Tube reactor for preparing succinic anhydride and method for preparing succinic anhydride

Abstract

The present invention provides a shell-and-tube reactor for preparing succinic anhydride, comprising: a tube layer and a shell layer. The tube layer is used for the hydrogenation reaction of maleic anhydride raw materials to prepare succinic anhydride, and the shell layer is used for circulating a cooling medium; a raw material heat exchanger is connected to the liquid-phase feed port at the bottom of the tube layer; the feed port of the gas-liquid separator is connected to the discharge port at the top of the tube layer; the gas-phase outlet at the top of the gas-liquid separator is connected to the gas-phase feed port at the lower part of the tube layer; a cooling medium storage tank is used for supplying the cooling medium to the shell layer. The present invention provides a method for preparing succinic anhydride. In the hydrogenation reaction stage, the cooling medium is introduced into the shell layer through the cooling medium storage tank to timely remove the reaction heat. The reactor of the present invention has the following characteristics: simple structure, flexible operation, easy to control, easy to remove the reaction heat, can directly use molten maleic anhydride feedstock, or can use a maleic anhydride solution with a higher concentration, reducing the solvent usage amount, reducing the energy consumption of subsequent solvent recovery, and the method of the present invention has a high effective utilization rate of the catalyst and saves investment.

Description

Technical Field

[0001] The present invention relates to a tubular reactor for preparing succinic anhydride and a method for preparing succinic anhydride. Background Art

[0002] Succinic anhydride is colorless needle-shaped or granular crystals with a slightly pungent odor; it can undergo hydrolysis, alcoholysis, esterification, halogenation, acylation and other reactions. Succinic anhydride is an important fine chemical raw material, widely used in surfactants, pharmaceuticals, food additives and intermediates in the pharmaceutical industry, and can be used to manufacture drugs such as carbenoxolone and succinimide.

[0003] According to the raw material sources, the methods for preparing succinic anhydride mainly include maleic anhydride method, succinic acid dehydration method, acetylene carbonylation method, etc. At present, the industrial production methods are mainly maleic anhydride method and succinic acid dehydration method.

[0004] Succinic acid dehydration method: Succinic acid is heated to above 260 °C, or a certain amount of tetralin and toluene are added and heated to above 200 °C at the same time, then succinic anhydride can be obtained by dehydration, or succinic acid and phosphorus oxychloride are heated under reflux to drive off hydrogen chloride gas, and then distilled under reduced pressure to collect the fraction at 160 - 165 °C (5.33 kPa), and white blocky succinic anhydride is obtained after cooling. Since the source channels of succinic acid are few, mainly relying on catalytic hydrogenation of maleic anhydride or electrolysis production, the production cost is high, and succinic anhydride is very easy to hydrolyze to form succinic acid. Therefore, this method has no development prospect either in terms of the rationality of the process route or the economy.

[0005] Direct catalytic hydrogenation method of maleic anhydride: Maleic anhydride is hydrogenated to obtain succinic anhydride in the presence of a palladium-alumina (or molybdate of copper) catalyst at 160 °C and 5.8 MPa. This method has high process conversion rate and yield, and no obvious side reactions. However, since the hydrogenation of maleic anhydride to succinic anhydride is a strong exothermic reaction, this causes the local temperature of the hydrogenation sites on the catalyst surface to be too high, leading to the polymerization and coking of organic substances on the catalyst surface and reducing the catalyst activity. Therefore, how to take effective measures to reduce the reaction heat release problem is the key and difficult point of the maleic anhydride hydrogenation process.

[0006] CN1078716A discloses a method for preparing succinic anhydride from maleic anhydride, which uses a common nickel-based hydrogenation catalyst to catalytically hydrogenate in a molten state to prepare succinic anhydride. The yield of succinic anhydride prepared by this method is relatively low, and the yield of succinic anhydride is only ≧ 90%, and this method for preparing succinic anhydride is only suitable for batch reactors, and the production efficiency is low.

[0007] CN103570650A discloses a process for continuously producing succinic anhydride and co-producing succinic acid by maleic anhydride hydrogenation. A two-stage hydrogenation reactor is adopted. At the outlet of the first-stage hydrogenation reactor, after the material is heat-exchanged, part of the reaction liquid enters the second-stage hydrogenation reactor, and the remaining reaction liquid is mixed with the raw material maleic anhydride solution and then re-enters the first-stage hydrogenation reactor device. Since the material at the outlet of the first reactor still contains a certain amount of maleic anhydride, and this material is recycled to the inlet of the first reactor again, the amount of maleic anhydride entering the first reactor does not decrease significantly. Therefore, the heat removal effect of this reactor is limited. Summary of the Invention

[0008] The object of the present invention is to propose a new liquid-phase hydrogenation reaction process and method for maleic anhydride to solve the problems in the prior art, such as large heat release in the reaction of maleic anhydride hydrogenation to succinic anhydride, difficult heat removal, large investment in production process, and high energy consumption. The process and method have the characteristics of easy heat removal, low investment, and low energy consumption.

[0009] The present invention provides a tubular reactor for preparing succinic anhydride, which includes: a tube layer and a shell layer. Among them, the tube layer is used for the hydrogenation reaction of maleic anhydride raw materials to prepare succinic anhydride, and the shell layer is used for circulating a cooling medium;

[0010] A raw material heat exchanger, and the raw material heat exchanger is connected to the liquid-phase feed inlet at the bottom of the tube layer;

[0011] A gas-liquid separator, and the feed inlet of the gas-liquid separator is connected to the outlet at the top of the tube layer; the gas-phase outlet at the top of the gas-liquid separator is connected to the gas-phase feed inlet at the lower part of the tube layer;

[0012] A cooling medium storage tank, and the cooling medium storage tank is used to provide a cooling medium to the shell layer.

[0013] Preferably, a circulating gas cooler is provided on the connecting pipeline between the gas-phase outlet at the top of the gas-liquid separator and the gas-phase feed inlet at the lower part of the tube layer.

[0014] Preferably, a raw material distributor is provided at the bottom of the tube layer for uniformly distributing the hydrogenation reaction materials step by step before contacting the catalyst in the tube layer for the hydrogenation reaction.

[0015] Preferably, the upper end of the shell layer is connected to the cooling medium storage tank, the cooling medium storage tank is connected to a circulating water pump, and the circulating water pump is connected to the lower end of the shell layer.

[0016] Preferably, the cooling medium storage tank is a circulating water tank.

[0017] Preferably, the cooling medium storage tank is provided with a cooling medium replenishment pipeline.

[0018] The present invention provides a method for preparing succinic anhydride. This method is carried out in the shell-and-tube reactor described in the present invention. The maleic anhydride raw material is heated to the reaction temperature through a raw material heat exchanger and enters the tube layer to contact with the catalyst and hydrogen for hydrogenation reaction. Among them, hydrogen enters the tube layer from the lower gas-phase feed port of the tube layer, and the hydrogenation reaction material flows out from the top discharge port of the tube layer and enters a gas-liquid separator for gas-liquid separation. The separated gas phase is partially or completely returned as recycled hydrogen after being cooled or not cooled. In the hydrogenation reaction stage, a cooling medium is introduced into the shell layer through a cooling medium storage tank to timely remove the reaction heat.

[0019] Preferably, the maleic anhydride raw material is molten maleic anhydride or a maleic anhydride solution; preferably, the maleic anhydride solution is a mixture of maleic anhydride and a solvent, where the solvent is one or more of acetic anhydride, γ-butyrolactone, dioxane, tetrahydrofuran, aromatic hydrocarbons, ethyl acetate, four-carbon dibasic acid esters, ethanol, isopropanol, hexane, cyclohexane, propylene oxide, ketones, and ethers.

[0020] Preferably, the concentration of the maleic anhydride solution is 1 to 90% by weight, preferably 10 to 40% by weight.

[0021] Preferably, the hydrogen is a mixed gas of recycled hydrogen and supplemented fresh hydrogen. Preferably, the molar ratio of the total hydrogen amount of the recycled hydrogen and the supplemented fresh hydrogen to the total maleic anhydride in the incoming maleic anhydride raw material is 5 to 100, preferably 10 to 40.

[0022] Preferably, the conditions for the hydrogenation reaction include: the temperature is 30 to 100 °C, preferably 40 to 80 °C, such as 40 °C, 41 °C, 42 °C, 43 °C, 44 °C, 45 °C, 46 °C, 47 °C, 48 °C, 49 °C, 50 °C, etc., and so on. Each reaction temperature is applicable to the present invention; and / or the pressure is 0.1 to 10 MPa, preferably 0.5 to 5 MPa.

[0023] Preferably, the recycled hydrogen is cooled to 30 to 80 °C, preferably cooled to 40 to 60 °C.

[0024] Preferably, 0.5 to 2% by volume of the separated gas phase is taken out as fuel gas, and the rest is used as recycled hydrogen. After being mixed with the supplemented fresh hydrogen, it enters the tube layer.

[0025] Preferably, the cooling medium is water. The cooling medium storage tank enters the shell layer from the lower part through a circulating water pump, and the circulating water coming out from the upper part of the shell layer returns to the cooling medium storage tank.

[0026] The reactor of the present invention has the following characteristics:

[0027] (1) Using the reactor described in the present invention, it has a simple structure, flexible operation, easy control, and the reaction heat is easily removed.

[0028] (2) By using the reactor and method of the present invention, it is possible to directly use molten maleic anhydride feedstock or a maleic anhydride solution with a relatively high concentration, reducing the amount of solvent used, thereby reducing the energy consumption for subsequent solvent recovery. Moreover, the method of the present invention has a high effective utilization rate of the catalyst and requires less investment. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a schematic flow chart of a method for preparing succinic anhydride according to a preferred embodiment of the present invention.

[0030] DESCRIPTION OF THE REFERENCE NUMERALS:

[0031] 1 Raw material heat exchanger; 2 Tube reactor; 3 Cooling medium storage tank; 4 Circulating water pump; 5 Gas-liquid separator; 6 Circulating gas cooler; 11 Maleic anhydride raw material; 12 Supplementary hydrogen; 13 Reaction product; 14 Cooling medium supplementary pipeline. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0033] The present invention will be specifically described below in conjunction with specific drawings and embodiments. It is necessary to point out here that the following embodiments are only for further illustration of the present invention and should not be construed as limiting the protection scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention still fall within the protection scope of the present invention.

[0034] As Figure 1 shown, the present invention provides a tube reactor 2 for preparing succinic anhydride, and the reactor includes: a tube layer and a shell layer. Among them, the tube layer is used for the hydrogenation reaction of maleic anhydride raw material to prepare succinic anhydride, and the shell layer is used for circulating the cooling medium;

[0035] Raw material heat exchanger 1, and the raw material heat exchanger is connected to the liquid phase feed port at the bottom of the tube layer;

[0036] Gas-liquid separator 5, the feed port of the gas-liquid separator is connected to the discharge port at the top of the tube layer; the gas phase outlet at the top of the gas-liquid separator is connected to the gas phase feed port at the lower part of the tube layer;

[0037] A cooling medium storage tank 3, which is used to supply cooling medium to the shell layer. The reactor of the present invention has a simple structure, flexible operation, easy control, and the reaction heat can be easily removed. By using the reactor of the present invention, molten maleic anhydride feedstock can be directly used, or maleic anhydride solution with a relatively high concentration can be used, reducing the solvent usage, resulting in reduced energy consumption for subsequent solvent recovery. Moreover, the catalyst in the method of the present invention has a high effective utilization rate and low investment.

[0038] According to a preferred embodiment of the present invention, preferably, a circulating gas cooler 6 is provided on the connecting pipeline between the gas phase outlet at the top of the gas-liquid separator and the gas phase inlet at the lower part of the tube layer.

[0039] According to a preferred embodiment of the present invention, preferably, a raw material distributor is provided at the bottom of the tube layer, which is used to uniformly distribute the hydrogenation reaction materials step by step and then contact with the catalyst in the tube layer to carry out the hydrogenation reaction.

[0040] According to a preferred embodiment of the present invention, preferably, the upper end of the shell layer is connected to the cooling medium storage tank 3, the cooling medium storage tank is connected to the circulating water pump 4, and the circulating water pump 4 is connected to the lower end of the shell layer. By providing the cooling medium storage tank, the reaction heat can be removed in time, and the catalyst utilization rate can be improved.

[0041] According to a preferred embodiment of the present invention, preferably, the cooling medium storage tank is a circulating water tank.

[0042] According to a preferred embodiment of the present invention, preferably, the cooling medium storage tank is provided with a cooling medium replenishment pipeline 14.

[0043] By using the hydrogenation reactor of the present invention, it has a simple structure, flexible operation, easy control, and the reaction heat can be easily removed.

[0044] The present invention provides a method for preparing succinic anhydride. This method is carried out in the shell-and-tube reactor of the present invention. The maleic anhydride raw material is heated to the reaction temperature through the raw material heat exchanger and enters the shell layer to contact with the catalyst and hydrogen for hydrogenation reaction. Among them, hydrogen enters the shell layer from the gas phase inlet at the lower part of the tube layer, and the hydrogenation reaction materials flow out from the outlet at the top of the tube layer and enter the gas-liquid separator for gas-liquid separation. The separated gas phase is partially or completely returned as circulating hydrogen after being cooled or not cooled. In the hydrogenation reaction stage, cooling medium is introduced into the shell layer through the cooling medium storage tank to remove the reaction heat in time.

[0045] By using the reactor and method of the present invention, molten maleic anhydride feedstock can be directly used, or a maleic anhydride solution with a relatively high concentration can be used, reducing the amount of solvent used and thus reducing the energy consumption for subsequent solvent recovery. Moreover, the method of the present invention has a high effective utilization rate of the catalyst and low investment. Preferably, the maleic anhydride raw material is molten maleic anhydride or a maleic anhydride solution; the maleic anhydride solution is a mixture of maleic anhydride and a solvent. There are no special requirements for the type of solvent. For the present invention, it is preferred that the solvent is one or more of acetic anhydride, γ-butyrolactone, dioxane, tetrahydrofuran, aromatic hydrocarbons, ethyl acetate, four-carbon dibasic acid esters, ethanol, isopropanol, hexane, cyclohexane, propylene oxide, ketones, and ethers.

[0046] The method of the present invention can use a maleic anhydride solution with a relatively high concentration, reducing the amount of solvent used. For the present invention, it is preferred that the concentration of the maleic anhydride solution is 1 to 90% by weight, preferably 10 to 40% by weight.

[0047] According to a preferred embodiment of the present invention, preferably, the hydrogen is a mixed gas of recycled hydrogen and supplemented fresh hydrogen. Preferably, the molar ratio of the total hydrogen amount of the recycled hydrogen and the supplemented fresh hydrogen to the total maleic anhydride in the incoming maleic anhydride raw material is 5 to 100, preferably 10 to 40. This can timely remove the reaction heat and improve the utilization rate of the catalyst.

[0048] According to a preferred embodiment of the present invention, preferably, the conditions for the hydrogenation reaction include: the temperature is 30 to 100 °C, preferably 40 to 80 °C, such as 40 °C, 41 °C, 42 °C, 43 °C, 44 °C, 45 °C, 46 °C, 47 °C, 48 °C, 49 °C, 50 °C, etc. By analogy, each reaction temperature is applicable to the present invention; and / or the pressure is 0.1 to 10 MPa, preferably 0.5 to 5 MPa. This can timely remove the reaction heat and improve the utilization rate of the catalyst.

[0049] According to a preferred embodiment of the present invention, preferably, the recycled hydrogen is cooled to 30 to 80 °C, preferably cooled to 40 to 60 °C. This can effectively improve the utilization rate of the catalyst.

[0050] According to a preferred embodiment of the present invention, preferably, 0.5 to 2% by volume of the separated gas phase is taken out as fuel gas, and the rest is used as recycled hydrogen. After being mixed with the supplemented fresh hydrogen, it enters the tube layer.

[0051] According to a preferred embodiment of the present invention, preferably, the cooling medium is water. The cooling medium storage tank enters the shell layer from the lower part through a circulating water pump, and the circulating water coming out from the upper part of the shell layer returns to the cooling medium storage tank.

[0052] By using the method of the present invention, molten maleic anhydride feedstock can be directly used, or a maleic anhydride solution with a relatively high concentration can be used, reducing the amount of solvent used and thus reducing the energy consumption for subsequent solvent recovery.

[0053] By using the method of the present invention, preferably, the reaction materials enter the reactor tube layer from the bottom of the reactor, and a feed distributor is arranged at the lower inlet, which can quickly and uniformly mix the gas-liquid two phases, reduce the temperature gradient and concentration gradient in the reaction tubes of the reactor, and have a high effective utilization rate of the catalyst and low investment.

[0054] The reactor and method of the present invention have the following characteristics:

[0055] (1) By using the reactor and method of the present invention, it has a simple structure, flexible operation, easy control, and the reaction heat can be easily removed.

[0056] (2) By using the reactor and method of the present invention, the molten maleic anhydride feedstock can be directly used, or a maleic anhydride solution with a higher concentration can be used, reducing the solvent usage amount, reducing the energy consumption for subsequent solvent recovery, and having a high effective utilization rate of the catalyst and low investment for the method of the present invention.

[0057] According to a preferred embodiment of the present invention, the reactor of the present invention includes a maleic anhydride raw material heat exchanger, a gas-liquid separator, a circulating gas cooler, a circulating water tank, a circulating water pump, etc. The raw material heat exchanger is connected to the bottom tube layer of the reactor, the outlet of the reactor tube layer is connected to the gas-liquid separator, the top of the gas-liquid separator is connected to the circulating gas cooler, the circulating gas cooler is connected to the bottom tube layer of the reactor, the upper shell layer of the reactor is connected to the circulating water tank, the circulating water tank is connected to the circulating water pump, and the circulating water pump is connected to the lower shell layer of the reactor.

[0058] According to a preferred embodiment of the present invention, the hydrogenation reactor is a shell-and-tube type tubular reactor. The molten maleic anhydride or maleic anhydride solution is heated to the required reaction temperature through the raw material heat exchanger and enters the reactor tube layer from the bottom of the reactor. After the circulating hydrogen is mixed with the supplemented fresh hydrogen, it enters the reactor tube layer from the bottom of the reactor. The reacted materials enter the gas-liquid separator. The separated gas phase is mixed with the supplemented fresh hydrogen and enters the reactor tube layer from the bottom of the reactor. The separated liquid phase is sent to the subsequent treatment system. The outlet of the circulating water tank enters the reactor shell layer from the lower part through the circulating water pump, and the circulating water coming out of the upper reactor shell layer returns to the circulating water tank. The reactor of the present invention has a simple structure, flexible operation, easy control, and the reaction heat can be easily removed.

[0059] According to a preferred embodiment of the present invention, the outlet of the circulating water tank enters the reactor shell layer from the lower part through the circulating water pump, and the circulating water coming out of the upper shell layer returns to the circulating water tank. The circulating water tank is provided with a circulating water supplement pipeline.

[0060] The materials entering the reactor of the present invention include hydrogen, maleic anhydride or maleic anhydride solution. The maleic anhydride is the molten maleic anhydride, and the maleic anhydride solution is a mixture of maleic anhydride and a solvent.

[0061] In the present invention, the catalyst is not limited, and any maleic anhydride hydrogenation catalyst can be used, such as the catalysts described in Chinese Patent Application CN202011118431.X and Chinese Patent Application CN202011120495.3.

[0062] In the present invention, optionally, when the gas phase and the liquid phase enter the reactor, they first pass through a distributor and then contact the catalyst.

[0063] In the present invention, after the hydrogenation reaction product is separated, all of the liquid phase is sent to the subsequent separation system.

[0064] According to a preferred embodiment of the present invention, as Figure 1 shown, the method of the present invention includes:

[0065] The maleic anhydride raw material 11 is heated to the reaction temperature through the raw material heat exchanger 1 and enters the shell side of the shell-and-tube reactor 2 to contact the catalyst and hydrogen for hydrogenation reaction. Among them, hydrogen enters the shell side from the lower gas-phase feed port of the tube side, and the hydrogenation reaction material flows out from the top discharge port of the tube side and enters the gas-liquid separator 5 for gas-liquid separation. Part or all of the separated gas phase is cooled by the circulating gas cooler 6 or not cooled and returned for use as recycled hydrogen, and together with the supplementary hydrogen 12, it is used as the hydrogen raw material. The separated liquid phase is sent as the reaction product 13 to the subsequent separation system. In the hydrogenation reaction stage, a cooling medium is introduced into the shell side through the cooling medium storage tank 3 to timely remove the reaction heat.

[0066] The following examples use the following catalyst:

[0067] Chinese Patent Application CN202011118431.X - Example 1

[0068] (1) Weigh 50.00 g of nickel basic carbonate (nickel content 45 wt%), 9.16 g of Cu(NO3)2·3H2O, 49.91 g of ethylenediaminetetraacetic acid, 500 g of deionized water, and 100 g of 25 wt% ammonia water, and introduce ammonia gas to adjust the pH value of the solution to 10.5. Stir at 45 °C until all solids are dissolved to obtain a solution of nickel-copper ammonia complex;

[0069] (2) Weigh 458.31 g of silica sol and mix it with the nickel-copper ammonia complex solution obtained in step (1) to obtain a mixed solution;

[0070] (3) Under stirring, age the mixed solution at 60 °C for 14 h, and then dry it at 120 °C for 12 h to obtain a catalyst precursor;

[0071] (4) Saturate the catalyst precursor with a cerium nitrate solution containing 11.41 g of Ce(NO3)3·6H2O to obtain a matrix catalyst;

[0072] (5) Dry the matrix catalyst at 115 °C for 12 h, and then calcine it at 400 °C for 4 h to form catalyst S1.

[0073] Based on the total weight of catalyst S1, catalyst S1 contains: 19 wt% of NiO, 2 wt% of CuO, 3 wt% of CeO2, and 76 wt% of SiO2.

[0074] Chinese Patent Application CN202011120495.3 - Example 1

[0075] (1) Weigh 10.90 g of Ni(NO3)3·6H2O and 5.04 g of Ce(NO3)3·6H2O cerium, dissolve them in water and make up the volume to 50.0 ml. Then immerse 50 g of the carrier SiO2 (specific surface area 300 m2 / g, water absorption rate 1.0 mL / g) in the nickel nitrate - cerium nitrate mixed solution, stir evenly, and let it stand for aging for 4 hours. Then dry it at 120 °C for 12 hours, and finally calcine it in air at 450 °C for 4 hours to obtain the composite oxide carrier E;

[0076] (2) Add the composite oxide carrier E to 100 ml of a ruthenium metal solution with a Ru content of 0.02 g / L and heat release. Under stirring conditions, add ammonia water with a mass concentration of 25% to adjust the pH value of the solution and maintain it at 9. React at 55 °C for 6 hours, then filter, and then dry it at 110 °C for 12 hours. Finally, calcine it in air at 500 °C for 4 hours to obtain the finished catalyst S1.

[0077] Catalyst S1 contains: Based on the mass of the catalyst carrier SiO2, the mass fraction of Ni in the catalyst is 7% of the carrier mass, the mass fraction of CeO2 is 4% of the carrier mass, and the mass fraction of Ru is 0.4% of the carrier mass.

[0078] Example 1

[0079] Adopt Figure 1 The maleic anhydride hydrogenation reaction method shown. The feedstock is a maleic anhydride solution, and the solvent used is γ - butyrolactone. The maleic anhydride content in the maleic anhydride solution is 25 wt%. This solution is heated to 40 °C and enters the reactor tube layer from the bottom of the reactor.

[0080] In the reactor, the molar ratio of hydrogen to maleic anhydride is 15, the reaction temperature of the reactor is 42 °C, and the reaction pressure is 1.5 MPa. The hydrogenation reaction product enters the gas-liquid separator. After separation, the liquid phase enters the subsequent separation system, and 1% by volume of the gas phase is taken out for fuel gas. The remaining gas phase is cooled to 40 °C by the circulating gas cooler and then mixed with the supplemented fresh hydrogen and enters the reactor tube layer from the bottom of the reactor. 32 °C circulating water is used to enter the shell layer of the hydrogenation reactor. The circulating water coming out of the shell layer of the reactor enters the circulating water tank and then enters the shell layer of the reactor through the circulating water pump. According to the actual operation situation, part of the circulating water can be taken out and a certain amount of fresh circulating water can be supplemented.

[0081] The catalyst loaded in the hydrogenation reactor is a Ni active component catalyst, and the specific composition can be seen in Chinese Patent CN202011118431.X - Example 1.

[0082] After passing through the hydrogenation reactor, the total conversion rate of maleic anhydride is 99.1%, and the total selectivity of succinic anhydride is 99.29%.

[0083] Example 2

[0084] Adopt Figure 1 The maleic anhydride hydrogenation reaction method shown, and the incoming material is molten maleic anhydride, which enters the tube layer of the hydrogenation reactor from the bottom of the reactor.

[0085] In the hydrogenation reactor, the molar ratio of hydrogen to maleic anhydride is 20, the reaction temperature of the hydrogenation reactor is 40 °C, and the reaction pressure is 1.7 MPa. After the hydrogenation reaction product is separated by gas-liquid separation, 1% by volume of the gas phase is taken out for fuel gas. The remaining gas phase is heat-exchanged to 40 °C by the circulating gas cooler and then mixed with the supplemented fresh hydrogen and enters the tube layer of the hydrogenation reactor from the bottom of the reactor. The liquid phase after gas-liquid separation is sent to the subsequent separation system.

[0086] Circulating water is used to enter the shell layer of the hydrogenation reactor. The circulating water coming out of the shell layer of the reactor enters the circulating water tank and then enters the shell layer of the hydrogenation reactor through the circulating water pump. According to the actual operation situation, part of the circulating water is taken out and a certain amount of fresh circulating water is supplemented.

[0087] The catalyst loaded in the hydrogenation reactor is a Ni active component catalyst, and the specific composition can be seen in Chinese Patent CN202011120495.3 - Example 1.

[0088] After passing through the hydrogenation reactor, the total conversion rate of maleic anhydride is 99.4%, and the total selectivity of succinic anhydride is 98.9%.

[0089] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A method for preparing succinic anhydride, characterized in that, This method is carried out in a shell-and-tube reactor. The reactor includes: a tube layer and a shell layer. Among them, the tube layer is used for the hydrogenation reaction of maleic anhydride raw materials to prepare succinic anhydride, and the shell layer is used for circulating a cooling medium. A raw material heat exchanger, which is connected to the liquid-phase feed port at the bottom of the tube layer. A gas-liquid separator, the feed port of which is connected to the discharge port at the top of the tube layer; the gas-phase outlet at the top of the gas-liquid separator is connected to the gas-phase feed port at the lower part of the tube layer. A cooling medium storage tank, which is used to supply the cooling medium to the shell layer. The maleic anhydride raw material is heated to the reaction temperature through the raw material heat exchanger and enters the tube layer to contact the catalyst and hydrogen for the hydrogenation reaction. Among them, hydrogen enters the tube layer from the gas-phase feed port at the lower part of the tube layer, and the hydrogenation reaction material flows out from the discharge port at the top of the tube layer and enters the gas-liquid separator for gas-liquid separation. The separated gas phase, part or all of it, is cooled to 40-60 °C and returned for use as recycled hydrogen. During the hydrogenation reaction stage, the cooling medium is introduced into the shell layer through the cooling medium storage tank to timely remove the reaction heat. The temperature of the hydrogenation reaction is 40-50 °C, and the pressure is 0.5-5 MPa. Hydrogen is a mixed gas of recycled hydrogen and supplemented fresh hydrogen. The molar ratio of the total hydrogen amount of the recycled hydrogen and the supplemented fresh hydrogen to the total maleic anhydride in the incoming maleic anhydride raw material is 5-100. The maleic anhydride raw material is molten maleic anhydride or a maleic anhydride solution, and the concentration of the maleic anhydride solution is 25-90 wt%.

2. The method according to claim 1, wherein, The maleic anhydride solution is a mixture of maleic anhydride and a solvent. Among them, the solvent is one or more of acetic anhydride, γ-butyrolactone, dioxane, tetrahydrofuran, aromatic hydrocarbons, ethyl acetate, four-carbon dibasic acid esters, ethanol, isopropanol, hexane, cyclohexane, propylene oxide, ketones, and ethers.

3. The method according to claim 1, wherein, The concentration of the maleic anhydride solution is 25-40 wt%.

4. The method according to claim 1, wherein, The molar ratio of the total hydrogen amount of the recycled hydrogen and the supplemented fresh hydrogen to the total maleic anhydride in the incoming maleic anhydride raw material is 10-40.

5. The method according to claim 1, wherein, 0.5-2 vol% of the separated gas phase is taken out as fuel gas, and the rest is used as recycled hydrogen. After being mixed with the supplemented fresh hydrogen, it enters the tube layer.

6. The method according to claim 1, wherein, The cooling medium is water. The cooling medium storage tank enters the shell layer from the lower part through a circulating water pump, and the circulating water coming out from the upper part of the shell layer returns to the cooling medium storage tank.

7. According to the method described in claim 1, wherein a circulating gas cooler is provided on the connecting pipeline between the gas-phase outlet at the top of the gas-liquid separator and the gas-phase feed port at the lower part of the tube layer; and / or a raw material distributor is provided at the bottom of the tube layer, which is used to uniformly distribute the hydrogenation reaction material step by step and then contact the catalyst in the tube layer for the hydrogenation reaction.

8. The method according to claim 1, wherein The upper end of the shell layer is connected to the cooling medium storage tank, the cooling medium storage tank is connected to the circulating water pump, and the circulating water pump is connected to the lower end of the shell layer. The cooling medium storage tank is provided with a cooling medium replenishment pipeline.

9. The method according to claim 8, wherein, The cooling medium storage tank is a circulating water tank.

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