Method and device for producing succinic anhydride by gas phase hydrogenation of maleic anhydride

Abstract

This invention discloses a method and apparatus for producing succinic anhydride by atmospheric pressure gas-phase hydrogenation of maleic anhydride without solvent. The method includes: (1) preheating maleic anhydride and then vaporizing it, and mixing it evenly with hydrogen; (2) injecting maleic anhydride and hydrogen into a hydrogenation reactor, where a double bond hydrogenation reaction occurs under the action of a hydrogenation catalyst to obtain the reaction product; (3) heat-exchanging the reaction product and then performing gas-liquid separation to obtain crude succinic anhydride and circulating hydrogen; (4) fractionating the crude succinic anhydride to obtain refined succinic anhydride and its byproducts; (5) washing the circulating hydrogen to remove uncondensed succinic anhydride and obtain hydrogen. The method of this invention avoids the use of expensive organic solvents and high-pressure hydrogenation equipment, which can significantly reduce investment costs. Moreover, this invention develops a circulating hydrogen washing system and other devices, which completely avoids the sublimation and blockage of the product succinic anhydride in the reactor pipeline and hydrogen circulation compressor, and can achieve long-term stable operation.

Description

Technical Field

[0001] This invention belongs to the field of fine chemical preparation technology, specifically relating to a method and apparatus for producing succinic anhydride by atmospheric pressure gas-phase hydrogenation of maleic anhydride without solvent. Background Technology

[0002] Succinic anhydride, also known as succinic anhydride or SA for short, is an important chemical intermediate, currently mainly used in food additives, and also in the production of pharmaceuticals, pesticides, and dyes. The condensation polymerization of succinic anhydride and butanediol can be used to prepare high-performance biodegradable plastic polybutylene succinate (PBS). The 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 the increasing environmental awareness of the public and the gradual implementation of my country's "plastic ban," biodegradable materials will be widely promoted and used, and high-performance PBS-type biodegradable plastic products will become increasingly popular. However, my country's succinic anhydride production technology is immature and has not yet achieved large-scale industrial production, which seriously restricts the healthy development of the PBS industry. my country's maleic anhydride production technology is mature and has achieved large-scale industrial production with an annual capacity exceeding 2 million tons. Therefore, using maleic anhydride as a raw material to produce succinic anhydride through directed hydrogenation is considered the best process route to meet the future demand for succinic anhydride in biodegradable plastics (PBS), with broad market prospects. However, currently, Chinese companies mainly use the energy-intensive maleic anhydride electrolysis method to produce succinic anhydride, which 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, highly efficient processes for the directional hydrogenation of maleic anhydride to produce succinic anhydride. Due to the high melting point (120°C) and the tendency of succinic anhydride vapor to sublimate, most currently developed catalytic hydrogenation processes for maleic anhydride to succinic anhydride employ a liquid-phase solvent method. This involves dissolving maleic anhydride in an organic solvent and then performing hydrogenation-separation to obtain succinic anhydride. For example, Chinese patent CN1453066 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 utilizes a nickel-based catalyst to achieve a maleic anhydride conversion rate greater than 99.7% and a succinic anhydride selectivity greater than 99%. Chinese patent CN102311332 discloses a method using γ-butyrolactone as a solvent and a 5wt%Pd2wt%Fe / C catalyst, with continuous reaction at 70℃ and 1.5MPa hydrogen pressure in a fixed-bed reactor for 300h, achieving 100% maleic anhydride conversion and 99.2% succinic anhydride selectivity. This patent uses an Fe / C catalyst to achieve efficient conversion of maleic anhydride, but still employs γ-butyrolactone as a solvent.

[0005] Therefore, most of the currently developed processes for the directional hydrogenation of maleic anhydride to produce succinic anhydride use expensive organic solvents, such as γ-butyrolactone and tetrahydrofuran. Furthermore, to overcome the mass transfer resistance of hydrogen in the solvent, the hydrogenation reaction needs to be carried out at a relatively high pressure (2-3 MPa). The use of high-pressure hydrogenation equipment and expensive organic solvents significantly increases the investment and production costs of the hydrogenation process for producing succinic anhydride. Summary of the Invention

[0006] To address the aforementioned problems in the prior art, this invention provides a method and apparatus for producing succinic anhydride through atmospheric pressure gas-phase hydrogenation of maleic anhydride without solvents. The method of this invention avoids the use of expensive organic solvents and allows for hydrogenation to be carried out at atmospheric pressure to obtain succinic anhydride, eliminating the need for high-pressure hydrogenation equipment and significantly reducing investment costs. Furthermore, this invention develops a circulating hydrogen scrubbing system and other devices, completely preventing the sublimation and blockage of the product succinic anhydride in the reactor pipelines and hydrogen circulation compressor, enabling long-term stable operation.

[0007] Specifically, the present invention is achieved through the following technical solutions:

[0008] In a first aspect, the present invention provides a method for producing succinic anhydride by solvent-free atmospheric pressure gas-phase hydrogenation of maleic anhydride, the method comprising the following steps:

[0009] (1) The raw material maleic anhydride is preheated and then vaporized and thoroughly mixed with hydrogen.

[0010] (2) The above-mentioned uniformly mixed maleic anhydride and hydrogen are injected into the hydrogenation reactor, and a double bond hydrogenation reaction occurs under the action of the hydrogenation catalyst to obtain the reaction product.

[0011] (3) After heat exchange, the reaction products are separated into gas and liquid to obtain crude succinic anhydride and recycled hydrogen.

[0012] (4) The crude succinic anhydride is fractionally distilled to obtain refined succinic anhydride and its by-products;

[0013] (5) Wash the circulating hydrogen to remove the uncondensed succinic anhydride and obtain hydrogen. Preferably, all the hydrogen is returned to step (1) for recycling.

[0014] The preheating temperature of the raw material maleic anhydride in step (1) is 50-100℃, preferably 55-65℃;

[0015] The maleic anhydride vaporization temperature is 190-230℃, preferably 200-220℃, and the vaporization pressure is atmospheric pressure.

[0016] The molar ratio of hydrogen to maleic anhydride in step (1) is 5-50:1, preferably 10-30:1.

[0017] The conditions for the double bond hydrogenation reaction between maleic anhydride and hydrogen in step (2) are: temperature 200-300℃, preferably 230-280℃; pressure atmospheric pressure; and mass hourly space velocity (HHSV) 0.1-1.0 h⁻¹. -1 Preferably, it is 0.2-0.5h. -1 .

[0018] Preferably, the double bond hydrogenation reaction between maleic anhydride and hydrogen in step (2) is carried out in a tubular reactor; the hydrogenation catalyst is a copper-based catalyst, preferably a leaf-shaped copper silicate catalyst.

[0019] The heat exchange described in step (3) is carried out in a heat exchanger. Specifically, the outlet temperature of the heat exchanger is controlled at 120-150℃, preferably at 125-135℃.

[0020] The gas-liquid separation in step (3) is carried out in a gas-liquid separator. Specifically, the temperature of the gas-liquid separator is 120-140℃, preferably 125-135℃.

[0021] The fractionation described in step (4) is conventional fractionation in the art.

[0022] The washing described in step (5) is carried out in the succinic anhydride washing and absorption system. The washing removes a small amount of uncondensed succinic anhydride from the circulating hydrogen gas, preventing the succinic anhydride from accumulating and clogging the pipeline in subsequent systems.

[0023] The succinic anhydride washing and absorption system employs two-stage or multi-stage absorption towers connected in series. The organic solvents in the absorption towers absorb the uncondensed succinic anhydride. The organic solvents are one or two of γ-butyrolactone and tetrahydrofuran. The temperature of the absorption towers is 20-100℃, preferably 50-60℃.

[0024] In a preferred embodiment, the absorbent discharged from the subsequent absorption tower can be used as the absorbent solvent for the preceding absorption tower. When the succinic anhydride concentration in the absorbent reaches 40-60%, the absorbent is discharged and enters the absorbent solvent regeneration system to regenerate the absorbent solvent.

[0025] In a further preferred embodiment, the regeneration of the absorbed solvent is carried out by a crystallization separation method, specifically at a crystallization separation temperature of 10-30°C, preferably 20-30°C.

[0026] In a second aspect, the present invention provides an apparatus for implementing the above-described method, comprising a succinic anhydride washing and absorption system and an absorbent regeneration system. The washing and absorption system consists of two or more absorption towers connected in series. The absorbent discharged from a subsequent absorption tower can be used as the absorbent solvent for a preceding absorption tower. When the succinic anhydride concentration in the absorbent reaches 40-60%, the absorbent is discharged and enters the absorbent regeneration system to regenerate the absorbent solvent. The absorbent regeneration system includes a crystallization vessel and a separation device. The absorbent discharged from the absorption tower enters the crystallization vessel for cooling and crystallization, and then enters the separation device to separate the succinic anhydride and the absorbent.

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] (1) The solvent-free method for producing succinic anhydride by atmospheric pressure directional hydrogenation of maleic anhydride developed in this invention can operate stably under atmospheric pressure, avoid the use of high-pressure equipment, significantly reduce the investment cost of preparing succinic anhydride by hydrogenation of maleic anhydride, and also avoid the use of large amounts of expensive organic solvents, resulting in low separation cost and thus significantly reducing production cost.

[0029] (2) The method for producing succinic anhydride by solvent-free atmospheric pressure directional hydrogenation of maleic anhydride developed in this invention has a maleic anhydride conversion rate of greater than 97% and a succinic anhydride selectivity of greater than 97%.

[0030] (3) The method and apparatus for producing succinic anhydride by solvent-free maleic anhydride under normal pressure and directional hydrogenation developed in this invention can effectively avoid the condensation of succinic anhydride and blockage of pipelines and compressors, and can achieve long-term stable operation.

[0031] Other features and advantages of the present invention will be described in the following detailed description section, but are not limited thereto. Attached Figure Description

[0032] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0033] Figure 1 This is a schematic diagram of the process for producing succinic anhydride from maleic anhydride by atmospheric pressure gas-phase hydrogenation according to the present invention.

[0034] The following are explanations of the reference numerals in the attached diagram: 1 Liquid raw material, 2 Vaporizer, 3 Reactor, 4 Heat exchanger, 5 Gas-liquid separator, 6 Absorber I, 7 Absorber II, 8 Cooling crystallization.

[0035] The dashed line indicates the gas flow direction, and the solid line indicates the reactant flow direction; the circulating liquid between absorber I and absorber II is the absorption medium (such as γ-butyrolactone or a γ-butyrolactone solution containing succinic anhydride). Detailed Implementation

[0036] The specific embodiments of the present invention will be described in detail below. The specific embodiments described herein are for illustration and explanation only, and are not intended to limit the present invention.

[0037] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field, or in accordance with the product instructions. Reagents, materials, or instruments whose manufacturers are not specified are all conventional products that can be purchased through legitimate channels.

[0038] The following combination Figure 1 The method for producing succinic anhydride by solvent-free maleic anhydride gas-phase hydrogenation at atmospheric pressure according to the present invention will be further described.

[0039] like Figure 1 As shown, maleic anhydride, the reactant, is preheated to 60-100℃ and then reacted with hydrogen at a hydrogen /

[0040] Maleic anhydride is mixed in a molar ratio of 5-50:1 and then vaporized in a vaporizer at a temperature of 190-230℃ and a pressure of atmospheric pressure. After the maleic anhydride is vaporized and thoroughly mixed with hydrogen, it enters a tubular hydrogenation reactor filled with a copper-based hydrogenation catalyst. The reactor temperature is maintained at 200-300℃, the pressure at atmospheric pressure, and the weight hourly space velocity (WHSV) is 0.2-0.5 h⁻¹. -1Under certain conditions, a hydrogenation reaction is carried out to obtain the reaction product. The reaction product is then fed into a heat exchanger for heat exchange, with the outlet temperature controlled at 120-150℃. After heat exchange, the product enters a gas-liquid separator, with the temperature controlled at 120-140℃, to obtain crude succinic anhydride and circulating hydrogen. The crude succinic anhydride is fractionated to obtain refined succinic anhydride and its byproducts. The circulating hydrogen enters a succinic anhydride washing and absorption system for two-stage or multi-stage absorption and separation to remove a small amount of uncondensed succinic anhydride from the circulating hydrogen, preventing succinic anhydride from accumulating and clogging pipelines in subsequent systems. All the circulating hydrogen after washing and removing the succinic anhydride is returned to the vaporizer in step (1) for recycling.

[0041] The apparatus for implementing the above method includes a succinic anhydride washing and absorption system and an absorbent regeneration system. The washing and absorption system consists of two or more absorption towers connected in series. The absorbent discharged from the subsequent absorption tower can be used as the absorbent solvent for the preceding absorption tower. When the succinic anhydride concentration in the absorbent reaches 40-60%, the absorbent is discharged and enters the absorbent regeneration system to regenerate the absorbent solvent. The absorbent regeneration system includes a crystallization vessel and a separation device. The absorbent discharged from the absorption tower enters the crystallization vessel for cooling and crystallization, and then enters the separation device to separate the succinic anhydride and the absorbent.

[0042] Example 1

[0043] This embodiment uses maleic anhydride as the reaction feed and foliated copper silicate as the catalyst. The specific process is as follows:

[0044] The maleic anhydride feedstock was preheated to 60°C and then pumped into a vaporizer (2) for vaporization and uniform mixing with circulating hydrogen. The vaporizer temperature was 200°C, the vaporizer pressure was atmospheric pressure, and the hydrogen / maleic anhydride molar ratio was 20. After the maleic anhydride feedstock was vaporized and thoroughly mixed with hydrogen, it entered the hydrogenation reactor (3), which was filled with a leaf-shaped copper silicate catalyst. The hydrogenation reactor temperature was 270°C, the hydrogenation reactor pressure was atmospheric pressure, and the weight hourly space velocity (WHSV) was 0.2 h⁻¹. -1 The hydrogenation reaction product enters heat exchanger (4) for heat exchange, with an outlet temperature of 125°C. After heat exchange, it enters gas-liquid separator (5) at a temperature of 125°C. The maleic anhydride hydrogenation product, succinic anhydride, is discharged through the gas-liquid separator. The recycled hydrogen gas after washing and removing succinic anhydride is compressed by a hydrogen recycling compressor and returned to the vaporizer for reuse. Samples are taken from the gas-liquid separator for analysis every 24 hours of reaction operation.

[0045] Example 1: Using the maleic anhydride gas-phase atmospheric pressure hydrogenation process of this invention, the circulating hydrogen undergoes heat exchange with condensate, followed by washing through a two-stage succinic anhydride washing and absorption system, and finally returns to the vaporizer (2) after compression by the hydrogen circulation compressor. Stable operation for 1000 hours showed no blockage in the pipelines or the hydrogen circulation compressor. At 270°C, atmospheric pressure, and a weight hourly space velocity of 0.2 h⁻¹. -1 Under the given conditions, maleic anhydride conversion was 100%, and succinic anhydride selectivity was greater than 99%. The reaction results are shown in Table 1.

[0046] Example 2

[0047] This embodiment uses maleic anhydride as the reaction feed and foliated copper silicate as the catalyst. The specific process is as follows:

[0048] The maleic anhydride feedstock was preheated to 80°C and then pumped into a vaporizer (2) for vaporization and uniform mixing with circulating hydrogen. The vaporizer temperature was 200°C, the vaporizer pressure was atmospheric pressure, and the hydrogen / maleic anhydride molar ratio was 30. After the maleic anhydride feedstock was vaporized and thoroughly mixed with hydrogen, it entered the hydrogenation reactor (3), which was filled with a leaf-shaped copper silicate catalyst. The hydrogenation reactor temperature was 260°C, the hydrogenation reactor pressure was atmospheric pressure, and the weight hourly space velocity (WHSV) was 0.2 h⁻¹. -1 The hydrogenation reaction product enters heat exchanger (4) for heat exchange, with an outlet temperature of 125°C. After heat exchange, it enters gas-liquid separator (5) at a temperature of 125°C. The maleic anhydride hydrogenation product, succinic anhydride, is discharged through the gas-liquid separator. The recycled hydrogen gas after washing and removing succinic anhydride is compressed by a hydrogen recycling compressor and returned to the vaporizer for reuse. Samples are taken from the gas-liquid separator for analysis every 24 hours of reaction operation.

[0049] Example 2: Using the maleic anhydride gas-phase atmospheric pressure hydrogenation process of this invention, the circulating hydrogen undergoes heat exchange with condensate, followed by washing through a two-stage succinic anhydride washing and absorption system, and finally returns to the vaporizer (2) after compression by the hydrogen circulation compressor. Stable operation for over 500 hours was observed, with no blockages found in the pipelines or the hydrogen circulation compressor. At 260°C, atmospheric pressure, and a weight hourly space velocity of 0.2 h⁻¹. -1 Under the given conditions, the maleic anhydride conversion rate was 98.7%, and the succinic anhydride selectivity was greater than 97%. The reaction results are shown in Table 1.

[0050] Example 3

[0051] This embodiment uses maleic anhydride as the reaction feed and foliated copper silicate as the catalyst. The specific process is as follows:

[0052] The maleic anhydride feedstock was preheated to 100°C and then pumped into a vaporizer (2) for vaporization and uniform mixing with circulating hydrogen. The vaporizer temperature was 200°C, the vaporizer pressure was atmospheric pressure, and the hydrogen / maleic anhydride molar ratio was 50. After the maleic anhydride feedstock was vaporized and thoroughly mixed with hydrogen, it entered the hydrogenation reactor (3), which was filled with a leaf-shaped copper silicate catalyst. The hydrogenation reactor temperature was 250°C, the hydrogenation reactor pressure was atmospheric pressure, and the weight hourly space velocity (WHSV) was 0.2 h⁻¹. -1 The hydrogenation reaction product enters heat exchanger (4) for heat exchange, with an outlet temperature of 125°C. After heat exchange, it enters gas-liquid separator (5) at a temperature of 125°C. The maleic anhydride hydrogenation product, succinic anhydride, is discharged through the gas-liquid separator. The recycled hydrogen gas after washing and removing succinic anhydride is compressed by a hydrogen recycling compressor and returned to the vaporizer for reuse. Samples are taken from the gas-liquid separator for analysis every 24 hours of reaction operation.

[0053] Example 3: Using the maleic anhydride gas-phase atmospheric pressure hydrogenation process of this invention, the circulating hydrogen undergoes heat exchange with condensate, followed by washing through a first-stage succinic anhydride washing and absorption system, and finally returns to the vaporizer (2) after compression by the hydrogen circulation compressor. Stable operation for over 500 hours was observed, with no blockages found in the pipelines or the hydrogen circulation compressor. At 250°C, atmospheric pressure, and a weight hourly space velocity of 0.2 h⁻¹. -1 Under the given conditions, the maleic anhydride conversion rate was 97.4%, and the succinic anhydride selectivity was greater than 97%. The reaction results are shown in Table 1.

[0054] Comparative Example 1

[0055] This comparative example uses maleic anhydride as the reaction feed and foliated copper silicate as the catalyst. The specific process is as follows:

[0056] The maleic anhydride feedstock was preheated to 60°C and then pumped into a vaporizer (2) for vaporization and uniform mixing with circulating hydrogen. The vaporizer temperature was 200°C, the vaporizer pressure was atmospheric pressure, and the hydrogen / maleic anhydride molar ratio was 30. After the maleic anhydride feedstock was vaporized and thoroughly mixed with hydrogen, it entered the hydrogenation reactor (3), which was filled with a leaf-shaped copper silicate catalyst. The hydrogenation reactor temperature was 230°C, the hydrogenation reactor pressure was atmospheric pressure, and the weight hourly space velocity (WHSV) was 0.2 h⁻¹. -1 The hydrogenation reaction products enter heat exchanger (4) for heat exchange, with an outlet temperature of 125°C. After heat exchange, they enter gas-liquid separator (5) at a temperature of 125°C. The maleic anhydride hydrogenation product, succinic anhydride, is discharged through the gas-liquid separator. The circulating hydrogen obtained from the gas-liquid separation is compressed by a hydrogen circulation compressor and returned to the vaporizer for reuse. The hydrogen consumed during the hydrogenation process is replenished through the outlet of the hydrogen circulation compressor. Samples are taken from the gas-liquid separator for analysis every 24 hours of reaction operation.

[0057] In this comparative example, due to the use of a traditional maleic anhydride gas-phase atmospheric pressure hydrogenation process, the circulating hydrogen, after heat exchange with condensate, is directly compressed by the hydrogen circulation compressor and returned to the vaporizer (2) without being washed by the succinic anhydride washing and absorption system. After 72 hours of operation, the pipeline and the hydrogen circulation compressor became blocked, forcing the system to stop. A large amount of white solid was found at the blockage points in the pipeline and the hydrogen circulation compressor. Analysis revealed that the white solid was succinic anhydride. This may be due to the condensation and accumulation of a small amount of uncondensed succinic anhydride in the circulating hydrogen in the pipeline. At 230°C, atmospheric pressure, and a weight hourly space velocity of 0.2 h⁻¹, the hydrogen was tested. -1 Under the given conditions, the maleic anhydride conversion rate was 93.3%, and the succinic anhydride selectivity was greater than 97%. The reaction results are shown in Table 1.

[0058] Table 1: Results of the directed catalytic hydrogenation of maleic anhydride to prepare succinic anhydride

[0059]

[0060] Reaction conversion rate (%) = (moles of reactants converted / moles of reactants in the raw materials) × 100%.

[0061] Product selectivity (%) = (moles of a certain product generated / reactants converted)

[0062] (Number of moles) × 100%.

[0063] As can be seen from the above examples and comparative examples, in the atmospheric pressure reaction of maleic anhydride gas-phase hydrogenation, the succinic anhydride washing and absorption system effectively solves the problem of system blockage caused by the sublimation of succinic anhydride, greatly improves the system's operating life, and ensures stable reaction operation.

[0064] Obviously, the above embodiments are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make various modifications and variations to the present invention without departing from the spirit and scope of the invention. Therefore, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention also intends to include these modifications and variations.

Claims

1. A method for producing succinic anhydride by solvent-free atmospheric pressure gas-phase hydrogenation of maleic anhydride, characterized in that, Includes the following steps: (1) The raw material maleic anhydride is preheated and then vaporized and thoroughly mixed with hydrogen; (2) Inject the homogeneous maleic anhydride and hydrogen gas from step (1) into the hydrogenation reactor, and the double bond hydrogenation reaction occurs under the action of the hydrogenation catalyst to obtain the reaction product; (3) After heat exchange, the reaction product obtained in step (2) is separated into gas and liquid to obtain crude succinic anhydride and recycled hydrogen. (4) The crude succinic anhydride obtained in step (3) is fractionated to obtain refined succinic anhydride and its by-products; (5) Wash the circulating hydrogen obtained in step (3) to remove the uncondensed succinic anhydride and obtain hydrogen. Return all the hydrogen to step (1) for recycling. In step (5), the washing is carried out in a succinic anhydride washing and absorption system to remove a small amount of uncondensed succinic anhydride from the circulating hydrogen gas. The succinic anhydride washing and absorption system uses two-stage or multi-stage absorption towers connected in series. The organic solvent in the absorption tower absorbs the uncondensed succinic anhydride. The organic solvent is one or two of γ-butyrolactone and tetrahydrofuran. The temperature of the absorption tower is 20-100℃.

2. The method according to claim 1, characterized in that, In step (1), the preheating temperature of the raw material maleic anhydride is 50-100℃; the vaporization temperature of the maleic anhydride is 190-230℃; the vaporization pressure is atmospheric pressure; and the molar ratio of hydrogen to maleic anhydride is 5-50:

1.

3. The method according to claim 2, characterized in that, In step (1), the preheating temperature of the raw material maleic anhydride is 55-65℃; the vaporization temperature of the maleic anhydride is 200-220℃; and the molar ratio of hydrogen to maleic anhydride is 10-30:

1.

4. The method according to claim 1, characterized in that, In step (2), the conditions for the double bond hydrogenation reaction between maleic anhydride and hydrogen are: temperature 200-300℃; pressure atmospheric pressure; and mass hourly space velocity (HHSV) 0.1-1.0 h⁻¹. -1 .

5. The method according to claim 4, characterized in that, In step (2), the conditions for the double bond hydrogenation reaction between maleic anhydride and hydrogen are: a temperature of 230-280℃ and a mass hourly space velocity of 0.2-0.5 h⁻¹. -1 .

6. The method according to claim 4 or 5, characterized in that, In step (2), the double bond hydrogenation reaction between maleic anhydride and hydrogen is carried out in a tubular reactor; the hydrogenation catalyst is a copper-based catalyst.

7. The method according to claim 6, characterized in that, The hydrogenation catalyst is a leaf-shaped copper silicate catalyst.

8. The method according to claim 1, characterized in that, In step (3), the heat exchange is carried out in a heat exchanger, and the outlet temperature of the heat exchanger is controlled at 120-150℃; the gas-liquid separation is carried out in a gas-liquid separator, and the temperature of the gas-liquid separator is 120-140℃.

9. The method according to claim 8, characterized in that, In step (3), the outlet temperature of the heat exchanger is controlled at 125-135℃; the temperature of the gas-liquid separator is 125-135℃.

10. The method according to claim 1, characterized in that, In step (5), the temperature of the absorption tower is 50-60℃.

11. The method according to claim 1 or 10, characterized in that, In step (5), the absorbent discharged from the next stage absorber can be used as the absorbent solvent of the previous stage absorber. When the succinic anhydride in the absorbent reaches a concentration of 40-60%, the absorbent is discharged and enters the absorbent solvent regeneration system to regenerate the absorbent solvent.

12. The method according to claim 11, characterized in that, The regeneration of the absorbent solvent is carried out by crystallization separation at a temperature of 10-30℃.

13. The method according to claim 12, characterized in that, The crystallization separation temperature is 20-30℃.

14. An apparatus for carrying out the method of claim 1, characterized in that, The apparatus includes a succinic anhydride washing and absorption system and an absorbent regeneration system. The washing and absorption system consists of two or more absorption towers connected in series. The absorbent discharged from the later absorption tower can be used as the absorbent solvent for the earlier absorption tower. When the succinic anhydride concentration in the absorbent reaches 40-60%, the absorbent is discharged and enters the absorbent regeneration system to regenerate the absorbent solvent. The absorbent regeneration system includes a crystallization kettle and a separation device. The absorbent discharged from the absorption tower enters the crystallization kettle for cooling and crystallization, and then enters the separation device to separate the succinic anhydride and the absorbent.

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