A hydrogenation catalyst, a method for preparing the same, and use thereof in the production of succinic anhydride

Abstract

The application relates to a hydrogenation catalyst, a preparation method thereof and application thereof in preparing succinic anhydride, belongs to the field of catalysis, and comprises an active component and silicon-doped porous boron nitride, wherein the active component is palladium and nickel. When the catalyst is prepared, the raw material cost is low, the prepared catalyst has high stability and good catalytic performance, has high initial conversion rate and selectivity in the preparation of succinic anhydride, the performance of the catalyst is stable after being repeatedly used for 500 hours, the conversion rate of maleic anhydride can be kept above 95.6%, and the selectivity of succinic anhydride can be kept above 96.3%.

Description

Technical Field

[0001] This invention belongs to the field of catalysis, and in particular relates to a hydrogenation catalyst, its preparation method, and its application in the preparation of succinic anhydride. Background Technology

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

[0003] In the existing technology, maleic anhydride hydrogenation catalysts mainly include nickel-based catalysts and palladium metal catalysts. Palladium metal catalysts have high activity and anti-coking properties, but their cost is high. Nickel-based catalysts are cheaper, but they are prone to coking and deactivate quickly.

[0004] The process of preparing succinic anhydride by hydrogenation of maleic anhydride includes two modes: solvent-based and solvent-free. In the solvent-based mode, the reaction temperature is generally 40~100℃, while in the solvent-free mode, the reaction temperature needs to be higher than the melting point of the product succinic anhydride, generally 130~160℃. The solvent-free mode has a fast reaction rate and high efficiency, but the high temperature will cause the catalyst performance to degrade. Under high temperature conditions or during long-term operation, there is a serious problem of heat generation, which can easily cause catalyst breakage, pulverization and side reactions, affecting the catalytic effect and service life.

[0005] Therefore, developing and preparing a low-cost, high-temperature resistant, and high-performance hydrogenation catalyst can effectively improve the hydrogenation reaction efficiency and increase product yield in the solvent-free preparation of succinic anhydride. Summary of the Invention

[0006] (a) Technical problems to be solved

[0007] To address the shortcomings of existing technologies, this invention provides a hydrogenation catalyst, its preparation method, and its application in the preparation of succinic anhydride.

[0008] (II) Technical Solution

[0009] To achieve the above objectives, the present invention provides the following technical solution:

[0010] A hydrogenation catalyst comprising an active component and silicon-doped porous boron nitride, wherein the active component is palladium and nickel.

[0011] A method for preparing a hydrogenation catalyst includes the following steps:

[0012] S1: Dissolve palladium and nickel sources in water and prepare a metal salt solution with a concentration of 100 mmol / L by a molar ratio of 1:4. Take 1 part of alumina powder by weight and place it in 40 to 60 parts of the metal salt solution. Impregnate for 10 to 30 hours, filter, and dry at 80 to 120°C for 6 to 12 hours to obtain the pretreated catalyst.

[0013] S2: By weight, add 0.5 to 0.7 parts of polyvinylpyrrolidone to 40 to 60 parts of water to prepare a mixed solution. Add 1 to 1.5 parts of silicon-doped porous boron nitride to the mixed solution and stir for 2 to 4 hours to obtain a silicon-doped porous boron nitride suspension.

[0014] S3: The pretreated catalyst is placed in a silicon-doped porous boron nitride suspension and impregnated for 0.5 to 1 hour. After filtration, it is dried at 60 to 90°C for 6 to 10 hours. Then, it is placed in a muffle furnace, heated to 450 to 550°C, and calcined for 4 to 6 hours. Finally, it is placed in a tube furnace at 200 to 300°C and reduced with hydrogen for 1 to 2 hours. After cooling to room temperature, the hydrogenation catalyst is obtained.

[0015] Furthermore, the method for preparing the silicon-doped porous boron nitride includes the following steps:

[0016] Q1: By weight, add 10 parts boric acid and 5-6 parts melamine to 200-300 parts of an aqueous ethanol solution with a mass concentration of 45-55%, stir evenly, heat to 80-90℃, stir for 2-3 hours, cool to room temperature, filter to obtain the reactant, place the reactant in a freeze dryer at -30-40℃, freeze dry for 4-8 hours to obtain the boron nitride precursor;

[0017] Q2: By weight, add the boron nitride precursor to 40-60 parts of an aqueous ethanol solution, then add 1-2 parts of tetraethyl orthosilicate and 0.2-0.3 parts of 3-aminopropyltriethoxysilane, heat to 60-80℃, stir for 1-2 hours, filter, and obtain organosilicon-doped boron nitride.

[0018] Q3: Place organosilicon-doped boron nitride in a tube furnace, purge with nitrogen, and then heat the furnace to 1000-1200℃ at a heating rate of 5-10℃ / min for pyrolysis reaction for 3-4 hours. After the reaction is complete, allow it to cool naturally to room temperature to obtain silicon-doped porous boron nitride.

[0019] Furthermore, the mass concentration of ethanol in the ethanol-water solution is 50-70%.

[0020] Furthermore, the palladium source is one or more of palladium chloride, palladium nitrate, and sodium chloropalladium.

[0021] Furthermore, the nickel source includes one or more of nickel nitrate, nickel chloride, nickel acetate, and nickel sulfate.

[0022] The application of the hydrogenation catalyst prepared by the above method in the preparation of succinic anhydride.

[0023] The above application is for the preparation of succinic anhydride, and the preparation method of succinic anhydride includes the following steps:

[0024] T1: Add the hydrogenation catalyst to the feeding tank and maleic anhydride to the raw material tank. Heat the raw material tank to 65~75℃ and keep it at that temperature until the maleic anhydride melts. Open the feeding tank and transfer the catalyst to the raw material tank. Turn on the stirrer and circulation pump and stir for 0.5~1h to obtain the raw material liquid.

[0025] 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 130~140℃, the reaction pressure at 2~4Mpa, react for 1~2h, check the outlet of the primary reactor, and when the maleic anhydride conversion rate is 40~50%, the primary hydrogenation reaction is completed.

[0026] T3: The reaction liquid enters the secondary reactor from the primary reactor. Hydrogen gas is introduced at the bottom of the reactor. The secondary reaction temperature is controlled at 140~160℃ and the reaction pressure is 4~6Mpa. The hydrogen-maleic anhydride molar ratio is (20~30):1. The reaction takes 3~4 hours and the secondary hydrogenation reaction is completed.

[0027] T4: The reaction liquid flowing out of the secondary reactor is subjected to gas-liquid separation. The catalyst and succinic anhydride product liquid are separated by pressure filtration. The product liquid is then distilled under reduced pressure to separate the byproduct γ-butyrolactone and the product succinic anhydride.

[0028] Furthermore, the molar ratio of hydrogen to maleic anhydride in T2 is (10~15):1.

[0029] Furthermore, the hydrogen-maleic anhydride molar ratio in T3 is (20~30):1.

[0030] By adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0031] 1. This invention uses palladium and nickel sources as active components, reducing catalyst costs. Silicon-doped porous boron nitride is used to form a porous protective layer for the active components. Boron nitride has a low coefficient of thermal expansion, which can reduce the damage caused by thermal deformation of the catalyst and reduce or eliminate temperature-induced performance degradation and particle breakage. The porous structure allows for a large specific surface area. Silicon doping helps improve the bonding strength between the porous boron nitride and the support, improving the high-temperature stability and lifespan of the catalyst, achieving high conversion rate and high selectivity after long-term high-temperature aging. Simultaneously, silicon doping also helps improve the dispersion of porous boron nitride, improving the initial catalytic performance of the catalyst.

[0032] 2. Through a two-stage hydrogenation reaction, the preheated feed slurry and hydrogen are subjected to a two-stage hydrogenation reaction. The reaction liquid is forced to backmix in two stages, so that the temperature of different reaction stages in the entire reactor is kept uniform. This helps to improve the adaptability and long-term catalytic activity of the catalyst. In addition, the two-stage hydrogenation reaction helps silicon doping to form a protective layer on the porous silicon nitride surface, which isolates palladium metal and prevents palladium metal from migrating and agglomerating in a large area, thereby improving the maleic anhydride conversion rate of the catalyst after long-term high-temperature aging.

[0033] 3. This invention provides a hydrogenation catalyst for the preparation of succinic anhydride in a solvent-free mode and its preparation method. The raw material cost is low, the stability is high, and the catalytic performance is good. It has a high initial conversion rate and selectivity in the preparation of succinic anhydride. At the same time, the catalyst is stable after being reused for 500 hours, and the maleic anhydride conversion rate can be maintained above 95.6% and the succinic anhydride selectivity can be maintained above 96.3%. Detailed Implementation

[0034] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this invention or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0035] Example 1

[0036] This invention provides a method for preparing succinic anhydride, specifically comprising the following steps:

[0037] I. Preparation of silicon-doped porous boron nitride, specifically including the following steps:

[0038] Q1: By weight, add 10 parts boric acid and 5.5 parts melamine to 250 parts of 50% ethanol aqueous solution, stir evenly, heat to 85°C, stir for 2 hours, cool to room temperature, filter to obtain the reactant, place the reactant in a freeze dryer at -35°C, freeze dry for 6 hours to obtain boron nitride precursor;

[0039] Q2: By weight, add 50 parts of boron nitride precursor to 60% ethanol aqueous solution, 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.

[0040] Q3: Place organosilicon-doped boron nitride in a tube furnace, purge with nitrogen, and then heat the furnace to 1100℃ at a heating rate of 7℃ / min for pyrolysis reaction for 3.5h. After the reaction is completed, allow it to cool naturally to room temperature to obtain silicon-doped porous boron nitride.

[0041] II. The preparation of a hydrogenation catalyst using the silicon-doped porous boron nitride prepared in this embodiment includes the following steps:

[0042] S1: Dissolve the palladium source and nickel source in water, and prepare a metal salt solution with a concentration of 100 mmol / L by a molar ratio of 1:4. Take 1 part of alumina powder by weight 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 the pretreated catalyst.

[0043] S2: By weight, add 0.6 parts 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 hours to obtain a silicon-doped porous boron nitride suspension.

[0044] S3: The pretreated catalyst was placed in a silicon-doped porous boron nitride suspension, impregnated for 1 hour, filtered, dried at 70°C for 8 hours, placed in a muffle furnace, heated to 500°C, calcined for 5 hours, and then placed in a tube furnace at 250°C for hydrogen reduction treatment for 1.5 hours. After cooling to room temperature, the hydrogenation catalyst was obtained.

[0045] The palladium source is palladium chloride.

[0046] The nickel source includes nickel nitrate.

[0047] III. The preparation of succinic anhydride using the hydrogenation catalyst prepared in this embodiment specifically includes the following steps:

[0048] 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 at that temperature until the maleic anhydride melts. Open the feeding tank and transfer the catalyst to the raw material tank. Turn on the stirrer and circulation pump and stir for 0.5 hours to obtain the raw material liquid.

[0049] 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℃ and the reaction pressure at 3 MPa, wherein the molar ratio of hydrogen to maleic anhydride is 12:1, react for 1.5 hours, check the outlet of the primary reactor, and when the maleic anhydride conversion rate reaches 45%, the primary hydrogenation reaction is completed.

[0050] T3: The reaction solution enters the secondary reactor from the primary reactor. Hydrogen gas is introduced at the bottom of the reactor. The secondary reaction temperature is controlled at 150℃ and the reaction pressure is 5 MPa. The hydrogen-maleic anhydride molar ratio is 25:1. The reaction takes 3.5 hours and the secondary hydrogenation reaction is completed.

[0051] T4: The reaction liquid flowing out of the secondary reactor is subjected to gas-liquid separation. The catalyst and succinic anhydride product liquid are separated by pressure filtration. The product liquid is then distilled under reduced pressure to separate the byproduct γ-butyrolactone and the product succinic anhydride.

[0052] Example 2

[0053] This invention provides a method for preparing succinic anhydride, specifically comprising the following steps:

[0054] I. Preparation of silicon-doped porous boron nitride, specifically including the following steps:

[0055] Q1: By weight, add 10 parts boric acid and 5 parts melamine to 200 parts of 45% ethanol aqueous solution, stir evenly, heat to 80℃, stir for 2 hours, cool to room temperature, filter to obtain the reactant, place the reactant in a freeze dryer at -30℃, freeze dry for 4 hours to obtain boron nitride precursor.

[0056] Q2: By weight, add 40 parts of boron nitride precursor to 50% ethanol aqueous solution, then add 1 part of tetraethyl orthosilicate and 0.2 parts of 3-aminopropyltriethoxysilane, heat to 60°C, stir for 1 hour, filter, and obtain organosilicon-doped boron nitride.

[0057] Q3: Place organosilicon-doped boron nitride in a tube furnace, purge with nitrogen, and then heat the furnace to 1000℃ at a heating rate of 5℃ / min for pyrolysis reaction for 3 hours. After the reaction is completed, allow it to cool naturally to room temperature to obtain silicon-doped porous boron nitride.

[0058] II. The preparation of a hydrogenation catalyst using the silicon-doped porous boron nitride prepared in this embodiment includes the following steps:

[0059] S1: Dissolve the palladium source and nickel source in water, and prepare a metal salt solution with a concentration of 100 mmol / L by a molar ratio of 1:4. Take 1 part of alumina powder by weight and place it in 40 parts of the metal salt solution. Impregnate for 10 h, filter, and dry at 80 °C for 6 h to obtain the pretreated catalyst.

[0060] S2: By weight, add 0.5 parts 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 hours to obtain a silicon-doped porous boron nitride suspension.

[0061] S3: The pretreated catalyst was placed in a silicon-doped porous boron nitride suspension and impregnated for 0.5 h. After filtration, it was dried at 60 °C for 6 h, placed in a muffle furnace, heated to 450 °C, calcined for 4 h, and then placed in a tube furnace at 200 °C for hydrogen reduction treatment for 1 h. After cooling to room temperature, the hydrogenation catalyst was obtained.

[0062] The palladium source is palladium nitrate.

[0063] The nickel source includes nickel chloride.

[0064] III. The preparation of succinic anhydride using the hydrogenation catalyst prepared in this embodiment specifically includes the following steps:

[0065] T1: Add the hydrogenation catalyst to the feeding tank and maleic anhydride to the feed tank. Heat the feed tank to 65°C and keep it at that temperature until the maleic anhydride melts. Open the feeding tank and transfer the catalyst to the feed tank. Turn on the stirrer and circulation pump and stir for 0.5 hours to obtain the feed liquid.

[0066] 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 130℃ and the reaction pressure at 2 MPa, wherein the molar ratio of hydrogen to maleic anhydride is 10:1, react for 1 hour, check the outlet of the primary reactor, and when the maleic anhydride conversion rate reaches 40%, the primary hydrogenation reaction is completed.

[0067] T3: The reaction liquid enters the secondary reactor from the primary reactor. Hydrogen gas is introduced at the bottom of the reactor. The secondary reaction temperature is controlled at 140℃ and the reaction pressure is 4 MPa. The hydrogen-maleic anhydride molar ratio is 20:1. The reaction is carried out for 3 hours, and the secondary hydrogenation reaction is completed.

[0068] T4: The reaction liquid flowing out of the secondary reactor is subjected to gas-liquid separation. The catalyst and succinic anhydride product liquid are separated by pressure filtration. The product liquid is then distilled under reduced pressure to separate the byproduct γ-butyrolactone and the product succinic anhydride.

[0069] Example 3

[0070] This invention provides a method for preparing succinic anhydride, specifically comprising the following steps:

[0071] I. Preparation of silicon-doped porous boron nitride, specifically including the following steps:

[0072] Q1: By weight, add 10 parts boric acid and 6 parts melamine to 300 parts of 55% ethanol aqueous solution, stir evenly, heat to 90°C, stir for 3 hours, cool to room temperature, filter to obtain the reactant, place the reactant in a freeze dryer at -40°C, freeze dry for 8 hours to obtain boron nitride precursor.

[0073] Q2: By weight, add 60 parts of boron nitride precursor to 70% ethanol aqueous solution, then add 2 parts of tetraethyl orthosilicate and 0.3 parts of 3-aminopropyltriethoxysilane, heat to 80°C, stir for 2 hours, filter, and obtain organosilicon-doped boron nitride.

[0074] Q3: Place organosilicon-doped boron nitride in a tube furnace, purge with nitrogen, and then heat the furnace to 1200℃ at a heating rate of 10℃ / min for 4 hours for pyrolysis. After the reaction is complete, allow it to cool naturally to room temperature to obtain silicon-doped porous boron nitride.

[0075] II. The preparation of a hydrogenation catalyst using the silicon-doped porous boron nitride prepared in this embodiment includes the following steps:

[0076] S1: Dissolve the palladium source and nickel source in water, and prepare a metal salt solution with a concentration of 100 mmol / L by a molar ratio of 1:4. Take 1 part of alumina powder by weight and 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 the pretreated catalyst.

[0077] S2: By weight, add 0.7 parts of polyvinylpyrrolidone to 60 parts of water to prepare a mixed solution. Add 1.5 parts of silicon-doped porous boron nitride to the mixed solution and stir for 4 hours to obtain a silicon-doped porous boron nitride suspension.

[0078] S3: The pretreated catalyst was placed in a silicon-doped porous boron nitride suspension and impregnated for 1 hour. After filtration, it was dried at 90°C for 10 hours, placed in a muffle furnace, heated to 550°C, and calcined for 6 hours. Then, it was placed in a tube furnace at 300°C and reduced with hydrogen for 2 hours. After cooling to room temperature, the hydrogenation catalyst was obtained.

[0079] The palladium source is sodium chloropalladium.

[0080] The nickel source includes nickel acetate.

[0081] III. The preparation of succinic anhydride using the hydrogenation catalyst prepared in this embodiment specifically includes the following steps:

[0082] 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 at that temperature until the maleic anhydride melts. Open the feeding tank and transfer the catalyst to the raw material tank. Turn on the stirrer and circulation pump and stir for 1 hour to obtain the raw material liquid.

[0083] 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 140℃ and the reaction pressure at 4 MPa, wherein the molar ratio of hydrogen to maleic anhydride is 15:1, react for 2 hours, check the outlet of the primary reactor, and when the maleic anhydride conversion rate reaches 50%, the primary hydrogenation reaction is completed.

[0084] T3: The reaction liquid enters the secondary reactor from the primary reactor. Hydrogen gas is introduced at the bottom of the reactor. The secondary reaction temperature is controlled at 160℃ and the reaction pressure is 6 MPa. The hydrogen-maleic anhydride molar ratio is 30:1. The reaction is carried out for 4 hours, and the secondary hydrogenation reaction is completed.

[0085] T4: The reaction liquid flowing out of the secondary reactor is subjected to gas-liquid separation. The catalyst and succinic anhydride product liquid are separated by pressure filtration. The product liquid is then distilled under reduced pressure to separate the byproduct γ-butyrolactone and the product succinic anhydride.

[0086] Example 4

[0087] This invention provides a method for preparing succinic anhydride, specifically comprising the following steps:

[0088] I. Preparation of silicon-doped porous boron nitride, specifically including the following steps:

[0089] Q1: By weight, 10 parts of boric acid and 5.2 parts of melamine were added to 220 parts of ethanol aqueous solution with a mass concentration of 48%, stirred evenly, heated to 83°C, stirred for 2.5 hours, cooled to room temperature, filtered, and the reactant was obtained. The reactant was placed in a freeze dryer at -32°C and freeze-dried for 5 hours to obtain boron nitride precursor.

[0090] Q2: By weight, add 45 parts of boron nitride precursor to 55% ethanol aqueous solution, 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.

[0091] Q3: Place organosilicon-doped boron nitride in a tube furnace, purge with nitrogen, and then heat the furnace to 1050℃ at a heating rate of 6℃ / min for pyrolysis reaction for 3.3h. After the reaction is completed, allow it to cool naturally to room temperature to obtain silicon-doped porous boron nitride.

[0092] II. The preparation of a hydrogenation catalyst using the silicon-doped porous boron nitride prepared in this embodiment includes the following steps:

[0093] S1: Dissolve the palladium source and nickel source in water, and prepare a metal salt solution with a concentration of 100 mmol / L by a molar ratio of 1:4. Take 1 part of alumina powder by weight and place it in 45 parts of metal salt solution. Impregnate for 15 h, filter, and dry at 90 °C for 7 h to obtain the pretreated catalyst.

[0094] S2: By weight, add 0.55 parts of polyvinylpyrrolidone to 45 parts of water to prepare a mixed solution. Add 1.2 parts of silicon-doped porous boron nitride to the mixed solution and stir for 2.5 hours to obtain a silicon-doped porous boron nitride suspension.

[0095] S3: The pretreated catalyst was placed in a silicon-doped porous boron nitride suspension and impregnated for 0.7 h. After filtration, it was dried at 70 °C for 7 h, placed in a muffle furnace, heated to 480 °C, calcined for 4.5 h, and then placed in a tube furnace at 230 °C for hydrogen reduction treatment for 1.2 h. After cooling to room temperature, the hydrogenation catalyst was obtained.

[0096] The palladium source is a mixture of palladium chloride, palladium nitrate and sodium chloropalladate in a mass ratio of 1:1:1.

[0097] The nickel source includes nickel sulfate.

[0098] III. The preparation of succinic anhydride using the hydrogenation catalyst prepared in this embodiment specifically includes the following steps:

[0099] T1: Add the hydrogenation catalyst to the feeding tank and maleic anhydride to the feed tank. Heat the feed tank to 68°C and keep it at that temperature until the maleic anhydride melts. Open the feeding tank and transfer the catalyst to the feed tank. Turn on the stirrer and circulation pump and stir for 0.6 hours to obtain the feed liquid.

[0100] T2: Transfer the feed liquid from the feed tank to the primary reactor, introduce hydrogen gas at the bottom of the primary reactor, control the primary reaction temperature at 133℃ and the reaction pressure at 2.5 MPa, wherein the molar ratio of hydrogen to maleic anhydride is 11:1, react for 1.2 hours, check the outlet of the primary reactor, and when the maleic anhydride conversion rate reaches 43%, the primary hydrogenation reaction is completed.

[0101] T3: The reaction solution enters the secondary reactor from the primary reactor. Hydrogen gas is introduced at the bottom of the reactor. The secondary reaction temperature is controlled at 145℃ and the reaction pressure is 4.5 MPa. The hydrogen-maleic anhydride molar ratio is 22:1. The reaction takes 3.2 hours, and the secondary hydrogenation reaction is completed.

[0102] T4: The reaction liquid flowing out of the secondary reactor is subjected to gas-liquid separation. The catalyst and succinic anhydride product liquid are separated by pressure filtration. The product liquid is then distilled under reduced pressure to separate the byproduct γ-butyrolactone and the product succinic anhydride.

[0103] Example 5

[0104] This invention provides a method for preparing succinic anhydride, specifically comprising the following steps:

[0105] I. Preparation of silicon-doped porous boron nitride, specifically including the following steps:

[0106] Q1: By weight, 10 parts of boric acid and 5.8 parts of melamine were added to 280 parts of 53% ethanol aqueous solution, stirred evenly, heated to 88°C, stirred for 2.8 hours, cooled to room temperature, filtered, and the reactant was obtained. The reactant was placed in a freeze dryer at -38°C and freeze-dried for 7 hours to obtain boron nitride precursor.

[0107] Q2: By weight, add 55 parts of boron nitride precursor to 65% ethanol aqueous solution, then add 1.8 parts of tetraethyl orthosilicate and 0.28 parts of 3-aminopropyltriethoxysilane, heat to 75°C, stir for 1.8 h, filter to obtain organosilicon-doped boron nitride.

[0108] Q3: Place organosilicon-doped boron nitride in a tube furnace, purge with nitrogen, and then heat the furnace to 1150°C at a heating rate of 9°C / min for pyrolysis reaction for 3.8 hours. After the reaction is complete, allow it to cool naturally to room temperature to obtain silicon-doped porous boron nitride.

[0109] II. The preparation of a hydrogenation catalyst using the silicon-doped porous boron nitride prepared in this embodiment includes the following steps:

[0110] S1: Dissolve the palladium source and nickel source in water, and prepare a metal salt solution with a concentration of 100 mmol / L by a molar ratio of 1:4. Take 1 part of alumina powder by weight and place it in 55 parts of the metal salt solution. Impregnate for 25 h, filter, and dry at 110 °C for 11 h to obtain the pretreated catalyst.

[0111] S2: By weight, add 0.65 parts of polyvinylpyrrolidone to 55 parts of water to prepare a mixed solution. Add 14 parts of silicon-doped porous boron nitride to the mixed solution and stir for 3.5 h to obtain a silicon-doped porous boron nitride suspension.

[0112] S3: The pretreated catalyst was placed in a silicon-doped porous boron nitride suspension and impregnated for 0.9 h. After filtration, it was dried at 85 °C for 9 h, placed in a muffle furnace, heated to 540 °C, calcined for 5.5 h, and then placed in a tube furnace at 280 °C for hydrogen reduction treatment for 1.7 h. After cooling to room temperature, the hydrogenation catalyst was obtained.

[0113] The palladium source is a mixture of palladium chloride and palladium nitrate in a mass ratio of 1:1.

[0114] The nickel source comprises a mixture of nickel nitrate, nickel chloride, nickel acetate, and nickel sulfate in a mass ratio of 1:1:1:1.

[0115] III. The preparation of succinic anhydride using the hydrogenation catalyst prepared in this embodiment specifically includes the following steps:

[0116] T1: Add the hydrogenation catalyst to the feeding tank and maleic anhydride to the feed tank. Heat the feed tank to 73°C and keep it at that temperature until the maleic anhydride melts. Open the feeding tank and transfer the catalyst to the feed tank. Turn on the stirrer and circulation pump and stir for 0.9 hours to obtain the feed liquid.

[0117] T2: Transfer the feed liquid from the feed tank to the primary reactor, introduce hydrogen gas into the bottom of the primary reactor, control the primary reaction temperature at 139℃ and the reaction pressure at 3.5 MPa, wherein the molar ratio of hydrogen to maleic anhydride is 14:1, react for 1.6 hours, check the outlet of the primary reactor, and when the maleic anhydride conversion rate reaches 48%, the primary hydrogenation reaction is completed.

[0118] T3: The reaction solution enters the secondary reactor from the primary reactor. Hydrogen gas is introduced at the bottom of the reactor. The secondary reaction temperature is controlled at 155℃ and the reaction pressure is 5.5 MPa. The hydrogen-maleic anhydride molar ratio is 28:1. The reaction takes 3.7 hours and the secondary hydrogenation reaction is completed.

[0119] T4: The reaction liquid flowing out of the secondary reactor is subjected to gas-liquid separation. The catalyst and succinic anhydride product liquid are separated by pressure filtration. The product liquid is then distilled under reduced pressure to separate the byproduct γ-butyrolactone and the product succinic anhydride.

[0120] Comparative Example 1

[0121] Unlike Example 1, silicon doping is not performed in the preparation of silicon-doped porous boron nitride.

[0122] I. Preparation of porous boron nitride, specifically including the following steps:

[0123] Q1: By weight, add 10 parts boric acid and 5.5 parts melamine to 250 parts of 50% ethanol aqueous solution, stir evenly, heat to 85°C, stir for 2 hours, cool to room temperature, filter to obtain the reactant, place the reactant in a freeze dryer at -35°C, freeze dry for 6 hours to obtain boron nitride precursor;

[0124] Q2: Place the boron nitride precursor in a tube furnace, purge with nitrogen, and then heat the furnace to 1100℃ at a heating rate of 7℃ / min for pyrolysis reaction for 3.5h. After the reaction is completed, allow it to cool naturally to room temperature to obtain porous boron nitride.

[0125] II. The preparation of a hydrogenation catalyst using the silicon-doped porous boron nitride prepared in this embodiment includes the following steps:

[0126] S1: Dissolve the palladium source and nickel source in water, and prepare a metal salt solution with a concentration of 100 mmol / L by a molar ratio of 1:4. Take 1 part of alumina powder by weight 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 the pretreated catalyst.

[0127] S2: By weight, add 0.6 parts 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 hours to obtain a porous boron nitride suspension.

[0128] S3: The pretreated catalyst was placed in a porous boron nitride suspension and impregnated for 1 hour. After filtration, it was dried at 70°C for 8 hours, placed in a muffle furnace, heated to 500°C, and calcined for 5 hours. Then it was placed in a tube furnace at 250°C and reduced with hydrogen for 1.5 hours. After cooling to room temperature, the hydrogenation catalyst was obtained.

[0129] The palladium source is palladium chloride.

[0130] The nickel source includes nickel nitrate.

[0131] Comparative Example 2

[0132] Unlike Example 1, the preparation of succinic anhydride only involves a first-order hydrogenation reaction.

[0133] This comparative example utilizes the hydrogenation catalyst prepared in Example 1 to prepare succinic anhydride, specifically including the following steps:

[0134] 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 at that temperature until the maleic anhydride melts. Open the feeding tank and transfer the catalyst to the raw material tank. Turn on the stirrer and circulation pump and stir for 0.5 hours to obtain the raw material liquid.

[0135] 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℃ and the reaction pressure at 3 MPa, wherein the molar ratio of hydrogen to maleic anhydride is 12:1, react for 1.5 hours, check the outlet of the primary reactor, and when the maleic anhydride conversion rate reaches 45%, the primary hydrogenation reaction is completed.

[0136] T3: The reaction liquid flowing out of the primary reactor is subjected to gas-liquid separation. The catalyst and succinic anhydride product liquid are separated by pressure filtration. The product liquid is then distilled under reduced pressure to separate the byproduct γ-butyrolactone and the product succinic anhydride.

[0137] Comparative Example 3

[0138] Unlike Example 1, the preparation of succinic anhydride only involves a second-order hydrogenation reaction.

[0139] This comparative example utilizes the hydrogenation catalyst prepared in Example 1 to prepare succinic anhydride, specifically including the following steps:

[0140] 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 at that temperature until the maleic anhydride melts. Open the feeding tank and transfer the catalyst to the raw material tank. Turn on the stirrer and circulation pump and stir for 0.5 hours to obtain the raw material liquid.

[0141] T2: The raw material liquid is introduced into the secondary reactor from the raw material tank. Hydrogen gas is introduced into the bottom of the reactor. The secondary reaction temperature is controlled at 150℃ and the reaction pressure is 5 MPa. The hydrogen-maleic anhydride molar ratio is 25:1. The reaction is carried out for 5 hours, and the secondary hydrogenation reaction is completed.

[0142] T4: The reaction liquid flowing out of the secondary reactor is subjected to gas-liquid separation. The catalyst and succinic anhydride product liquid are separated by pressure filtration. The product liquid is then distilled under reduced pressure to separate the byproduct γ-butyrolactone and the product succinic anhydride.

[0143] Specifically, the following steps are included:

[0144] 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 at that temperature until the maleic anhydride melts. Open the feeding tank and transfer the catalyst to the raw material tank. Turn on the stirrer and circulation pump and stir for 0.5 hours to obtain the raw material liquid.

[0145] 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℃ and the reaction pressure at 3 MPa, wherein the molar ratio of hydrogen to maleic anhydride is 12:1, react for 1.5 hours, check the outlet of the primary reactor, and when the maleic anhydride conversion rate reaches 45%, the primary hydrogenation reaction is completed.

[0146] T3: The reaction solution enters the secondary reactor from the primary reactor. Hydrogen gas is introduced at the bottom of the reactor. The secondary reaction temperature is controlled at 150℃ and the reaction pressure is 5 MPa. The hydrogen-maleic anhydride molar ratio is 25:1. The reaction takes 3.5 hours and the secondary hydrogenation reaction is completed.

[0147] T4: The reaction liquid flowing out of the secondary reactor is subjected to gas-liquid separation. The catalyst and succinic anhydride product liquid are separated by pressure filtration. The product liquid is then distilled under reduced pressure to separate the byproduct γ-butyrolactone and the product succinic anhydride.

[0148] Comparative Example 4

[0149] The difference from Example 1 is that silicon doping is not performed in the preparation of silicon-doped porous boron nitride, and only a secondary hydrogenation reaction is performed in the preparation of succinic anhydride.

[0150] I. Preparation of porous boron nitride, specifically including the following steps:

[0151] Q1: By weight, add 10 parts boric acid and 5.5 parts melamine to 250 parts of 50% ethanol aqueous solution, stir evenly, heat to 85°C, stir for 2 hours, cool to room temperature, filter to obtain the reactant, place the reactant in a freeze dryer at -35°C, freeze dry for 6 hours to obtain boron nitride precursor;

[0152] Q2: Place the boron nitride precursor in a tube furnace, purge with nitrogen, and then heat the furnace to 1100℃ at a heating rate of 7℃ / min for pyrolysis reaction for 3.5h. After the reaction is completed, allow it to cool naturally to room temperature to obtain porous boron nitride.

[0153] II. The preparation of a hydrogenation catalyst using the silicon-doped porous boron nitride prepared in this embodiment includes the following steps:

[0154] S1: Dissolve the palladium source and nickel source in water, and prepare a metal salt solution with a concentration of 100 mmol / L by a molar ratio of 1:4. Take 1 part of alumina powder by weight 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 the pretreated catalyst.

[0155] S2: By weight, add 0.6 parts 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 hours to obtain a porous boron nitride suspension.

[0156] S3: The pretreated catalyst was placed in a porous boron nitride suspension and impregnated for 1 hour. After filtration, it was dried at 70°C for 8 hours, placed in a muffle furnace, heated to 500°C, and calcined for 5 hours. Then it was placed in a tube furnace at 250°C and reduced with hydrogen for 1.5 hours. After cooling to room temperature, the hydrogenation catalyst was obtained.

[0157] The palladium source is palladium chloride.

[0158] The nickel source includes nickel nitrate.

[0159] III. The preparation of succinic anhydride using the hydrogenation catalyst prepared in this embodiment specifically includes the following steps:

[0160] 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 at that temperature until the maleic anhydride melts. Open the feeding tank and transfer the catalyst to the raw material tank. Turn on the stirrer and circulation pump and stir for 0.5 hours to obtain the raw material liquid.

[0161] T2: Transfer the raw material liquid from the raw material tank to the secondary reactor, introduce hydrogen gas at the bottom of the reactor, control the secondary reaction temperature at 150℃ and the reaction pressure at 5 MPa, wherein the hydrogen-maleic anhydride molar ratio is 25:1, and the reaction is completed in 3.5 hours;

[0162] T3: The reaction liquid flowing out of the secondary reactor is subjected to gas-liquid separation. The catalyst and succinic anhydride product liquid are separated by pressure filtration. The product liquid is then distilled under reduced pressure to separate the byproduct γ-butyrolactone and the product succinic anhydride.

[0163] Table 1 shows the activity data and reaction stability test results of the catalyst prepared in this invention in the preparation of succinic anhydride.

[0164] Proof of effectiveness

[0165] Table 1

[0166]

[0167] Based on Examples 1 to 5 and the data in Table 1, it can be seen that after 500 hours of use, the catalyst prepared by the present invention can maintain a maleic anhydride conversion rate of over 95.6% and a maleic anhydride selectivity of over 96.3% when used to prepare succinic anhydride. This proves that the catalyst prepared by the present invention still has good catalytic performance, selectivity and stability after 500 hours of use.

[0168] Analysis of Comparative Example 1, combined with data from Table 1 and Example 1, shows that the catalyst prepared in Comparative Example 1 exhibits a decreased initial conversion rate in the preparation of succinic anhydride. After 500 hours of use, the conversion rate of maleic anhydride decreases, and the selectivity of succinic anhydride also declines. This indicates that silicon doping of boron nitride in the preparation of silicon-doped porous boron nitride can improve the catalytic performance, selectivity, and stability of the prepared catalyst.

[0169] Based on the data from Comparative Examples 2 and 3, combined with Example 1 and Table 1, it can be seen that in the preparation of succinic anhydride, whether only a single-stage hydrogenation reaction or a two-stage hydrogenation reaction is performed, the conversion rate of maleic anhydride and the selectivity of succinic anhydride both significantly decrease after 500 hours of catalyst use. This indicates that a two-stage hydrogenation reaction can further enhance the catalytic performance, selectivity, and conversion efficiency of the catalyst in the preparation of succinic anhydride.

[0170] In Comparative Example 4, the preparation of silicon-doped porous boron nitride was carried out without silicon doping. In the application of the hydrogenation catalyst in the preparation of succinic anhydride, only a two-stage hydrogenation reaction was performed. Compared to the catalyst prepared in Example 1, the catalyst prepared in Comparative Example 4 showed significantly lower initial conversion of succinic anhydride and, after 500 hours of use, lower conversion of maleic anhydride and lower selectivity of succinic anhydride. This indicates that the addition of silicon-doped silicon nitride in the catalyst preparation process, in the presence of a two-stage hydrogenation reaction, provides the catalyst with good stability, selectivity, and high conversion, demonstrating a synergistic effect between the two.

[0171] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A process for the preparation of a hydrogenation catalyst, characterized in that: The method comprises the following steps: S1: dissolving a palladium source and a 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, 1 part of aluminum oxide powder is taken by weight, and is placed in 40-60 parts of the metal salt solution for immersion treatment for 10-30 hours, filtration, and drying at 80-120 DEG C for 6-12 hours to obtain a pretreated catalyst; S2: 0.5-0.7 parts of polyvinylpyrrolidone is added to 40-60 parts of water by weight to prepare a mixed solution, 1-1.5 parts of silicon-doped porous boron nitride is added to the mixed solution, and stirring is conducted for 2-4 hours to obtain a silicon-doped porous boron nitride suspension; S3: the pretreated catalyst is placed in the silicon-doped porous boron nitride suspension, immersion treatment is conducted for 0.5-1 hour, filtration is conducted, drying is conducted at 60-90 DEG C for 6-10 hours, the catalyst is placed in a muffle furnace, heating is conducted to 450-550 DEG C, calcination is conducted for 4-6 hours, then the catalyst is placed in a 200-300 DEG C tube furnace, hydrogen reduction treatment is conducted for 1-2 hours, and cooling is conducted to room temperature to obtain a hydrogenation catalyst; and the preparation method of the silicon-doped porous boron nitride comprises the following steps: Q1: 10 parts of boric acid and 5-6 parts of melamine are added to 200-300 parts of an ethanol aqueous solution with a mass concentration of 45-55% by weight, stirring is uniformly conducted, heating is conducted to 80-90 DEG C, stirring is conducted for 2-3 hours, cooling is conducted to room temperature, filtration is conducted, the reaction product is placed in a freeze dryer at minus 30-40 DEG C, and freeze drying is conducted for 4-8 hours to obtain a boron nitride precursor; Q2: the boron nitride precursor is added to 40-60 parts of an ethanol aqueous solution by weight, then 1-2 parts of tetraethyl orthosilicate and 0.2-0.3 parts of 3-aminopropyl triethoxysilane are added, heating is conducted to 60-80 DEG C, stirring is conducted for 1-2 hours, and filtration is conducted to obtain silicon-doped boron nitride; Q3: the silicon-doped boron nitride is placed in a tube furnace, nitrogen is introduced, then the furnace is heated to 1000-1200 DEG C at a heating rate of 5-10 DEG C / min, pyrolysis reaction is conducted for 3-4 hours, after the reaction is completed, natural cooling is conducted to room temperature, and the silicon-doped porous boron nitride is obtained; The hydrogenation catalyst is used for preparing succinic anhydride, and the preparation steps of the succinic anhydride are as follows: T1: the hydrogenation catalyst is added to a feeding tank, maleic anhydride is added to a raw material tank, the raw material tank is heated to 65-75 DEG C, and is kept warm until the maleic anhydride is melted, the feeding tank is opened, the catalyst is transferred to the raw material tank, a stirrer and a circulating pump are started, and stirring is conducted for 0.5-1 hour to obtain a raw material liquid; T2: the raw material liquid is transferred from the raw material tank to a first reactor, hydrogen is introduced into the bottom of the first reactor, the first reaction temperature is controlled to be 130-140 DEG C, the reaction pressure is controlled to be 2-4 MPa, reaction is conducted for 1-2 hours, the outlet of the first reactor is detected, and the first hydrogenation reaction is completed until the maleic anhydride conversion rate is 40-50%. ​ T3: the reaction liquid from the first reactor enters the second reactor, hydrogen is passed at the bottom of the reactor, the temperature of the second reactor is controlled at 140-160 DEG C, the reaction pressure is 4-6 MPa, the molar ratio of hydrogen to maleic anhydride is (20-30):1, the reaction is carried out for 3-4 h, and the secondary hydrogenation reaction is completed; T4: the reaction liquid from the second reactor is subjected to gas-liquid separation, the catalyst and the succinic anhydride product liquid are separated by pressurized filtration, the product liquid is subjected to vacuum rectification, and the by-product gamma-butyrolactone and the product succinic anhydride are separated.

2. The process for preparing a hydrogenation catalyst according to claim 1, characterized by: The mass concentration of ethanol in the aqueous ethanol solution is 50-70%.

3. The method of claim 1, wherein: The palladium source is one or more of palladium chloride, palladium nitrate and sodium chloropalladate.

4. The method of claim 1, wherein: The nickel source includes one or more of nickel nitrate, nickel chloride, nickel acetate and nickel sulfate.

5. The process for preparing a hydrogenation catalyst according to claim 1, characterized by: The molar ratio of hydrogen to maleic anhydride in T2 is (10-15):

1.

6. A hydrogenation catalyst characterized by: The preparation method is prepared by using any one of claims 1-5. The preparation method is prepared by using any one of claims 1-5.

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