High-dispersity alkyne hydrogenation catalyst as well as preparation method and application thereof

Abstract

The invention provides a high-dispersity alkyne hydrogenation catalyst as well as a preparation method and application thereof. According to the invention, the assistant is introduced, the isoelectric point regulator is added in the preparation process of alumina, and corresponding alkalization, acidification, irradiation and crystallization surface treatment methods are combined to change the surface properties and inhibit the sintering phenomenon of active components at high temperature, so that the dispersity of Pd metal on the surface of the catalyst can be greatly improved, and the catalytic performance and selectivity are obviously improved. In a C4 alkyne hydrogenation reaction, the content of alkyne in a product can be greatly reduced, and the loss of butadiene is reduced.

Description

Technical Field

[0001] The invention belongs to the field of catalysts, and in particular relates to a high-dispersity alkyne hydrogenation catalyst and a preparation method and application thereof. Background Art

[0002] At present, the main source of C4 hydrocarbons in China is the by-products of ethylene cracking units. The C4 components in the cracking gas contain a large number of acetylene-like substances such as methylacetylene, ethylacetylene, and vinylacetylene. After hydrogenation to increase the saturation, 1,3-butadiene, one of the important industrial raw materials, can be obtained, thereby improving the comprehensive benefits of the steam cracking unit, increasing the utilization rate and added value of the by-products of the ethylene unit, and having considerable economic benefits. In the hydrogenation process, not only should alkynes be eliminated as much as possible, but also the loss of 1,3-butadiene should be reduced as much as possible, which places high demands on the catalytic performance and selectivity of the catalyst. In addition, in order to achieve long-term operation of the unit and reduce production costs, the catalyst should have high stability.

[0003] Studies have shown that noble metal catalysts have high selectivity for hydrogenation of alkynes. Chinese patent CN113663688A discloses a method for preparing an alkyne-containing carbon tetrahydrogenation catalyst with a bimodal pore distribution structure. The target catalyst is obtained by sequentially impregnating the carrier in A: Pd salt solution; B: microemulsion containing Ni and Cu precursor salts, oil phase, surfactant and cosurfactant; C: Mo salt solution; D: microemulsion containing Pd precursor salt, oil phase, surfactant and cosurfactant, drying and calcining. The catalyst can be used in the process of alkyne-containing carbon tetrahydrogenation and has good hydrogenation activity and high anti-coking property.

[0004] Chinese patent CN101428228A discloses a method for preparing a selective hydrogenation catalyst. A catalyst precursor is prepared by preparing a solution containing 0.1-0.5% palladium, impregnating it on an alumina carrier containing an alkali metal, an alkaline earth metal or a mixture thereof, and drying and calcining it. The catalyst precursor is impregnated with a soluble salt solution containing copper, IVA elements and an auxiliary metal in steps or co-impregnated, and the catalyst is obtained by drying and calcining it. The catalyst is suitable for selective hydrogenation and removal of alkynes from acetylene-rich residual materials after butadiene extraction, but is only suitable for treating C4 materials with high alkyne content and very low butadiene content.

[0005] Patent CN104096572A discloses a hydrogenation catalyst, in which the active components described in the catalyst are Pd, Ag, and Ni, wherein Pd and Ag are loaded by aqueous solution impregnation method, and Ni is loaded by W / O microemulsion impregnation method. After adopting this method, Pd / Ag and Ni are located in pores of different pore sizes, and the green oil generated by the reaction is saturated with hydrogen in the macropores, and the amount of catalyst coking is reduced. However, the reduction temperature of Ni often reaches about 450°C. At this temperature, the reduced Pd metal is very easy to aggregate, which greatly reduces the activity of the catalyst. It is necessary to greatly increase the amount of active components to compensate for the loss of activity, but it will cause a decrease in selectivity.

[0006] The above invention attempts to improve the catalytic performance and selectivity of the catalyst from various angles, but the utilization efficiency of the active components of the catalyst is limited, and no more effective solution can be given for the spontaneous agglomeration of precious metals contained in the active components on the surface during the reduction process. On the other hand, the preparation process is long and complicated, and more additives are added, the production cost is high, and generally organic substances such as surfactants and organic ligands are used, which is not environmentally friendly. Therefore, there is still a need to develop a catalyst with a simple preparation method, good performance and stability. Summary of the invention

[0007] In order to improve the deficiencies in the prior art, the present invention provides a highly dispersed alkyne hydrogenation catalyst and a preparation method thereof. The present invention adds an appropriate amount of isoelectric point regulator during the preparation of the alumina carrier, and performs targeted surface treatment on the formed alumina carrier, thereby significantly improving the density of hydroxyl groups on the surface of the alumina carrier, thereby affecting the distribution state of the noble metal active components on the surface and improving the dispersion of the noble metal.

[0008] One of the purposes of the present invention is to provide a highly dispersed alkyne hydrogenation catalyst, comprising a modified alumina carrier and active components and additives loaded on the carrier, wherein the dispersion of the active components on the catalyst surface is 40-70%.

[0009] According to the present invention, in the highly dispersed alkyne hydrogenation catalyst:

[0010] The dispersion degree of the active components on the catalyst surface is 45-65%;

[0011] The total weight of the catalyst is 100%, and the content of the auxiliary agent is 0.01-10%, preferably 0.05-8%;

[0012] The average pore size of the catalyst is 30 to 200 nm, preferably 50 to 150 nm; the most probable pore size is 80 to 250 nm, preferably 100 to 200 nm; the specific surface area is 5 to 100 m 2 / g, preferably 10 to 70 m 2 / g; the bulk density is 0.4-1.3 g / mL, preferably 0.5-1.2 g / mL.

[0013] According to the present invention, in the highly dispersed alkyne hydrogenation catalyst:

[0014] The active component is Pd;

[0015] The auxiliary agent is selected from at least one of Ag and Ce;

[0016] The modified alumina carrier comprises alumina and other oxides, and the other oxides are selected from at least one of vanadium pentoxide, antimony pentoxide, silicon oxide, tin oxide, zirconium oxide, manganese oxide, cerium oxide, iron oxide, ferrous oxide, titanium oxide, copper oxide, zinc oxide, lanthanum oxide, nickel oxide, magnesium oxide, yttrium oxide, gallium oxide, and indium oxide, preferably at least one of vanadium pentoxide, antimony pentoxide, silicon oxide, tin oxide, titanium oxide, zirconium oxide, nickel oxide, magnesium oxide, gallium oxide, and copper oxide.

[0017] The second object of the present invention is to provide a method for preparing the above-mentioned high-dispersion alkyne hydrogenation catalyst, comprising: immersing the modified alumina carrier in a metal compound solution containing an active component precursor compound and an auxiliary agent precursor compound, taking it out, drying and calcining it to obtain the high-dispersion alkyne hydrogenation catalyst.

[0018] According to the present invention, in the method for preparing the highly dispersed alkyne hydrogenation catalyst:

[0019] The active component precursor compound is selected from one of palladium nitrate, palladium chloride, palladium oxide, palladium hydroxide, and sodium tetrachloropalladate, preferably at least one of palladium nitrate and palladium chloride;

[0020] The auxiliary agent precursor compound is selected from at least one of silver nitrate, cerium nitrate and cerium chloride, preferably at least one of silver nitrate and cerium nitrate;

[0021] In the metal compound solution, the molar concentration of the active component precursor compound is 0.05 to 10 mol / L;

[0022] In the metal compound solution, the molar concentration of the auxiliary agent precursor compound is 0.05 to 10 mol / L;

[0023] The drying conditions are: drying temperature is 60-200°C, and drying time is 5-20h; preferably, drying temperature is 80-150°C, and drying time is 6-16h;

[0024] The calcination conditions are: calcination temperature is 200-1200° C., and calcination time is 2-24 hours; preferably, calcination temperature is 300-1000° C., and calcination time is 5-12 hours.

[0025] According to the present invention, the modified alumina carrier is prepared by the following steps: mixing components including an alumina precursor, a forming agent, a pore expanding agent, an isoelectric point regulating agent, and a crosslinking agent solution to obtain a mixture, kneading and molding, extruding and pelletizing, drying, and calcining to obtain a modified alumina precursor, and then surface treating the modified alumina precursor to obtain the modified alumina carrier.

[0026] According to the present invention, in the preparation of the modified alumina carrier:

[0027] The alumina precursor is selected from at least one of boehmite powder, pseudo-boehmite powder, alumina trihydrate powder, fast-release alumina powder, and θ-alumina powder;

[0028] The molding agent is selected from at least one of starch, methyl cellulose, carboxymethyl cellulose, ethyl cellulose and hydroxypropyl methyl cellulose;

[0029] The pore-enlarging agent is selected from at least one of sesbania powder, starch, polyethylene glycol, polyethylene microspheres, polyethylene oxide, polystyrene, and polypropylene glycol;

[0030] The isoelectric point regulator is selected from at least one of oxides having an isoelectric point of less than 6 or greater than 8. Preferably, the oxide having an isoelectric point of less than 6 is selected from at least one of vanadium pentoxide, antimony pentoxide, silicon oxide, tin oxide, zirconium oxide, manganese oxide, cerium oxide, iron oxide, ferrous oxide, and titanium oxide, preferably at least one of vanadium pentoxide, antimony pentoxide, silicon oxide, tin oxide, titanium oxide, and zirconium oxide; and / or, the oxide having an isoelectric point greater than 8 is selected from at least one of copper oxide, zinc oxide, lanthanum oxide, nickel oxide, magnesium oxide, yttrium oxide, gallium oxide, and indium oxide, preferably at least one of nickel oxide, magnesium oxide, gallium oxide, and copper oxide;

[0031] The crosslinking agent in the crosslinking agent solution is selected from at least one of nitric acid, sulfuric acid, hydrochloric acid, phosphoric acid, acetic acid, citric acid, oxalic acid, ascorbic acid, and salicylic acid;

[0032] The solvent in the crosslinker solution is selected from at least one of water, methanol, ethanol and ethylene glycol, preferably water and / or ethanol.

[0033] According to the present invention, in the preparation of the modified alumina carrier:

[0034] The total weight of the alumina precursor, the forming agent, the pore expanding agent, and the isoelectric point regulating agent is 100%, the amount of the forming agent is 0.1-15%, the amount of the pore expanding agent is 0.05-15%, and the amount of the isoelectric point regulating agent is 0.02-12%; preferably, based on the total weight of the alumina precursor, the forming agent, the pore expanding agent, and the isoelectric point regulating agent is 100%, the amount of the forming agent is 1-12%, the amount of the pore expanding agent is 1-10%, and the amount of the isoelectric point regulating agent is 0.1-8%;

[0035] The molar concentration of the crosslinking agent solution is 0.001 to 10 mol / L, preferably 0.05 to 5 mol / L; and / or,

[0036] Based on 100 g of the aluminum oxide precursor, the amount of the crosslinking agent solution is 50 to 1000 mL, preferably 100 to 800 mL.

[0037] According to the present invention, in the preparation of the modified alumina carrier:

[0038] The drying conditions are: drying temperature is 60-200°C, and drying time is 5-20h; preferably, drying temperature is 80-150°C, and drying time is 6-16h;

[0039] The calcination conditions are: calcination temperature is 500-1500°C, and calcination time is 1-24h; preferably, calcination temperature is 800-1300°C, and calcination time is 3-15h;

[0040] The surface treatment is selected from at least two of acidification or alkalization, crystallization, and irradiation. Preferably, when the isoelectric point regulator is an oxide with an isoelectric point of less than 6 and acidification is used, the pH of the acidification treatment needs to be 0.1 to 2 lower than the isoelectric point value of the isoelectric point regulator, preferably 0.3 to 1.5 lower; and / or, when the isoelectric point regulator is an oxide with an isoelectric point greater than 8 and acidification is not used and alkalization is used, the pH of the alkalization treatment needs to be 0.1 to 2 higher than the isoelectric point value of the isoelectric point regulator, preferably 0.3 to 1.5 higher;

[0041] Wherein, the acidification conditions are: temperature of 30-100°C, time of 0.5-12h, acidifier selected from at least one of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, sodium bisulfate, acetic acid, oxalic acid, and citric acid, and the concentration of the acidifier solution is 0.01-10 mol / L; preferably, the acidification conditions are: temperature of 35-80°C, time of 1-8h, acidifier selected from at least one of sulfuric acid, hydrochloric acid, nitric acid, acetic acid, and citric acid, and the concentration of the acidifier solution is 0.1-5 mol / L;

[0042] The alkalization conditions are as follows: the temperature is 30-100°C, the time is 0.5-12h, the alkalizer is selected from at least one of sodium hydroxide, potassium hydroxide, barium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate, and ammonia water, and the concentration of the alkalizer solution is 0.01-10 mol / L; preferably, the alkalization conditions are as follows: the temperature is 35-80°C, the time is 1-8h, the alkalizer is selected from at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate, and the concentration of the alkalizer solution is 0.1-5 mol / L;

[0043] The crystallization conditions are: temperature of 50-300°C, time of 0.5-20h, and the crystallization solvent is selected from at least one of water, methanol, ethanol, ethylene glycol, and ethylenediamine; preferably, the crystallization conditions are: temperature of 100-200°C, time of 1-15h, and the crystallization solvent is selected from at least one of water, methanol, and ethanol;

[0044] The irradiation conditions are as follows: the ray source is γ-ray, the irradiation dose rate is 0.01-50 kGy / min, and the irradiation time is 0.1-10 h; preferably, the irradiation conditions are as follows: the ray source is γ-ray, the irradiation dose rate is 0.5-20 kGy / min, and the irradiation time is 0.2-6 h.

[0045] The third object of the present invention is to provide an application of the above-mentioned high-dispersion alkyne hydrogenation catalyst or the high-dispersion alkyne hydrogenation catalyst obtained by the above-mentioned preparation method in the selective hydrogenation reaction of carbon four.

[0046] The present invention provides a highly dispersed supported catalyst, which can greatly increase the density of hydroxyl groups on the surface of an alumina carrier by introducing an additive, adding a regulator to change the isoelectric point of the carrier surface, and adopting a corresponding surface treatment method. In the subsequently prepared noble metal catalyst, the noble metal active component can form a highly dispersed, small-size active center on the carrier surface. And through the combination of the formula, the preparation method, and the change of the process parameters, the density of the active components on the catalyst surface can be finely controlled, thereby adapting to different types of multiphase catalytic systems. DETAILED DESCRIPTION

[0047] The present invention is described in detail below in conjunction with specific embodiments. It is necessary to point out that the following embodiments are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made to the present invention by those skilled in the art based on the contents of the present invention still fall within the scope of protection of the present invention.

[0048] The raw materials used in the examples and comparative examples, unless otherwise specified, are disclosed in the prior art, for example, they can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0049] Example 1

[0050] Prepare 250 mL of 0.5 mol / L nitric acid aqueous solution, add it to a mixture of 200 g of pseudo-boehmite powder, 10 g of ethyl cellulose, 8 g of sesbania powder and 6 g of silicon oxide (isoelectric point 2.2), put it into a kneader and knead it to form a plastic semi-solid, then extrude it into spherical particles with a diameter of 3 mm, dry it at 120°C for 6 h, calcine it at 1160°C for 6 h, then crystallize the particles in 200 mL of methanol at 150°C for 12 h, finally acidify it with 200 mL of citric acid solution at 40°C and pH 1.5 for 7 h, and dry it at 120°C for 6 h to obtain the carrier.

[0051] Take the above carrier, prepare 150 mL of a mixed aqueous solution of palladium nitrate and silver nitrate containing 5 g of palladium and 5 g of silver, saturate the carrier with the above solution, take it out after 5 minutes, dry it at 120°C for 6 hours, and calcine it in air at 450°C for 8 hours to obtain the target catalyst A1.

[0052] Example 2

[0053] Prepare 250mL of 0.25mol / L sulfuric acid aqueous solution, add it to a mixture of 200g of pseudo-boehmite powder, 12g of methyl cellulose, 6g of sesbania powder and 6g of nickel oxide (isoelectric point 10.5), put it into a kneader and knead it to form a plastic semi-solid, then extrude it into spherical particles with a diameter of 3mm, dry it at 120℃ for 6h, calcine it at 1200℃ for 6h, then crystallize the particles at 180℃ for 8h in 150mL of 2mol / L ethanol aqueous solution, finally alkalize it with 200mL of sodium hydroxide aqueous solution at 45℃ and pH value of 11.5 for 8h, and dry it at 120℃ for 6h to obtain the carrier.

[0054] Take the above carrier, prepare 150 mL of a mixed aqueous solution of palladium nitrate and silver nitrate containing 5 g of palladium and 5 g of silver, saturate the carrier with the above solution, take it out after 5 minutes, dry it at 120°C for 6 hours, and calcine it in air at 400°C for 8 hours to obtain the target catalyst A2.

[0055] Example 3

[0056] Prepare 250mL of an aqueous solution of 0.2mol / L sulfuric acid and 0.2mol / L citric acid, add it to a mixture of 120g of θ-alumina powder, 80g of fast-release alumina powder, 10g of ethyl cellulose, 8g of starch and 8g of vanadium pentoxide (isoelectric point 1.3), put it into a kneader and knead it to form a plastic semisolid, then extrude it into spherical particles with a diameter of 3mm, dry it at 120°C for 6h, calcine it at 1120°C for 6h, then acidify the particles with 200mL of sulfuric acid solution at 70°C and pH value of 0.5 for 5h, finally irradiate the particles with gamma rays at an irradiation dose rate of 3kGy / min for 4h, and dry it at 120°C for 6h to obtain a carrier.

[0057] Take the above carrier, prepare 150 mL of a mixed aqueous solution of palladium nitrate and silver nitrate containing 5 g of palladium and 5 g of silver, saturate the carrier with the above solution, take it out after 5 minutes, dry it at 120°C for 6 hours, and calcine it in air at 480°C for 8 hours to obtain the target catalyst A3.

[0058] Example 4

[0059] Prepare 250mL of an aqueous solution of 0.2mol / L hydrochloric acid, 0.2mol / L acetic acid, and 0.1mol / L citric acid, add it to a mixture of 100g of boehmite powder, 100g of alumina trihydrate powder, 10g of ethyl cellulose, 8g of starch, and 8g of copper oxide (isoelectric point 9.5), put it into a kneader and knead it to form a plastic semisolid, then extrude it into spherical particles with a diameter of 3mm, dry it at 120°C for 6h, calcine it at 1060°C for 6h, and then irradiate the particles with gamma rays at a irradiation dose rate of 2kGy / min for 5h, finally alkalize it with 200mL of potassium hydroxide at 50°C and pH value of 10.5 for 6h, and dry it at 120°C for 6h to obtain a carrier.

[0060] Take the above carrier, prepare 150 mL of a mixed aqueous solution of palladium nitrate and silver nitrate containing 5 g of palladium and 5 g of silver, saturate the carrier with the above solution, take it out after 5 minutes, dry it at 120°C for 6 hours, and calcine it in air at 420°C for 8 hours to obtain the target catalyst A4.

[0061] Example 5

[0062] Prepare 250mL of an aqueous solution of 0.2mol / L nitric acid, 0.15mol / L sulfuric acid and 0.2mol / L citric acid, add it to a mixture of 100g of pseudo-boehmite powder, 100g of fast-dealumina powder, 10g of hydroxymethyl cellulose, 10g of polypropylene glycol and 8g of antimony pentoxide (isoelectric point 2), put it into a kneader and knead it to form a plastic semi-solid, then extrude it into spherical particles with a diameter of 3mm, dry it at 120℃ for 6h, calcine it at 1150℃ for 6h, crystallize the particles at 120℃ for 12h in 150mL of 2mol / L ethanol aqueous solution, irradiate the particles under γ rays with an irradiation dose rate of 5kGy / min for 2h, finally acidify it with 200mL of sulfuric acid at 60℃ and pH value of 1.1 for 5h, and dry it at 120℃ for 6h to obtain the carrier.

[0063] Take the above carrier, prepare 150 mL of a mixed aqueous solution of palladium nitrate and silver nitrate containing 5 g of palladium and 5 g of silver, saturate the carrier with the above solution, take it out after 5 minutes, dry it at 120°C for 6 hours, and calcine it in air at 400°C for 8 hours to obtain the target catalyst A5.

[0064] Example 6

[0065] Prepare 250mL of an aqueous solution of 0.15mol / L nitric acid, 0.15mol / L acetic acid, and 0.1mol / L citric acid, add it to a mixture of 200g of boehmite powder, 12g of carboxymethyl cellulose, 8g of starch, 6g of polyacrylamide, and 6g of vanadium pentoxide (isoelectric point 1.3), put it into a kneader and knead it to form a plastic semisolid, then extrude it into spherical particles with a diameter of 3mm, dry it at 120°C for 6h, calcine it at 1190°C for 6h, crystallize the particles in 200mL of methanol at 120°C for 15h, then acidify it with 200mL of sulfuric acid solution at 50°C and pH value of 0.4 for 6h, finally irradiate the particles with gamma rays at an irradiation dose rate of 2kGy / min for 5h, and dry it at 120°C for 6h to obtain a carrier.

[0066] Take the above carrier, prepare 150 mL of a mixed aqueous solution of palladium nitrate and silver nitrate containing 5 g of palladium and 5 g of silver, saturate the carrier with the above solution, take it out after 5 minutes, dry it at 120°C for 6 hours, and calcine it in air at 850°C for 8 hours to obtain the target catalyst A6.

[0067] Comparative Example 1

[0068] Prepare 250 mL of 0.25 mol / L sulfuric acid aqueous solution, add to a mixture of 200 g of quick-release alumina powder, 10 g of hydroxymethyl cellulose, and 8 g of polyethylene microspheres, put into a kneader and knead to form a plastic semisolid, then extrude into spherical particles with a diameter of 3 mm, dry at 120°C for 6 h, and calcine at 1160°C for 6 h to obtain a carrier.

[0069] Take the above carrier, prepare 150 mL of a mixed aqueous solution of palladium nitrate and silver nitrate containing 5 g of palladium and 5 g of silver, saturate the carrier with the above solution, take it out after 5 minutes, dry it at 120°C for 6 hours, and calcine it in air at 450°C for 8 hours to obtain the target catalyst B1.

[0070] Comparative Example 2

[0071] Prepare 250 mL of 0.5 mol / L nitric acid aqueous solution, add it to a mixture of 200 g of pseudo-boehmite powder, 10 g of ethyl cellulose, and 8 g of sesbania powder, put it into a kneader and knead it to form a plastic semisolid, then extrude it into spherical particles with a diameter of 3 mm, and then crystallize the particles in 200 mL of methanol at 150 ° C for 12 h, finally acidify it with 40 ° C, 0.1 mol / L, 200 mL of citric acid solution for 7 h, and dry it at 120 ° C for 6 h to obtain the carrier.

[0072] Take the above carrier, prepare 150 mL of a mixed aqueous solution of palladium nitrate and silver nitrate containing 5 g of palladium and 5 g of silver, saturate the carrier with the above solution, take it out after 5 minutes, dry it at 120°C for 6 hours, and calcine it in air at 420°C for 8 hours to obtain the target catalyst B2.

[0073] Comparative Example 3

[0074] Prepare 250mL of 0.3mol / L hydrochloric acid and 0.2mol / L acetic acid aqueous solution, add to a mixture of 200g pseudo-boehmite powder, 10g starch, 8g polypropylene glycol, and 6g nickel oxide (isoelectric point 10.5), put into a kneader and knead to form a plastic semisolid, then extrude into spherical particles with a diameter of 3mm, dry at 120°C for 6h, calcine at 1090°C for 6h, and then crystallize the particles at 150°C in 200mL of methanol for 12h, finally acidify with 40°C, 0.1mol / L, 200mL citric acid solution for 7h, and dry at 120°C for 6h to obtain the carrier.

[0075] Take the above carrier, prepare 150 mL of a mixed aqueous solution of palladium nitrate and silver nitrate containing 5 g of palladium and 5 g of silver, saturate the carrier with the above solution, take it out after 5 minutes, dry it at 120°C for 6 hours, and calcine it in air at 480°C for 8 hours to obtain the target catalyst B3.

[0076] Comparative Example 4

[0077] Prepare 250mL of 0.15mol / L nitric acid, 0.15mol / L acetic acid, and 0.05mol / L citric acid aqueous solution, add to a mixture of 100g pseudo-boehmite powder, 100g θ-alumina powder, 10g starch, 8g sesbania powder, and 6g vanadium pentoxide (isoelectric point 1.3), put into a kneader and knead to form a plastic semisolid, then extrude into spherical particles with a diameter of 3mm, dry at 120°C for 6h, calcine at 1190°C for 6h, then acidify the particles with 200mL of citric acid solution at 40°C, pH value of 0.5, for 7h, and dry at 120°C for 6h to obtain a carrier.

[0078] Take the above carrier, prepare 150 mL of a mixed aqueous solution of palladium nitrate and silver nitrate containing 5 g of palladium and 5 g of silver, saturate the carrier with the above solution, take it out after 5 minutes, dry it at 120°C for 6 hours, and calcine it in air at 410°C for 8 hours to obtain the target catalyst B4.

[0079] Comparative Example 5

[0080] Prepare 250 mL of 0.25 mol / L sulfuric acid aqueous solution, add to a mixture of 200 g of quick-release alumina powder, 10 g of hydroxymethyl cellulose, and 8 g of polyethylene microspheres, put into a kneader and knead to form a plastic semisolid, then extrude into spherical particles with a diameter of 3 mm, dry at 120°C for 6 h, and calcine at 1160°C for 6 h to obtain a carrier.

[0081] Take the above carrier, prepare 150 mL of a mixed aqueous solution of palladium nitrate and silver nitrate containing 5 g of palladium and 5 g of silver, saturate the carrier with the above solution, take it out after 5 minutes, dry it at 120°C for 6 hours, and calcine it in air at 850°C for 8 hours to obtain the target catalyst B5.

[0082] Comparative Example 6

[0083] Prepare 250 mL of an aqueous solution of 0.2 mol / L nitric acid, 0.15 mol / L sulfuric acid and 0.2 mol / L citric acid, add it to a mixture of 200 g of pseudo-boehmite powder, 10 g of starch, 8 g of polyethylene glycol and 6 g of silicon oxide (isoelectric point 2.2), put it into a kneader and knead it to form a plastic semi-solid, then extrude it into spherical particles with a diameter of 3 mm, dry it at 120°C for 6 h, calcine it at 1150°C for 6 h, crystallize the particles in 200 mL of methanol at 170°C for 10 h, finally acidify it with 200 mL of citric acid solution at 40°C and pH 1.5 for 7 h, and dry it at 120°C for 6 h to obtain the carrier.

[0084] Take the above carrier, prepare 150 mL of a palladium nitrate aqueous solution containing 5 g of palladium, saturate the carrier with the above solution, take it out after 5 minutes, dry it at 120°C for 6 hours, and calcine it in air at 450°C for 8 hours to obtain the target catalyst B6.

[0085] Test Example 1 Characterization of Catalyst Physical Properties

[0086] The Pd dispersion was tested on a Micromeritics AutoChem 2920 adsorption instrument. The catalyst was tested before and after reduction treatment. The sample was first purged with He gas at 400°C for 1 hour, reduced to 150°C and reduced with H2 for 1 hour, then reduced to 50°C and injected with CO by pulse injection, and the CO signal was recorded by TCD. When calculating the dispersion, the adsorption ratio (molar ratio) of CO to Pd was 1:1.2.

[0087] The specific surface area of ​​the catalysts of the embodiments and comparative examples was measured by the BET method using nitrogen physical adsorption; the bulk density of the catalyst was measured by weighing 50 mL of the carrier mass (the arithmetic mean of three test results was taken); the average pore size and the most probable pore size were measured by the mercury intrusion method. The above test results are summarized in Table 1.

[0088] Table 1

[0089]

[0090] As can be seen from Table 1, the method of the present invention can significantly improve the dispersion of Pd metal on the catalyst surface without affecting the specific surface area, bulk density, average pore size, and most probable pore size. When the reduction temperature is too high, the surface-treated carrier can effectively suppress the sintering phenomenon of metal Pd on the catalyst surface, maintaining highly dispersed, small-particle active centers. After a long period of catalytic reaction and regeneration treatment, the surface-treated carrier can better maintain the high dispersion of Pd metal on the catalyst surface, so that the catalyst maintains a high catalytic performance. At the same time, by adjusting the type of raw materials, the preferred raw material ratio, the combination and order of the surface treatment method, and the reduction temperature, the regulation of the dispersion of metal Pd on the catalyst surface can be achieved, and then different heterogeneous catalytic systems can be adapted.

[0091] Test Example 2 Evaluation of Catalytic Performance of Catalyst

[0092] Catalysts A1-A6 and B1-B5 were evaluated for their catalytic performance of C4 selective hydrogenation. The reaction conditions for C4 selective hydrogenation were:

[0093] The molar ratio of acetylene to hydrogen is 1:10, the reaction temperature is 45°C, the reaction pressure is 0.8 MPa, the composition of the mixed C4 is shown in Table 2, and the volume space velocity is 40 h -1 The residual amount of alkyne and the loss of butadiene in the reaction of each catalyst are listed in Table 3.

[0094] Table 2

[0095] Components Mass fraction / % Isobutane 1.72 n-Butane 4.04 Cis-2-Butene 3.24 trans-2-butene 4.42 1-Butene 13.17 Isobutylene 19.16 1,2-Butadiene 0.22 1,3-Butadiene 53.48 Methylacetylene(MA) 0.12 Vinyl acetylene (VA) 0.40 Ethylacetylene (EA) 0.13

[0096] The raw materials and products were analyzed by gas chromatography. The total alkyne residue was the sum of the residues of VA, EA and MA in the product. The butadiene loss was calculated as follows: L = ω f -ω p , where L is the loss of butadiene; ω f is the butadiene content in the raw material; ω p It is the butadiene content in the product.

[0097] After the initial evaluation, catalysts A1-A6 and B1-B5 were regenerated under the following conditions: a steam to air volume ratio of 1:2, a reaction temperature of 500°C, a reaction pressure of 0.1 MPa, and a volume space velocity of 5000 h -1 After the regeneration treatment, the catalytic performance of the C4 selective hydrogenation of catalysts A1-A6 and B1-B6 was evaluated at 110°C under the same conditions as above. The residual amount of acetylene and the loss of butadiene of each catalyst in the reaction are listed in Table 3.

[0098] Table 3

[0099]

[0100] It can be seen from the results in Table 3 that the activity and selectivity of the catalyst prepared by the method provided by the present invention are better than those of the catalyst prepared by the prior art method. In particular, the catalysts A1, A2, A5 and A6 prepared under the optimal conditions have better catalytic performance.

[0101] By comparing Example 1 with Example 3, and by comparing Example 1 with Example 2, it can be seen that both the acidification and alkalization treatment processes can improve the performance of the catalyst.

[0102] By comparing Example 1 with Comparative Example 6, it can be seen that the introduction of the auxiliary agent can increase the dispersion of the active components, thereby improving the catalyst performance.

[0103] By comparing Example 1 with Comparative Example 5, it can be seen that the catalyst prepared by using multiple surface treatment methods has better catalytic performance than the catalyst prepared by using a single surface treatment method.

[0104] By comparing Example 1 with Comparative Example 3, it can be seen that when the acidification / alkalinization conditions selected are inconsistent with the conditions required by the isoelectric point regulator, the catalyst performance and selectivity are not significantly improved.

[0105] By comparing Comparative Example 2 with Comparative Example 5, it can be seen that the reduction should be carried out in a suitable temperature range, and too high a reduction temperature will lead to a decrease in the catalytic performance and selectivity of the catalyst.

[0106] By comparing Example 5 with Example 6 and Comparative Example 5, it can be seen that the surface-treated catalyst can effectively suppress the performance degradation caused by high-temperature reduction and maintain a high alkyne conversion rate and selectivity.

[0107] By comparing Example 1 with Comparative Example 1, and Example 6 with Comparative Example 5, it can be seen that the above-mentioned surface treatment method can enable the catalyst to maintain a relatively high catalytic performance after a long period of catalytic reaction and regeneration treatment, and can be reused many times.

Claims

1. A highly dispersed alkyne hydrogenation catalyst, comprising a modified alumina carrier and active components and additives loaded on the carrier, wherein the dispersion of the active components on the catalyst surface is 40-70%.

2. The catalyst according to claim 1, characterized in that The dispersion degree of the active components on the catalyst surface is 45-65%; and / or, Based on the total weight of the catalyst as 100%, the content of the auxiliary agent is 0.01 to 10%, preferably 0.05 to 8%; and / or, The catalyst has an average pore size of 30 to 200 nm, preferably 50 to 150 nm; and / or a maximum pore size of 80 to 250 nm, preferably 100 to 200 nm; and / or a specific surface area of ​​5 to 100 m 2 / g, preferably 10 to 70 m 2 / g; and / or, a bulk density of 0.4 to 1.3 g / mL, preferably 0.5 to 1.2 g / mL.

3. The catalyst according to claim 1 or 2, characterized in that The active component is Pd; and / or, The auxiliary agent is selected from at least one of Ag and Ce; and / or, The modified alumina carrier comprises alumina and other oxides, and the other oxides are selected from at least one of vanadium pentoxide, antimony pentoxide, silicon oxide, tin oxide, zirconium oxide, manganese oxide, cerium oxide, iron oxide, ferrous oxide, titanium oxide, copper oxide, zinc oxide, lanthanum oxide, nickel oxide, magnesium oxide, yttrium oxide, gallium oxide, and indium oxide, preferably at least one of vanadium pentoxide, antimony pentoxide, silicon oxide, tin oxide, titanium oxide, zirconium oxide, nickel oxide, magnesium oxide, gallium oxide, and copper oxide.

4. A method for preparing the highly dispersed alkyne hydrogenation catalyst according to any one of claims 1 to 3, comprising: The modified alumina carrier is immersed in a metal compound solution containing an active component precursor compound and an auxiliary agent precursor compound, taken out, dried, and calcined to obtain the alkyne hydrogenation catalyst with high dispersion.

5. The preparation method according to claim 4, characterized in that: The active component precursor compound is selected from one of palladium nitrate, palladium chloride, palladium oxide, palladium hydroxide, and sodium tetrachloropalladate, preferably at least one of palladium nitrate and palladium chloride; and / or, The auxiliary agent precursor compound is selected from at least one of silver nitrate, cerium nitrate and cerium chloride, preferably at least one of silver nitrate and cerium nitrate; and / or, In the metal compound solution, the molar concentration of the active component precursor compound is 0.05 to 10 mol / L; and / or, In the metal compound solution, the molar concentration of the auxiliary agent precursor compound is 0.05 to 10 mol / L; and / or, The drying conditions are: drying temperature of 60-200°C, drying time of 5-20h; preferably, drying temperature of 80-150°C, drying time of 6-16h; and / or, The calcination conditions are: calcination temperature is 200-1200° C., and calcination time is 2-24 hours; preferably, calcination temperature is 300-1000° C., and calcination time is 5-12 hours.

6. The preparation method according to claim 4, characterized in that: The modified alumina carrier is prepared by the following steps: mixing components including an alumina precursor, a forming agent, a pore expanding agent, an isoelectric point regulating agent, and a crosslinking agent solution to obtain a mixture, kneading and molding, extruding and pelletizing, drying, and calcining to obtain a modified alumina precursor, and then surface treating the modified alumina precursor to obtain the modified alumina carrier.

7. The preparation method according to claim 6, characterized in that: The alumina precursor is selected from at least one of boehmite powder, pseudo-boehmite powder, alumina trihydrate powder, fast-release alumina powder, and θ-alumina powder; and / or, The molding agent is selected from at least one of starch, methyl cellulose, carboxymethyl cellulose, ethyl cellulose and hydroxypropyl methyl cellulose; and / or, The pore-enlarging agent is selected from at least one of sesbania powder, starch, polyethylene glycol, polyethylene microspheres, polyethylene oxide, polystyrene, and polypropylene glycol; and / or, The isoelectric point regulator is selected from at least one of oxides having an isoelectric point of less than 6 or greater than 8. Preferably, the oxide having an isoelectric point of less than 6 is selected from at least one of vanadium pentoxide, antimony pentoxide, silicon oxide, tin oxide, zirconium oxide, manganese oxide, cerium oxide, iron oxide, ferrous oxide, and titanium oxide, preferably at least one of vanadium pentoxide, antimony pentoxide, silicon oxide, tin oxide, titanium oxide, and zirconium oxide; and / or, the oxide having an isoelectric point greater than 8 is selected from at least one of copper oxide, zinc oxide, lanthanum oxide, nickel oxide, magnesium oxide, yttrium oxide, gallium oxide, and indium oxide, preferably at least one of nickel oxide, magnesium oxide, gallium oxide, and copper oxide; and / or, The crosslinking agent in the crosslinking agent solution is selected from at least one of nitric acid, sulfuric acid, hydrochloric acid, phosphoric acid, acetic acid, citric acid, oxalic acid, ascorbic acid and salicylic acid; and / or, The solvent in the crosslinker solution is selected from at least one of water, methanol, ethanol and ethylene glycol, preferably water and / or ethanol.

8. The preparation method according to claim 6, characterized in that: Based on the total weight of the alumina precursor, the forming agent, the pore expanding agent, and the isoelectric point regulating agent as 100%, the amount of the forming agent is 0.1-15%, the amount of the pore expanding agent is 0.05-15%, and the amount of the isoelectric point regulating agent is 0.02-12%; preferably, based on the total weight of the alumina precursor, the forming agent, the pore expanding agent, and the isoelectric point regulating agent as 100%, the amount of the forming agent is 1-12%, the amount of the pore expanding agent is 1-10%, and the amount of the isoelectric point regulating agent is 0.1-8%; and / or, The molar concentration of the crosslinking agent solution is 0.001 to 10 mol / L, preferably 0.05 to 5 mol / L; and / or, Based on 100 g of the aluminum oxide precursor, the amount of the crosslinking agent solution is 50 to 1000 mL, preferably 100 to 800 mL.

9. The preparation method according to claim 6, characterized in that: The drying conditions are: drying temperature of 60-200°C, drying time of 5-20h; preferably, drying temperature of 80-150°C, drying time of 6-16h; and / or, The calcination conditions are: calcination temperature of 500-1500° C., calcination time of 1-24 hours; preferably, calcination temperature of 800-1300° C., calcination time of 3-15 hours; and / or, The surface treatment is selected from at least two of acidification or alkalization, crystallization, and irradiation. Preferably, when the isoelectric point regulator is an oxide with an isoelectric point less than 6 and acidification is used, the pH of the acidification treatment needs to be 0.1 to 2 lower than the isoelectric point value of the isoelectric point regulator, preferably 0.3 to 1.5 lower; and / or, when the isoelectric point regulator is an oxide with an isoelectric point greater than 8 and acidification is not used and alkalization is used, the pH of the alkalization treatment needs to be 0.1 to 2 higher than the isoelectric point value of the isoelectric point regulator, preferably 0.3 to 1.5 higher.

10. The preparation method according to claim 9, characterized in that: The acidification conditions are: temperature of 30-100°C, time of 0.5-12h, and / or, the acidifier is selected from at least one of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, sodium bisulfate, acetic acid, oxalic acid, and citric acid, and / or, the concentration of the acidifier solution is 0.01-10 mol / L; preferably, the acidification conditions are: temperature of 35-80°C, time of 1-8h, and / or, the acidifier is selected from at least one of sulfuric acid, hydrochloric acid, nitric acid, acetic acid, and citric acid, and / or, the concentration of the acidifier solution is 0.1-5 mol / L; and / or, The alkalization conditions are: temperature of 30-100°C, time of 0.5-12h, and / or, the alkalizer is selected from at least one of sodium hydroxide, potassium hydroxide, barium hydroxide, sodium carbonate, sodium bicarbonate, potassium carbonate, and ammonia water, and / or, the concentration of the alkalizer solution is 0.01-10 mol / L; preferably, the alkalization conditions are: temperature of 35-80°C, time of 1-8h, and / or, the alkalizer is selected from at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate, and / or, the concentration of the alkalizer solution is 0.1-5 mol / L; and / or, The crystallization conditions are: temperature of 50-300°C, time of 0.5-20h, and / or, the crystallization solvent is selected from at least one of water, methanol, ethanol, ethylene glycol, and ethylenediamine; preferably, the crystallization conditions are: temperature of 100-200°C, time of 1-15h, and / or, the crystallization solvent is selected from at least one of water, methanol, and ethanol; and / or, The irradiation conditions are: the ray source is γ rays, and / or the irradiation dose rate is 0.01 to 50 kGy / min, and / or the irradiation time is 0.1 to 10 h; preferably, the irradiation conditions are: the ray source is γ rays, and / or the irradiation dose rate is 0.5 to 20 kGy / min, and / or the irradiation time is 0.2 to 6 h.

11. Use of the high-dispersion alkyne hydrogenation catalyst according to any one of claims 1 to 3 or the high-dispersion alkyne hydrogenation catalyst obtained by the preparation method according to claims 4 to 10 in a C4 selective hydrogenation reaction.

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