requirements of low-carbon and environmental protection. CN201010509425.7 discloses a method for co-expanding pores with hydrothermal and templating agent to prepare alumina carrier with macroporous structure. Through hydrothermal auxiliary pore-enlarging action, the dosage of templating agent can be reduced to 3-10%, However, the auxiliary water heat causes the increase of energy consumption. CN200310103035.X discloses a preparation method of macroporous alumina. Polyvinyl alcohol, polypropanol and polyethylene glycol soft template are used for pore expansion. By adding 1% polyethylene glycol, the pore volume is greater than 100 nm. 26.2% of the total pore volume. Soft templating agents have the advantages of low dosage and good pore-enlarging effect, but higher molecular weight alcohol-based soft templating agents have poor solubility in water, which limits their use in expanding macroporous alumina. CN200910204238.5 (CN102040235) discloses a three-dimensional ordered macroporous alumina and a preparation method thereof. The method includes the following steps: assembling monodisperse polymer microspheres into a colloidal crystal template, then filling the template with alumina sol prepared by a specific method, and finally drying and calcining to obtain macroporous alumina. The method can well control the aluminum sol and the composite process of the aluminum sol and the polymer microspheres, without destroying the network structure of the alumina gel as much as possible, so that the prepared alumina not only has three-dimensional ordered macropore channels but also Has a high specific surface area. According to the invention, through the small window holes formed by moderate sintering of the template, the large holes in the material are connected with the surrounding large holes through 12 small window holes. The alumina of the invention is suitable for use as a catalyst carrier for heavy oil and an adsorption and separation material for organic macromolecules. In the application of catalyst carrier materials, it is beneficial to improve the mass transfer capacity of the material in the catalyst, and it is beneficial to improve the activity and selectivity of the catalyst. CN201410148773.4 discloses a preparation method of alumina porous microspheres. Octanol is mixed, stirred, and used as the oil phase; 3) Span80 and porogen are added to the oil phase, and stirred; 4) The clear oil phase obtained in step 3) is poured into the water phase with continuous stirring and emulsification; 5) The step 4) The resultant is vacuum filtered, and the obtained filter cake is washed and then dried to obtain alumina porous microspheres. The microsphere has an internal closed macroporous structure, and the size of the microsphere is 1 μm-100 μm. The invention utilizes the sol-gel process in the porogen and the emulsion to obtain the metal porous microsphere with the internal closed macroporous structure. Porous microspheres were prepared using the principle of phase separation. The inner closed pore size is 50nm-5μm. The inner closed pore size is 50nm-5μm. The inner pore size of the alumina porous microspheres is closed, that is to say, the inner pores of the alumina carrier do not have continuity. The porogen is polyvinylpyrrolidone, polyacrylamide or polyacrylic acid. The invention uses a large amount of surfactants, chelating agents and porogens, has many raw materials for preparation and complicated synthesis process.

The above macroporous alumina is mainly prepared by using cellulose, polyalcohol, polystyrene, etc. as pore-enlarging agents to prepare macroporous alumina.

There are also many alumina supports with macropores and mesopores, that is, composite pore structures. CN101200297A discloses the preparation method of monolithic macroporous alumina: adopting inverse concentrated emulsion method to prepare monolithic macroporous organic template with styrene and divinylbenzene as monomers; using aluminum isopropoxide or pseudoboehmite as precursor Al ₂ O ₃ hydrosol was prepared from the composite material; the Al ₂ O ₃ hydrosol was filled into the monolithic macroporous organic template; the monolithic organic/inorganic composite after filling was dried and calcined at 600℃-900℃ to remove the template. Monolithic macroporous alumina is obtained. The advantage of this method is that the preparation process is simple and feasible, and the prepared monolithic macroporous alumina has micron-scale interconnected macropore channels, and the pore diameter is 1-50 μm. This method is simple and easy to prepare monolithic macroporous alumina, but the volume fraction of the water phase in this method accounts for 75%-90%, and the volume fraction of organic monomers is relatively low accordingly. This method can reduce the consumption of organic monomers. At the same time, the preparation efficiency of the prepared template is also low, which is not conducive to the batch preparation of macroporous alumina in subsequent steps. CN201110032234.0 A preparation method of alumina carrier with composite pore structure, comprising at least one selected from aluminum isopropoxide, aluminum sec-butoxide, aluminum nitrate, aluminum chloride, aluminum sol and pseudo-boehmite powder The aluminum-containing compound and the composite templating agent are mixed and calcined, the composite templating agent is a mesoporous templating agent and a macroporous particle templating agent, and the mesoporous templating agent is selected from polyethylene glycol-polypropylene glycol-polyethylene glycol tri-block at least one of segment polymer, polyethylene glycol, dodecylamine, cetyltrimethylammonium bromide, lauric acid, stearic acid and fatty alcohol polyoxyethylene ether, the macroporous particle template The agent is selected from polystyrene microspheres, polymethyl methacrylate microspheres, biomaterial particles, asphalt particles or heavy oil residues with a particle size greater than 50 nm; the mesoporous template agent, macroporous particle template agent and aluminum-containing compound The weight ratio is 0.1-2:0.1-0.7:1, wherein the weight of the aluminum-containing compound is based on alumina. The present invention also discloses an alumina carrier having both mesoporous channels and macroporous channels prepared by the above method, wherein the mesopores account for 40%-90% of the total pore volume, and the macropores account for 10%-60% of the total pore volume . CN201210328824.2 discloses a solid-phase preparation method of γ-alumina with gradient distribution pores. The method is to obtain the precursor ammonium aluminum carbonate through solid-phase reaction, and obtain a γ-alumina with higher specific surface area, gradient distribution pores and larger pore volume after calcination. The most prominent technical feature of the present invention is that the raw material solid-phase reaction synthesis technology is adopted, and the properties of the obtained γ-alumina are controlled by synthesis conditions. At the same time, the method of the invention is simple, easy to operate, does not need to add a pore-enlarging agent, saves costs, and is suitable for industrialized mass production. The preparation process of the alumina carrier of the present invention comprises the following steps: (1) fully grinding aluminum nitrate, ammonium bicarbonate and surfactant evenly, and aging for a certain period of time in a closed container at a specific temperature to obtain the precursor, ammonium aluminum carbonate; (2) ) After (1) the prepared precursor ammonium aluminum carbonate is dried and then mixed with the peptizing agent to form, generally can be extruded by an extruder; (3) the obtained molded product of (2) is dried and has Oxygen calcination produces the final alumina support. The inducer in step (1) is polyethylene glycol in liquid form, and the amount added is equivalent to 0.1-10.0% of the weight of aluminum nitrate. The drying process of the ammonium aluminum carbonate described in step (2) is generally drying at 50-180° C. for 1-20 hours. The roasting process described in step (3) is roasting at 350-900° C. for 1-10 hours. The invention uses the precursor ammonium aluminum carbonate to decompose to prepare γ-alumina at a certain temperature. During the decomposition process of ammonium aluminum carbonate, gases such as NH ₃ and CO ₂ are generated, and the generation and escape of these gases will create some large pores. At the same time, the morphology of alumina is topologically transformed from the morphology of ammonium aluminum carbonate. The slower heating rate during the roasting process is conducive to the slow escape of gaseous substances, and it is not easy to cause the carrier to collapse. The method is simple and does not need to add any physical pore expanding agent. CN201310097588.2 discloses a γ-alumina particle and its preparation method: 1) Dissolving a soluble aluminum salt in an aqueous solution with a pH value of less than or equal to 3 acidified by an acid, the amount of the soluble aluminum salt added is such that the prepared The molar concentration of aluminum ions in the aluminum-containing aqueous solution is 0.01-5 mol/L; 2) an alkaline precipitating agent is added to the aluminum-containing aqueous solution obtained in step 1), and the amount of the alkaline precipitating agent added makes the pH value of the solution after the reaction Between 5-12; 3) After stirring the mixed precipitate solution obtained in step 2) at room temperature for 0.1-3h, put it into a water bath or a hydrothermal kettle, and age it at a temperature of 50-150°C for 6- 24h; 4) After stirring the aged solution in step 3) evenly, use the spray drying method to dry. During spray drying, control the inlet air temperature to be 150-400°C and the outlet air temperature to be 60-110°C. The thermal efficiency of spray drying is 50% or more; 5) heating the dried alumina precursor powder obtained in step 4) to 250°C-350°C at a first heating rate at room temperature, and then heating to 400°C-800°C at a second heating rate, Incubate for 0.5-20h to obtain final product γ-alumina particles; wherein, the first heating rate is less than the second heating rate, and the first heating rate and the second heating rate are in the range of 0.1-10°C/min Inside. The prepared γ-alumina has been verified and tested by experiments, and its specific surface area is in the range of 180m2/g-260m2/g, and has a high specific surface area. The prepared γ-alumina particles have a hollow foam-like morphology and a composite pore structure of micropore-mesopore-macropore as observed under a scanning electron microscope. In this way, when γ-alumina is used as a catalyst carrier, its hollow foam-like morphology can effectively disperse the active components in the catalyst. The hollow foam-like morphology and composite pore structure are beneficial to the material transport during the catalytic process, thereby accelerating the catalytic reaction rate. The composite pore size structure refers to including not only micropores with a pore size of less than 2 nm, but also mesopores with a pore size of between 2 nm and 50 nm, and macropores with a pore size of greater than 50 nm. Step 1) also includes adding a pore-forming agent to the prepared aluminum-containing aqueous solution, and the amount of the pore-forming agent added is such that the molar concentration of the pore-forming agent in the aqueous solution after adding is 0.01-5 times the molar concentration of aluminum ions. The pore-forming agent is cetyltrimethylammonium bromide (CTAB), sodium dodecylbenzenesulfonate (SDBS), polyvinyl alcohol (PVA), polyethylene glycol (PEG) and hexametaphosphoric acid one or more of sodium. CN101863499A (201010187094.X) provides a preparation method of macroporous-mesoporous alumina. It includes the following steps: a. First, the reaction assistant and the aluminum salt are dissolved in the organic solvent solution, the molar ratio of the two substances of the reaction assistant: aluminum ion is 3-5:1, and then the template agent is added to the above solution and dissolved, the aluminum The molar ratio of ions to template agent is 1:0.015-0.025, and the pH value of the final solution is controlled at 3.5-6.0; b. The solution prepared in step a is subjected to aging treatment to gradually remove the organic solvent and water in the system to obtain macropores -Mesoporous alumina precursor; c. After calcination at 400-800°C, macroporous-mesoporous alumina powder is obtained. The invention has simple process, regular pore channels, concentrated pore size distribution and can be controlled and adjusted according to specific application conditions, so it has important application value in heterogeneous catalysis, adsorption separation, catalyst carrier, energy material and the like in the petrochemical field. Make full use of the steric framework effect and coordination effect of reaction assistants and template agents, as well as the complexation of organic polymers and reaction assistants to inorganic ions, so as to prepare macroporous-mesoporous alumina materials with adjustable pore size in one step. . The prepared macroporous-mesoporous alumina material has a specific surface area of up to 250-320 m ² /g, regular pore channels, pore size distribution in mesopores of 5-40 nm and macropores of 50-150 nm, and can be adjusted according to actual conditions. The reaction assistant is an organic acid, and the aluminum salt is an inorganic aluminum salt. The templating agent is a triblock copolymer. The organic solvent is anhydrous alcohol, ether or ketone solvent. The organic acid is citric acid or lauric acid. The triblock copolymer is P123 or F127. Tie-Zhen Ren et al. (Langmuir, 2004, 20: 1531-1534) used nonionic surfactant Brij 56 aluminum sec-butoxide to synthesize macroporous-mesoporous alumina by hydrothermal method and microwave-assisted method under acidic conditions. Porous alumina powder is alumina with macropore diameter of 0.8-2μm, mesopore diameter of 5-8nm, and pore wall of 0.4-1.4μm. The disadvantage is that the aluminum alkoxide is expensive, the synthesized macroporous-mesoporous alumina has small pore volume, irregular pore channels, too large pore size distribution, and cannot achieve effective adjustment of pore structure. Therefore, it has a great use effect and scope. limitations. Jean-Philippe Dacquin et al. (J.Am.Chem.Soc., 2009, 131: 12896-12897) introduced polystyrene droplets with a single dispersed phase in a mixed solution using P123 as a template by a sol-gel method to achieve the formation of macropores in macroporous-mesoporous alumina. The disadvantage is that the macropore pore size (300 nm or 400 nm) is completely determined by the size of the secondary introduced polystyrene droplets, that is, the macropore pore size depends on the polystyrene droplet size. The adjustment of the pore size cannot be achieved by partially changing the composition of the solution itself and by the interaction of organic molecules in the system. Huining Li et al. (Inorganic Chemistry, 2009, 48: 4421) also adopted the sol-gel method using F127 as a template to introduce polymethyl methacrylate (PMMA) droplets with a single dispersed phase into the mixed solution to achieve large The disadvantage of the formation of macropores in pore-mesoporous alumina is that the size of the macropores is also completely determined by the size of the droplets of polymethyl methacrylate introduced twice, and cannot be achieved by partially changing the components of the solution system. The adjustment of the pore size can realize the formation of the macropore-mesoporous composite pore structure, so the controllable adjustment of the macropore-mesoporous pore size cannot be realized. limitations.

The above composite porous alumina carrier generally adopts organic high polymer such as polyvinyl alcohol, polymethacrylic acid, etc. as template agent or pore expander. As a result, the preparation of composite porous and macroporous alumina materials has problems such as the toxicity of the template monomer, the large amount of template, the high preparation cost, and the cumbersome preparation process. At the same time, there is also the problem of environmental pollution caused by emissions during the roasting process. There are also patents on the addition of saccharide compounds to polymer microsphere emulsions.

CN201310142454.8 discloses a preparation method of alumina hollow spheres, which is to prepare chitosan-acetic acid-water solution; Polystyrene spheres: α-alumina powder in a mass ratio of 1:5-1:15 to take each raw material; mix and stir the polystyrene spheres with the chitosan-acetic acid-water solution to make the surface of the polystyrene spheres evenly coated. Coated with a layer of chitosan-acetic acid-water solution; then put the polystyrene ball and α-alumina powder coated with chitosan-acetic acid-water solution into the ball milling device, and rotate the bag at a speed of 5-30r/s The core-shell spheres are prepared by coating for 2-24 hours; after calcining the core-shell spheres, alumina hollow spheres with a diameter of 0.2-2 mm and a wall thickness of 20-100 μm are prepared. CN201110170283.0 discloses a three-dimensional ordered macroporous alumina and a preparation method thereof. The three-dimensional ordered macroporous alumina has a macropore diameter of 50-1000 nm, a particle size of 1-50 mm, and a mechanical strength of 80-280 g/mm. The method includes the following steps: adding sugar compounds and concentrated sulfuric acid to the monodisperse polymer microsphere emulsion to obtain a modified polymer microsphere colloidal crystal template, then filling with alumina sol, and then aging and calcining to obtain a three-dimensional Ordered macroporous alumina. The diameter of the polymer microspheres is 50-1000nm, and one or more of polystyrene microspheres, polymethyl methacrylate microspheres, poly(n-butyl acrylate) microspheres and poly(iso-octyl acrylate) microspheres can be used. Various, preferably polystyrene microspheres. The monodispersity means that the standard deviation of the diameter of the polymer microspheres is not more than 10%. The saccharide organic matter is one or more of soluble monosaccharide and polysaccharide, preferably one or more of sucrose, glucose and chitosan. The method can greatly increase the adhesion of alumina precursors, enhance the mechanical strength of the material, and the macroporous material is not easily broken into fine powder when the template is removed by high-temperature calcination, and a high integrity can still be maintained. Chitosan is widely used in the field of ceramic coating adsorption materials. "Study on Adsorption Properties of Mesoporous Chitosan-Aluminum Hydroxide Composites" (Author: Peng Shaohua] Soochow University, "Journal of Suzhou Institute of Science and Technology: Natural Science Edition, 2013, Vol. 30, Issue 4): Using chitosan and AlCl ₃ as raw materials, chitosan and α-Al(OH) ₃ composites were prepared. It was characterized by X-ray powder diffraction, transmission electron microscopy, infrared, thermogravimetry and specific surface meter. The results showed that the composite of α-Al(OH) ₃ and chitosan exhibited typical mesoporous properties, and the BET specific surface area was 55.4m2·g ^-1 , the average pore size of BJH is 3.3nm; the specific preparation method is: weigh 2.0g aluminum chloride hexahydrate and dissolve it in 5.0mL hydrochloric acid with pH value of 1, add 2.0g chitosan, add 10.0g mL distilled water was stirred, and the pH of the solution was adjusted to 1 with dilute hydrochloric acid. Let stand for 30min (the solution becomes paste), adjust the pH value of the solution to 8 with a NaOH solution with a pH value of 14, a white flocculent precipitate is produced, suction filtration, wash off the residual NaOH with distilled water, and put it in an oven , the product was obtained after incubating at 120 °C for 5 h. As in the above steps, products with mass ratios of chitosan and aluminum chloride of 1:2, 1:3, 2:1, and 3:1 were prepared respectively.

"Preparation and Characterization of Chitosan/Alumina Composite Aerogels" (Chang Xinhong; School of Chemistry and Chemical Engineering, Luoyang Normal University, Journal of Luoyang Normal University, Vol. 31, No. 11, 2012): Using chitosan and inorganic aluminum A new type of chitosan/alumina composite aerogel was prepared by the sol-gel method, using the salt AlCl ₃ .6H ₂ O as raw material, using CO ₂ supercritical drying and freeze drying, respectively. The results show that the content of chitosan affects the specific surface area and pore volume of the composite aerogel. With the increase of chitosan content, the specific surface area of the mixed aerogel gradually decreases. Different drying methods also have obvious effects on the specific surface area and other properties of the composite aerogels. Composite aerogels contain micropores and mesopores. CN201110022814.1 An ordered mesoporous metal oxide material with super large pore size, which is characterized in that an amphiphilic block copolymer with super large molecular weight hydrophobic segment is used as a structure directing agent, and according to the principle of ligand-assisted self-assembly, in During the process of solvent volatilization, the mesoporous material precursor interacts with the structure-directing agent, and forms microphase separation according to the difference in hydrophilicity and hydrophobicity, and finally forms an ordered mesoscopic structure; after removing the structure-directing agent, it forms a large pore size The ordered mesoporous metal oxide material; wherein, the molecular weight of the hydrophobic block of the block copolymer is greater than 10000g/mol; the mesopore diameter of the ordered mesoporous metal oxide material is between 10-50nm, The wall thickness is between 4-20nm. The hydrophilic block of the block copolymer is a polyoxyethylene block; the hydrophobic block of the block copolymer is polystyrene or its derivative, polyacrylate or its derivative, polymethacrylate One of its derivatives, polylactic acid poles or derivatives, or a copolymer of two or more of the above-mentioned polymers. The invention prepares mesoporous alumina, similar to CN101153051A, CN1631796A, CN101134567A, CN101823706A and CN101863499A. CN201310258011.5 relates to a tooth spherical alumina carrier, a tooth spherical alumina hydrotreating catalyst and a preparation method thereof, comprising the following components: peptizer, 0.5-4 parts by weight; lubricant, 0.2-2 parts by weight; dispersant , 0.2-3 parts by weight; pore expanding agent, 0.3-4 parts by weight; aluminum hydroxide, 100 parts by weight. The pore expander is one or a mixture of polyvinyl alcohol, sodium polyacrylate, starch derivatives or carbon black. In the invention, the anionic surfactant is added to reduce the addition amount of various auxiliary components, while the specific surface area is increased by 246 m ² /g, and the pore-expanding agent sodium polyacrylate is added. The tooth spherical alumina carrier of the invention greatly reduces the content of various auxiliary agents such as peptizers, pore expanders, dispersants, anionic surfactants and other components, which not only saves the cost, but also has a specific surface area. Large, high mechanical strength advantages. The invention uses peptizer, lubricant, dispersant, pore expander and other reagents, and the prepared alumina carrier has a unimodal pore distribution. CN201110116418.5 provides a mesoporous spherical alumina and a method for preparing the mesoporous spherical alumina guided by a template agent. Using the oil column forming method, a template agent with a guiding function is added to the aluminum sol during the preparation of the aluminum sol. During the molding and aging process of the aluminum sol, due to the existence of the template agent with a guiding function, a large number of alumina balls are produced. mesoporous structure. The template agent is an organic monomer or a linear polymer, and the organic monomer is one of acrylic acid, ammonium acrylate, acrylamide, and allyl alcohol. The mesoporous spherical alumina has a specific surface area of 150-300m ² /g, a particle diameter of 0.1-5mm, a pore volume of 0.7-1.5ml/g, a pore diameter of 2-40nm with more than 97% of the pores, and a bulk density of 0.30-0.80 g/cm ³ , the crushing strength is 70-250 N/grain. The mesoporous spherical alumina prepared by the template agent in the invention has relatively concentrated pore diameters, and the mesoporous spherical alumina can be used in petrochemical and fine chemical industries as catalysts or catalyst carriers.

Macroporous alumina and composite porous alumina can improve the activity, selectivity and stability of the catalyst to varying degrees. The solubility of polyvinyl alcohol-based templates in water is affected by the degree of polymerization, which limits their use in the preparation of ultra-porous alumina.

The prior art is mainly to change the chemical composition and type of the carrier, and add a co-agent to improve the performance of the catalyst. Since mercaptan has the greatest impact on the quality of petroleum products, it not only has a foul smell, but also is highly corrosive, and also affects the stability of the product. Therefore, the desulfanization catalyst is required to have the characteristics of high catalyst desulfanization activity, high diolefin hydrogenation selectivity, and low octane number loss.

SUMMARY OF THE INVENTION

The problem to be solved by the present invention is to provide an FCC gasoline desulfurization catalyst, which has the characteristics of high desulfurization activity, high diolefin hydrogenation selectivity and low loss of octane number. The catalyst uses alumina as a carrier, and the alumina carrier uses chitosan as a pore-enlarging agent to synthesize an alumina carrier with a macroporous structure. Macroporous alumina has the characteristics of adjustable pore size and the ratio of macropores can be effectively controlled.

The invention provides a catalyst for FCC gasoline desulfurization. The catalyst comprises an alumina carrier with a macroporous structure and metal active components nickel and molybdenum supported on the carrier. The alumina with a macroporous structure is based on weight percent. The carrier is 66-91wt%, and the alumina carrier adopts chitosan as a pore-enlarging agent. The carrier contains auxiliary components phosphorus and magnesium, and the content of the auxiliary components phosphorus and magnesium accounts for the percentage of the carrier mass, respectively P ₂ O ₅ 0.1-2.5wt%, MgO 0.1-2.5wt%, pore size distribution 60-180nm, preferably 65-150nm, macropore ratio 2-75%, preferably 5-65%, pore volume 0.8-2.0ml/g, preferably 0.8-1.3ml/g or preferably 1.6-2.0ml/g, specific surface area 250-300m ² /g. The nickel oxide content is 5-19 wt %, and the molybdenum oxide content is 2-15 wt %.

Preferably, the alumina carrier with macroporous structure further contains an auxiliary component cerium, and the content of the auxiliary component cerium oxide is 0.1-2.5 wt % of the mass of the support.

Preferably, the catalyst has an alumina carrier with a macroporous structure of 71-88 wt % and a nickel oxide content of 6-17 wt % in weight percent. The molybdenum oxide content is 5-12 wt%.

The preparation method of the desulfurization catalyst comprises the following steps: preparing a cobalt- and molybdenum-containing soluble salt into an impregnating solution, impregnating an alumina carrier with a macroporous structure, drying at 120-160° C. for 4-8 hours, 650-800° C. It is calcined at ℃ for 5-9 hours to obtain a dethiol catalyst.

The alumina carrier of the present invention has a macroporous structure, and the pore size can be adjusted by changing the added amount of the pore-enlarging agent and the molecular weight of the pore-enhancing agent. The pore size distribution can vary between 60-180 nm, such as 60-90 nm, 100-160 nm, 120-180 nm, etc. The macroporous ratio is 2-75%, which can be adjusted to 5-30%, 35-50%, 55-75% and other ranges.

The present invention also provides a method for preparing an alumina carrier with a macroporous structure. First, chitosan is acidified with an acid solution, then pseudo-boehmite and succulent powder are added into a kneader to mix evenly, and then phosphoric acid and nitric acid are added. Magnesium mixed solution, finally adding the acid solution containing chitosan into the pseudo-boehmite and kneading evenly, the addition amount of the acid solution containing the pore-enlarging agent is 0.1-8wt% of the pseudo-boehmite, preferably 0.2-5.0 wt%, through extrusion-forming-drying-calcination, an alumina carrier with macroporous structure is obtained.

Cerium can also be introduced into the preparation method of the alumina carrier with macroporous structure, for example, cerium nitrate and magnesium nitrate are mixed into the carrier to obtain an alumina carrier containing phosphorus, magnesium and cerium.

The process of acidifying the chitosan with the acid solution is as follows: firstly, the chitosan pore-enlarging agent is added to deionized water at 30-95° C., and then the acid is added dropwise until the chitosan is completely dissolved to obtain the acid containing the pore-enlarging agent. solution. The acid may be an inorganic acid or an organic acid, preferably acetic acid, formic acid, malic acid, lactic acid and the like. The amount of acid added is suitable for completely dissolving chitosan. Water-soluble chitosan can also be used, such as carboxylated chitosan, chitosan salts, chitosan sulfate and the like. Chitosan acid solution is best to use ultrasonic vibration or magnetic stirring. Ultrasonic vibration for more than 10min, magnetic stirring for 0.5-2h. Ultrasonic vibration or magnetic stirring is performed on the pore-enlarging agent, the dispersibility of the pore-enlarging agent is good, the alumina carrier is more likely to generate macropores, and the pore size distribution is more concentrated, and the pore size distribution is 70-180nm. The added amount of the saffron powder is 0.1-7wt% of the pseudo-boehmite.

The extrusion process is as follows: add the prepared acid solution containing the pore-enlarging agent to the saffron powder and the pseudo-boehmite and mix evenly, then extrude, shape, and dry at 100-160 ° C for 3-9 hours at 650 °C. After calcination at -800°C for 4-8 hours, an alumina carrier with macroporous structure is finally obtained.

The alumina carrier of the present invention adopts chitosan as a pore-enlarging agent, and the prepared alumina carrier contains a macroporous structure and a mesoporous structure at the same time. 50%, is an alumina carrier with meso-macropores. Moreover, the pore size is not a uniform pore size structure.

The alumina carrier with macroporous structure obtained by the preparation method of the present invention can also use phosphorus and magnesium to modify the surface of the carrier. When spraying the surface of the carrier with an aqueous solution of phosphoric acid and magnesium nitrate, the surface modification of the carrier is preferably carried out by the following steps: configuring an aqueous solution containing phosphoric acid and magnesium nitrate to spray an alumina carrier with a macroporous structure, drying and calcining to obtain an auxiliary phosphorus Surface-modified alumina carrier with magnesium, the content of phosphorus pentoxide and magnesium oxide in the alumina carrier with macroporous structure is controlled in the range of 0.1-2.5wt%, and the surface of the carrier is phosphorus pentoxide and magnesium oxide. The content is 1.1-1.6 times the internal phosphorus pentoxide and magnesium oxide content.

The above-mentioned alumina carrier containing auxiliary components phosphorus, magnesium and cerium can also use phosphorus, magnesium and cerium to modify the surface of the carrier, and configure the aqueous solution containing phosphoric acid, magnesium nitrate and cerium nitrate to spray the surface of the carrier, preferably by the following Steps to modify the surface of the carrier: configure an aqueous solution containing phosphoric acid, magnesium nitrate and cerium nitrate to spray an alumina carrier with a macroporous structure, and obtain an alumina carrier whose surface is modified with additives phosphorus, magnesium and cerium after drying and calcination , control the content of phosphorus pentoxide, magnesium oxide and cerium oxide in the alumina carrier with macroporous structure in the range of 0.1-2.5wt%, and make the content of phosphorus pentoxide, magnesium oxide and cerium oxide on the surface of the carrier It is 1.1-1.6 times the content of internal phosphorus pentoxide, magnesium oxide and cerium oxide.

Compared with the prior art, the present invention has the following advantages:

1. The catalyst carrier of the present invention uses chitosan as the pore-enlarging agent, and the pore-enlarging agent chitosan is inexpensive, environmentally friendly and non-toxic, and is suitable for industrial production. The obtained alumina carrier with macroporous structure has adjustable pore size and can effectively control the macropore ratio. Moreover, the carrier also contains mesopores and is a meso-macroporous alumina carrier. The catalyst carrier has a macroporous structure, the catalyst is not easy to be coked and deactivated, and has good stability.

2. In the present invention, cerium can also be introduced into the alumina carrier and on the surface of the carrier, so that the cerium content on the surface of the carrier is higher than that in the carrier. Hydrogenation selectivity.

3. The alumina carrier with macroporous structure obtained by the present invention uses phosphorus and magnesium or phosphorus, magnesium and cerium to modify the surface of the alumina carrier with macroporous structure, and makes phosphorus pentoxide and magnesium oxide on the surface of the carrier. , The content of cerium oxide is 1.1-1.6 times of the content of internal phosphorus pentoxide, magnesium oxide and cerium oxide. The surface of the carrier is modified by spraying, which can effectively peptize part of the micropores on the surface of the carrier, which is beneficial to reduce the proportion of micropores on the surface of the carrier, increase the ratio of meso-macropores on the surface of the carrier, and promote the production of more pores on the surface of the carrier. The active site loading center increases the desulfanization activity. Moreover, the structure of the inner and outer components of the carrier with different concentrations makes it difficult for the diene to enter the inside of the pore, and the polymerization reaction occurs to block the pore. Impregnation method should not be used to improve the surface of the carrier. Impregnating the surface of the carrier will cause a large amount of water to enter the carrier, which cannot achieve the purpose of increasing the ratio of meso-macropores on the surface of the carrier.

4. The desulfurization catalyst of the present invention is suitable for removing mercaptans and/or diolefins in liquefied petroleum gas, FCC gasoline, catalytic pyrolysis gasoline and/or coking gasoline; or for catalyzing the selective hydrogenation of diolefins. That is to say, the catalyst does not hydrogenate the olefins in the feedstock, and removes mercaptans and/or diolefins in light hydrocarbons such as liquefied petroleum gas, FCC gasoline, catalytic pyrolysis gasoline and/or coker gasoline, and the catalyst has good selectivity. The octane RON of gasoline loses about 0.3-0.4 points. The catalyst has high desulfanization activity, high diolefin hydrogenation selectivity and low octane loss.

Description of drawings

FIG. 1 is a pore size distribution diagram of the alumina carrier with macroporous structure prepared in Example 3. FIG.

Detailed ways

The present invention will be described in further detail below by means of examples, but these examples should not be construed as limiting the present invention.

Source of main raw materials used for catalyst preparation: all raw materials and reagents used in the present invention are commercially available products.

Example 1

First, 8.0 g of the water-soluble chitosan pore-enlarging agent was added to deionized water at 50° C., and then acetic acid was added dropwise until the chitosan was completely dissolved to obtain an acid solution containing the pore-enlarging agent. Weigh 1.46 g of phosphoric acid and 7.35 g of magnesium nitrate, respectively, and completely dissolve phosphoric acid and magnesium nitrate in 70 g of distilled water to prepare an aqueous solution containing phosphorus and magnesium. Weigh 350g of pseudo-boehmite powder and 20.0g of succulent powder into the kneader, mix well, then add the mixed solution of phosphoric acid and magnesium nitrate, and finally add the acid solution containing chitosan to the pseudo-boehmite The stone is kneaded evenly, and is formed into a clover shape through kneading-extrusion. It was dried at 120°C for 8 hours and calcined at 700°C for 4 hours to obtain an alumina carrier 1 containing phosphorus and magnesium. In carrier 1, phosphorus pentoxide is 0.5 wt %, and magnesium oxide is 0.8 wt %. The specific surface area and pore size distribution of alumina supports with macroporous structure are shown in Table 1.

Nickel nitrate and ammonium molybdate were prepared into an impregnation solution, and ammonia water was added to adjust the pH value to dissolve all the salts, and then the alumina carrier 1 was impregnated, dried at 130° C. for 6 hours, and calcined at 680° C. for 8 hours to obtain catalyst 1. The main composition of catalyst 1 is: the alumina carrier with macroporous structure is 79 wt %, the content of nickel oxide is 12 wt %, and the content of molybdenum oxide is 9 wt %.

Example 2

8.0 g of the water-soluble chitosan pore-enlarging agent was added to deionized water at 50° C., and then acetic acid was added dropwise until the chitosan was completely dissolved to obtain an acid solution containing the pore-enlarging agent. Weigh 1.09 g of phosphoric acid and 9.12 g of magnesium nitrate, respectively, and completely dissolve phosphoric acid and magnesium nitrate in 70 g of distilled water to prepare an aqueous solution containing phosphorus and magnesium. Weigh 350g of pseudo-boehmite powder and 20.0g of succulent powder into the kneader, mix well, then add the mixed solution of phosphoric acid and magnesium nitrate, and finally add the acid solution containing chitosan to the pseudo-boehmite The stone is kneaded evenly, and is formed into a clover shape through kneading-extrusion. It was dried at 120°C for 8 hours and calcined at 700°C for 4 hours to obtain an alumina carrier 1 containing phosphorus and magnesium. Then use phosphorus and magnesium to modify the surface of the carrier, configure an aqueous solution containing phosphoric acid and magnesium nitrate to spray the alumina carrier 1 with macroporous structure, dry it at 120 °C for 8 hours, and bake it at 700 °C for 4 hours to obtain auxiliary phosphorus and In the alumina carrier 2 whose surface is modified by magnesium, the content of phosphorus pentoxide and magnesium oxide on the surface of the carrier is 1.2 times that of the internal phosphorus pentoxide and magnesium oxide. The specific surface area and pore size distribution of alumina supports with macroporous structure are shown in Table 1.

Nickel nitrate and ammonium molybdate were made into impregnation solution, ammonia water was added to adjust pH value to make the salt completely dissolved, and alumina carrier 2 was impregnated, dried at 130°C for 6 hours, and calcined at 720°C for 5 hours to obtain catalyst 2. The main composition of catalyst 2 is: the alumina carrier with macroporous structure is 79.5 wt %, the content of nickel oxide is 10.5 wt %, and the content of molybdenum oxide is 10 wt %.

Example 3

The preparation method of the carrier was carried out according to Example 1. The difference is that the auxiliary component in the carrier also contains cerium, the water-soluble chitosan pore-enlarging agent is replaced with a water-insoluble chitosan pore-enlarging agent, and the chitosan formic acid solution is stirred with a magnetic stirrer for 30 minutes to obtain Alumina support 3 with macroporous structure. The percentage of the content of auxiliary components phosphorus, magnesium and cerium in the carrier to the mass of the carrier is 1.8wt%, 2.0wt% and 0.6wt% respectively. Its specific surface area and pore size distribution are shown in Table 1.

Nickel nitrate and ammonium molybdate were prepared into an impregnation solution, and ammonia water was added to adjust the pH value to dissolve all the salts, and then the alumina carrier 3 was impregnated, dried at 130° C. for 6 hours, and calcined at 750° C. for 5 hours to obtain catalyst 3. The main composition of catalyst 3 is: the alumina carrier with macroporous structure is 81.5 wt %, the content of nickel oxide is 6 wt %, and the content of molybdenum oxide is 12.5 wt %.

Example 4

The preparation method of the carrier was carried out according to Example 3. The difference is that the water-soluble chitosan pore-expanding agent is replaced with a water-insoluble chitosan pore-expanding agent, and the chitosan acetic acid solution is oscillated with ultrasonic waves for 15 minutes. The alumina carrier with macroporous structure was obtained. The content of auxiliary components phosphorus, magnesium and cerium in the carrier accounts for 1.6 wt %, 1.6 wt % and 0.6 wt % of the carrier mass, respectively. The surface of the carrier is modified with phosphorus, magnesium and cerium to obtain carrier 4. The content of phosphorus pentoxide, cerium oxide and magnesium oxide on the surface of carrier 4 is 1.5 times that of the internal phosphorus pentoxide, cerium oxide and magnesium oxide. The specific surface area and pore size distribution of alumina carrier 4 with macroporous structure are shown in Table 1.

Nickel nitrate and ammonium molybdate were prepared into an impregnation solution, and ammonia water was added to adjust the pH to dissolve all the salts, and then the alumina carrier 4 was impregnated, dried at 130° C. for 6 hours, and calcined at 750° C. for 5 hours to obtain catalyst 4. The main composition of catalyst 4 is: the alumina carrier with macroporous structure is 77.5 wt %, the content of nickel oxide is 16 wt %, and the content of molybdenum oxide is 6.5 wt %.

Example 5

The preparation method of the carrier is carried out according to Example 2, the difference is that the content of phosphorus pentoxide and magnesium oxide on the surface of the carrier is 1.4 times that of the internal phosphorus pentoxide and magnesium oxide. The main composition of the catalyst 5 is: the alumina carrier with macroporous structure is 80.5 wt %, the nickel oxide content is 5.5 wt %, and the molybdenum oxide content is 14 wt %.

Example 6

The preparation method of the carrier is carried out according to Example 4, except that the content of phosphorus pentoxide, cerium oxide and magnesium oxide on the surface is 1.3 times that of the inner phosphorus pentoxide, cerium oxide and magnesium oxide. The main composition of the catalyst 6 is: the alumina carrier with macroporous structure is 78wt%, the content of nickel oxide is 13.5wt%, and the content of molybdenum oxide is 8.5wt%.

Table 1 Specific surface area and pore size distribution of macroporous alumina supports

Catalysts 1-4 were loaded into fixed bed reactors, respectively, and the catalyst reaction performance was evaluated. The catalyst was pre-sulfurized with sulfurized oil. The sulfurization pressure was 3.2MPa, the volume ratio of hydrogen to oil was 300, and the volumetric space velocity of sulfurized oil was 3.5h ^-1 . After the sulfurization treatment is completed, switch to full-distillate FCC gasoline replacement treatment for 6 hours, and then adjust to the reaction process conditions to carry out the desulfurization reaction. FCC raw material gasoline sulfur content 556μg/g, mercaptan sulfur 35μg/g, olefin content 47.35v%, RON 88.36. The reaction process conditions were as follows: the reactor temperature was 115°C, the volumetric space velocity was 3.3h ^-1 , the volume ratio of hydrogen to oil was 11:1, and the reaction pressure was 2.1MPa. After about 55 hours of reaction, samples were taken for analysis. The reaction results of catalysts 1-4 are as follows: catalyst 1 has a sulfur content of 544 μg/g, mercaptan sulfur 5 μg/g, olefin content of 46.59v%, RON 87.93, and gasoline yield of 97.8 wt%; catalyst 2 has a sulfur content of 547 μg/g, mercaptan sulfur 3μg/g, olefin content 46.83v%, RON 87.95, gasoline yield 98.2wt%; catalyst 3 sulfur content 545μg/g, mercaptan sulfur 3μg/g, olefin content 46.85v%, RON 88.01, gasoline yield 98.0wt% ; catalyst 4 sulfur content 548μg/g, mercaptan sulfur 2μg/g, olefin content 46.82v%, RON 88.03, gasoline yield 98.5wt%; catalyst product mercaptan sulfur less than 4μg/g, olefin content basically unchanged, the reaction The octane number loss is 0.3-0.4, the catalyst activity is high, the selectivity is good, and the octane number loss is low. The stability test of the catalyst was carried out. The reaction was run for 400h. The sulfur content of catalyst 1 was 542 μg/g, the mercaptan sulfur was 4 μg/g, the olefin content was 46.56v%, the RON was 7.91, and the gasoline yield was 97.9wt%; the sulfur content of catalyst 2 was 546 μg/g. Thiol sulfur 3μg/g, olefin content 46.82v%, RON 7.94, gasoline yield 98.0wt%; Catalyst 3 sulfur content 545μg/g, mercaptan sulfur 3μg/g, olefin content 46.84v%, RON 7.98, gasoline yield 98.1wt%; catalyst 4 sulfur content 547μg/g, mercaptan sulfur 2μg/g, olefin content 46.83v%, RON 8.04, gasoline yield 98.4wt%; product mercaptan sulfur less than 4μg/g after catalyst running for 400h, olefin content The content is basically unchanged, the catalyst is not easy to coke and deactivate, and the stability is good.

Catalysts 5 to 6 were loaded into fixed bed reactors, respectively, and the catalyst reaction performance was evaluated. The catalyst was pre-sulfurized with sulfurized oil. The sulfurization pressure was 3.2MPa, the volume ratio of hydrogen to oil was 300, and the volumetric space velocity of sulfurized oil was 3.5h ^-1 . After the sulfurization treatment is completed, switch to full-distillate FCC gasoline replacement treatment for 6 hours, and then adjust to the reaction process conditions to carry out the desulfurization reaction. FCC raw material gasoline sulfur content 733μg/g, mercaptan sulfur 28μg/g, olefin content 44.68v%, RON 9.24. The reaction process conditions were as follows: the reactor temperature was 145°C, the volumetric space velocity was 2.2h ^-1 , the volume ratio of hydrogen to oil was 14:1, and the reaction pressure was 2.7MPa. After the reaction for about 55 hours, sampling and analysis showed that the sulfur content of catalyst 5 was 724 μg/g, mercaptan sulfur 2 μg/g, olefin content 43.95v%, RON 8.95, and gasoline yield 98.3 wt%; catalyst 6 sulfur content was 725 μg/g, mercaptan sulfur 2 μg /g, olefin content 44.19v%, RON 9.01, gasoline yield 98.6wt%. The catalyst has high activity, good selectivity, low octane number loss, and the catalyst has strong adaptability to oils with different sulfur content, mercaptan sulfur content and olefin content.

Of course, the present invention can also have other various embodiments, without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and deformations according to the present invention, but these corresponding changes and deformation should belong to the protection scope of the present invention.

Claims (3)

1. a catalyst for FCC gasoline desulfurization, characterized in that: The catalyst includes an alumina carrier with a macroporous structure and metal active components nickel and molybdenum supported on the carrier. In terms of weight percentage, the alumina carrier with a macroporous structure is 71-88 wt%, and the alumina carrier adopts chitosan As a pore-enlarging agent, the carrier contains auxiliary components phosphorus, magnesium and cerium, and the content of the auxiliary components phosphorus, magnesium and cerium accounts for the percentage of the mass of the carrier, respectively P ₂ O ₅ 0.1-2.5wt%, MgO 0.1 -2.5wt%, CeO ₂ 0.1-2.5wt%; The alumina carrier has a pore size distribution of 60-180nm, a macropore ratio of 2-75%, a pore volume of 0.8-2.0ml/g, and a specific surface area of 250-300m ² /g; The alumina carrier has a mesoporous range of 5-50 nm, and a mesoporous ratio of 15-75%; The catalyst active component has a nickel oxide content of 6-17 wt % and a molybdenum oxide content of 5-12 wt %; The preparation method of the alumina carrier with macroporous structure includes the following steps: firstly, acidifying chitosan with an acid solution, then adding pseudoboehmite and succulent powder into a kneader to mix evenly, and then adding phosphoric acid and magnesium nitrate and cerium nitrate, and finally add the acid solution containing chitosan into the pseudo-boehmite and knead evenly. Extrusion-forming-drying-calcining to obtain alumina carrier with macroporous structure; For the obtained alumina carrier with macroporous structure, the surface of the carrier is modified with phosphorus, magnesium and cerium: an aqueous solution containing phosphoric acid, magnesium nitrate and cerium nitrate is configured to spray the alumina carrier with macroporous structure, and after drying, The alumina carrier surface-modified with the additives phosphorus, magnesium and cerium is obtained by roasting, and the content of phosphorus pentoxide, magnesium oxide and cerium oxide in the alumina carrier with macroporous structure is controlled to be in the range of 0.1-2.5wt% The content of phosphorus pentoxide, magnesium oxide and cerium oxide on the surface of the carrier is 1.1-1.6 times that of the internal phosphorus pentoxide, magnesium oxide and cerium oxide. 2. the preparation method of a kind of catalyst for FCC gasoline desulfurization according to claim 1, is characterized in that: comprise the steps: The soluble salt containing nickel and molybdenum is prepared into an impregnation solution, and the alumina carrier with macroporous structure is impregnated, dried at 120-160 ° C for 4-8 hours, and calcined at 650-800 ° C for 5-9 hours to obtain the desulfurized alcohol. catalyst; The preparation method of the alumina carrier with macroporous structure includes the following steps: firstly, acidifying chitosan with an acid solution, then adding pseudoboehmite and succulent powder into a kneader to mix evenly, and then adding phosphoric acid and magnesium nitrate and cerium nitrate, and finally add the acid solution containing chitosan into the pseudo-boehmite and knead evenly. Extrusion-forming-drying-calcining to obtain alumina carrier with macroporous structure; For the obtained alumina carrier with macroporous structure, the surface of the carrier is modified with phosphorus, magnesium and cerium: an aqueous solution containing phosphoric acid, magnesium nitrate and cerium nitrate is configured to spray the alumina carrier with macroporous structure, and after drying, The alumina carrier surface-modified with the additives phosphorus, magnesium and cerium is obtained by roasting, and the content of phosphorus pentoxide, magnesium oxide and cerium oxide in the alumina carrier with macroporous structure is controlled to be in the range of 0.1-2.5wt% The content of phosphorus pentoxide, magnesium oxide and cerium oxide on the surface of the carrier is 1.1-1.6 times that of the internal phosphorus pentoxide, magnesium oxide and cerium oxide. 3. the preparation method of a kind of catalyst for FCC gasoline desulfurization according to claim 2, it is characterized in that: described acidifying chitosan with acid solution is: at first chitosan pore expander is added to 30- deionized water at 95° C., and then acid was added dropwise until the chitosan was completely dissolved to obtain an acid solution containing a pore-enlarging agent.