Hydrogenation catalyst, preparation method thereof and application of hydrogenation catalyst in preparation of succinic anhydride

Abstract

The invention relates to a hydrogenation catalyst and a preparation method and application thereof in preparation of succinic anhydride, and belongs to the field of catalysis, the hydrogenation catalyst comprises active components and silicon-doped porous boron nitride, and the active components are palladium and nickel. When the catalyst is prepared, the cost of raw materials is low, the prepared catalyst is high in stability and good in catalytic performance and has high initial conversion rate and selectivity in butanedioic anhydride preparation, meanwhile, the performance of the catalyst is stable after the catalyst is repeatedly used for 500 h, the conversion rate of maleic anhydride can be kept at 95.6% or above, and the selectivity of butanedioic anhydride can be kept at 96.3% or above.

Description

Technical Field

[0001] The present invention belongs to the field of catalysis, and particularly relates to a hydrogenation catalyst, a preparation method thereof, and an application thereof in the preparation of succinic anhydride. Background Art

[0002] The maleic anhydride hydrogenation method uses maleic anhydride as a raw material and directly hydrogenates it to prepare succinic anhydride. This method has the advantages of simple process flow, low operating cost, high equipment utilization rate, and high product purity, and is the most widely used production process in the current preparation of succinic anhydride.

[0003] In the prior art, the maleic anhydride hydrogenation catalysts mainly include nickel-based catalysts and palladium metal catalysts. The palladium metal catalyst has high activity and anti-coking performance, but its cost is high. The nickel-based catalyst is cheap, but it is easy to coke and the catalyst deactivates quickly.

[0004] In the process of preparing succinic anhydride by hydrogenating maleic anhydride, there are two modes: with solvent and without solvent. In the mode with solvent, the reaction temperature is generally 40-100 °C. In the mode without solvent, the reaction temperature needs to be higher than the melting point of the product succinic anhydride, generally 130-160 °C. Among them, the mode without solvent has a fast reaction speed and high efficiency, but the high temperature conditions will cause the performance of the catalyst to decline, and there is a serious problem of heat generation during high temperature conditions or long-term operation, which is likely to cause the catalyst to crack, powder, and produce side reactions, affecting the catalytic effect and service life.

[0005] Therefore, it is necessary to develop a hydrogenation catalyst with low cost, high temperature resistance, and good catalytic performance, which can effectively improve the hydrogenation reaction efficiency and increase the product yield in the solvent-free mode preparation of succinic anhydride. Summary of the Invention

[0006] (I) Technical Problems to be Solved Aiming at the deficiencies of the prior art, the present invention provides a hydrogenation catalyst, a preparation method thereof, and an application thereof in the preparation of succinic anhydride.

[0007] (II) Technical Solutions To achieve the above objectives, the present invention is achieved through the following technical solutions: A hydrogenation catalyst, comprising an active component and silicon-doped porous boron nitride, and the active component is palladium and nickel.

[0008] A preparation method of a hydrogenation catalyst, comprising the following steps: S1: Dissolve the palladium source and nickel source in water. Prepare a metal salt solution with a concentration of 100 mmol / L according to a molar ratio of 1:4 of the palladium source to the nickel source. Take 1 part of alumina powder by weight and place it in 40 - 60 parts of the metal salt solution. Perform impregnation treatment for 10 - 30 h, filter, and dry at 80 - 120 °C for 6 - 12 h to obtain a pretreated catalyst. S2: By weight, add 0.5 - 0.7 parts of polyvinylpyrrolidone to 40 - 60 parts of water to prepare a mixed solution. Add 1 - 1.5 parts of silicon-doped porous boron nitride to the mixed solution and stir for 2 - 4 h to obtain a silicon-doped porous boron nitride suspension. S3: Place the pretreated catalyst in the silicon-doped porous boron nitride suspension, perform impregnation treatment for 0.5 - 1 h, filter, dry at 60 - 90 °C for 6 - 10 h, put it into a muffle furnace, heat it to 450 - 550 °C, calcine for 4 - 6 h, then put it into a tube furnace at 200 - 300 °C, pass hydrogen for reduction treatment for 1 - 2 h, and cool to room temperature to obtain a hydrogenation catalyst.

[0009] Further, the preparation method of the silicon-doped porous boron nitride includes the following steps: Q1: By weight, add 10 parts of boric acid and 5 - 6 parts of melamine to 200 - 300 parts of an ethanol aqueous solution with a mass concentration of 45 - 55%. Stir evenly, heat to 80 - 90 °C, stir for 2 - 3 h, cool to room temperature, filter to obtain a reactant. Place the reactant in a freeze dryer at -30 - 40 °C for freeze-drying for 4 - 8 hours to obtain a boron nitride precursor. Q2: By weight, add the boron nitride precursor to 40 - 60 parts of an ethanol aqueous solution, then add 1 - 2 parts of tetraethyl orthosilicate and 0.2 - 0.3 parts of 3-aminopropyltriethoxysilane, heat to 60 - 80 °C, stir for 1 - 2 h, filter to obtain organosilicon-doped boron nitride. Q3: Place the organosilicon-doped boron nitride in a tube furnace, pass nitrogen, and then increase the temperature of the furnace to 1000 - 1200 °C at a heating rate of 5 - 10 °C / min for pyrolysis reaction for 3 - 4 h. After the reaction, naturally cool to room temperature to obtain silicon-doped porous boron nitride.

[0010] Further, the mass concentration of ethanol in the ethanol aqueous solution is 50 - 70%.

[0011] Further, the palladium source is one or more of palladium chloride, palladium nitrate, and sodium chloropalladate.

[0012] Further, the nickel source includes one or more of nickel nitrate, nickel chloride, nickel acetate, and nickel sulfate.

[0013] Application of the hydrogenation catalyst prepared by the above preparation method in the preparation of succinic anhydride.

[0014] The above application is for the preparation of succinic anhydride. The preparation method of succinic anhydride includes the following steps: T1: Add a hydrogenation catalyst to the feeding tank, and maleic anhydride to the raw material tank. Heat the raw material tank to 65 - 75 °C and keep it warm until the maleic anhydride melts. Open the feeding tank, transfer the catalyst to the raw material tank, start the stirrer and the circulation pump, and stir for 0.5 - 1 h to obtain a raw material liquid. T2: Transfer the raw material liquid from the raw material tank to the first - stage reactor. Pass hydrogen at the bottom of the first - stage reactor. Control the first - stage reaction temperature at 130 - 140 °C, the reaction pressure at 2 - 4 Mpa, and react for 1 - 2 h. Detect the outlet of the first - stage reactor until the conversion rate of maleic anhydride reaches 40 - 50%, and the first - stage hydrogenation reaction is completed. T3: The reaction liquid enters the second - stage reactor from the first - stage reactor. Pass hydrogen at the bottom of the reactor. Control the second - stage reaction temperature at 140 - 160 °C, the reaction pressure at 4 - 6 Mpa, where the hydrogen - maleic anhydride molar ratio is (20 - 30):1, and react for 3 - 4 h. The second - stage hydrogenation reaction is completed. T4: Perform gas - liquid separation on the reaction liquid flowing out of the second - stage reactor. Adopt the method of pressure filtration to separate the catalyst and the succinic anhydride product liquid. The product liquid is subjected to vacuum distillation to separate out the by - product γ - butyrolactone and the product succinic anhydride.

[0015] Furthermore, in T2, the molar ratio of hydrogen to maleic anhydride is (10 - 15):1.

[0016] Furthermore, in T3, the hydrogen - maleic anhydride molar ratio is (20 - 30):1.

[0017] After adopting the above - mentioned technical solution, compared with the prior art, the present invention has the following beneficial effects: 1. The present invention uses a palladium source and a nickel source as active components, reducing the catalyst cost. The porous protection of the active components is formed by silicon - doped porous boron nitride. Boron nitride has a low coefficient of thermal expansion, which can reduce the deformation hazard caused by heat of the catalyst, reduce or eliminate the performance decline and particle breakage caused by temperature. The porous structure enables it to have a large specific surface area. Silicon doping helps to improve the bonding strength between the active component porous boron nitride and the carrier, improve the high - temperature stability and service life of the catalyst, achieve high conversion rate and high selectivity after long - term high - temperature aging. At the same time, silicon doping also helps to improve the dispersibility of porous boron nitride and improve the initial catalytic performance of the catalyst.

[0018] 2. Through two-stage hydrogenation reaction, the preheated raw material slurry and hydrogen undergo two-stage hydrogenation reaction. The reaction liquid is forced to backmix through two stages to keep the temperature balanced in different reaction stages throughout the reactor, which helps improve the adaptability and long-term catalytic activity of the catalyst. In addition, the two-stage hydrogenation reaction helps form a protective layer of silicon doping on the surface of porous silicon nitride to isolate palladium metal, prevent the migration and aggregation of palladium metal in a large area, and improve the maleic anhydride conversion rate of the catalyst after long-term high-temperature aging.

[0019] 3. The present invention provides a hydrogenation catalyst for preparing succinic anhydride in a solvent-free mode and its preparation method, which have low raw material cost, high stability, and good catalytic performance, and have high initial conversion rate and selectivity in the preparation of succinic anhydride. At the same time, the performance of the catalyst is stable after being reused for 500 h, and the maleic anhydride conversion rate can remain above 95.6%, and the succinic anhydride selectivity can remain above 96.3%. Detailed implementation mode

[0020] The technical solutions in the present invention will be clearly and completely described below in conjunction with the embodiments in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. The description of at least one exemplary embodiment below is actually only illustrative and in no way serves as a limitation to the present invention and its application or use. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0021] Example 1 The present invention provides a method for preparing succinic anhydride, which specifically includes the following steps: I. Preparation of silicon-doped porous boron nitride, which specifically includes the following steps: Q1: By weight, add 10 parts of boric acid and 5.5 parts of melamine to 250 parts of an ethanol aqueous solution with a mass concentration of 50%, stir evenly, heat to 85 °C, stir for 2 h, cool to room temperature, filter to obtain a reactant, and place the reactant in a freeze dryer at -35 °C for freeze drying for 6 hours to obtain a boron nitride precursor; Q2: By weight, add the boron nitride precursor to 50 parts of an ethanol aqueous solution with a mass concentration of 60%, then add 1.5 parts of tetraethyl orthosilicate and 0.25 parts of 3-aminopropyltriethoxysilane, heat to 70 °C, stir for 1.5 h, filter to obtain organosilicon-doped boron nitride; Q3: Place the organosilicon-doped boron nitride in a tubular furnace, introduce nitrogen, and then increase the temperature in the furnace to 1100 °C at a heating rate of 7 °C / min for pyrolysis reaction for 3.5 h. After the reaction is completed, naturally cool to room temperature to obtain silicon-doped porous boron nitride.

[0022] II. Preparation of a hydrogenation catalyst using the silicon-doped porous boron nitride prepared in this example specifically includes the following steps: S1: Dissolve a palladium source and a nickel source in water. The palladium source and the nickel source are formulated into a metal salt solution with a concentration of 100 mmol / L according to a molar ratio of 1:4. By weight, take 1 part of alumina powder and place it in 50 parts of the metal salt solution, impregnate for 20 h, filter, and dry at 100 °C for 9 h to obtain a pretreated catalyst; S2: By weight, add 0.6 part of polyvinylpyrrolidone to 50 parts of water to prepare a mixed solution. Add 1 part of silicon-doped porous boron nitride to the mixed solution and stir for 3 h to obtain a silicon-doped porous boron nitride suspension; S3: Place the pretreated catalyst in the silicon-doped porous boron nitride suspension, impregnate for 1 h, filter, dry at 70 °C for 8 h, put it into a muffle furnace, heat up to 500 °C, calcine for 5 h, then put it into a tube furnace at 250 °C, conduct hydrogen reduction treatment for 1.5 h, and cool to room temperature to obtain a hydrogenation catalyst.

[0023] The palladium source is palladium chloride.

[0024] The nickel source includes nickel nitrate.

[0025] III. Preparation of succinic anhydride using the hydrogenation catalyst prepared in this example specifically includes the following steps: T1: Add the hydrogenation catalyst to the feeding tank and maleic anhydride to the raw material tank. Heat the raw material tank to 70 °C and keep it warm until the maleic anhydride melts. Open the feeding tank, transfer the catalyst to the raw material tank, turn on the stirrer and the circulation pump, and stir for 0.5 h to obtain a raw material liquid; T2: Transfer the raw material liquid from the raw material tank to the first-stage reactor. Pass hydrogen at the bottom of the first-stage reactor, control the first-stage reaction temperature at 135 °C and the reaction pressure at 3 Mpa, where the molar ratio of hydrogen to maleic anhydride is 12:1, react for 1.5 h, detect the outlet of the first-stage reactor until the conversion rate of maleic anhydride reaches 45%, and the first-stage hydrogenation reaction is completed; T3: The reaction liquid enters the second-stage reactor from the first-stage reactor. Pass hydrogen at the bottom of the reactor, control the second-stage reaction temperature at 150 °C and the reaction pressure at 5 Mpa, where the hydrogen-maleic anhydride molar ratio is 25:1, react for 3.5 h, and the second-stage hydrogenation reaction is completed; T4: Perform gas-liquid separation on the reaction liquid flowing out of the second-stage reactor. Use the method of pressure filtration to separate the catalyst and the succinic anhydride product liquid. The product liquid is subjected to vacuum distillation to separate out the by-product γ-butyrolactone and the product succinic anhydride.

[0026] Example 2 The present invention provides a method for preparing succinic anhydride, which specifically includes the following steps: I. Preparation of silicon-doped porous boron nitride, specifically including the following steps: Q1: By weight, add 10 parts of boric acid and 5 parts of melamine to 200 parts of an ethanol aqueous solution with a mass concentration of 45%, stir evenly, heat to 80 °C, stir for 2 h, cool to room temperature, filter to obtain a reactant, and place the reactant in a freeze dryer at -30 °C for freeze drying for 4 hours to obtain a boron nitride precursor; Q2: By weight, add the boron nitride precursor to 40 parts of an ethanol aqueous solution with a mass concentration of 50%, then add 1 part of tetraethyl orthosilicate and 0.2 part of 3-aminopropyltriethoxysilane, heat to 60 °C, stir for 1 h, filter to obtain organosilicon-doped boron nitride; Q3: Place the organosilicon-doped boron nitride in a tubular furnace, introduce nitrogen, and then heat the furnace to 1000 °C at a heating rate of 5 °C / min for pyrolysis reaction for 3 h. After the reaction is completed, naturally cool to room temperature to obtain silicon-doped porous boron nitride.

[0027] II. Preparation of a hydrogenation catalyst using the silicon-doped porous boron nitride prepared in this example, specifically including the following steps: S1: Dissolve the palladium source and nickel source in water. The palladium source and nickel source are prepared into a metal salt solution with a concentration of 100 mmol / L according to a molar ratio of 1:4. By weight, take 1 part of alumina powder and place it in 40 parts of the metal salt solution for impregnation treatment for 10 h, filter, and dry at 80 °C for 6 h to obtain a pretreated catalyst; S2: By weight, add 0.5 part of polyvinylpyrrolidone to 40 parts of water to prepare a mixed solution, add 1 part of silicon-doped porous boron nitride to the mixed solution, and stir for 2 h to obtain a silicon-doped porous boron nitride suspension; S3: Place the pretreated catalyst in the silicon-doped porous boron nitride suspension for impregnation treatment for 0.5 h, filter, dry at 60 °C for 6 h, put it into a muffle furnace, heat to 450 °C, calcine for 4 h, then put it into a 200 °C tubular furnace, introduce hydrogen for reduction treatment for 1 h, and cool to room temperature to obtain a hydrogenation catalyst.

[0028] The palladium source is palladium nitrate.

[0029] The nickel source includes nickel chloride.

[0030] III. Preparation of succinic anhydride using the hydrogenation catalyst prepared in this example, specifically including the following steps: T1: Add the hydrogenation catalyst to the feeding tank, add maleic anhydride to the raw material tank, heat the raw material tank to 65 °C and keep it warm until the maleic anhydride melts. Open the feeding tank, transfer the catalyst to the raw material tank, turn on the stirrer and the circulation pump, and stir for 0.5 h to obtain a raw material liquid; T2: Transfer the raw material liquid from the raw material tank to the first-stage reactor. Pass hydrogen at the bottom of the first-stage reactor, control the first-stage reaction temperature at 130 °C, the reaction pressure at 2 Mpa, where the molar ratio of hydrogen to maleic anhydride is 10:1, react for 1 h, detect the outlet of the first-stage reactor until the conversion rate of maleic anhydride reaches 40%, and the first-stage hydrogenation reaction is completed; T3: The reaction liquid enters the second-stage reactor from the first-stage reactor. Pass hydrogen at the bottom of the reactor, control the second-stage reaction temperature at 140 °C, the reaction pressure at 4 Mpa, where the hydrogen-maleic anhydride molar ratio is 20:1, react for 3 h, and the second-stage hydrogenation reaction is completed; T4: Carry out gas-liquid separation on the reaction liquid flowing out of the second-stage reactor. Adopt the method of pressure filtration to separate the catalyst and the succinic anhydride product liquid. The product liquid is subjected to vacuum distillation to separate out the by-product γ-butyrolactone and the product succinic anhydride.

[0031] Example 3 The present invention provides a preparation method of succinic anhydride, which specifically includes the following steps: I. Prepare silicon-doped porous boron nitride, which specifically includes the following steps: Q1: By weight, add 10 parts of boric acid and 6 parts of melamine to 300 parts of an ethanol aqueous solution with a mass concentration of 55%, stir evenly, heat to 90 °C, stir for 3 h, cool to room temperature, filter to obtain a reactant, and place the reactant in a freeze dryer at -40 °C for freeze drying for 8 hours to obtain a boron nitride precursor; Q2: By weight, add the boron nitride precursor to 60 parts of an ethanol aqueous solution with a mass concentration of 70%, then add 2 parts of tetraethyl orthosilicate and 0.3 parts of 3-aminopropyltriethoxysilane, heat to 80 °C, stir for 2 h, filter to obtain organosilicon-doped boron nitride; Q3: Place the organosilicon-doped boron nitride in a tubular furnace, pass nitrogen, and then heat the furnace to 1200 °C at a heating rate of 10 °C / min for pyrolysis reaction for 4 h. After the reaction is completed, naturally cool to room temperature to obtain silicon-doped porous boron nitride.

[0032] II. Use the silicon-doped porous boron nitride prepared in this example to prepare a hydrogenation catalyst, which specifically includes the following steps: S1: Dissolve the palladium source and the nickel source in water. The palladium source and the nickel source are prepared into a metal salt solution with a concentration of 100 mmol / L according to a molar ratio of 1:4. By weight, take 1 part of alumina powder, place it in 60 parts of the metal salt solution, impregnate for 30 h, filter, and dry at 120 °C for 12 h to obtain a pretreated catalyst; S2: Add 0.7 parts of polyvinylpyrrolidone to 60 parts of water by weight to prepare a mixed solution. Add 1.5 parts of silicon-doped porous boron nitride to the mixed solution and stir for 4 h to obtain a silicon-doped porous boron nitride suspension. S3: Place the pretreated catalyst in the silicon-doped porous boron nitride suspension, impregnate for 1 h, filter, dry at 90 °C for 10 h, put it into a muffle furnace, heat up to 550 °C, calcine for 6 h, then put it into a 300 °C tubular furnace, carry out hydrogen reduction treatment for 2 h, and cool to room temperature to obtain a hydrogenation catalyst.

[0033] The palladium source is sodium chloropalladate.

[0034] The nickel source includes nickel acetate.

[0035] III. Use the hydrogenation catalyst prepared in this example to prepare succinic anhydride, which specifically includes the following steps: T1: Add the hydrogenation catalyst to the feeding tank and maleic anhydride to the raw material tank. Heat the raw material tank to 75 °C and keep it warm until the maleic anhydride melts. Open the feeding tank, transfer the catalyst to the raw material tank, turn on the stirrer and the circulation pump, and stir for 1 h to obtain a raw material liquid. T2: Transfer the raw material liquid from the raw material tank to the first-stage reactor. Pass hydrogen at the bottom of the first-stage reactor, control the first-stage reaction temperature at 140 °C, the reaction pressure at 4 Mpa, where the molar ratio of hydrogen to maleic anhydride is 15:1, react for 2 h, detect the outlet of the first-stage reactor until the conversion rate of maleic anhydride reaches 50%, and the first-stage hydrogenation reaction is completed. T3: The reaction liquid enters the second-stage reactor from the first-stage reactor. Pass hydrogen at the bottom of the reactor, control the second-stage reaction temperature at 160 °C, the reaction pressure at 6 Mpa, where the hydrogen-maleic anhydride molar ratio is 30:1, react for 4 h, and the second-stage hydrogenation reaction is completed. T4: Carry out gas-liquid separation on the reaction liquid flowing out of the second-stage reactor. By means of pressure filtration, separate the catalyst and the succinic anhydride product liquid. The product liquid is subjected to vacuum distillation to separate out the by-product γ-butyrolactone and the product succinic anhydride.

[0036] Example 4 The present invention provides a method for preparing succinic anhydride, which specifically includes the following steps: I. Prepare silicon-doped porous boron nitride, which specifically includes the following steps: Q1: Add 10 parts of boric acid and 5.2 parts of melamine to 220 parts of an ethanol aqueous solution with a mass concentration of 48% by weight, stir evenly, heat to 83 °C, stir for 2.5 h, cool to room temperature, filter to obtain a reactant, place the reactant in a freeze dryer at -32 °C, and carry out freeze drying for 5 hours to obtain a boron nitride precursor. Q2: Add boron nitride precursor by weight parts to 45 parts of an ethanol aqueous solution with a mass concentration of 55%, then add 1.2 parts of tetraethyl orthosilicate and 0.23 parts of 3-aminopropyltriethoxysilane, heat to 65 °C, stir for 1.2 h, filter to obtain organosilicon-doped boron nitride; Q3: Place the organosilicon-doped boron nitride in a tube furnace, introduce nitrogen, then heat the furnace to 1050 °C at a heating rate of 6 °C / min for pyrolysis reaction for 3.3 h. After the reaction ends, naturally cool to room temperature to obtain silicon-doped porous boron nitride.

[0037] II. Prepare a hydrogenation catalyst using the silicon-doped porous boron nitride prepared in this example, which specifically includes the following steps: S1: Dissolve palladium source and nickel source in water. The palladium source and nickel source are prepared into a metal salt solution with a concentration of 100 mmol / L according to a molar ratio of 1:4. Take 1 part of alumina powder by weight parts and place it in 45 parts of the metal salt solution, impregnate for 15 h, filter, and dry at 90 °C for 7 h to obtain a pretreated catalyst; S2: Add 0.55 parts of polyvinylpyrrolidone to 45 parts of water by weight parts to prepare a mixed solution. Add 1.2 parts of silicon-doped porous boron nitride to the mixed solution and stir for 2.5 h to obtain a silicon-doped porous boron nitride suspension; S3: Place the pretreated catalyst in the silicon-doped porous boron nitride suspension, impregnate for 0.7 h, filter, dry at 70 °C for 7 h, put it into a muffle furnace, heat to 480 °C, calcine for 4.5 h, then put it into a tube furnace at 230 °C, introduce hydrogen for reduction treatment for 1.2 h, and cool to room temperature to obtain a hydrogenation catalyst.

[0038] The palladium source is a mixture of palladium chloride, palladium nitrate, and sodium chloropalladate mixed in a mass ratio of 1:1:1.

[0039] The nickel source includes nickel sulfate.

[0040] III. Prepare succinic anhydride using the hydrogenation catalyst prepared in this example, which specifically includes the following steps: T1: Add the hydrogenation catalyst to the feeding tank, add maleic anhydride to the raw material tank, heat the raw material tank to 68 °C, keep warm until the maleic anhydride melts, open the feeding tank, transfer the catalyst to the raw material tank, turn on the stirrer and circulation pump, and stir for 0.6 h to obtain a raw material liquid; T2: Transfer the raw material liquid from the raw material tank to the first-stage reactor, introduce hydrogen at the bottom of the first-stage reactor, control the first-stage reaction temperature to be 133 °C, the reaction pressure to be 2.5 Mpa, where the molar ratio of hydrogen to maleic anhydride is 11:1, react for 1.2 h, detect the outlet of the first-stage reactor until the conversion rate of maleic anhydride is 43%, and the first-stage hydrogenation reaction is completed; T3: The reaction solution enters the secondary reactor from the primary reactor. Hydrogen is introduced at the bottom of the reactor. The temperature of the secondary reaction is controlled at 145 °C, and the reaction pressure is 4.5 Mpa. The molar ratio of hydrogen to maleic anhydride is 22:1. The reaction lasts for 3.2 h, and the secondary hydrogenation reaction is completed. T4: The reaction solution flowing out of the secondary reactor is subjected to gas-liquid separation by means of pressure filtration to separate the catalyst and the succinic anhydride product solution. The product solution is subjected to vacuum distillation to separate the by-product γ-butyrolactone and the product succinic anhydride.

[0041] Example 5 The present invention provides a method for preparing succinic anhydride, which specifically includes the following steps: I. Preparation of silicon-doped porous boron nitride, which specifically includes the following steps: Q1: By weight, 10 parts of boric acid and 5.8 parts of melamine are added to 280 parts of an ethanol aqueous solution with a mass concentration of 53%. After stirring evenly, it is heated to 88 °C, stirred for 2.8 h, cooled to room temperature, filtered to obtain a reactant. The reactant is placed in a freeze dryer at -38 °C and freeze-dried for 7 hours to obtain a boron nitride precursor. Q2: By weight, the boron nitride precursor is added to 55 parts of an ethanol aqueous solution with a mass concentration of 65%. Then, 1.8 parts of tetraethyl orthosilicate and 0.28 parts of 3-aminopropyltriethoxysilane are added. It is heated to 75 °C, stirred for 1.8 h, and filtered to obtain organosilicon-doped boron nitride. Q3: The organosilicon-doped boron nitride is placed in a tube furnace, and nitrogen is introduced. Then, at a heating rate of 9 °C / min, the temperature in the furnace is raised to 1150 °C, and a pyrolysis reaction is carried out for 3.8 h. After the reaction ends, it is naturally cooled to room temperature to obtain silicon-doped porous boron nitride.

[0042] II. Preparation of a hydrogenation catalyst using the silicon-doped porous boron nitride prepared in this example, which specifically includes the following steps: S1: The palladium source and the nickel source are dissolved in water. The palladium source and the nickel source are prepared into a metal salt solution with a concentration of 100 mmol / L according to a molar ratio of 1:4. By weight, 1 part of alumina powder is taken and placed in 55 parts of the metal salt solution, impregnated for 25 h, filtered, and dried at 110 °C for 11 h to obtain a pretreated catalyst. S2: By weight, 0.65 part of polyvinylpyrrolidone is added to 55 parts of water to prepare a mixed solution. 14 parts of silicon-doped porous boron nitride are added to the mixed solution and stirred for 3.5 h to obtain a silicon-doped porous boron nitride suspension. S3: Place the pretreatment catalyst in a silicon-doped porous boron nitride suspension, soak it for 0.9 h, filter, dry it at 85 °C for 9 h, put it into a muffle furnace, heat it up to 540 °C, calcine it for 5.5 h, then put it into a tube furnace at 280 °C, reduce it with hydrogen for 1.7 h, and cool it to room temperature to obtain the hydrogenation catalyst.

[0043] The palladium source is a mixture of palladium chloride and palladium nitrate mixed in a mass ratio of 1:1.

[0044] The nickel source includes a mixture of nickel nitrate, nickel chloride, nickel acetate and nickel sulfate mixed in a mass ratio of 1:1:1:1.

[0045] III. Prepare succinic anhydride using the hydrogenation catalyst prepared in this example, which specifically includes the following steps: T1: Add the hydrogenation catalyst to the feeding tank, add maleic anhydride to the raw material tank, heat the raw material tank to 73 °C, keep it warm until the maleic anhydride melts, open the feeding tank, transfer the catalyst to the raw material tank, turn on the stirrer and the circulation pump, and stir for 0.9 h to obtain the raw material liquid; T2: Transfer the raw material liquid from the raw material tank to the first-stage reactor, introduce hydrogen at the bottom of the first-stage reactor, control the first-stage reaction temperature at 139 °C, the reaction pressure at 3.5 Mpa, where the molar ratio of hydrogen to maleic anhydride is 14:1, react for 1.6 h, detect the outlet of the first-stage reactor until the conversion rate of maleic anhydride reaches 48%, and the first-stage hydrogenation reaction is completed; T3: The reaction liquid enters the second-stage reactor from the first-stage reactor, introduce hydrogen at the bottom of the reactor, control the second-stage reaction temperature at 155 °C, the reaction pressure at 5.5 Mpa, where the hydrogen-maleic anhydride molar ratio is 28:1, react for 3.7 h, and the second-stage hydrogenation reaction is completed; T4: Carry out gas-liquid separation on the reaction liquid flowing out of the second-stage reactor, adopt the method of pressure filtration to separate the catalyst and the succinic anhydride product liquid, and subject the product liquid to vacuum distillation to separate out the by-product γ-butyrolactone and the product succinic anhydride.

[0046] Comparative Example 1 Different from Example 1, in the preparation of silicon-doped porous boron nitride, no silicon doping is carried out.

[0047] I. Prepare porous boron nitride, which specifically includes the following steps: Q1: By weight, add 10 parts of boric acid and 5.5 parts of melamine to 250 parts of an ethanol aqueous solution with a mass concentration of 50%, stir evenly, heat to 85 °C, stir for 2 h, cool to room temperature, filter to obtain the reactant, place the reactant in a freeze dryer at -35 °C, and freeze dry for 6 hours to obtain the boron nitride precursor; Q2: Place the boron nitride precursor in a tubular furnace, introduce nitrogen gas, then increase the temperature in the furnace to 1100 °C at a heating rate of 7 °C / min, carry out the pyrolysis reaction for 3.5 h, and after the reaction is completed, naturally cool to room temperature to obtain porous boron nitride.

[0048] II. Prepare a hydrogenation catalyst using the silicon-doped porous boron nitride prepared in this example, which specifically includes the following steps: S1: Dissolve the palladium source and nickel source in water. The palladium source and nickel source are formulated into a metal salt solution with a concentration of 100 mmol / L according to a molar ratio of 1:4. By weight, take 1 part of alumina powder and place it in 50 parts of the metal salt solution, carry out impregnation treatment for 20 h, filter, and dry at 100 °C for 9 h to obtain a pretreated catalyst. S2: By weight, add 0.6 part of polyvinylpyrrolidone to 50 parts of water to prepare a mixed solution, add 1 part of porous boron nitride to the mixed solution, and stir for 3 h to obtain a porous boron nitride suspension. S3: Place the pretreated catalyst in the porous boron nitride suspension, carry out impregnation treatment for 1 h, filter, dry at 70 °C for 8 h, put it into a muffle furnace, heat up to 500 °C, calcine for 5 h, then put it into a 250 °C tubular furnace, introduce hydrogen for reduction treatment for 1.5 h, and cool to room temperature to obtain a hydrogenation catalyst.

[0049] The palladium source is palladium chloride.

[0050] The nickel source includes nickel nitrate.

[0051] Comparative Example 2 The difference from Example 1 is that in the preparation of succinic anhydride, only the primary hydrogenation reaction is carried out.

[0052] This comparative example uses the hydrogenation catalyst prepared in Example 1 to prepare succinic anhydride, which specifically includes the following steps: T1: Add the hydrogenation catalyst to the feeding tank, add maleic anhydride to the raw material tank, heat the raw material tank to 70 °C, keep it warm until the maleic anhydride melts, open the feeding tank, transfer the catalyst to the raw material tank, turn on the stirrer and circulation pump, and stir for 0.5 h to obtain a raw material liquid. T2: Transfer the raw material liquid from the raw material tank to the primary reactor, introduce hydrogen gas at the bottom of the primary reactor, control the primary reaction temperature at 135 °C, the reaction pressure at 3 Mpa, where the molar ratio of hydrogen to maleic anhydride is 12:1, react for 1.5 h, detect the outlet of the primary reactor until the conversion rate of maleic anhydride reaches 45%, and the primary hydrogenation reaction is completed. T3: Carry out gas-liquid separation on the reaction liquid flowing out of the primary reactor, use the method of pressure filtration to separate the catalyst and the succinic anhydride product liquid, and carry out vacuum distillation on the product liquid to separate the by-product γ-butyrolactone and the product succinic anhydride.

[0053] Comparative Example 3 Different from Example 1, in the preparation of succinic anhydride, only the secondary hydrogenation reaction was carried out.

[0054] This comparative example used the hydrogenation catalyst prepared in Example 1 to prepare succinic anhydride, which specifically included the following steps: T1: Add the hydrogenation catalyst to the feeding tank, add maleic anhydride to the raw material tank, heat the raw material tank to 70 °C, keep warm until the maleic anhydride melts, open the feeding tank, transfer the catalyst to the raw material tank, turn on the stirrer and the circulation pump, and stir for 0.5 h to obtain the raw material liquid; T2: Feed the raw material liquid from the raw material tank into the secondary reactor, introduce hydrogen at the bottom of the reactor, control the secondary reaction temperature at 150 °C, the reaction pressure at 5 Mpa, where the hydrogen-maleic anhydride molar ratio is 25:1, react for 5 h, and the secondary hydrogenation reaction is completed; T4: Carry out gas-liquid separation on the reaction liquid flowing out of the secondary reactor, adopt the method of pressure filtration to separate the catalyst and the succinic anhydride product liquid, and carry out vacuum distillation on the product liquid to separate out the by-product γ-butyrolactone and the product succinic anhydride.

[0055] Specifically, it includes the following steps: T1: Add the hydrogenation catalyst to the feeding tank, add maleic anhydride to the raw material tank, heat the raw material tank to 70 °C, keep warm until the maleic anhydride melts, open the feeding tank, transfer the catalyst to the raw material tank, turn on the stirrer and the circulation pump, and stir for 0.5 h to obtain the raw material liquid; T2: Transfer the raw material liquid from the raw material tank to the primary reactor, introduce hydrogen at the bottom of the primary reactor, control the primary reaction temperature at 135 °C, the reaction pressure at 3 Mpa, where the molar ratio of hydrogen to maleic anhydride is 12:1, react for 1.5 h, detect the outlet of the primary reactor until the conversion rate of maleic anhydride reaches 45%, and the primary hydrogenation reaction is completed; T3: Feed the reaction liquid from the primary reactor into the secondary reactor, introduce hydrogen at the bottom of the reactor, control the secondary reaction temperature at 150 °C, the reaction pressure at 5 Mpa, where the hydrogen-maleic anhydride molar ratio is 25:1, react for 3.5 h, and the secondary hydrogenation reaction is completed; T4: Carry out gas-liquid separation on the reaction liquid flowing out of the secondary reactor, adopt the method of pressure filtration to separate the catalyst and the succinic anhydride product liquid, and carry out vacuum distillation on the product liquid to separate out the by-product γ-butyrolactone and the product succinic anhydride.

[0056] Comparative Example 4 The difference from Example 1 is that in the preparation of silicon-doped porous boron nitride, silicon doping was not carried out, and in the preparation of succinic anhydride, only the secondary hydrogenation reaction was carried out.

[0057] I. Preparation of porous boron nitride, which specifically includes the following steps: Q1: Add 10 parts by weight of boric acid and 5.5 parts of melamine to 250 parts of an ethanol aqueous solution with a mass concentration of 50%. Stir evenly, heat to 85 °C, stir for 2 h, cool to room temperature, filter to obtain a reactant. Place the reactant in a freeze dryer at -35 °C and freeze-dry for 6 hours to obtain a boron nitride precursor; Q2: Place the boron nitride precursor in a tubular furnace, introduce nitrogen, and then heat the furnace to 1100 °C at a heating rate of 7 °C / min for pyrolysis reaction for 3.5 h. After the reaction ends, naturally cool to room temperature to obtain porous boron nitride.

[0058] II. Use the silicon-doped porous boron nitride prepared in this example to prepare a hydrogenation catalyst, which specifically includes the following steps: S1: Dissolve the palladium source and nickel source in water. The palladium source and nickel source are prepared into a metal salt solution with a concentration of 100 mmol / L according to a molar ratio of 1:4. Take 1 part by weight of alumina powder and place it in 50 parts of the metal salt solution, impregnate for 20 h, filter, and dry at 100 °C for 9 h to obtain a pretreated catalyst; S2: Add 0.6 part by weight of polyvinylpyrrolidone to 50 parts of water to prepare a mixed solution. Add 1 part of porous boron nitride to the mixed solution and stir for 3 h to obtain a porous boron nitride suspension; S3: Place the pretreated catalyst in the porous boron nitride suspension, impregnate for 1 h, filter, dry at 70 °C for 8 h, put it into a muffle furnace, heat to 500 °C, calcine for 5 h, then put it into a 250 °C tubular furnace, introduce hydrogen for reduction treatment for 1.5 h, and cool to room temperature to obtain a hydrogenation catalyst.

[0059] The palladium source is palladium chloride.

[0060] The nickel source includes nickel nitrate.

[0061] III. Use the hydrogenation catalyst prepared in this example to prepare succinic anhydride, which specifically includes the following steps: T1: Add the hydrogenation catalyst to the feeding tank, add maleic anhydride to the raw material tank, heat the raw material tank to 70 °C and keep it warm until the maleic anhydride melts. Open the feeding tank, transfer the catalyst to the raw material tank, turn on the stirrer and circulation pump, and stir for 0.5 h to obtain a raw material liquid; T2: Transfer the raw material liquid from the raw material tank to the secondary reactor, introduce hydrogen at the bottom of the reactor, control the secondary reaction temperature at 150 °C and the reaction pressure at 5 Mpa, where the hydrogen-maleic anhydride molar ratio is 25:1, and react for 3.5 h to complete the secondary hydrogenation reaction; T3: The reaction liquid flowing out of the secondary reactor is subjected to gas-liquid separation by means of pressure filtration to separate the catalyst and the succinic anhydride product liquid. The product liquid is subjected to vacuum distillation to separate out the by-product γ-butyrolactone and the product succinic anhydride.

[0062] Table 1 shows the activity data of the catalyst prepared by the present invention in the preparation of succinic anhydride and the test results of reaction stability.

[0063] Effect verification Table 1 Combined with Examples 1 to 5 and the data in Table 1, it can be seen that after the catalyst prepared by the present invention is used for 500 hours in the preparation of succinic anhydride, the conversion rate of maleic anhydride can be maintained above 95.6%, and the selectivity of succinic anhydride can be maintained above 96.3%. It is proved that the catalyst prepared by the present invention still has good catalytic performance, selectivity and stability after being used for 500 hours.

[0064] Analyzing the content of Comparative Example 1 in combination with the data in Table 1 and the data of Example 1, the initial conversion rate of the catalyst prepared in Comparative Example 1 in the preparation of succinic anhydride decreases, and after the catalyst is used for 500 hours, the conversion rate of maleic anhydride and the selectivity of succinic anhydride decrease. It shows that doping boron nitride with silicon in the preparation of silicon-doped porous boron nitride can improve the catalytic performance, selectivity and stability of the prepared catalyst.

[0065] According to the content of Comparative Example 2 and Comparative Example 3 in combination with Example 1 and the data in Table 1, in the preparation of succinic anhydride, when only the first-stage hydrogenation reaction is carried out to prepare succinic anhydride, or only the second-stage hydrogenation reaction is carried out to prepare succinic anhydride, after the catalyst is used for 500 hours, the conversion rate of maleic anhydride and the selectivity of succinic anhydride both decrease significantly. It shows that the two-stage hydrogenation reaction can further enhance the catalytic performance, selectivity and conversion efficiency of the catalyst in the preparation of succinic anhydride.

[0066] In the preparation of silicon-doped porous boron nitride in Comparative Example 4, no silicon doping is carried out. At the same time, in the application of the hydrogenation catalyst in the preparation of succinic anhydride, only the second-stage hydrogenation reaction is carried out. Compared with the performance of the catalyst prepared in Example 1, the initial conversion rate of succinic anhydride and the conversion rate of maleic anhydride and the selectivity of succinic anhydride after being used for 500 h of the catalyst prepared in Comparative Example 4 all decrease significantly in the preparation of succinic anhydride. It shows that adding silicon-doped silicon nitride in the preparation of the catalyst, in the presence of the two-stage hydrogenation reaction, the catalyst has good stability, selectivity and high conversion rate, and there is a synergistic effect between the two.

[0067] The above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and all should be covered within the protection scope of the present invention.

Claims

1. A method for preparing a hydrogenation catalyst, characterized in that: It includes the following steps: S1: Dissolve the palladium source and nickel source in water. The palladium source and nickel source are prepared into a metal salt solution with a concentration of 100 mmol / L according to a molar ratio of 1:

4. By weight, take 1 part of alumina powder and place it in 40 - 60 parts of the metal salt solution. Immerse it for 10 - 30 h, filter, and dry it at 80 - 120 °C for 6 - 12 h to obtain a pretreated catalyst; S2: By weight, add 0.5 - 0.7 part of polyvinylpyrrolidone to 40 - 60 parts of water to prepare a mixed solution. Add 1 - 1.5 parts of silicon-doped porous boron nitride to the mixed solution and stir for 2 - 4 h to obtain a silicon-doped porous boron nitride suspension; S3: Place the pretreated catalyst in the silicon-doped porous boron nitride suspension, immerse it for 0.5 - 1 h, filter, dry it at 60 - 90 °C for 6 - 10 h, put it into a muffle furnace, heat it up to 450 - 550 °C, calcine it for 4 - 6 h, then put it into a tube furnace at 200 - 300 °C, pass hydrogen for reduction treatment for 1 - 2 h, and cool it to room temperature to obtain a hydrogenation catalyst.

2. The preparation method of a hydrogenation catalyst according to claim 1, wherein: The preparation method of the silicon-doped porous boron nitride includes the following steps: Q1: By weight, add 10 parts of boric acid and 5 - 6 parts of melamine to 200 - 300 parts of an ethanol aqueous solution with a mass concentration of 45 - 55%. Stir evenly, heat it to 80 - 90 °C, stir for 2 - 3 h, cool it to room temperature, filter to obtain a reactant. Place the reactant in a freeze dryer at -30 - 40 °C and freeze-dry it for 4 - 8 h to obtain a boron nitride precursor; Q2: By weight, add the boron nitride precursor to 40 - 60 parts of an ethanol aqueous solution, then add 1 - 2 parts of tetraethyl orthosilicate and 0.2 - 0.3 part of 3-aminopropyltriethoxysilane, heat it to 60 - 80 °C, stir for 1 - 2 h, filter to obtain organosilicon-doped boron nitride; Q3: Place the organosilicon-doped boron nitride in a tube furnace, pass nitrogen, and then increase the temperature in the furnace to 1000 - 1200 °C at a heating rate of 5 - 10 °C / min for pyrolysis reaction for 3 - 4 h. After the reaction ends, naturally cool it to room temperature to obtain silicon-doped porous boron nitride.

3. The preparation method of a hydrogenation catalyst according to claim 2, characterized in that: The mass concentration of ethanol in the ethanol aqueous solution is 50 - 70%.

4. The preparation method of a hydrogenation catalyst according to claim 1, characterized in that: The palladium source is one or more of palladium chloride, palladium nitrate, and sodium chloropalladate.

5. The preparation method of a hydrogenation catalyst according to claim 1, wherein: The nickel source includes one or more of nickel nitrate, nickel chloride, nickel acetate, and nickel sulfate.

6. A hydrogenation catalyst, characterized in that: It is prepared by using the preparation method described in any one of claims 1 - 5.

7. Use of a hydrogenation catalyst in the preparation of succinic anhydride, characterized in that: The hydrogenation catalyst is prepared by using the preparation method described in any one of claims 1 - 5; the steps for using the hydrogenation catalyst to prepare succinic anhydride are as follows: T1: Add the hydrogenation catalyst to the feeding tank, add maleic anhydride to the raw material tank, heat the raw material tank to 65 - 75 °C, keep it warm until the maleic anhydride melts, open the feeding tank, transfer the catalyst to the raw material tank, turn on the stirrer and the circulation pump, and stir for 0.5 - 1 h to obtain a raw material liquid; T2: Transfer the raw material liquid from the raw material tank to the first-stage reactor. Pass hydrogen at the bottom of the first-stage reactor. Control the first-stage reaction temperature at 130 - 140 °C, the reaction pressure at 2 - 4 Mpa, and react for 1 - 2 h. Detect the outlet of the first-stage reactor until the maleic anhydride conversion rate reaches 40 - 50%, and the first-stage hydrogenation reaction is completed. T3: The reaction liquid enters the second-stage reactor from the first-stage reactor. Pass hydrogen at the bottom of the reactor. Control the second-stage reaction temperature at 140 - 160 °C, the reaction pressure at 4 - 6 Mpa, where the hydrogen-maleic anhydride molar ratio is (20 - 30):1, and react for 3 - 4 h. The second-stage hydrogenation reaction is completed. T4: Perform gas-liquid separation on the reaction liquid flowing out of the second-stage reactor. Adopt the method of pressure filtration to separate the catalyst and the succinic anhydride product liquid. The product liquid is subjected to vacuum distillation to separate out the by-product γ-butyrolactone and the product succinic anhydride.

8. The application according to claim 7, wherein: In the above T2, the hydrogen-maleic anhydride molar ratio is (10 - 15):

1.

9. The application according to claim 7, wherein: In T3, the hydrogen-maleic anhydride molar ratio is (20 - 30):1.

Images