Composite carrier supported palladium catalyst for preparing succinic anhydride through maleic anhydride hydrogenation as well as preparation method and application of composite carrier supported palladium catalyst

Abstract

The invention provides a composite carrier supported palladium catalyst for preparing succinic anhydride through maleic anhydride hydrogenation and a preparation method and application thereof.The structural general formula of the composite carrier supported palladium catalyst is Pd-A-X-Y / (Z1 + Z2), Z1 in a composite carrier is made of a high-specific-surface-area porous material, Z2 is made of a high-thermal-conductivity compact material, and X is larger than or equal to 1 and smaller than or equal to 2. The active component is composed of metal Pd and transition metal such as Ni or precious metal such as Ru, and the auxiliary agent is composed of oxides of alkali metal, alkaline earth metal or rare earth elements and oxides of high-valence elements such as Mo. The catalyst is prepared by an impregnation method, and the composite carrier supported palladium catalyst has excellent low-temperature activity, tolerance and stability in a reaction for preparing succinic anhydride by maleic anhydride hydrogenation, can bear high maleic anhydride concentration and high liquid hourly space velocity at low temperature, low pressure and low hydrogen-anhydride ratio, and simultaneously obtains high maleic anhydride conversion rate and succinic anhydride selectivity.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts and their preparation, and specifically relates to a composite support-supported palladium catalyst for the hydrogenation of maleic anhydride to succinic anhydride, its preparation method and application. Background Art

[0002] Succinic anhydride is an important chemical raw material, and succinic anhydride and its downstream products are widely used in fields such as food, surfactants, coatings, medicine, agriculture, plastics, etc.

[0003] Succinic anhydride is usually prepared by directly hydrogenating maleic anhydride, and noble metal Pd catalysts, non-noble metal Ni catalysts or bimetallic active component catalysts are mostly used. There have been a large number of patents on the preparation of succinic anhydride by batch hydrogenation of maleic anhydride in a kettle using powder catalysts. However, these methods use a batchwise manner in a kettle, and the catalysts used are all supported powder catalysts prepared with a single-property carrier, resulting in low catalytic reaction efficiency, and the subsequent separation process of the catalyst is cumbersome and has large losses, which is not suitable for the large-scale production of succinic anhydride. Therefore, in order to meet the large-scale liquid-phase hydrogenation of maleic anhydride to prepare succinic anhydride, a better choice is to use a fixed-bed continuous reaction method, and for this purpose, it is necessary to develop a solid particle catalyst with excellent performance.

[0004] At present, there have been a large number of patents on using supported particle catalysts, including particle catalysts supporting non-noble metal single active components and noble metal-supported particle catalysts, for the continuous hydrogenation of maleic anhydride to prepare succinic anhydride. For example: CN101502802B discloses a Ni-based supported catalyst using high-specific-surface SiO 2 , Al 2 O 3 or SiO 2 -Al 2 O 3 as the carrier for the continuous hydrogenation of maleic anhydride in a fixed bed to prepare succinic anhydride. The concentration of the γ-butyrolactone solution of the raw material maleic anhydride is 0.08 g / mL. Under the conditions of a temperature of 60-180 °C, a hydrogen pressure of 0.9-10 MPa, and a liquid hourly space velocity of 1.4 h -1 , the conversion rate of maleic anhydride ≥ 99.98%, and the selectivity of succinic anhydride ≥ 98.85%. However, this technical solution does not have a hydrogen-to-anhydride molar ratio, and the reaction temperature and pressure are relatively high, and the concentration of the maleic anhydride raw material is too low. CN114433100A discloses a high-specific-surface SiO 2 as the carrier, and a bimetallic Ni-Cu catalyst 15-25 wt% Ni-1-3 wt% Cu-3-6 wt% Ce / 66-81 wt% SiO 2 is prepared by Ce modification. Using a fixed-bed reactor, at a temperature of 80-140 °C, a pressure of 0.5-2.0 MPa, a hydrogen / maleic anhydride molar ratio of 10-30, and a maleic anhydride space velocity of 0.1-0.5 h-1 、 Under the condition that the concentration of maleic anhydride in the γ-butyrolactone solution is 10-30 wt%, the conversion rate of maleic anhydride is 97.8-100%, and the selectivity of succinic anhydride is 98.0-99.6%. This technical solution requires a hydrogenation reaction at a relatively high temperature. CN105597742A discloses using carriers such as alumina, titanium oxide, activated carbon or molecular sieve with a specific surface area of 100-350 m 2 / g to prepare a noble metal Pd-supported particulate catalyst containing a promoter by an impregnation method. In its examples, the content of catalyst promoters such as CeO 2 etc. is 2-10 wt%, and the Pd content is 0.1-1.0 wt%. The conditions for the continuous liquid-phase hydrogenation reaction of maleic anhydride in a trickle bed are: reaction temperature 130-160 °C, hydrogen pressure 1.0-1.5 MPa, hydrogen-to-anhydride molar ratio 50-100, weight ratio of maleic anhydride to solvent γ-butyrolactone 1:5-15, and space velocity of the feed liquid 0.8-1.5 h -1 , the conversion rate of maleic anhydride is greater than 99.9%, and the selectivity of succinic anhydride is greater than 99.2%. This catalyst requires a high reaction temperature and hydrogen-to-anhydride ratio, as well as a low concentration of maleic anhydride solution. CN106669730B uses a porous ceramic carrier to prepare a Sn-modified 0.1-3.0 wt% Pd-0.1-1.0 wt% Ni / porous ceramic dual-active component catalyst by multiple impregnations. At a temperature of 90-150 °C, a pressure of 0.5-3 MPa, a concentration of the γ-butyrolactone solution of raw material maleic anhydride of 5-20 wt%, a space velocity of the feed liquid of 0.1-1.0 h -1 and a hydrogen-to-anhydride ratio of 50-200, using a fixed-bed hydrogenation reactor, the conversion rate of maleic anhydride is 80-98.5%, and the selectivity of succinic anhydride is 80.7-99.8%. This catalyst requires relatively high reaction temperature and hydrogen-to-anhydride ratio, while the concentration of maleic anhydride solution is relatively low.

[0005] It can be seen that whether it is a single noble metal catalyst or a noble metal-non-noble metal dual-active component catalyst, a single high specific surface carrier with extremely poor thermal conductivity is used for the reaction of preparing succinic anhydride by liquid-phase hydrogenation of maleic anhydride. As a result, when the catalyst is used in the hydrogenation reaction of maleic anhydride, usually higher reaction temperature and hydrogen pressure are required, as well as lower concentration of raw material maleic anhydride solution, lower space velocity of maleic anhydride solution, and high hydrogen-to-anhydride molar ratio.

[0006] In summary, due to the use of a single high-specific-surface-area porous support with poor thermal conductivity in the prior art, the high dispersion of the catalyst metal active component is blindly pursued to achieve high maleic anhydride hydrogenation reaction activity. As a result, the thermal conductivity of the supported metal particle catalyst is extremely poor, leading to local overheating of the catalyst particles during the catalytic reaction, easy agglomeration and growth of the metal active component, and easy coking on the catalyst surface, thereby affecting the catalyst activity and service life. When used in the maleic anhydride hydrogenation reaction, in order to obtain a better catalytic reaction effect, it is necessary to reduce the maleic anhydride concentration and maleic anhydride space velocity of the raw materials, and increase the reaction temperature, hydrogen pressure and hydrogen-to-anhydride ratio, resulting in high energy consumption, low device productivity and increased investment for producing succinic anhydride.

[0007] Catalytic hydrogenation is an exothermic reaction. For the hydrogenation of maleic anhydride to succinic anhydride, the reaction heat ΔH at 298K 0 298 is -136.9 kJ / mol. When using a γ-butyrolactone solution with a maleic anhydride concentration of 22 wt% as the reaction raw material, at a hydrogen-to-anhydride molar ratio of 20, a reaction temperature of 100 °C, and a reaction pressure of 0.5 MPa, when the maleic anhydride conversion rate is 98%, the adiabatic temperature rise of this reaction will reach 63 °C. Maleic anhydride hydrogenation can produce a variety of products and is a typical series reaction. The reaction first produces succinic anhydride, and succinic anhydride is further hydrogenated and dehydrated to produce γ-butyrolactone, and γ-butyrolactone is further hydrogenated and dehydrated to produce tetrahydrofuran or hydrogenated and ring-opened to produce 1,4-butanediol. Therefore, controlling the maleic anhydride hydrogenation reaction to stay at the stage of producing succinic anhydride and preventing the further hydrogenation of succinic anhydride to produce deeply hydrogenated products is the key. To achieve this goal, it is crucial to develop a catalyst with high activity and high selectivity. At the same time, effectively controlling the surface temperature and temperature distribution of the catalyst plays a decisive role in controlling the reaction to stay at the stage of producing succinic anhydride. The higher the surface temperature of the catalyst, the easier it is to produce deeply hydrogenated products and the lower the selectivity of succinic anhydride. Traditional hydrogenation catalysts and their preparation methods mainly consider the dispersion of active components, improve the reaction activity of the catalyst and the effective utilization rate of active components, especially noble metals, and basically use high-specific-surface-area porous supports, while ignoring the thermal conductivity of the catalyst itself.

[0008] Therefore, it is very necessary for the large-scale industrial production of succinic anhydride to provide a catalyst for the preparation of succinic anhydride by maleic anhydride hydrogenation that can be used under low temperature, low pressure, low hydrogen-to-anhydride ratio and high-concentration raw materials and high space velocity conditions, and has high activity, high selectivity and long service life. Summary of the Invention

[0009] Aiming at the above deficiencies existing in the prior art, the purpose of the present invention is to provide a catalyst for the preparation of succinic anhydride by maleic anhydride hydrogenation that can be used under low temperature, low pressure, low hydrogen-to-anhydride ratio and high-concentration, high space velocity conditions, and has high activity, high selectivity and long service life, and its preparation method and application.

[0010] To achieve the above object, the technical solution of the present invention is specifically as follows:

[0011] A composite support-supported palladium catalyst for the hydrogenation of maleic anhydride to succinic anhydride, and the structural general formula of the composite support-supported palladium catalyst is:

[0012] Pd-A-X-Y / (Z1+Z2);

[0013] In the formula, Pd is used as the first active component, and the content is 0.05-0.75 wt%; the second active component A is selected from non-noble metals Cu, Co or Ni, or noble metals Ru, Pt, Rh, Os, Au or Ag, or any combination of these metal elements, and the content of A is 0.01-10.00 wt%; the first promoter X is selected from oxides of alkali metals, oxides of alkaline earth metals, oxides of rare earth elements or any combination of them, and the content is 0.01-10.0 wt%, and the second promoter Y is selected from oxides of Nb, Sb, V, Sn, Pb, Se, Te, Mo, W, Fe, Ga, In, Cr, Mn, Ir, Re, Zn, B, P or any combination of these oxides, and the content is 1.00-20.00 wt%;

[0014] The support material Z1 in the composite support (Z1+Z2) is a pore material support with a specific surface area ≥100 m 2 / g, and the pore material support Z1 is selected from at least one of SiO 2 , Al 2 O 3 , TiO 2 , ZrO 2 , carbon, molecular sieve, clay or light magnesium oxide, and the content is 50-90 wt%; the support material Z2 is a heat-conducting material support with a thermal conductivity ≥20 W / (m·K), and the support material Z2 is selected from at least one of BeO, MgO, α-Al 2 O 3 , α-SiO 2 , BN, AlN, Si 3 N 4 , SiC, ZrC, Mo 2 C, W 2 C, WC, Si, graphite, graphene, PCD ceramic (polycrystalline diamond), MoS 2 or WS 2 and the content is 8-48 wt%; the content of the composite support (Z1+Z2) accounts for 58-98 wt% of the total content of the catalyst.

[0015] Further, the Pd content in the composite support-supported palladium catalyst is 0.10-0.50 wt%, such as 0.10 wt%, 0.20 wt%, 0.30 wt%, 0.40 wt% or 0.50 wt%.

[0016] Further, the second active component A is selected from Cu, Co or Ni with a content of 0.50-7.50 wt%, or Pt, Rh or Os with a content of 0.02-0.50 wt%, or Ru, Au or Ag with a content of 0.05-2.00 wt%, or any combination of these metals.

[0017] Further, the second active component A is selected from Cu, Co or Ni with a content of 1.0-5.0 wt%, such as 1.0, 2.0, 3.0, 4.0 or 5.0 wt%; or the second active component A is selected from Pt with a content of 0.05-0.2 wt%, such as 0.05 wt%, 0.1 wt%, 0.15 wt% or 0.2 wt%; or is selected from Ru with a content of 0.1-1.0 wt%, such as 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt% or 1.0 wt%; or is selected from Ag with a content of 0.5-2.0 wt%, such as 0.5 wt%, 1.0 wt%, 1.5 wt% or 2.0 wt%.

[0018] Further, the first promoter X is an alkali metal oxide with a content of 0.05-5.00 wt%, an alkaline earth metal oxide with a content of 0.10-7.50 wt% or a rare earth oxide with a content of 0.10-7.50 wt%, or any combination thereof.

[0019] Further, the first promoter X is an oxide of Li, Na, K or Rb with a content of 0.20-2.00 wt%, an oxide of Mg, Ca, Sr or Ba with a content of 0.50-5.00 wt%, or an oxide of Cs, La, Ce, Nd, Sm or Yb with a content of 0.20-6.00 wt%, or any combination of these substances.

[0020] Further, the first promoter X is selected from oxides of Li or K with a content of 0.5-1.0 wt%, such as 0.5 wt%, 0.7 wt%, 0.9 wt% or 1.0 wt%; or is selected from oxides of Mg or Ca with a content of 1.0-3.0 wt%, such as 1.0 wt%, 1.5 wt%, 2.0 wt%, 2.5 wt% or 3.0 wt%; or is selected from oxides of Cs, La or Ce with a content of 0.5-2.5 wt%, such as 0.5 wt%, 1.0 wt%, 1.5 wt%, 2.0 wt% or 2.5 wt%.

[0021] Furthermore, the second auxiliary agent Y is selected from Nb 2 O 5 , Sb 2 O 5 , Sb 2 O 3 、V 2 O 5 、MoO 3 、MoO

[0022] 2 , WO 3 SnO 2 , PbO 2 , SeO 2 、TeO 2 , Fe 2 O 3 , Fe 3 O 4 ,FeO,Ga 2 O 3 、In 2 O 3 Cr 2 O 3 、MnO 2 , Mn 2 O 3 , Mn 3 O 4 、IrO 2 、Re 2 O 7 , ZnO, B 2 O 3 or P 2 O 5 , or any combination thereof, the content of which is 3.00 to 15.00 wt%.

[0023] Furthermore, the second auxiliary agent Y is selected from MoO 3 , WO 3 SnO 2 , Fe 2 O 3 Cr 2 O 3 、MnO 2 , ZnO or P 2 O 5 Or any combination thereof, the content of which is 5.0 to 10.0 wt%.

[0024] Furthermore, the carrier material Z1 is selected from a material with a specific surface area of ​​≥ 250 m 2 / g porous, mesoporous or macroporous SiO 2 、TiO 2, ZrO 2 , Al 2 O 3 , carbon, molecular sieve or clay, or any combination of these substances; wherein, the specific surface area ≥ 250 m 2 / g of the SiO 2 includes amorphous SiO 2 , silica sol, silica gel or mesoporous SiO 2 , the Al 2 O 3 includes amorphous Al 2 O 3 , activated Al 2 O 3 , γ-Al 2 O 3 , θ-Al 2 O 3 or mesoporous Al 2 O 3 , the TiO 2 includes amorphous TiO 2 , rutile, anatase or mesoporous TiO 2 , the carbon includes activated carbon, carbon nanotubes, graphene or mesoporous carbon, the molecular sieve includes USY, MOR, β, ZSM-5, ZSM-22, TS-1, ZRP, MCM-22, MCM-41, MCM-48, MCM-49, MCM-50, SAPO-34, SBA-15, KIT-6 or ZEO-3, the clay includes bentonite, kaolin, montmorillonite or palygorskite, and the content of the carrier material Z1 is 60-85 wt%;

[0025] Further, the carrier material Z1 is selected from porous silica sol with a specific surface area ≥ 500 m 2 / g, SiO 2 -Al 2 O 3 , activated carbon or molecular sieve, or mesoporous SiO 2 , mesoporous Al 2 O 3 , mesoporous TiO 2 , mesoporous carbon or mesoporous molecular sieve, or macroporous molecular sieve, or any combination of these substances; wherein, the molecular sieve with a specific surface area ≥ 500 m 2 / g includes porous molecular sieves MOR, ZSM-5, TS-1, ZRP, MCM-22, or mesoporous molecular sieves MCM-41, MCM-48, MCM-50, SBA-15 or KIT-6, or macroporous molecular sieve ZEO-3;

[0026] Further, the carrier material Z2 is selected from BeO, α-Al 2 O 3 , hexagonal boron nitride (HBN), cubic boron nitride (CBN), AlN, Si 3 N 4 , SiC, WC, Si, graphite, graphene, PCD ceramics or MoS 2 , or any combination of these substances, and the content of the carrier material Z2 is 10-35 wt%;

[0027] Further, the carrier material Z2 is BeO, CBN, AlN, Si 3 N 4 , SiC, Si, graphite, multi-layer graphene, PCD ceramics or MoS 2 , or any combination of them, with a thermal conductivity greater than 100 W / (m·K).

[0028] The present invention provides a method for preparing a composite carrier-supported palladium catalyst for the hydrogenation of maleic anhydride to succinic anhydride. When the second active component A is selected as a non-noble metal, the preparation of the composite carrier-supported palladium catalyst includes the following steps:

[0029] T1: Mix the carrier materials Z1 and Z2 powders and carry out ball milling to obtain a composite carrier powder U1;

[0030] T2: Prepare an aqueous solution of the compound of the second active component A and an aqueous solution of the compound of the second promoter Y respectively, mix the two to obtain a mixed solution, then immerse the composite carrier powder U1 in the mixed solution, and then heat and evaporate to dryness, pulverize and calcine in sequence under stirring to obtain a catalyst precursor powder U2;

[0031] T3: Prepare an aqueous solution of the compound of the first promoter X, then immerse the catalyst precursor powder U2 in the solution of the first promoter X, and heat and evaporate to dryness, pulverize and calcine in sequence under stirring to obtain a catalyst precursor powder U3;

[0032] T4: Take the catalyst precursor powder U3, add a binder (which is also a pore-forming agent), and then knead, form and calcine in sequence to obtain a catalyst precursor particle U4;

[0033] T5: Prepare an aqueous solution of the compound of Pd, then immerse the catalyst precursor particle U4 prepared in step T4, and let it stand at 50-85 °C for 0.5-5.0 hours, then take out the impregnated U4 particles, and dry and calcine them to obtain the finished catalyst.

[0034] Further, in step T1, the carrier material Z1 and Z2 powders are ultrafine powders with a particle size ≤ 10 μm. In a high-energy ball mill, they are ball-milled at a rotational speed ≥ 200 r / min for 5 - 200 min to obtain the composite carrier powder U1; preferably, they are ball-milled at a rotational speed ≥ 1000 r / min for 30 - 60 min.

[0035] Further, in steps T2 and T3, when preparing the solutions of the corresponding components, the soluble salts of the second promoter Y, the non-noble metal second active component A, or the corresponding elements of the first promoter X, or the insoluble compounds of the corresponding elements of these components are first made into soluble nitrates, chlorides, ammonium salts, or complexes, and dissolved with demineralized water at 15 - 85°C.

[0036] Further, in step T4, the binder is selected from at least one of water, nitric acid, acetic acid, citric acid, sorbic acid, ethylene glycol, 1,4-butanediol, glycerol, erythritol, vegetable oil, sesbania powder, methyl cellulose, lignin, or starch, and the addition amount is 2.0 - 20 wt% of the total material amount; preferably nitric acid, acetic acid, ethylene glycol, glycerol, sesbania powder, methyl cellulose, starch, or their aqueous solutions, and the addition amount is 5 - 10 wt% of the total material amount;

[0037] The shaping is carried out by rolling balls, tabletting, or extrusion to make the catalyst precursor powder into spherical balls with a diameter of 1.0 - 5.0 mm, hedgehog balls, cylinders with a length of 1 - 5 mm, clovers with a length of 1 - 8 mm, strip-shaped composite carrier particles or catalyst precursor particles with a length of 1 - 8 mm; preferably spherical balls with a diameter of 1.5 - 3.0 mm, hedgehog balls, cylinders with a length of 2 - 3 mm, clovers with a length of 2 - 5 mm, strip-shaped catalyst precursor particles with a length of 2 - 5 mm.

[0038] Further, in step T5, the compound of the first active component Pd is selected from palladium-containing halides, nitrates, acetates, haloacids and their salts, or complexes and their salts, preferably palladium chloride, palladium nitrate, palladium acetate, ammonium chloropalladate, palladium acetylacetonate, palladium ammine complex salt, or Schiff base palladium complex; the molar concentration of the Pd compound aqueous solution is 0.01 - 2.00 mol / L, preferably 0.02 - 0.50 mol / L.

[0039] Further, in each step of the above catalyst preparation, the drying is carried out at 120 - 250°C for 0.2 - 5.0 hours in a flowing air or nitrogen atmosphere, preferably at 150 - 220°C for 0.5 - 2.5 hours; the calcination is carried out at 250 - 400°C for 0.5 - 3.0 hours and 450 - 750°C for 1.5 - 10.0 hours in a flowing air or nitrogen atmosphere, preferably at 300 - 350°C for 1.0 - 2.0 hours and 550 - 650°C for 3.0 - 6.0 hours.

[0040] The present invention also provides a method for preparing a palladium catalyst supported on a composite support for the hydrogenation of maleic anhydride to succinic anhydride. When the second active component A is a noble metal, the preparation of the palladium catalyst supported on the composite support includes the following steps:

[0041] E1: Mix the carrier materials Z1 and Z2 powders and carry out ball milling to obtain a composite support powder. Then add a binder (which is also a pore-forming agent), and then successively carry out kneading, shaping, and calcination to obtain composite support particles F1;

[0042] E2: Prepare an aqueous solution of a compound of the second promoter Y, then immerse the composite support particles F1 in the aqueous solution of the compound of the second promoter Y, then take out the impregnated F1 particles, and then carry out drying and calcination to obtain catalyst precursor particles F2;

[0043] E3: Prepare an aqueous solution of a compound of the first promoter X, then immerse the catalyst precursor particles F2 in the solution of the first promoter X, then take out the impregnated F2 particles, and then carry out drying and calcination to obtain catalyst precursor particles F3;

[0044] E4: Prepare a mixed aqueous solution of a compound of Pd and a compound of the second active component A, then immerse the catalyst precursor particles F3, stand at 50-85 °C for 0.5-5.0 hours, then take out the impregnated F3 particles, and carry out drying and calcination to obtain the finished catalyst.

[0045] Further, in step E1, the carrier materials Z1 and Z2 powders are ultrafine powders with a particle size ≤ 10 μm. In a high-energy ball mill, ball mill at a rotation speed ≥ 200 r / min for 5-200 min to obtain a composite support powder U1; preferably, ball mill at a rotation speed ≥ 1000 r / min for 30-60 min.

[0046] Further, in step E1, the binder is selected from at least one of water, citric acid, tricarballylic acid, glycerol, erythritol, vegetable oil, sesbania powder, methylcellulose, lignin, polyethylene glycol (PEG), polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), or starch, and the addition amount is 2.0-20 wt% of the total material amount; preferably citric acid, vegetable oil, sesbania powder, methylcellulose, PEG 200-2000, starch, or their aqueous solutions, and the addition amount is 5-10 wt% of the total material amount;

[0047] The shaping is carried out by rolling balls, pressing tablets or extrusion to form spherical, hedgehog-shaped, cylindrical with a length of 1-5 mm, clover-shaped with a length of 1-8 mm, strip-shaped composite support particles or catalyst precursor particles with a diameter of 1.0-5.0 mm from the catalyst precursor powder; preferably spherical, hedgehog-shaped with a diameter of 1.5-3.0 mm, cylindrical with a length of 2-3 mm, clover-shaped with a length of 2-5 mm, strip-shaped catalyst precursor particles with a length of 2-5 mm.

[0048] Further, in steps E2 and E3, when preparing the solutions of the corresponding components, soluble salts of the corresponding elements of the second promoter Y or the first promoter X, or insoluble compounds of the corresponding elements of these components are first made into soluble nitrates, chlorides, ammonium salts or complexes, and dissolved with demineralized water at 15-85 °C.

[0049] Further, in step E4, the compound of the first active component Pd is selected from palladium-containing halides, nitrates, acetates, haloacids and their salts or complexes and their salts, preferably palladium chloride, palladium nitrate, palladium acetate, ammonium chloropalladate, palladium acetylacetonate, palladium ammonia complex salt or Schiff base palladium complex; the molar concentration of the aqueous solution of the Pd compound is 0.01-2.00 mol / L, preferably 0.02-0.50 mol / L;

[0050] The compound of the noble metal second active component A is selected from nitrates, acetates, halides, haloacids and their salts, complexes and their salts of the corresponding elements, preferably ruthenium chloride, ruthenium acetate, ammonium chlororuthenate, chloroplatinic acid, chloroplatinic acid amide, rhodium chloride, rhodium iodide, rhodium acetate, osmium tetroxide, iridium chloride, chloroiridic acid, rhenium heptoxide, rhenium chloride, gold trichloride, chloroauric acid or silver nitrate; the molar concentration of the compound of the noble metal second active component A is 0.01-2.00 mol / L, preferably 0.02-0.50 mol / L.

[0051] Further, in each step of the above catalyst preparation, the drying is carried out at 120-250 °C for 0.2-5.0 hours, preferably 150-220 °C for 0.5-2.5 hours in a flowing air or nitrogen atmosphere; the calcination is carried out at 250-400 °C for 0.5-3.0 hours and 450-750 °C for 1.5-10.0 hours in a flowing air or nitrogen atmosphere, preferably 300-350 °C for 1.0-2.0 hours and 550-650 °C for 3.0-6.0 hours.

[0052] Further, when the carrier material Z1 is selected as a molecular sieve, the molecular sieve is an H-type molecular sieve.

[0053] The present invention also provides an application of a palladium catalyst supported on a composite carrier in the hydrogenation of maleic anhydride to prepare succinic anhydride. A fixed-bed reactor is selected as the hydrogenation reactor, and the finished particle catalyst of the composite palladium catalyst is filled in the fixed-bed reactor. The hydrogenation reaction conditions are as follows: the feed temperature is 30 - 80°C, the hydrogen pressure is 0.2 - 2.0 MPa, the molar ratio of hydrogen to anhydride is 2 - 20, and the space velocity of the maleic anhydride solution is 1.0 - 10.0 h -1 and the concentration of the maleic anhydride solution is 15 - 50 wt%.

[0054] Preferably, the hydrogenation reaction conditions of maleic anhydride are as follows: the feed temperature is 50 - 70°C, the hydrogen pressure is 0.5 - 1.0 MPa, the molar ratio of hydrogen to anhydride is 5 - 15, and the space velocity of the maleic anhydride solution is 3.0 - 5.0 h -1 and the concentration of the maleic anhydride solution is 20 - 30 wt%.

[0055] Furthermore, the solvent of the maleic anhydride solution is selected from γ-butyrolactone, γ-valerolactone, δ-valerolactone, ε-caprolactone, N-methylpyrrolidone, tetrahydrofuran, methyltetrahydrofuran, tetrahydropyran, 1,3-dioxolane or 1,4-dioxane; preferably γ-butyrolactone, tetrahydrofuran or 1,4-dioxane.

[0056] Furthermore, the fixed-bed reactor is an isothermal reactor or an adiabatic reactor.

[0057] Furthermore, before the hydrogenation reaction starts, the finished particle catalyst filled in the fixed-bed reactor is first reduced and activated. The reduction and activation conditions are as follows: the temperature is 100 - 500°C, the hydrogen pressure is 0.2 - 2.0 MPa, the hydrogen space velocity is 50 - 2000 h -1 and the reduction and activation time is 2 - 72 h; after the reduction is completed, the temperature is lowered to the reaction temperature in a hydrogen atmosphere, and the maleic anhydride solution controlled by a feed pump is continuously fed into the reactor for the subsequent hydrogenation reaction.

[0058] Preferably, the reduction and activation conditions are as follows: the temperature is 150 - 350°C, the hydrogen pressure is 0.5 - 1.0 MPa, the hydrogen space velocity is 200 - 500 h -1 and the reduction and activation time is 5 - 24 h.

[0059] Compared with the prior art, the present invention has the following beneficial effects:

[0060] (1) For the first time, the present invention prepares a composite support by means of high-energy ball milling, adding a binder / pore former, kneading and molding, high-temperature roasting, etc. from two substances with different properties, namely a high specific surface area porous material and a high thermal conductivity material. As a result, the composite support not only has a high specific surface area but also has good thermal conductivity, thereby endowing the supported metal catalyst with good active metal dispersion and excellent thermal conductivity. This can not only ensure the excellent hydrogenation reaction activity of the catalyst but also avoid local overheating on the surface of the catalyst particles during the reaction, which may cause agglomeration of metal particles and surface coking, leading to catalyst deactivation and shortening of the service life.

[0061] (2) In the catalyst of the present invention, the introduction of an electronic promoter (the first promoter) improves the properties of the active sites on the catalyst surface, passivates the adsorption active sites of the C=O bond, and avoids or reduces the generation of C=O hydrogenation by-products in the raw material maleic anhydride or the product succinic anhydride molecules. The introduction of a structural promoter (the second promoter) has the effect of dispersing and isolating the active metal components, avoiding the aggregation of the active components during calcination and reduction, and maintaining an appropriate interaction force between the active metal and the support, reducing the interaction force between the catalyst surface and the product, enabling the generated succinic anhydride to desorb quickly, and avoiding deep hydrogenation or the generation of other by-products covering the hydrogenation active sites on the catalyst surface or blocking the pores.

[0062] (3) In the catalyst of the present invention, by adding inexpensive transition metals such as Ni, Cu, etc. as the second active component, or by adding other noble metals such as Ru, Ag, etc. as the second active component, the loading amount of the expensive noble metal Pd can be reduced, and the Pd loading amount can be reduced to less than 0.3 wt%, thereby achieving the purpose of reducing the catalyst cost. For the first time, the present invention applies a double noble metal supported catalyst to the hydrogenation reaction of maleic anhydride and has achieved good results, with a maleic anhydride conversion rate of nearly 100% and a succinic anhydride selectivity of greater than 99.2%. In addition, the catalyst preparation method provided by the present invention is simple to operate, has a short process, and good repeatability.

[0063] (4) The present invention provides a high-performance catalyst for the continuous liquid-phase hydrogenation of maleic anhydride to prepare succinic anhydride. Due to the use of a composite support, it has excellent thermal conductivity, so it can be operated under high load, can handle materials with high concentration and high space velocity, and has the advantages of high activity, high selectivity, and high stability. Compared with the prior art, under the same operating load, the operating conditions are milder: the reaction temperature, hydrogen pressure, and hydrogen-to-anhydride ratio are lower, and the service life is longer; while under the same operating conditions, the operating load can be increased and the device production capacity can be improved. When this catalyst is used in the industrial production of succinic anhydride, the catalyst usage cost is low, and the energy consumption and device investment are low. Detailed implementation mode

[0064] The present invention will be further described below in conjunction with specific embodiments. It should be noted that the embodiments described in this part are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative work fall within the scope of protection of the present invention.

[0065] Symbol description: MP is mesoporous, HBN is hexagonal boron nitride, AC is activated carbon, CNTs are carbon nanotubes, CF is carbon fiber, GP is graphite, GPE is graphene, AGC is attapulgite, and PC is porous ceramic.

[0066] Examples 1 to 10 are for the preparation of Pd-non-precious metal dual-active component catalysts supported on dual carriers, and Examples 11 to 15 are for the preparation of Pd-precious metal dual-active component catalysts supported on dual carriers.

[0067] Example 1

[0068] The preparation of the catalyst includes the following steps:

[0069] T1: Take 650 g of γ-Al (support material Z1) with a particle size ≤ 10 μm and a specific surface area of 280 m 2 / g and 200 g of SiC powder (support material Z2) with a particle size ≤ 10 μm and a thermal conductivity of 78 W / (m·K), put them into a high-energy ball mill, and ball mill at 1000 r / min for 10 min to obtain a uniformly mixed composite support γ-Al 2 O 3 +SiC powder U1; 2 O 3 +SiC powder U1;

[0070] T2: Take 110.38 g of ammonium heptamolybdate (NH 4 ) 6 Mo 7 O 24 ·4H 2 O and dissolve it in 1.0 L of deionized water at 45 °C to obtain a precursor solution of the second promoter MoO 3 ; Take 247.69 g of nickel nitrate Ni(NO 3 ) 2 ·6H 2 O and dissolve it in 1.0 L of deionized water at 45 °C to obtain a precursor solution of the second active component metal Ni; Mix the precursor solution of the second promoter with the precursor solution of the second active component to obtain a mixed solution; Then immerse the composite support powder U1 obtained in step T1 in the mixed solution for 30 min, then heat and evaporate to dryness with stirring, grind it, and calcine it in flowing air at 350 °C for 1.0 h and at 650 °C for 5.0 h to obtain the catalyst precursor powder U2;

[0071] T3: Take 17.65 g of cerium nitrate Ce(NO 3 ) 3 ·6H 2 O, dissolve it in 1.0 L of demineralized water at 45 °C to obtain the precursor solution of the first promoter CeO 2 . Then immerse the catalyst precursor U2 in the precursor solution of the first promoter, heat and evaporate to dryness under stirring, grind it, and calcine it in flowing air at 350 °C for 1.0 h and at 650 °C for 5.0 h to obtain the catalyst precursor powder U3;

[0072] T4: Take the catalyst precursor powder U3 obtained in step T3, add 100 g of methyl cellulose and 100 g of 10 wt% nitric acid aqueous solution, knead it, extrude it into clover-shaped particles with a diameter of 2.2 mm and a length of 2 - 3 mm, and then calcine it in flowing air at 350 °C for 1.0 h and at 650 °C for 5.0 h to obtain the catalyst precursor particles U4;

[0073] T5: Take 6.01 g of palladium chloride PdCl 2 ·2H 2 O, dissolve it in 1.0 L of demineralized water at 45 °C to obtain the precursor solution of the first active component Pd, then mix it with 22 g of polyvinylpyrrolidone and 54 g of ethanol, add 120 g of 40% formaldehyde solution, stir at room temperature for 1.0 h to obtain a liquid mixture, then immerse the liquid mixture in the catalyst precursor particles U4 obtained in step T4, let it stand at 60 °C for 3.0 h, filter, wash it with demineralized water, and then dry it in an air atmosphere and calcine it in flowing air at 350 °C for 1.0 h and at 650 °C for 5.0 h to obtain the catalyst.

[0074] The composition and content of each component of the palladium catalyst supported on the composite support prepared in this example are: 0.3Pd - 5.0Ni - 0.7CeO 2 -9.0MoO 3 / (65.0Al 2 O 3 +20.0SiC), that is, in the composition of this catalyst, the Pd content is 0.3 wt%, the content of the second active component Ni is 5.0 wt%, the content of the first promoter CeO 2 is 0.7 wt%, the content of the second promoter MoO 3 is 9.0 wt%, the content of the Z1 support γ - Al 2 O 3 in the composite support is 65.0 wt%, and the content of the Z2 support SiC is 20.0 wt%.

[0075] Example 2

[0076] Compared with Example 1, the catalyst preparation steps in Example 2 are different in that:

[0077] The carrier material Z1 in step T1: 650 g, specific surface area 280 m 2 / g γ-Al 2 O 3 Replaced with 700g with a specific surface area of ​​315m 2 / g mesoporous alumina (MPAl 2 O 3 ); Carrier material Z2: 200g SiC powder with a thermal conductivity of 78W / (m·K) is replaced with 150g AlN powder with a thermal conductivity of 116W / (m·K); In step T2, 110.38g ammonium heptamolybdate and 247.69g nickel nitrate are replaced with 89.53g ammonium heptamolybdate and 346.77g nickel nitrate respectively; In step T3, 17.65g cerium nitrate is replaced with 12.61g cerium nitrate; In step T4, the extruded strips are formed into clover particles with a diameter of 2.2mm and a length of 2-3mm, and are replaced with cylindrical particles with a diameter of 2.0mm and a height of 2.0mm; In step T5, 6.01g palladium chloride is replaced with 4.01g palladium chloride. The composition and content of each component of the composite carrier-supported palladium catalyst prepared in this embodiment are: 0.2Pd-7.0Ni-0.5CeO 2 -7.3MoO 3 / (70.0MPAl 2 O 3 +15.0AlN).

[0078] Example 3

[0079] Compared with Example 2, the catalyst preparation steps in Example 3 are different in that:

[0080] Replace the carrier material Z1 in step T1 with 550 g of the carrier material Z1 with a specific surface area of ​​273 m 2 / g mesoporous silica (MPSiO 2 ); the carrier material Z2 was replaced with 300 g of hexagonal boron nitride (HBN) powder with a thermal conductivity of 54 W / (m·K); in step T2, 89.53 g of ammonium heptamolybdate and 346.77 g of nickel nitrate were replaced with 125.63 g of tin tetrachloride SnCl 4 ·5H 2 O and 445.84g nickel nitrate. The composition and content of each component of the composite carrier-supported palladium catalyst prepared in this embodiment are: 0.2Pd-9.0Ni-0.5CeO 2 -5.4SnO 2 / (55.0MPSiO 2 +30.0HBN).

[0081] Example 4

[0082] Compared with Example 1, the difference in the catalyst preparation steps in Example 4 is as follows:

[0083] Replace the carrier material Z1 in step T1 with 750 g of HZSM-5 molecular sieve with a specific surface area of 380 m 2 / g; replace the carrier material Z2 with 180 g of graphite (GP) powder with a thermal conductivity of 120 W / (m·K); replace 110.38 g of ammonium heptamolybdate and 247.69 g of nickel nitrate in step T2 with 273.68 g of chromium nitrate Cr(NO 3 ) 3 ·9H 2 O and 24.77 g of nickel nitrate; replace 17.65 g of cerium nitrate in step T3 with 26.58 g of lanthanum nitrate La(NO 3 ) 3 ·6H 2 O. The composition and content of each component of the palladium catalyst supported on the composite carrier prepared in this example are: 0.3Pd-0.5Ni-1.0La 2 O 3 -5.2Cr 2 O 3 / (75.0 HZSM-5 + 18.0 GP).

[0084] Example 5

[0085] Compared with Example 2, the difference in the catalyst preparation steps in Example 5 is as follows:

[0086] Replace the carrier material Z1 and the carrier material Z2 in step T1 with 500 g of activated carbon (AC) with a specific surface area of 920 m 2 / g and 380 g of BeO powder with a thermal conductivity of 238 W / (m·K); replace 89.53 g of ammonium heptamolybdate and 346.77 nickel nitrate in step T2 with 73.28 g of ammonium heptatungstate (NH 4 ) 6 W 7 O 24 ·6H 2 O and 232.62 g of copper nitrate Cu(NO 3 ) 2 ·6H 2 O; replace 12.61 g of cerium nitrate in step T3 with 23.07 g of lithium nitrate LiNO 3 . The composition and content of each component of the palladium catalyst supported on the composite carrier prepared in this example are: 0.2Pd-5.0Cu-0.5Li 2 O-6.3WO 3 / (50.0AC + 38.0BeO).

[0087] Example 6

[0088] Compared with Example 2, the difference in the catalyst preparation steps in this example is that:

[0089] The carrier materials Z1 and Z2 in step T1 are respectively replaced with 660 g of attapulgite (AGC) with a specific surface area of 185 m 2 / g and 200 g of silicon powder with a thermal conductivity of 76 W / (m·K); 89.53 g of ammonium heptamolybdate and 346.77 g of nickel nitrate in step T2 are replaced with 255.89 g of zinc nitrate Zn(NO 3 ) 2 ·6(H 2 O) and 244.70 g of cobalt nitrate Co(NO 3 ) 2 ·6H 2 O; 12.61 g of cerium nitrate in step T3 is replaced with 413.52 g of magnesium nitrate Mg(NO 3 ) 2 ·6H 2 O. The composition and content of each component of the palladium catalyst supported on the composite carrier prepared in this example are: 0.2Pd - 6.3Co - 6.5MgO - 7.0ZnO / (66.0AGC + 20.0Si).

[0090] Example 7

[0091] Compared with Example 2, the difference in the catalyst preparation steps in this example is that:

[0092] The carrier materials Z1 and Z2 in step T1 are respectively replaced with 740 g of mesoporous molecular sieve HMCM - 41 with a specific surface area of 870 m 2 / g and 100 g of graphene (GPE) with a thermal conductivity of 1560 W / (m·K); 89.53 g of ammonium heptamolybdate and 346.77 nickel nitrate in step T2 are replaced with 154.53 g of ammonium heptamolybdate and 148.62 g of nickel nitrate; 12.61 g of cerium nitrate in step T3 is replaced with 2.77 g of cesium nitrate CsNO 3 . The composition and content of each component of the palladium catalyst supported on the composite carrier prepared in this example are: 0.2Pd - 3.0Ni - 0.2Cs 2 O - 12.6MoO 3 / (74.0HMCM - 48 + 10.0GPE).

[0093] Example 8

[0094] Compared with Example 1, the difference in the catalyst preparation steps in this example is as follows:

[0095] The support materials Z1 and Z2 in step T1 are respectively replaced with 560 g of mesoporous carbon (MPC) with a specific surface area of 850 m 2 / g and 300 g of MoS 2 powder with a thermal conductivity of 52 W / (m·K); 110.38 g of ammonium heptamolybdate in step T2 is replaced with 378.94 g of chromium nitrate Cr(NO 3 ) 3 ·9H 2 O; 17.65 g of cerium nitrate in step T3 is replaced with 141.20 g of cerium nitrate; 6.01 g of palladium chloride in step T5 is replaced with 2.00 g of palladium chloride. The composition and content of each component of the palladium catalyst supported on the composite support prepared in this example are: 0.1Pd - 5.0Ni - 5.6CeO 2 -7.2Cr 2 O 3 / (56.0MPC + 30.0MoS 2 )。

[0096] Example 9

[0097] Compared with Example 2, the difference in the catalyst preparation steps in this example is as follows:

[0098] The support materials Z1 and Z2 in step T1 are respectively replaced with 700 g of γ-Al 2 with a specific surface area of 280 m / g and 140 g of α-Al 2 O 3 with a thermal conductivity of 26 W / (m·K); 89.53 g of ammonium heptamolybdate and 346.77 g of nickel nitrate in step T2 are replaced with 186.12 g of tin tetrachloride SnCl 2 ·5H 3 O and 99.08 g of nickel nitrate; 12.61 g of cerium nitrate in step T3 is replaced with 244.25 g of calcium nitrate Ca(NO 4 ) 2 ·4H 3 ) 2 ·4H 2 O. The composition and content of each component of the palladium catalyst supported on the composite support prepared in this example are: 0.2Pd - 2.0Ni - 5.8CaO - 8.0SnO 2 / (70.0γ-Al 2 O 3 +14.0α-Al 2 O 3 )。

[0099] Example 10

[0100] Compared with Example 2, the difference in the catalyst preparation steps in this example is as follows:

[0101] The carrier materials Z1 and Z2 in step T1 are respectively replaced with 660 g of silica gel with a specific surface area of 320 m 2 / g and 200 g of WC with a thermal conductivity of 82 W / (m·K); 89.53 g of ammonium heptamolybdate and 346.77 g of nickel nitrate in step T2 are replaced with 139.59 g of tin tetrachloride and 336.87 g of nickel nitrate; 12.61 g of cerium nitrate in step T3 is replaced with 21.46 g of potassium nitrate KNO 3 . The composition and content of each component of the palladium catalyst supported on the composite carrier prepared in this example are: 0.2Pd-6.8Ni-1.0K 2 O-6.0SnO 2 / (66.0SiO 2 +20.0CF).

[0102] Comparative Example 1

[0103] Compared with Example 3, the difference in the catalyst preparation steps in this comparative example is: the carrier materials Z1 and Z2 in step T1 are replaced with 850 g of mesoporous silica (MPSiO 2 / g) powder. The composition and content of each component of the palladium catalyst supported on the composite carrier prepared in this comparative example are: 0.2Pd-9.0Ni-0.5CeO 2 -5.4SnO 2 / 85.0MPSiO 2 . 2 .

[0104] Comparative Example 2

[0105] Refer to the method of Patent CN103769117B to prepare a 5.6Ni-12.9ZnO-10.6MoO 3 / 70.9AC catalyst, and form it into cylindrical particles with a diameter of Ф2.0×2.0 by tabletting.

[0106] Comparative Example 3

[0107] Refer to the method of Patent CN114289024A to prepare a 12.6Ni-1.5Cu-0.1Cs 2 O / 85.8γ-Al 2 O 3 catalyst, and form it into clover-shaped particles with a diameter of Ф2.0×2.0~3.0 by extrusion.

[0108] Example 11

[0109] The preparation of the catalyst comprises the following steps:

[0110] E1: Take 700 g of support material Z1 with a particle size ≤ 10 μm and a specific surface area of 280 m 2 / g of γ-Al 2 O 3 and 200 g of support material Z2, SiC powder with a particle size ≤ 10 μm and a thermal conductivity of 78 W / (m·K), put them into a high-energy ball mill and ball mill at 1000 r / min for 10 min to obtain a uniformly mixed composite support Al 2 O 3 +SiC powder; add 100 g of methyl cellulose and 100 g of 10 wt% nitric acid aqueous solution to the composite support powder, knead and extrude into clover-shaped particles with a diameter of 2.2 mm and a length of 2 - 3 mm, and then calcine in flowing air at 350 °C for 1.0 h and 650 °C for 5.0 h to obtain catalyst precursor particles F1;

[0111] E2: Take 105.47 g of ammonium heptamolybdate (NH 4 ) 6 Mo 7 O 24 ·4H 2 O and dissolve it in 1.0 L of deionized water at 45 °C to obtain a precursor solution of the second promoter MoO 3 ; then immerse the composite support particles F1 obtained in step E1 in the mixed solution for 45 min, and then take out the impregnated F1 particles and dry them in flowing air at 180 °C for 1.0 h, calcine at 350 °C for 1.0 h and 650 °C for 5.0 h to obtain catalyst precursor particles F2;

[0112] E3: Take 17.65 g of cerium nitrate Ce(NO 3 ) 3 ·6H 2 O, dissolve it in 1.0 L of deionized water at 45 °C to obtain a precursor solution of the first promoter CeO 2 ; then immerse the catalyst precursor F2 obtained in step E2 in the precursor solution of the first promoter, and then take out the impregnated F2 particles and dry them in flowing air at 180 °C for 1.0 h, calcine at 350 °C for 1.0 h and 650 °C for 5.0 h to obtain catalyst precursor particles F3;

[0113] E4: Mix 4.01 g of palladium chloride PdCl 2 ·2H 2 O and 10.26 g of ruthenium chloride RuCl 2 ·3H 2 O, dissolve them in 1.0 L of deionized water at 45 °C to obtain a precursor mixed solution of the first and second active components Pd and Ru;

[0114] E5: Mix 22 g of polyvinylpyrrolidone and 54 g of ethanol, add them to the mixed solution of the first and second active components obtained in step E4, then add 120 g of 40% formaldehyde solution, stir at room temperature for 1.0 h to obtain a liquid mixture. Then immerse the catalyst precursor particles F3 obtained in step E3 in the liquid mixture, then let it stand at 60 °C for 3.0 h, filter, wash with demineralized water, and then dry in flowing air at 180 °C for 1 h, calcine at 350 °C for 1.0 h and calcine at 650 °C for 5.0 h to obtain the catalyst.

[0115] The composition and content of each component of the palladium catalyst supported on the composite support prepared in this example are: 0.2Pd - 0.5Ru - 0.7CeO 2 - 8.6MoO 3 / (70.0γ - Al 2 O 3 + 20.0SiC)

[0116] Example 12

[0117] Compared with Example 11, the difference in the catalyst preparation steps in this example is as follows:

[0118] Replace the carrier materials Z1 and Z2 in step E1 with 680 g of mordenite HMOR with a specific surface area of 410 m 2 / g and 200 g of silicon powder with a thermal conductivity of 76 W / (m·K); replace 105.47 g of ammonium heptamolybdate in step E2 with 130.00 g of ammonium heptamolybdate; replace 17.65 g of cerium nitrate in step E3 with 6.45 g of potassium nitrate KNO 3 ; replace 4.01 g of palladium chloride and 10.26 g of ruthenium chloride in step E4 with 2.00 g of palladium chloride and 20.52 g of ruthenium chloride. The composition and content of each component of the palladium catalyst supported on the composite support prepared in this example are: 0.1Pd - 1.0Ru - 0.3K 2 O - 10.6MoO 3 / (68.0HMOR + 20.0Si).

[0119] Example 13

[0120] Compared with Example 11, the difference in the catalyst preparation steps in this example is as follows:

[0121] Replace the carrier materials Z1 and Z2 in step E1 with 600 g of mordenite with a specific surface area of 380 m 2HZSM-5 zeolite at 280 g of graphite (GP) with a thermal conductivity of 120 W / (m·K); replace 105.47 g of ammonium heptamolybdate in step E2 with 73.58 g of ammonium heptamolybdate; replace 17.65 g of cerium nitrate in step E3 with 343.54 g of magnesium nitrate Mg(NO 3 ) 2 ·6H 2 O; replace 4.01 g of palladium chloride and 10.26 g of ruthenium chloride in step E4 with 6.01 g of palladium chloride and 6.16 g of ruthenium chloride. The composition and content of each component of the palladium catalyst supported on the composite support prepared in this example are: 0.3Pd-0.3Ru-5.4MgO-6.0MoO 3 / (60.0HZSM-5+28.0GP).

[0122] Example 14

[0123] Compared with Example 11, the difference in the catalyst preparation steps in this example is that: the support materials Z1 and Z2 in step E1 are respectively replaced with 630 g of mesoporous molecular sieve SBA-15 with a specific surface area of 1120 m 2 / g and 300 g of SiC powder with a thermal conductivity of 78 W / (m·K); replace 105.47 g of ammonium heptamolybdate in step E2 with 74.81 g of ammonium heptamolybdate; replace 17.65 g of cerium nitrate in step E3 with 12.61 g of cerium nitrate; replace 4.01 g of palladium chloride and 10.26 g of ruthenium chloride in step E4 with 6.01 g of palladium chloride and 2.10 g of chloroplatinic acid H 2 PtCl 6 . The composition and content of each component of the palladium catalyst supported on the composite support prepared in this example are: 0.3Pd-0.1Pt-0.5CeO 2 -6.1MoO 3 / (63.0SBA-15+30.0SiC).

[0124] Example 15

[0125] Compared with Example 11, the difference in the catalyst preparation steps in this example is that: the support materials Z1 and Z2 in step E1 are respectively replaced with 750 g of activated carbon (AC) with a specific surface area of 920 m 2 / g and 150 g of hexagonal boron nitride (HBN) with a thermal conductivity of 54 W / (m·K); replace 105.47 g of ammonium heptamolybdate in step E2 with 91.98 g of ammonium heptamolybdate; replace 17.65 g of cerium nitrate in step E3 with 7.56 g of cerium nitrate; replace 10.26 g of ruthenium chloride in step E4 with 31.50 g of silver nitrate AgNO 3。The composition and the content of each component of the palladium catalyst supported on the composite support prepared in this example are: 0.2Pd - 2.0Ag - 0.3CeO 2 -7.5MoO 3 / (75.0AC + 15.0HBN).

[0126] Comparative Example 4

[0127] Compared with Example 11, the difference in the catalyst preparation steps in this comparative example is that: the support materials Z1 and Z2 in Step E1 are replaced with 900 g of γ-Al with a specific surface area of 280 m 2 / g 2 O 3 。The composition and the content of each component of the palladium catalyst supported on the composite support prepared in this example are: 0.2Pd - 0.5Ru - 0.7CeO 2 -8.6MoO 3 / 90.0γ-Al 2 O 3 。

[0128] Comparative Example 5

[0129] Prepare 0.5Pd / 99.5γ-Al 2 O 3 particle catalyst (clover with Ф2.0×2.0~3.0) according to the method of Patent CN105597742A.

[0130] Comparative Example 6

[0131] Prepare 0.3Pd - 0.1Ni - 1.0SnO 2 / 98.6PC particle catalyst (sphere with Ф2.6) according to the method of Patent CN106669730B.

[0132] Examples 16 - 30 and Comparative Examples 7 - 12

[0133] Catalyst performance evaluation experiment

[0134] Respectively take 100 g of the particle catalysts prepared in Examples 1 - 15 and Comparative Examples 1 - 6, and load them into a fixed-bed tubular reactor. The 20 - 30 wt% maleic anhydride γ-butyrolactone solution and hydrogen are continuously fed into the reactor respectively through a feed pump and a flow meter. Under the reaction conditions of a feed temperature of 50 - 70°C, a hydrogen pressure of 0.5 - 1.0 MPa, a hydrogen-to-anhydride molar ratio of 5 - 15, and a maleic anhydride solution space velocity of 3.0 - 5.0 h -1 , maleic anhydride is catalytically hydrogenated to succinic anhydride, and the reaction is carried out for 100 h. The reaction conditions and results of the maleic anhydride hydrogenation to succinic anhydride for each example and comparative example are shown in Table 1.

[0135] Table 1 Reaction conditions and results of maleic anhydride hydrogenation to succinic anhydride for examples and comparative examples

[0136]

[0137]

[0138] From the evaluation results of Examples 16 - 25 on the catalysts of Examples 1 - 10 in Table 1, it can be seen that the supported Pd-non-precious metal Ni, Co or Cu dual-active component catalysts prepared with high specific surface area and high thermal conductivity composite carriers all have good catalytic performance for the hydrogenation of maleic anhydride to succinic anhydride. Under the mild reaction conditions of temperature 50 - 70 °C, hydrogen pressure 0.5 - 1.0 MPa, molar ratio of hydrogen to anhydride 5 - 15, and at a relatively high load with maleic anhydride γ-butyrolactone solution concentration of 20 - 30 wt% and space velocity of 3 - 5 h -1 , the conversion rate of maleic anhydride ≥ 99.5%, and the selectivity of succinic anhydride ≥ 98.0%.

[0139] Comparing the experimental results of Examples 1 - 10 and 16 - 25 with those of Comparative Examples 1 - 3 and 7 - 9, it can be seen that:

[0140] 1) For catalysts prepared by the same method with the same types and contents of active components and promoters, the hydrogenation activity of maleic anhydride is quite similar. However, the selectivity of succinic anhydride of the catalysts with composite carriers (Examples 3 and 18) is 99.2%, which is 4.6% higher than that of the catalysts with single high specific surface area carriers (Comparative Examples 1 and 7) with a succinic anhydride selectivity of 94.6%.

[0141] 2) According to the method disclosed in the existing patent, for non-precious metal catalysts supported on a single high specific surface area carrier, under the same reaction process conditions (temperature 60 °C, hydrogen pressure 1.0 MPa, molar ratio of hydrogen to anhydride 10, maleic anhydride γ-butyrolactone solution concentration 25 wt% and space velocity 3 h -1 ), the conversion rate of maleic anhydride of the catalysts with single-active component Ni (Comparative Examples 2 and 8) is only 52.8% and the selectivity of succinic anhydride is 95.2%. The conversion rate of maleic anhydride of the catalysts with dual-active component Ni-Cu (Comparative Examples 3 and 9) is only 76.5% and the selectivity of succinic anhydride is 96.5%. Both are much lower than the conversion rate of maleic anhydride and the selectivity of succinic anhydride of the supported Pd-non-precious metal dual-active component catalysts with composite carriers (Examples 1 - 10 and 16 - 25).

[0142] From the performance evaluation results of the catalysts in Examples 11 to 15 and 26 to 30, it can be seen that the supported Pd-Ru and other double noble metal catalysts prepared with high specific surface area and high thermal conductivity composite carriers all have good catalytic performance for the hydrogenation of maleic anhydride to prepare succinic anhydride. Under the mild reaction conditions of temperature 50 - 70 °C, hydrogen pressure 0.5 - 1.0 MPa, and molar ratio of hydrogen to anhydride 5 - 15, as well as at a relatively high load with a maleic anhydride γ-butyrolactone solution concentration of 20 - 30 wt% and a space velocity of 3 - 5 h -1 , the conversion rate of maleic anhydride ≥ 99.5%, and the selectivity of succinic anhydride ≥ 99.0%;

[0143] Comparing the experimental results of Examples 11 to 15 and 26 to 30 with those of Comparative Examples 4 to 6 and 10 to 12, it can be known that:

[0144] 1) For the catalysts with the same types and contents of active components and additives prepared by the same method, the conversion rate of maleic anhydride all reached 100%. However, for the catalysts with composite carriers (Examples 11 and 26), the selectivity of succinic anhydride (99.5%) is 3.3% higher than that of the catalysts with a single high specific surface area carrier (Comparative Examples 1 and 7) (96.2%);

[0145] 2) According to the method disclosed in the existing patent, for the Pd catalysts supported on a single high specific surface area carrier prepared, under the same reaction process conditions (temperature 50 °C, hydrogen pressure 0.75 MPa, molar ratio of hydrogen to anhydride 15, maleic anhydride γ-butyrolactone solution concentration 20 wt%, and space velocity 5 h -1 ), for the catalysts with a single active component Pd (Comparative Examples 5 and 11), the conversion rate of maleic anhydride is only 95.0% and the selectivity of succinic anhydride is 95.6%. For the catalysts with a double active component Pd-Ni (Comparative Example 6), the conversion rate of maleic anhydride is only 88.5% and the selectivity of succinic anhydride is 94.8%. Both are much lower than the conversion rate of maleic anhydride and the selectivity of succinic anhydride of the supported Pd-Ru and other double noble metal catalysts with composite carriers (Examples 11 to 15 and 26 to 30).

[0146] Example 31

[0147] Catalyst stability experiment

[0148] According to the same catalyst formulation and preparation method as in Example 1, 2.5 kg of the composition 0.3Pd - 5.0Ni - 0.7CeO 2 -9.0MoO 3 / (65.0γ-Al 2 O 3The granular catalyst (Ф2.2×2 - 3 clover) of 0.2Pd - 0.5Ru - 0.7CeO₂ - 8.6MoO₃ / (70.0γ - Al₂O₃ + 20.0SiC) was prepared according to the same catalyst formulation and preparation method as in Example 11, and loaded into a fixed - bed tubular reactor. The γ - butyrolactone solution of 25wt% maleic anhydride and hydrogen were continuously fed into the reactor respectively through a feed pump and a flow meter. Under the conditions of a feed temperature of 60°C, a hydrogen pressure of 1.0MPa, a hydrogen - to - anhydride molar ratio of 10, and a maleic anhydride solution space velocity of 3.0h⁻¹, maleic anhydride was catalytically hydrogenated to form succinic anhydride. The reaction was carried out for 8000h, and the results are shown in Table 2. -1 Under the above conditions, maleic anhydride was catalytically hydrogenated to form succinic anhydride. The reaction was carried out for 8000h, and the results are shown in Table 2.

[0149] Table 2 Stability test of maleic anhydride hydrogenation to succinic anhydride over Pd - Ni bimetallic active component catalyst supported on γ - Al₂O₃ and SiC dual carriers 2 ₂ 3 and SiC dual carriers

[0150]

[0151] From the results of the catalytic reaction stability test shown in Table 2, it can be seen that for the Pd - non - noble metal dual - active - component catalyst supported on the composite carrier, the maleic anhydride conversion rate and succinic anhydride selectivity remained above 99.2% after running for 8000h, indicating that the catalyst has good stability in the maleic anhydride hydrogenation reaction.

[0152] Example 32

[0153] Catalyst stability experiment

[0154] According to the same catalyst formulation and preparation method as in Example 11, 2.5 kg of granular catalyst with a composition of 0.2Pd - 0.5Ru - 0.7CeO₂ - 8.6MoO₃ / (70.0γ - Al₂O₃ + 20.0SiC) (Ф2.2×2 - 3 clover) was prepared and loaded into a fixed - bed tubular reactor. The γ - butyrolactone solution of 20wt% maleic anhydride and hydrogen were continuously fed into the reactor respectively through a feed pump and a flow meter. Under the conditions of a feed temperature of 50°C, a hydrogen pressure of 0.75MPa, a hydrogen - to - anhydride molar ratio of 15, and a maleic anhydride solution space velocity of 5.0h⁻¹, maleic anhydride was catalytically hydrogenated to form succinic anhydride. The reaction was carried out for 8000h, and the results are shown in Table 3. 2 ₂ 3 / (70.0γ - Al₂O₃ 2 ₂ 3 +20.0SiC) was prepared and loaded into a fixed - bed tubular reactor. The γ - butyrolactone solution of 20wt% maleic anhydride and hydrogen were continuously fed into the reactor respectively through a feed pump and a flow meter. Under the conditions of a feed temperature of 50°C, a hydrogen pressure of 0.75MPa, a hydrogen - to - anhydride molar ratio of 15, and a maleic anhydride solution space velocity of 5.0h⁻¹, maleic anhydride was catalytically hydrogenated to form succinic anhydride. The reaction was carried out for 8000h, and the results are shown in Table 3. -1 Under the above conditions, maleic anhydride was catalytically hydrogenated to form succinic anhydride. The reaction was carried out for 8000h, and the results are shown in Table 3.

[0155] Table 3 Stability test of maleic anhydride hydrogenation to succinic anhydride over Pd - Ru bimetallic active component catalyst supported on γ - Al₂O₃ and SiC dual carriers 2 ₂ 3 and SiC dual carriers

[0156]

[0157] As can be seen from the catalytic reaction stability test shown in Table 3, for the Pd-non-noble metal dual active component catalyst supported on the composite support, the maleic anhydride conversion rate and succinic anhydride selectivity remain above 99.7% and 99.5% respectively after running for 8000 h, indicating that the catalyst has excellent stability in the maleic anhydride hydrogenation reaction.

[0158] In summary, for the catalyst prepared by the method of the present invention using the composite support of high specific surface area porous material and high thermal conductivity material, whether it is loaded with noble metal-non-noble metal dual metal active components such as Pd-Ni, Co or Cu, or loaded with dual noble metal active components such as Pd-Ru, Pt or Ag, it has excellent low-temperature activity and the performance of withstanding high-load operation for the reaction of liquid-phase selective hydrogenation of maleic anhydride to prepare succinic anhydride.

[0159] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A composite carrier-supported palladium catalyst for hydrogenating maleic anhydride to succinic anhydride, characterized in that: The general structural formula of the composite carrier-supported palladium catalyst is: Pd-AXY / (Z1+Z2); In the formula, Pd is the first active component, and its content is 0.05-0.75wt%; the second active component A is selected from non-precious metals Cu, Co or Ni, or precious metals Ru, Pt, Rh, Os, Au or Ag, or any combination of these metal elements, and the content of A is 0.01-10.00wt%; the first auxiliary agent X is selected from alkali metal oxides, alkaline earth metal oxides, rare earth element oxides or any combination thereof, and its content is 0.01-10.0wt%; the second auxiliary agent Y is selected from Nb, Sb, V, Sn, Pb, Se, Te, Mo, W, Fe, Ga, In, Cr, Mn, Ir, Re, Zn, B, P oxides or any combination of these oxides, and its content is 1.00-20.00wt%; The carrier material Z1 in the composite carrier (Z1+Z2) has a specific surface area of ​​≥100m 2 / g of porous material carrier, the porous material carrier Z1 is selected from at least one of SiO2, Al2O3, TiO2, ZrO2, carbon, molecular sieve, clay or light magnesium oxide, with a content of 50-90wt%; the carrier material Z2 is a thermally conductive material carrier with a thermal conductivity ≥20W / (m·K), the carrier material Z2 is selected from at least one of BeO, MgO, α-Al2O3, α-SiO2, BN, AlN, Si3N4, SiC, ZrC, Mo2C, W2C, WC, Si, graphite, graphene, PCD ceramics, MoS2 or WS2, with a content of 8-48wt%; the content of the composite carrier (Z1+Z2) accounts for 58-98wt% of the total content of the catalyst.

2. A composite carrier-supported palladium catalyst for hydrogenating maleic anhydride to succinic anhydride according to claim 1, characterized in that: The content of Pd in ​​the composite carrier-supported palladium catalyst is 0.1-0.5wt%; The second active component A is 0.5-7.5wt% of Cu, Co or Ni, or 0.02-0.5wt% of Pt, Rh or Os, or 0.05-2.0wt% of Ru, Au or Ag, or any combination of these metals; The first auxiliary agent X is selected from alkali metal oxides with a content of 0.05-5.00 wt%, or alkaline earth metal oxides with a content of 0.10-7.50 wt%, or rare earth oxides with a content of 0.10-7.50 wt%, or any combination thereof; The second auxiliary agent Y is selected from Nb2O5, Sb2O5, Sb2O3, V2O5, MoO3, MoO2, WO3, SnO2, PbO2, SeO2, TeO2, Fe2O3, Fe3O4, FeO, Ga2O3, In2O3, Cr2O3, MnO2, Mn2O3, Mn3O4, IrO2, Re2O7, ZnO, B2O3 or P2O5, or any combination thereof, and its content is 3.0 to 15.0 wt%.

3. A composite carrier-supported palladium catalyst for hydrogenating maleic anhydride to succinic anhydride according to claim 2, characterized in that: In the composite carrier-supported palladium catalyst, the second active component A is selected from 1.0-5.0wt% of Cu, Co or Ni, or 0.05-0.2wt% of Pt, or 0.1-1.0wt% of Ru, or 0.5-2.0wt% of Ag; The first auxiliary agent X is an oxide of Li, Na, K or Rb with a content of 0.20-2.00wt%, or an oxide of Mg, Ca, Sr or Ba with a content of 0.50-5.00wt%, or an oxide of Cs, La, Ce, Nd, Sm or Yb with a content of 0.20-6.00wt%, or any combination of these substances; The second auxiliary agent Y is MoO3, WO3, SnO2, Fe2O3, Cr2O3, MnO2, ZnO or P2O5 or any combination thereof, and its content is 5.0-10.0wt%.

4. A composite carrier-supported palladium catalyst for hydrogenating maleic anhydride to succinic anhydride according to claim 3, characterized in that: The first auxiliary agent X is selected from oxides of Li or K, with a content of 0.50-1.00 wt%, or selected from oxides of Mg or Ca, with a content of 1.00-3.0%, or selected from oxides of Cs, La or Ce, with a content of 0.50-2.50 wt%.

5. The composite carrier-supported palladium catalyst for hydrogenating maleic anhydride to succinic anhydride according to claim 1, characterized in that: The carrier material Z1 is selected from a material with a specific surface area of ​​≥ 250 m 2 / g of porous, mesoporous or macroporous SiO2, TiO2, ZrO2, Al2O3, carbon, molecular sieve or clay, or any combination of these substances; wherein the specific surface area is ≥250m 2 / g of the SiO2 includes amorphous SiO2, silica sol, silica gel or mesoporous SiO2, the Al2O3 includes amorphous Al2O3, activated Al2O3, γ-Al2O3, θ-Al2O3 or mesoporous Al2O3, the TiO2 includes amorphous TiO2, rutile, anatase or mesoporous TiO2, the carbon includes activated carbon, carbon nanotubes, graphene or mesoporous carbon, the molecular sieve includes USY, MOR, β, ZSM-5, ZSM-22, TS-1, ZRP, MCM-22, MCM-41, MCM-48, MCM-49, MCM-50, SAPO-34, SBA-15, KIT-6 or ZEO-3, the clay includes bentonite, kaolin, montmorillonite or attapulgite, and the content of the carrier material Z1 is 60-85wt%; The carrier material Z2 is selected from BeO, α-Al2O3, hexagonal boron nitride, cubic boron nitride, AlN, Si3N4, SiC, WC, Si, graphite, graphene, PCD ceramic or MoS2 with a thermal conductivity of ≥40W / (m·K), or any combination of these substances, and the content of the carrier material Z2 is 10 to 35wt%.

6. A composite carrier-supported palladium catalyst for hydrogenating maleic anhydride to succinic anhydride according to claim 5, characterized in that: The carrier material Z1 is selected from a material with a specific surface area of ​​≥500 m 2 / g of porous silica sol, SiO2-Al2O3, activated carbon or molecular sieve, or mesoporous SiO2, mesoporous Al2O3, mesoporous TiO2, mesoporous carbon or mesoporous molecular sieve, or macroporous molecular sieve, or any combination of these substances; wherein the specific surface area is ≥500m 2 / g molecular sieves include porous molecular sieves MOR, ZSM-5, TS-1, ZRP, MCM-22, or mesoporous molecular sieves MCM-41, MCM-48, MCM-50, SBA-15 or KIT-6, or macroporous molecular sieves ZEO-3; The carrier material Z2 is BeO, CBN, AlN, Si3N4, SiC, Si, graphite, multilayer graphene, PCD ceramic or MoS2 with a thermal conductivity of ≥100 W / (m·K), or any combination thereof.

7. A method for preparing a composite carrier-supported palladium catalyst according to any one of claims 1 to 6, characterized in that: When the second active component A is a non-precious metal, the preparation of the composite carrier-supported palladium catalyst comprises the following steps: T1: Mix the carrier materials Z1 and Z2 powders and ball mill them to obtain composite carrier powder U1; T2: preparing an aqueous solution of a compound of the second active component A and an aqueous solution of a compound of the second auxiliary agent Y respectively, and mixing the two to obtain a mixed solution, then immersing the composite carrier powder U1 in the mixed solution, and then heating to dryness, crushing and calcining under stirring in sequence to obtain a catalyst precursor powder U2; T3: preparing an aqueous solution of a compound of the first auxiliary agent X, then immersing the catalyst precursor powder U2 in the solution of the first auxiliary agent X, heating to dryness, crushing and calcining under stirring, to obtain a catalyst precursor powder U3; T4: Take the catalyst precursor powder U3, add a binder, and then knead, shape, and calcine in sequence to obtain catalyst precursor particles U4; T5: preparing an aqueous solution of a Pd compound, then impregnating the catalyst precursor particles U4 obtained in step T4, and leaving the particles at 50-85° C. for 0.5-5.0 hours, then taking out the impregnated U4 particles, drying and calcining them to obtain a finished catalyst; In step T4, the binder is selected from at least one of water, nitric acid, acetic acid, citric acid, sorbic acid, ethylene glycol, 1,4-butanediol, glycerol, erythritol, vegetable oil, sesbania powder, methyl cellulose, lignin or starch, and the added amount is 2.0 to 20 wt% of the total material amount.

8. A method for preparing a composite carrier-supported palladium catalyst according to any one of claims 1 to 6, characterized in that: When the second active component A is a noble metal, the preparation of the composite carrier-supported palladium catalyst comprises the following steps: E1: The carrier materials Z1 and Z2 powders are mixed and ball-milled to obtain composite carrier powder, and then a binder is added, followed by kneading, molding, and calcining to obtain composite carrier particles F1; E2: preparing an aqueous solution of a compound of the second auxiliary agent Y, and then immersing the composite carrier particles F1 in the aqueous solution of the compound of the second auxiliary agent Y, and then taking out the impregnated F1 particles, and then drying and calcining to obtain catalyst precursor particles F2; E3: preparing an aqueous solution of a compound of the first auxiliary agent X, and then immersing the catalyst precursor particles F2 in the solution of the first auxiliary agent X, and then taking out the immersed F2 particles, and then drying and calcining them to obtain catalyst precursor particles F3; E4: preparing a mixed aqueous solution of a Pd compound and a compound of the second active component A, then impregnating the catalyst precursor particles F3, leaving the mixture at 50-85° C. for 0.5-5.0 hours, then taking out the impregnated F3 particles, drying and calcining them to obtain a finished catalyst; In step E1, the binder is selected from at least one of water, citric acid, sorbic acid, glycerol, erythritol, vegetable oil, sesbania powder, methyl cellulose, lignin, polyethylene glycol, polyvinyl alcohol, polyvinyl pyrrolidone or starch, and the added amount is 2.0 to 20 wt% of the total material amount.

9. An application of the composite carrier-supported palladium catalyst as claimed in claim 1, characterized in that: In the reaction of preparing succinic anhydride by hydrogenation of maleic anhydride, a fixed bed reactor is selected as the hydrogenation reactor, and the fixed bed reactor is filled with the finished particle catalyst of the composite palladium catalyst. The hydrogenation reaction conditions are: feed temperature 30-80°C, hydrogen pressure 0.2-2.0MPa, hydrogen anhydride molar ratio 2-20, maleic anhydride solution space velocity 1.0-10.0h -1 , maleic anhydride solution concentration 15-50wt%; Preferably, the reaction conditions for maleic anhydride hydrogenation are: feed temperature 50-70°C, hydrogen pressure 0.5-1.0 MPa, hydrogen anhydride molar ratio 5-15, maleic anhydride solution space velocity 3.0-5.0 h -1 , maleic anhydride solution concentration 20~30wt%.

10. The use according to claim 9, characterized in that: Before the hydrogenation reaction begins, the finished particle catalyst loaded into the fixed bed reactor is first reduced and activated. The reduction and activation conditions are: temperature 100-500°C, hydrogen pressure 0.2-2.0MPa, hydrogen space velocity 50-2000h -1 , reduction activation time 2 to 72 hours; after the reduction is completed, the temperature is lowered to the reaction temperature in a hydrogen atmosphere, and the maleic anhydride solution controlled by a feed pump is continuously fed into the reactor for subsequent hydrogenation reaction; preferably, the reduction activation conditions are: temperature 150 to 350°C, hydrogen pressure 0.5 to 1.0 MPa, hydrogen space velocity 200 to 500 h -1 , reduction activation time 5 to 24 hours.

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