Method for preparing succinic anhydride through continuous hydrogenation of maleic anhydride in slurry bed reactor

Abstract

The invention relates to the technical field of preparation of fine chemicals, and particularly discloses a method for preparing butanedioic anhydride through continuous hydrogenation of maleic anhydride in a slurry bed reactor, and the method comprises the following steps: by taking liquid maleic anhydride as a raw material, carrying out direct liquid-phase hydrogenation on maleic anhydride in the slurry bed reactor under the action of a catalyst to prepare butanedioic anhydride, no solvent is used in the reaction process, the separation and purification process of butanedioic anhydride is omitted, hydrogen and raw materials enter the reactor together, the raw materials and the catalyst are promoted to be evenly mixed through stirring of a stirring paddle in the reactor, and therefore the conversion efficiency of the raw materials in the reactor is adjusted; an over-temperature condition in the reactor is prevented, and a reaction product passes through a two-layer separation device to intercept a catalyst in the reactor, so that the catalyst keeps excellent activity and service life; the slurry bed stirring process can reduce by-products generated by excessive hydrogenation of maleic anhydride or succinic anhydride, and ensures uniform mixing of the catalyst and reactants.

Description

Technical Field

[0001] This invention relates to the field of fine chemical preparation technology, and more specifically, to a method for the continuous hydrogenation of maleic anhydride to prepare succinic anhydride using a slurry bed reactor. Background Technology

[0002] Maleic anhydride, also known as maleic anhydride, abbreviated as MA, has the chemical formula C4H2O3, a molecular weight of 98.057, and a density of 1.5±0.1 g / cm³. 3 It has a melting point of 51-56℃ and a boiling point of 202.0℃; the main production methods include benzene oxidation and C4 olefin process; succinic anhydride, also known as succinic anhydride, abbreviated as SA, has the chemical formula C4H4O3, a molecular weight of 100.07, and a density of 1.234 g / cm³. 3 It has a melting point of 119.6℃ and a boiling point of 261℃; it can be obtained by direct catalytic hydrogenation of maleic anhydride or by dehydration of succinic acid. Both maleic anhydride and succinic anhydride are important chemical intermediates, currently mainly used as food additives, but also in the production of pharmaceuticals, pesticides, and dyes. Furthermore, the condensation polymer of succinic anhydride and butanediol can be used to prepare high-performance biodegradable plastic polybutylene succinate (PBS). PBS structural units contain easily hydrolyzed ester groups, which, under conditions such as composting and contact with specific microorganisms, are easily decomposed and metabolized by various microorganisms in nature or enzymes in animals and plants, ultimately resulting in complete degradation into CO2 and H2O, thus avoiding environmental pollution.

[0003] With increasing environmental awareness, biodegradable materials have been widely adopted, and high-performance PBS-based biodegradable plastic products are gaining popularity. However, my country's succinic anhydride production technology is still immature, hindering large-scale industrial production and severely restricting the development of the PBS industry. In my country, maleic anhydride production technology is mature, with an annual capacity exceeding 2 million tons. Therefore, producing succinic anhydride from maleic anhydride via directed hydrogenation is considered the optimal process to meet the future demand for succinic anhydride in biodegradable PBS, and it has broad market prospects. However, currently, Chinese companies mainly use the energy-intensive maleic anhydride electrolysis method to produce succinic anhydride. This process is complex, costly, and has low capacity, making large-scale expansion difficult.

[0004] To overcome the shortcomings of traditional electrolysis processes, researchers have focused on developing novel and efficient methods for the directional hydrogenation of maleic anhydride to produce succinic anhydride. Currently developed catalytic hydrogenation processes for maleic anhydride to succinic anhydride mostly employ liquid-phase solvent methods, i.e., dissolving maleic anhydride in an organic solvent, followed by hydrogenation-separation to obtain succinic anhydride. Patent CN1453066A discloses a method using a nickel-based catalyst and tetrahydrofuran, toluene, and 1,4-dioxane as solvents to directly hydrogenate succinic anhydride at a hydrogen pressure of 0.5–3 MPa and a temperature of 120–180 °C. This patent achieves a maleic anhydride conversion rate greater than 99.7% and a succinic anhydride selectivity greater than 99%. However, the increased temperature introduces many byproducts, leading to a decrease in product selectivity. Patent CN102311332B discloses a method using γ-butyrolactone as a solvent, employing 5wt% Pd and 2wt% Fe / C catalysts, and continuously reacting for 300 hours in a fixed-bed reactor at 70℃ and 1.5MPa hydrogen pressure, achieving 100% maleic anhydride conversion and 99.2% succinic anhydride selectivity. However, the solvent used in this patent has an excessively high boiling point, resulting in inadequate removal of reaction heat and a risk of runaway reactions. Furthermore, the use of large quantities of solvent increases costs. Patent CN103570650B discloses a method for the continuous hydrogenation of maleic anhydride to produce succinic anhydride and co-production of succinic acid. This method involves catalytic hydrogenation of maleic anhydride solution in a series of fixed-bed and trickle-bed reactors, removing the heat released during the reaction through external circulation. The catalyst used is a nickel-based catalyst. Specifically, the primary reactor is a fixed-bed reactor with a reaction temperature of 60-200℃ and a pressure of 1-10 MPa. The secondary reactor is a trickle-bed reactor with a reaction temperature of 35-180℃ and a pressure of 0.5-10 MPa. The maleic anhydride conversion rate is >99%, and the succinic anhydride selectivity is >99%. This method features high conversion and selectivity; however, it requires organic solvents for raw material preparation, and the subsequent product and solvent separation consumes a lot of energy. Furthermore, the use of fixed-bed and trickle-bed reactors results in large catalyst particles and high mass transfer resistance in liquid-phase hydrogenation, severely impacting the catalyst's catalytic hydrogenation performance. Patent CN107253938B discloses a method for the direct hydrogenation of maleic anhydride to prepare high-purity succinic anhydride. In this method, maleic anhydride is directly hydrogenated via a fixed bed, and hydrogen is added through four stages of cold hydrogen injection and then recycled. This ensures that the maleic anhydride fully participates in the reaction as it descends from the top, and reduces the formation of other heavy components such as butyrolactone. This production process uses a nickel-based catalyst, with a hydrogenation reaction pressure of 5-7 MPa and a temperature of 85-110℃. The reaction temperature is controlled by the circulation volume of the reaction liquid. The conversion rate of maleic anhydride is >98%, but the crude product contains only 70-85% butyrolactone and only 15-30% succinic anhydride. Furthermore, this method requires four stages of cold hydrogen and a large amount of reaction liquid circulation to control the exothermic reaction, making the entire process quite complex. Additionally, the main product obtained by this method is γ-butyrolactone, with poor selectivity for succinic anhydride.

[0005] In summary, the hydrogenation of maleic anhydride to succinic anhydride is highly exothermic (ΔHm = 121 KJ / mol) and the reaction is rapid, making it prone to hot spots and runaway temperatures during low-temperature liquid-phase hydrogenation, which hinders bed temperature control. Furthermore, excessively high bed temperatures can lead to over-hydrogenation of succinic anhydride, generating byproducts such as γ-butyrolactone, resulting in a reduced succinic anhydride yield. This invention provides a method for the continuous hydrogenation of maleic anhydride to prepare succinic anhydride using a slurry bed reactor. Summary of the Invention

[0006] To address the problems in existing technologies, such as the high exothermic reaction and rapid reaction of maleic anhydride double bond hydrogenation to succinic anhydride, which easily leads to hot spots and runaway temperatures during low-temperature liquid-phase hydrogenation, making bed temperature control difficult; and the excessively high bed temperature causing over-hydrogenation of succinic anhydride to generate byproducts such as γ-butyrolactone, resulting in reduced succinic anhydride yield, this invention provides a method for the continuous hydrogenation of maleic anhydride to prepare succinic anhydride using a slurry bed reactor. This invention employs slurry bed technology, changing the previous fixed-bed production method. In fixed-bed processes, maleic anhydride is prone to coking, and pure maleic anhydride feed easily causes blockage in the fixed-bed reaction tubes. The heat transfer efficiency of the fixed-bed reactor is low, and excessive exothermic reactions affect the temperature control of the entire reaction process. Excessively high reaction temperatures also affect product selectivity and catalyst activity. Furthermore, in a fixed-bed reactor, the contact time between the feedstock and product and the catalyst is short due to airflow and gravity, significantly reducing the catalyst space velocity, resulting in reduced yield and excessively high production costs. Using a slurry bed reactor can solve the above problems to a certain extent. In a slurry bed reactor, the stirring paddle can ensure that the raw materials and catalyst are in full contact to a large extent, thereby improving the reaction efficiency. The coil heat exchanger can also remove the heat released by the reaction from the reactor as quickly as possible, so that the reaction temperature is kept under control. This can achieve the purpose of increasing the yield of succinic anhydride and amplifying the catalyst space velocity.

[0007] This invention provides a method for the continuous hydrogenation of maleic anhydride to prepare succinic anhydride using a slurry bed reactor, employing the following technical solution: A method for the continuous hydrogenation of maleic anhydride to prepare succinic anhydride using a slurry bed reactor includes the following steps: (1) The hydrogenation catalyst is reduced and then loaded into a slurry bed reactor; (2) After preheating the raw material maleic anhydride to form liquid maleic anhydride, it is introduced into a slurry bed reactor together with hydrogen to carry out hydrogenation reaction, and a mixture of reaction products and hydrogenation catalyst is obtained; (3) After the above mixture is separated for the first time by the mesh metal filter in the middle of the reactor, it flows to the sintered metal filter at the top of the reactor for a second separation and filtration, retaining the catalyst in the reactor to obtain the reaction product; (4) Collect the above reaction products and distill them to obtain succinic anhydride.

[0008] A slurry bed reactor equipped with heat exchange coils is selected. The heat generated during the reaction is removed through the coil heat exchanger, maintaining a stable reaction temperature within the slurry bed reactor. The heat exchange coils play a crucial role in maintaining a constant temperature within the slurry bed reactor. The heat exchange coils utilize spiral stainless steel tubing with a spiral diameter matching that of the agitator blades. They are connected to the outside of the reactor via a lid. Thermal oil is used as the medium, and temperature control is achieved by regulating the circulation rate of the thermal oil circulation pump.

[0009] The slurry bed reactor is fed by bottom gas-liquid mixing, using a combination of straight and curved pipes to pump the gas-liquid mixture into the reactor. After being injected, it is fully mixed with the catalyst slurry in the reactor under the turbulent action of the agitator, and then undergoes a hydrogenation reaction to obtain the product.

[0010] The hydrogenation of maleic anhydride to produce succinic anhydride is an exothermic reaction. Since the hydrogenation of a large amount of maleic anhydride without solvent releases a lot of heat, the temperature rises excessively, which affects the hydrogenation process and consequently the selectivity of the product succinic anhydride. The slurry bed process can not only increase the catalyst space velocity, but also use coil heat exchange to remove heat in time. At the same time, stirring can quickly distribute the heat throughout the reaction system, thus achieving the optimal state for the hydrogenation reaction.

[0011] Based on a conventional slurry bed reactor, we improved the subsequent product-catalyst separation process. A two-stage separation device was adopted. The first stage uses a mesh metal filter, installed in the middle of the slurry bed reactor, to filter the catalyst, initially separating the reaction slurry from the solid catalyst, retaining over 90% of the catalyst below the mesh metal filter. The second stage uses a sintered metal filter, installed above the mesh metal filter. This filter maximizes catalyst retention inside the reactor, thereby separating and collecting the product.

[0012] Preferably, the hydrogenation catalyst in step (1) is one or more of the following: powdered nickel silicate catalyst, granular nickel silicate catalyst, supported nickel-based catalyst, and supported copper-nickel-based catalyst.

[0013] Preferably, the hydrogenation catalyst in step (1) is a powdered nickel silicate catalyst.

[0014] Preferably, the reduction of the hydrogenation catalyst in step (1) refers to the following: reduction using hydrogen gas, reduction temperature of 300-400℃, reduction time of 12-24h, and hydrogen flow rate of 50-200mL / min.

[0015] Preferably, in step (2), the liquid maleic anhydride is pure liquid, the preheating temperature of the raw maleic anhydride is 55-80℃, the raw maleic anhydride is first preheated in the raw material tank, melted into liquid, and the liquid maleic anhydride is obtained and stored in the raw material tank.

[0016] Preferably, the hydrogen flow rate required for the hydrogenation reaction in step (2) is 100-1000 mL / min.

[0017] Preferably, in step (2), the liquid maleic anhydride and hydrogen are fed in a co-feed manner, and the two reactants are mixed and then enter the reactor together. The mixing ratio of hydrogen and liquid maleic anhydride is 10-100:1.

[0018] Preferably, the reaction temperature of the slurry bed reactor for the hydrogenation reaction in step (2) is 120-160℃, the reaction pressure is 1-5MPa, and the space velocity is 0.1-20.

[0019] Preferably, the reaction temperature of the slurry bed reactor for the hydrogenation reaction in step (2) is 130-150℃.

[0020] Preferably, the slurry bed reactor uses coil heat exchange for heat exchange, and the heat exchange medium is heat transfer oil. The temperature inside the reactor is controlled by controlling the circulation rate of the heat transfer oil.

[0021] Preferably, in step (2), liquid maleic anhydride and hydrogen enter through the bottom of the slurry bed reactor; the gas-liquid mixture of liquid maleic anhydride and hydrogen is stirred by a stirring paddle to form a uniform slurry with the catalyst and complete the hydrogenation reaction. The slurry flows from bottom to top until it reaches the mesh metal filter in the middle of the reactor for the first separation.

[0022] Preferably, in step (3), the mixture undergoes a first solid-liquid separation through a mesh metal filter in the middle of the reactor, trapping a large amount of catalyst below the mesh metal filter to continue participating in the reaction; the product slurry after the initial separation continues to rise to the second separation device.

[0023] Preferably, the mesh metal filter in step (3) is a multi-layer stainless steel mesh with a mesh size of 100-500 mesh.

[0024] Preferably, the product slurry after preliminary separation in step (3) is further separated into solid and liquid by passing it through a sintered metal filter at the top of the reactor, while retaining the residual catalyst in the reactor; the sintered metal filter has a mesh size of 200-500.

[0025] Preferably, in step (4), the reaction products are collected in a collection tank at a temperature of 120-140°C.

[0026] Preferably, in step (4), the collected reaction products are distilled to obtain pure succinic anhydride, removing light components and impurities from the products; the distillation is carried out under reduced pressure.

[0027] Preferably, the pressure of the vacuum distillation is 10-30 mmHg and the temperature is 180-250℃.

[0028] In summary, the present invention has the following beneficial effects: This invention develops a method for producing succinic anhydride by hydrogenation of maleic anhydride using a slurry bed process, and optimizes the slurry bed separation process.

[0029] The slurry bed reactor of the present invention can achieve a high conversion rate of maleic anhydride, while obtaining high selectivity for succinic anhydride.

[0030] The slurry bed process of this invention can significantly increase the yield of succinic anhydride. Attached Figure Description

[0031] The accompanying drawings are part of the specification and, together with the detailed description, provide a further explanation of the invention, but are not intended to limit the invention.

[0032] Figure 1 This is a process flow diagram of the preparation of succinic anhydride by hydrogenation of maleic anhydride in the slurry bed reactor of the present invention. Detailed Implementation

[0033] The present invention will be further described in detail below with reference to embodiments and comparative examples. The following embodiments are not intended to limit the scope of protection of the present invention. Those skilled in the art can make appropriate extensions in conjunction with the present invention specification and the entire text, and these extensions should all be within the scope of protection of the present invention.

[0034] Example 1 A method for the continuous hydrogenation of maleic anhydride to prepare succinic anhydride using a slurry bed reactor includes the following steps: (1) Weigh 10 g of powdered nickel silicate catalyst and reduce it with hydrogen at 350 °C for 24 hours with a hydrogen flow rate of 500 mL / min. After reduction, it is loaded into a slurry bed reactor.

[0035] (2) The raw material maleic anhydride is first preheated in the raw material tank at a temperature of 55°C, melting into a liquid state to obtain liquid maleic anhydride, which is then stored in the raw material tank. The reaction temperature of the slurry bed reactor is set at 120°C and the reaction pressure at 3MPa. Liquid maleic anhydride and hydrogen are introduced through the bottom of the slurry bed reactor at a flow rate of 1000mL / min and a flow rate of 0.5mL / min. The mixing ratio of hydrogen to liquid maleic anhydride is controlled at 30:1. The gas-liquid mixture of liquid maleic anhydride and hydrogen is stirred by a stirrer to form a uniform slurry with the catalyst and complete the hydrogenation reaction. The slurry flows from bottom to top until it reaches the 3-layer stainless steel mesh with a mesh size of 100 mesh in the middle of the reactor for the first separation. After the initial separation, the product slurry continues to pass through the sintered metal filter at the top of the reactor for further solid-liquid separation, while retaining the residual catalyst in the reactor. The sintered metal filter has a mesh size of 300 mesh.

[0036] (3) The reaction products were collected in a product collection tank at a temperature of 120°C. The pressure of vacuum distillation was controlled at 10 mmHg and the temperature at 250°C. The collected reaction products were subjected to vacuum distillation to obtain pure succinic anhydride, removing light components and impurities from the products. Samples were taken from the product collection tank for analysis. The reaction results are shown in Table 1.

[0037] Example 2 A method for the continuous hydrogenation of maleic anhydride to prepare succinic anhydride using a slurry bed reactor includes the following steps: (1) Weigh 20 g of powdered nickel silicate catalyst and reduce it with hydrogen at 350 °C for 24 hours with a hydrogen flow rate of 500 mL / min. After reduction, it is loaded into a slurry bed reactor.

[0038] (2) The raw material maleic anhydride is first preheated in the raw material tank at a temperature of 68°C, melting into a liquid state to obtain liquid maleic anhydride, which is then stored in the raw material tank. The reaction temperature of the slurry bed reactor is set at 130°C and the reaction pressure at 5MPa. Liquid maleic anhydride and hydrogen are introduced through the bottom of the slurry bed reactor at a flow rate of 500mL / min and a flow rate of 6mL / min for liquid maleic anhydride. The mixing ratio of hydrogen to liquid maleic anhydride is controlled at 50:1. The gas-liquid mixture of liquid maleic anhydride and hydrogen is stirred by a stirring paddle to form a uniform slurry with the catalyst and complete the hydrogenation reaction. The slurry flows from bottom to top until it reaches the 3-layer stainless steel mesh with a mesh size of 200 in the middle of the reactor for the first separation. After the initial separation, the product slurry continues to pass through the sintered metal filter at the top of the reactor for further solid-liquid separation, while retaining the residual catalyst in the reactor. The sintered metal filter has a mesh size of 400.

[0039] (3) The reaction products were collected in a product collection tank at a temperature of 130°C. The pressure of vacuum distillation was controlled at 20 mmHg and the temperature at 220°C. The collected reaction products were subjected to vacuum distillation to obtain pure succinic anhydride, removing light components and impurities from the products. Samples were taken from the product collection tank for analysis. The reaction results are shown in Table 1.

[0040] Example 3 A method for the continuous hydrogenation of maleic anhydride to prepare succinic anhydride using a slurry bed reactor includes the following steps: (1) Weigh 15g of powdered nickel silicate catalyst, reduce it with hydrogen at 350℃ for 24 hours with a hydrogen flow rate of 500mL / min, and then load it into a slurry bed reactor.

[0041] (2) The raw material maleic anhydride is first preheated in the raw material tank at a temperature of 80°C, melting into a liquid state to obtain liquid maleic anhydride, which is then stored in the raw material tank. The reaction temperature of the slurry bed reactor is set at 160°C and the reaction pressure at 1 MPa. Liquid maleic anhydride and hydrogen are introduced through the bottom of the slurry bed reactor at a flow rate of 100 mL / min and a flow rate of 3 mL / min for liquid maleic anhydride. The mixing ratio of hydrogen to liquid maleic anhydride is controlled at 80:1. The gas-liquid mixture of liquid maleic anhydride and hydrogen is stirred by a stirrer to form a uniform slurry with the catalyst, and the hydrogenation reaction is completed. The slurry flows from bottom to top until it reaches the 3-layer stainless steel mesh with a mesh size of 400 in the middle of the reactor for the first separation. After the initial separation, the product slurry continues to pass through the sintered metal filter at the top of the reactor for further solid-liquid separation, while retaining the residual catalyst in the reactor. The sintered metal filter has a mesh size of 500.

[0042] (3) The reaction products were collected in a product collection tank at a temperature of 140°C. The pressure of vacuum distillation was controlled at 30 mmHg and the temperature at 180°C. The collected reaction products were subjected to vacuum distillation to obtain pure succinic anhydride, removing light components and impurities from the products. Samples were taken from the product collection tank for analysis. The reaction results are shown in Table 1.

[0043] Comparative Example 1 A method for the continuous hydrogenation of maleic anhydride to prepare succinic anhydride in a fixed-bed reactor includes the following steps: (1) Weigh 10 g of powdered nickel silicate catalyst, reduce it with hydrogen at 350 °C for 24 hours with a hydrogen flow rate of 500 mL / min, and load it into a fixed bed reactor.

[0044] (2) The raw material maleic anhydride is first preheated in the raw material tank at a temperature of 55°C until it melts into a liquid state, and the liquid maleic anhydride is obtained and stored in the raw material tank. The reaction temperature of the fixed bed reactor is set at 120°C and the reaction pressure is 3MPa. The liquid maleic anhydride and hydrogen are introduced through the bottom of the fixed bed reactor at a flow rate of 1000mL / min and a flow rate of 0.5mL / min. The mixing ratio of hydrogen to liquid maleic anhydride is controlled at 30:1.

[0045] (3) The reaction products were collected in a product collection tank at a temperature of 120°C. The pressure of vacuum distillation was controlled at 10 mmHg and the temperature at 250°C. The collected reaction products were subjected to vacuum distillation to obtain pure succinic anhydride, removing light components and impurities from the products. Samples were taken from the product collection tank for analysis. The reaction results are shown in Table 1.

[0046] Test methods The reaction liquid products were detected and analyzed using an Agilent 6890 test column with AB-InoWax (30 m × 0.32 mm × 0.5 μm), and each analyte was quantified by external standard method. Reaction conversion rate (%) = (moles of reactants converted / moles of reactants in raw materials) × 100%.

[0047] Product selectivity (%) = (moles of a certain product generated / moles of reactants converted) × 100%.

[0048] The test results are shown in Table 1 below: Table 1 Results of the directed catalytic hydrogenation of maleic anhydride to prepare succinic anhydride Note: Other substances in Table 1 include propanol, butanol, propionic acid, butyric acid, etc.

[0049] As shown in Table 1, the method for continuous hydrogenation of maleic anhydride to prepare succinic anhydride provided by the present invention in a slurry bed reactor can achieve a high conversion rate of maleic anhydride and obtain a high selectivity for succinic anhydride, which can significantly increase the yield of succinic anhydride.

[0050] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A method for the continuous hydrogenation of maleic anhydride to prepare succinic anhydride using a slurry bed reactor, characterized in that, Includes the following steps: (1) The hydrogenation catalyst is reduced and then loaded into a slurry bed reactor; (2) After preheating the raw material maleic anhydride to form liquid maleic anhydride, it is introduced into a slurry bed reactor together with hydrogen to carry out hydrogenation reaction, and a mixture of reaction products and hydrogenation catalyst is obtained; (3) After the above mixture is separated for the first time by the mesh metal filter in the middle of the reactor, it flows to the sintered metal filter at the top of the reactor for a second separation and filtration, retaining the catalyst in the reactor to obtain the reaction product; (4) Collect the above reaction products and distill them to obtain succinic anhydride.

2. The method for continuous hydrogenation of maleic anhydride to prepare succinic anhydride in a slurry bed reactor according to claim 1, characterized in that, The hydrogenation catalyst in step (1) is one or more of the following: powdered nickel silicate catalyst, granular nickel silicate catalyst, supported nickel-based catalyst, and supported copper-nickel-based catalyst.

3. The method for continuous hydrogenation of maleic anhydride to prepare succinic anhydride in a slurry bed reactor according to claim 1, characterized in that, The reduction of the hydrogenation catalyst in step (1) refers to the use of hydrogen gas for reduction, with a reduction temperature of 300-400℃, a reduction time of 12-24h, and a hydrogen flow rate of 50-200mL / min.

4. The method for continuous hydrogenation of maleic anhydride to prepare succinic anhydride in a slurry bed reactor according to claim 1, characterized in that, In step (2), the liquid maleic anhydride is pure liquid. The preheating temperature of the raw maleic anhydride is 55-80℃. The raw maleic anhydride is first preheated in the raw material tank and melted into a liquid state to obtain liquid maleic anhydride, which is then stored in the raw material tank.

5. The method for continuous hydrogenation of maleic anhydride to prepare succinic anhydride in a slurry bed reactor according to claim 1, characterized in that, The hydrogen flow rate required for the hydrogenation reaction in step (2) is 100-1000 mL / min.

6. The method for continuous hydrogenation of maleic anhydride to prepare succinic anhydride in a slurry bed reactor according to claim 3, characterized in that, In step (2), the liquid maleic anhydride and hydrogen are fed in a co-feed manner. The two reactants are mixed and then enter the reactor together. The mixing ratio of hydrogen and liquid maleic anhydride is 10-100:

1.

7. The method for continuous hydrogenation of maleic anhydride to prepare succinic anhydride in a slurry bed reactor according to claim 1, characterized in that, In step (2), the slurry bed reactor for hydrogenation reaction has a reaction temperature of 120-160℃, a reaction pressure of 1-5MPa, and a space velocity of 0.1-20.

8. The method for continuous hydrogenation of maleic anhydride to prepare succinic anhydride in a slurry bed reactor according to claim 1, characterized in that, The slurry bed reactor uses coil heat exchange for heat exchange, with heat transfer oil as the heat exchange medium. The temperature inside the reactor is controlled by controlling the circulation rate of the heat transfer oil.

9. The method for continuous hydrogenation of maleic anhydride to prepare succinic anhydride in a slurry bed reactor according to claim 1, characterized in that, In step (3), the mesh metal filter is a multi-layer stainless steel mesh with a mesh size of 100-500 mesh; the sintered metal filter has a mesh size of 200-500 mesh.

10. The method for continuous hydrogenation of maleic anhydride to prepare succinic anhydride in a slurry bed reactor according to claim 1, characterized in that, In step (4), the collected reaction products are distilled to obtain pure succinic anhydride, removing light components and impurities from the products; the distillation is carried out under reduced pressure, with a pressure of 10-30 mmHg and a temperature of 180-250℃.

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