Hydrogenation reaction system and maleic anhydride hydrogenation method

Abstract

The application discloses a hydrogenation reaction system and a maleic anhydride hydrogenation method. The hydrogenation reaction system comprises a reactor I and a reactor II. The reactor I comprises a barrel I and a center pipe I, the center pipe I is provided with a hole in the pipe wall, and the barrel I and the center pipe I are communicated through the hole. The reactor II comprises a barrel II and a built-in center pipe II, the center pipe II is provided with a hole in the pipe wall, and the barrel II and the center pipe II are communicated through the hole. The maleic anhydride hydrogenation method is that a mixture of maleic anhydride solution and hydrogen is sequentially subjected to hydrogenation reaction in the reactor I and the reactor II, and then butane diacid anhydride products are obtained through gas-liquid separation. The system can effectively control the reaction rate and temperature rise of the maleic anhydride hydrogenation reaction process, solves the problems of concentrated heat release and easy generation of local hot spots in the maleic anhydride hydrogenation reaction process, and improves the conversion rate and selectivity of the maleic anhydride hydrogenation process.

Description

Technical Field

[0001] This invention belongs to the field of succinic anhydride production technology, specifically relating to a hydrogenation reaction system and a method for hydrogenating maleic anhydride. Background Technology

[0002] Currently, the main methods for producing succinic anhydride are succinic acid dehydration, bio-fermentation, and maleic anhydride catalytic hydrogenation. Among them, maleic anhydride catalytic hydrogenation has the highest conversion rate and the best product quality, making it most suitable for large-scale industrialization. However, the production of succinic anhydride by maleic anhydride hydrogenation is a strongly exothermic reaction (ΔH = 128 kJ / mol). Conventional trickle bed hydrogenation and conventional liquid phase hydrogenation industrial reactor structures make it difficult to remove the heat of reaction in time, resulting in uncontrollable temperature during the reaction process. This leads to problems such as local hot spots in the catalyst bed, severe side reactions, and catalyst bed caking, making it difficult to balance the conversion rate and selectivity of the reaction process, and even more difficult to achieve a high selectivity.

[0003] CN103570650A proposes a process for the continuous production of succinic anhydride and succinic acid from maleic anhydride via hydrogenation. This method employs a two-stage hydrogenation reactor. The first-stage reactor is a fixed-bed reactor where hydrogen and the reaction liquid flow from bottom to top. The second-stage reactor is a trickle-bed reactor where both hydrogen and the reaction liquid flow from top to bottom, utilizing external circulation to remove heat and control the average operating temperature of the entire reactor, ensuring temperature uniformity. However, the first-stage reactor uses a co-current upward flow of hydrogen and the reaction liquid. Due to the high exothermic nature of the maleic anhydride hydrogenation reaction, conventional techniques cannot guarantee uniform mixing and distribution of materials, thus failing to ensure uniform reaction and address localized hot spots. Furthermore, the second-stage reactor uses a co-current downward flow of a trickle-bed reactor, which further hinders the timely removal of reaction heat and the resolution of localized hot spots.

[0004] CN 105801536B proposes a method for preparing succinic anhydride by liquid-phase selective hydrogenation of maleic anhydride. The liquid-phase hydrogenation reaction employs a two-stage low-temperature, low-pressure reaction process using two reactors: a primary reactor and a secondary reactor, connected in series. Maleic anhydride, solvent, and hydrogen enter the primary reactor for partial catalytic selective hydrogenation. After the reaction, the remaining maleic anhydride, the generated succinic anhydride, and the solvent mixture enter the secondary reactor for complete catalytic selective hydrogenation. The product from the secondary reactor is then subjected to gas-liquid separation and distillation to obtain the succinic anhydride product. However, this method uses a two-stage reactor with liquid-phase hydrogenation of the reaction liquid. Due to the high exothermic nature of the maleic anhydride hydrogenation reaction, conventional liquid-phase hydrogenation mixing and reaction techniques cannot guarantee uniform mixing and distribution of the materials, nor can they ensure uniform reaction or address localized hot spots. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention discloses a hydrogenation reaction system and a method for hydrogenating maleic anhydride. The system of this invention can effectively control the reaction rate and temperature rise during the maleic anhydride hydrogenation reaction, solving the problems of concentrated exothermic reaction and the easy generation of local hot spots, thereby improving the conversion rate and selectivity of the maleic anhydride hydrogenation process.

[0006] The hydrogenation reaction system of the present invention includes reactor I and reactor II; Reactor I includes a cylindrical body I and a built-in central tube I, which are coaxially arranged. The central tube I has a hole in its wall, and the cylindrical body I and the central tube I are connected through the hole. The annular area between the cylindrical body I and the central tube I is the reaction zone I. The bottom of the central tube I is provided with a feed inlet I, and the top of the cylindrical body I is provided with a discharge outlet I. The central tube I may have the same or different size as the feed inlet I. Reactor II includes a cylindrical body II and a built-in central tube II, which are coaxially arranged. The central tube II has an opening in its wall, and the cylindrical body II and the central tube II are connected through the opening. The annular area between the cylindrical body II and the central tube II is the reaction zone II. The bottom of the cylindrical body II is provided with a feed inlet II, and the top of the central tube II is provided with a discharge outlet II. The central tube I may have the same or different size as the feed inlet I. The feed inlet I is connected to the feed pipeline, and the discharge outlet I is connected to the feed inlet II through a pipeline.

[0007] In the hydrogenation reaction system of the present invention, the height-to-diameter ratio of reactor I is 2 to 20, preferably 3 to 8, and the height-to-diameter ratio of reactor II is 0.5 to 5, preferably 0.5 to 3.0; the volume ratio of reactor I to reactor II is 1:1.1 to 1:10, preferably 1:1.5 to 1:5.

[0008] In the hydrogenation reaction system of the present invention, the diameter ratio of the central tube to the cylinder is 1:2 to 1:200.

[0009] In the hydrogenation reaction system of the present invention, a portion of the surface of the central tube I is perforated, with the perforation extending from the bottom of the central tube I to 1 / 2 to 4 / 5 of its axial length (the bottom being the starting point of the axial length); the size of the perforation on the surface of the central tube I is generally 1 mm to 100 mm; the area of ​​the perforation on the surface of the central tube I is not less than the cross-sectional area of ​​the inlet I; a portion of the surface of the central tube II is perforated, with the perforation extending from the top of the central tube II to 1 / 2 to 4 / 5 of its axial length (the top being the starting point of the axial length); the size of the perforation on the surface of the central tube II is generally 1 mm to 100 mm; the area of ​​the perforation on the surface of the central tube II is not less than the cross-sectional area of ​​the outlet II; generally, the perforation areas of the central tubes I and II are the same.

[0010] In the hydrogenation reaction system of the present invention, the top of the outer shell of the reactor (reactor I and II) is an upper end cap and the bottom is a lower end cap. The center position of the inner wall of the upper end cap and the center position of the inner wall of the lower end cap are fixedly welded along the reactor axis to a central tube (central tube I and II).

[0011] In the hydrogenation reaction system of the present invention, reactors I and II are filled with hydrogenation catalysts commonly used in the art; the type of catalyst can be set as needed, and can be the same or different; the number of catalyst beds can also be set as needed.

[0012] The hydrogenation reaction system of this invention further includes a raw material mixing device for mixing liquid-phase raw materials and hydrogen gas. This device can be any equipment with liquid-liquid and / or gas-liquid mixing capabilities, such as a static mixer, dissolved gas pump, mechanical stirring equipment, colloid mill, microporous plate nano / micro hydrogen dispersion assembly, microbubble generator, ceramic membrane nano / micro hydrogen dispersion assembly, or microchannel mixer. The raw material mixing device is generally located before the reactor inlet. For example, it can be used to mix the liquid-phase raw materials (maleic anhydride and solvent) and hydrogen gas in a maleic anhydride hydrogenation reaction.

[0013] The hydrogenation reaction system of the present invention further includes a heat extraction device for extracting heat from the effluent of reactor I and for exchanging heat from the feed of reactor II to the required reaction temperature of the material, such as a heat exchanger or a water cooler.

[0014] The hydrogenation reaction system of the present invention further includes a supplementary hydrogen pipeline, which is generally directly connected to the raw material mixing equipment to provide the hydrogen required for the hydrogenation reaction in reactor II.

[0015] The hydrogenation reaction system of the present invention further includes a gas-liquid separation device for separating the effluents of reactors I and II into gas and liquid phases. This is generally accomplished by a gas-liquid separation tank, in which gas is separated from the top and liquid phase products are obtained from the bottom.

[0016] The maleic anhydride hydrogenation method of the present invention includes the following: (1) The mixture of maleic anhydride solution and hydrogen is used as the first mixed feed into the central tube I of reactor I through the feed port I. It diffuses into the cylinder I filled with hydrogenation catalyst through the opening on the wall of the central tube I, and the first-stage hydrogenation reaction occurs from bottom to top. The effluent of the first-stage hydrogenation reaction leaves reactor I through the discharge port I. (2) The mixture of the primary hydrogenation reaction effluent and the supplementary hydrogen is used as the second mixed feed into the cylinder II filled with hydrogenation catalyst through the feed port II of reactor II. The secondary hydrogenation reaction occurs from bottom to top. After the reaction is completed, the secondary hydrogenation reaction effluent diffuses into the central tube II through the opening on the tube wall of the central tube II, and leaves reactor II through the discharge port II. After gas-liquid separation, succinic anhydride product is obtained.

[0017] In the method of the present invention, the first mixed feed in step (1) is a liquid material with hydrogen as the dispersed phase and maleic anhydride solution as the continuous phase; the dispersion size of hydrogen is generally 100nm~1000μm, preferably 50μm~600μm; one or more of the following mixing equipment are generally used: static mixer, dissolved gas pump, mechanical stirring equipment, colloid mill, microporous plate nano / micro hydrogen dispersion component, microbubble generator, ceramic membrane nano / micro hydrogen dispersion component, microchannel mixer, etc.

[0018] In the method of the present invention, the solvent in step (1) is selected from one or more of benzene, toluene, xylene, acetone, tetrahydrofuran, γ-butyrolactone, methyl acetone, cyclohexanone, ethyl acetate, diethyl succinate or ethylene glycol monomethyl ether; the concentration of maleic anhydride solution is generally 0.03 to 0.3 g / mL, preferably 0.05 to 0.15 g / mL.

[0019] In the method of the present invention, the hydrogen gas used is generally hydrogen gas with a purity greater than 90 (v)%, and preferably 99.9% pure hydrogen.

[0020] In the method of the present invention, the outer surfaces of the central tubes I and II are wrapped with one or more layers of wire mesh to prevent catalyst particles from leaking out along the openings on the surface of the central tubes. The mesh aperture is generally smaller than the nominal diameter of the minimum cross-section of the catalyst particles.

[0021] In the method of this invention, hydrogen (Nm2) is produced in reactors (I and II). 3 / h) and fresh ingredients (m 3 The volumetric flow rate ratio of maleic anhydride to solvent (sum of maleic anhydride and solvent) is 5:1 to 100:1, preferably 10:1 to 60:1.

[0022] In the method of this invention, the hydrogenation reaction conditions in reactor I are as follows: reaction temperature is 40–200°C, preferably 50–90°C; reaction pressure is generally 0.5–10.0 MPa, preferably 1–5.0 MPa; and liquid hourly space velocity is generally 1–20.0 h⁻¹. -1 Preferably 3.0~10.0h -1 .

[0023] In the method of this invention, the hydrogenation reaction conditions in reactor II are as follows: the reaction temperature is generally 40–100°C, preferably 50–70°C; the reaction pressure is generally 0.5–10.0 MPa, preferably 1–5.0 MPa; and the liquid hourly space velocity is generally 0.1–5.0 h⁻¹. -1 Preferably 0.5–3.0 h -1 .

[0024] In the method of the present invention, the sum of the maleic anhydride hydrogenation reaction conversion rates of reactors I and II is 100%, wherein the maleic anhydride hydrogenation reaction conversion rate of reactor I is generally 10% to 99%, preferably 50% to 95%, and the maleic anhydride hydrogenation reaction conversion rate of reactor II is generally 1% to 90%, preferably 5% to 50%, and the maleic anhydride hydrogenation reaction conversion rate of reactor I is higher than that of reactor II.

[0025] In the method of the present invention, the hydrogenation catalyst is preferably a supported nickel-based catalyst, wherein the catalyst support can be one or more of SiO2, Al2O3, SiO2-Al2O3, TiO2, activated carbon or molecular sieve, etc.; the catalyst shape can be one of spherical, strip-shaped, clover-shaped, toothed spherical, etc., preferably spherical or toothed spherical catalyst.

[0026] In the method of the present invention, the liquid material obtained by gas-liquid separation can be partially recycled back to reactors I and II, and part of the material can be sent to the subsequent succinic anhydride product fractionation unit, or it can be sent entirely to the subsequent succinic anhydride product fractionation unit without recycling. If the reaction product is partially recycled, the recycled material recycled back to reactor I accounts for 5 to 80 wt% of the fresh material at the inlet of reactor I, preferably 10 to 30 wt%; the recycled material recycled back to reactor II accounts for 1 to 30 wt% of the fresh material at the inlet of reactor I, preferably 5 to 20 wt%.

[0027] In the method of this invention, the material in reactor I is the material in the early stage of the maleic anhydride hydrogenation reaction. Due to the high concentration of maleic anhydride and the fast reaction rate, it is very easy to cause problems such as concentrated exothermic reaction and local hot spots. This leads to problems such as local catalyst coking and severe side reactions in the reactor, and uneven reaction in the upper and lower parts along the axis of the reactor, that is, the heat of reaction is concentrated in the lower part. Since the material in reactor II is the material in the later stage of the reaction, the concentration of maleic anhydride is low, the reaction rate is slow, and the mass transfer driving force is small. Therefore, a slightly lower space velocity is required to achieve complete conversion of maleic anhydride, which makes it more likely to cause problems such as long local residence time and more side reactions. In this invention, reactor I includes a central tube I. The reactants diffuse from the openings on the surface of the central tube I into the catalyst bed. On one hand, the residence time of the material on the catalyst surface at different locations can be controlled by adjusting parameters such as the opening area and position of the central tube I, thus effectively controlling the reaction process. On the other hand, after the material diffuses into the catalyst through the central tube I, it experiences both radial and axial flow within reactor I, resulting in a more uniform reaction, reduced local hot spots, and improved heat uniformity. Furthermore, the high space velocity and upflow micro-expanded bed flow within reactor I help alleviate problems such as local hot spots and catalyst coking, further facilitating long-term, high-efficiency operation. In the structure of reactor II, a reactor containing a central tube II is incorporated. The reactants diffuse from the catalyst bed through a central hole on the outside of the central tube II into and exit the central tube II. This allows for control of parameters such as the opening area and height of the central tube II, controlling the residence time of the material on the catalyst surface at different locations within reactor II. This achieves both complete and efficient conversion of maleic anhydride and effective control of deep side reactions. Furthermore, the gradual diffusion of the material from the catalyst bed to the central tube II before exiting the reactor, along with the simultaneous radial and axial flow within reactor II, promotes uniform reaction intensity and temperature distribution along both axes, reducing side reactions. Note: The early reaction stage, as described in this article, refers to the phase where the maleic anhydride concentration in the maleic anhydride solution within the reactor is greater than or equal to the succinic anhydride concentration. The later reaction stage refers to the phase where the maleic anhydride concentration in the maleic anhydride solution within the reactor is less than the succinic anhydride concentration. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of a hydrogenation reaction system and a maleic anhydride hydrogenation method according to the present invention.

[0029] Wherein, 1 is maleic anhydride solution, 2 is hydrogen, 3 is mixer, 4 is feed to maleic anhydride hydrogenation reaction system, 5 is reactor I, 6 is central tube I, 7 is annular region I, 8 is an opening on central tube I, 9 is catalyst bed I, 10 is reaction discharge from reactor I, 11 is heat exchanger, 12 is hydrogen, 13 is mixer, 14 is reaction feed to reactor II, 15 is reactor II, 16 is central tube II, 17 is annular region II, 18 is central tube II, 19 is catalyst bed II, 20 is reaction discharge from reactor II, 21 is heat exchanger, 22 is gas-liquid separator feed, 23 is gas-liquid separator, 24 is separated gas, and 25 is separated hydrogenation product. Detailed Implementation

[0030] The present invention will now be described in detail with reference to the accompanying drawings and embodiments, but this does not limit the scope of the invention.

[0031] With attachment Figure 1 The application process of the hydrogenation reaction system and maleic anhydride hydrogenation method of the present invention is illustrated by the following example: After maleic anhydride solution 1 and hydrogen gas 2 are uniformly mixed in mixer 3 to form reaction feed 4, it is first introduced into the maleic anhydride hydrogenation reaction system. It first enters the central tube 6 through the bottom of reactor I 5, and then diffuses through the opening 8 on the central tube 1 to the annular region I 7. The maleic anhydride hydrogenation reaction occurs from bottom to top in the catalyst bed I 9. After the reaction is completed, it diffuses back into the central tube I 6 and exits the reactor as reactor I effluent 10. After being cooled to a suitable temperature by heat exchanger 11, it enters mixer 13 together with hydrogen gas 12 for uniform mixing. This mixture then enters catalyst bed II 19 as feed to reactor II 15. The maleic anhydride hydrogenation reaction occurs from bottom to top in catalyst bed I 19. After the reaction is completed, it diffuses back into the central tube II 18 and exits the reactor as reactor II effluent 20. After being cooled to a suitable temperature by heat exchanger 21, it enters gas-liquid separator 23, where gas 24 and liquid product 25 are separated.

[0032] The method of this invention was applied to the hydrogenation reaction of maleic anhydride. Both the maleic anhydride feedstock and the γ-butyrolactone solvent were commercially available, and their specific properties are shown in Tables 1 and 2, respectively. The catalyst properties are shown in Table 3.

[0033] Table 1 Properties of maleic anhydride raw materials Table 2. Solvent properties of γ-butyrolactone Table 3 Physicochemical properties of catalysts Comparative Example 1 A conventional fixed-bed hydrogenation process is employed, using two upflow hydrogenation reactors connected in series. Maleic anhydride undergoes hydrogenation in the first and second reactors sequentially. First, the maleic anhydride feedstock is dissolved in γ-butyrolactone solvent and mixed thoroughly to prepare a maleic anhydride solution. After being heated to the reactor inlet temperature, this solution is mixed with hydrogen and enters from the bottom of the upflow hydrogenation reactor, undergoing hydrogenation from bottom to top through the catalyst bed. The resulting hydrogenated product is then heated again and mixed with supplemental hydrogen before entering from the bottom of the second upflow hydrogenation reactor, undergoing hydrogenation from bottom to top through the catalyst bed. After the hydrogenation reaction is complete, the product leaves the reactor and undergoes gas-liquid separation in a separator. Part of the separated material is recycled, while the other part enters the separation unit.

[0034] The operating conditions for the first hydrogenation reactor are as follows: The reactor inlet temperature is 50℃; The reaction pressure is 6.0–6.5 MPaG; Reactor height-to-diameter ratio: 2.5 Volumetric hourly space velocity: 2.5 h -1 maleic anhydride concentration: 10 g / mL Hydrogen (Nm 3 / h) and fresh ingredients (m 3 The volume ratio of the solution (a solution of maleic anhydride dissolved in γ-butyrolactone solvent) is 100:1. The mass ratio of reaction products entering the primary reactor cycle to fresh feedstock is 30%. The operation of the second hydrogenation reactor is as follows: The reactor inlet temperature is 50℃; The reaction pressure is 6.0–6.5 MPaG; Volumetric hourly space velocity: 1.0 h -1 ; Reactor height-to-diameter ratio: 2.5; Hydrogen (Nm 3 / h) and fresh ingredients (m 3 The volume ratio of the solution (a solution of maleic anhydride dissolved in γ-butyrolactone solvent) is 300:1. The mass ratio of reaction products entering the second reactor cycle to fresh feedstock is 30%. Under these reaction conditions, maleic anhydride and γ-butyrolactone solvents listed in Tables 1 and 2 were used as raw materials and continuously fed into the first and second reactors to carry out hydrogenation reactions to obtain hydrogenated products. The reaction results are shown in Table 4.

[0035] Comparative Example 2 The maleic anhydride hydrogenation process employs a conventional series connection of an upflow fixed bed and a downflow trickle bed. Maleic anhydride undergoes hydrogenation sequentially in the first and second reactors. First, the maleic anhydride feedstock is dissolved in γ-butyrolactone solvent and mixed thoroughly to prepare a maleic anhydride solution. After being heated to the reactor inlet temperature, this solution is mixed with hydrogen and enters from the bottom of the upflow hydrogenation reactor, undergoing hydrogenation from bottom to top through the catalyst bed. The resulting hydrogenated product is then heated again and mixed with supplemental hydrogen before entering from the top of the downflow hydrogenation reactor, undergoing hydrogenation from top to bottom through the catalyst bed. After the hydrogenation reaction is complete, the product leaves the reactor and undergoes gas-liquid separation in a separator. Part of the separated material is recycled, while the other part enters the separation unit.

[0036] The operating conditions for the first hydrogenation reactor are as follows: The reactor inlet temperature is 50℃; The reaction pressure is 6.0–6.5 MPaG; Reactor height-to-diameter ratio: 3.0 Volumetric hourly space velocity: 3.0 h -1 maleic anhydride concentration: 10 g / mL Hydrogen (Nm 3 / h) and fresh ingredients (m 3 The volume ratio of the solution (a solution of maleic anhydride dissolved in γ-butyrolactone solvent) is 150:1. The mass ratio of reaction products entering the primary reactor cycle to fresh feedstock is 30%. The operation of the second hydrogenation reactor is as follows: The reactor inlet temperature is 50℃; The reaction pressure is 6.0–6.5 MPaG; Volumetric hourly space velocity: 1.0 h -1 ; Reactor height-to-diameter ratio: 2.5; Hydrogen (Nm 3 / h) and fresh ingredients (m 3 The volume ratio of the solution (a solution of maleic anhydride dissolved in γ-butyrolactone solvent) is 300:1. The mass ratio of reaction products entering the second reactor cycle to fresh feedstock is 30%. Under these reaction conditions, maleic anhydride and γ-butyrolactone solvents listed in Tables 1 and 2 were used as raw materials and continuously fed into the first and second reactors to carry out hydrogenation reactions to obtain hydrogenated products. The reaction results are shown in Table 4.

[0037] Example 1 Using the method of this invention, reactor I and reactor II are set up. First, a pre-prepared 15% maleic anhydride (γ-butyrolactone solvent) solution is mixed evenly with hydrogen and then enters the maleic anhydride hydrogenation system, where it undergoes hydrogenation reaction sequentially through reactor I and reactor II. When the reaction feed enters reactor I, it diffuses into annular space I through the openings on the surface of the central tube I inside reactor I, where hydrogenation reaction occurs in the catalyst bed. The reaction effluent leaves annular space I, is heated and temperature-controlled, and then is evenly mixed with supplementary hydrogen. It then enters the catalyst bed in annular space II for hydrogenation reaction. The reaction effluent diffuses into central tube II through the openings on the surface of central tube II and then leaves reactor II for gas-liquid separation. After gas-liquid separation, the separated gas is led out of the reaction system, and part of the separated liquid enters the subsequent separation unit, while part is recycled back to the maleic anhydride hydrogenation reactor.

[0038] Reaction conditions for reactor I: The reaction temperature is 50℃~90℃; The reaction pressure is 3.0–4.0 MPaG; Volumetric hourly space velocity: 8.0 h -1 ; Height-to-diameter ratio: 8.0; Hydrogen (Nm 3 / h) and fresh ingredients (m 3 The volume ratio of the solution (a solution of maleic anhydride dissolved in γ-butyrolactone solvent) is 60:1. The mass ratio of the reaction product entering sub-reactor I to the fresh feedstock is 20%. maleic anhydride concentration: 12 g / mL Reaction conditions for reactor II: The reaction temperature is 50℃~90℃; The reaction pressure is 3.0–4.0 MPaG; Volumetric hourly space velocity: 0.7 h -1 ; Reactor II height-to-diameter ratio: 2.5; Hydrogen (Nm 3 / h) and fresh ingredients (m 3 The volume ratio of the solution (a solution of maleic anhydride dissolved in γ-butyrolactone solvent) is 20:1. The mass ratio of the reaction product entering sub-reactor II to the fresh feedstock is 30%. Under these reaction conditions, maleic anhydride and γ-butyrolactone solvents listed in Tables 1 and 2 were used as raw materials and subjected to hydrogenation reaction using the maleic anhydride hydrogenation system and hydrogenation method of this invention to obtain hydrogenated products. The reaction results are shown in Table 4.

[0039] Example 2 The reaction system and method are the same as in Example 1. The difference from the example is the reaction conditions, which are as follows: Reaction conditions for reactor I: The reaction temperature is 50℃~80℃; The reaction pressure is 3.0–4.0 MPaG; Volumetric hourly space velocity: 6.0 h -1 ; Reactor I height-to-diameter ratio: 3.0; Hydrogen (Nm 3 / h) and fresh ingredients (m 3 The volume ratio of the solution (a solution of maleic anhydride dissolved in γ-butyrolactone solvent) is 45:1. The mass ratio of the reaction product entering sub-reactor I to the fresh feedstock is 25%. maleic anhydride concentration: 12 g / mL Reaction conditions for reactor II: The reaction temperature is 50℃~90℃; The reaction pressure is 3.0–4.0 MPaG; Volumetric hourly space velocity: 1.0 h -1 ; Reactor II height-to-diameter ratio: 1.0; Hydrogen (Nm 3 / h) and fresh ingredients (m 3 The volume ratio of the solution (a solution of maleic anhydride dissolved in γ-butyrolactone solvent) is 25:1. The mass ratio of the reaction product entering reactor II for recycling to the fresh feed is 20%. Under these reaction conditions, maleic anhydride and γ-butyrolactone solvents listed in Tables 1 and 2 were used as raw materials and subjected to hydrogenation reaction using the maleic anhydride hydrogenation system and hydrogenation method of this invention to obtain hydrogenated products. The reaction results are shown in Table 4.

[0040] Example 3 The reaction system and method are the same as in Example 1. The difference from the example is the reaction conditions, which are as follows: Reaction conditions for reactor I: The reaction temperature is 50℃~90℃; The reaction pressure is 3.0–4.0 MPaG; Volumetric hourly space velocity: 4.0 h -1 ; Reactor I height-to-diameter ratio: 3.0; Hydrogen (Nm 3 / h) and fresh ingredients (m 3 The volume ratio of the solution (a solution of maleic anhydride dissolved in γ-butyrolactone solvent) is 30:1. The mass ratio of the reaction product entering sub-reactor I to the fresh feedstock is 10%. maleic anhydride concentration: 12 g / mL Reaction conditions for reactor II: The reaction temperature is 50℃~90℃; The reaction pressure is 3.0–4.0 MPaG; Volumetric hourly space velocity: 1.5h -1 ; Reactor II height-to-diameter ratio: 1.0; Hydrogen (Nm 3 / h) and fresh ingredients (m 3 The volume ratio of the solution (a solution of maleic anhydride dissolved in γ-butyrolactone solvent) is 30:1. The mass ratio of the reaction product entering reactor II for recycling to the fresh feed is 15%. Under these reaction conditions, maleic anhydride and γ-butyrolactone solvents listed in Tables 1 and 2 were used as raw materials and subjected to hydrogenation reaction using the maleic anhydride hydrogenation system and hydrogenation method of this invention to obtain hydrogenated products. The reaction results are shown in Table 4.

[0041] Table 4 Reaction Results As can be seen from the effects of this embodiment and the comparative example, the hydrogenation system and maleic anhydride hydrogenation method of the present invention allow the reaction feed to undergo hydrogenation reaction by sequentially passing through reactor I and reactor II, which contain a central tube. The materials in reactor I are all materials from the early stage of the maleic anhydride hydrogenation reaction. The reactants diffuse to the catalyst bed through the openings on the surface of the central tube I. That is, by controlling parameters such as the opening area and opening position of the central tube I, the residence time of the materials on the catalyst surface at different positions can be controlled, thereby effectively controlling the reaction process in the early stage, uniformizing the heat of reaction, and reducing side reactions. The materials in reactor II are all the remaining reactants from the later stage of the maleic anhydride hydrogenation reaction. Due to the low concentration and slow reaction rate of maleic anhydride, the central tube II in reactor II allows the reactants to diffuse away from the catalyst bed through the central tube II. In this way, by controlling parameters such as the opening area and opening height of the central tube II, the residence time of the materials on the catalyst surface at different positions in reactor II can be controlled, thereby achieving complete and efficient conversion of maleic anhydride and effectively controlling deep side reactions.

Claims

1. A hydrogenation reaction system, characterized in that: Including reactor I and reactor II; Reactor I includes a cylindrical body I and a built-in central tube I, which are coaxially arranged. A portion of the wall of the central tube I is perforated, and the perforated area extends from the bottom of the central tube I to 1 / 2 to 4 / 5 of the axial length of the central tube I. The cylindrical body I and the central tube I are connected through the perforation. The annular area between the cylindrical body I and the central tube I is the reaction zone I. The bottom of the central tube I is provided with a feed inlet I, and the top of the cylinder I is provided with a discharge outlet I. The reaction feed enters the central tube I through the feed inlet I and diffuses into the cylinder I filled with hydrogenation catalyst through the openings on the wall of the central tube I. The first-stage hydrogenation reaction occurs from bottom to top in the cylinder I. Reactor II comprises a cylindrical body II and an internal central tube II, which are coaxially arranged. A portion of the wall of the central tube II is perforated, extending from the top of the central tube II to 1 / 2 to 4 / 5 of its axial length. The cylindrical body II and the central tube II are connected through the perforations. The annular region between the cylindrical body II and the central tube II is the reaction zone II. The bottom of the cylindrical body II is provided with a feed inlet II, and the top of the central tube II is provided with a discharge outlet II. The feed inlet I is connected to the feed pipeline, and the discharge outlet I is connected to the feed inlet II via a pipeline. A secondary hydrogenation reaction occurs from bottom to top within the reaction zone II. After the reaction is completed, the effluent from the secondary hydrogenation reaction diffuses into the central tube II through the perforations on its wall and exits the reactor II through the discharge outlet II.

2. The hydrogenation reaction system according to claim 1, characterized in that: The height-to-diameter ratio of reactor I is 2 to 20, and the height-to-diameter ratio of reactor II is 0.5 to 5; the volume ratio of reactor I to reactor II is 1:1.1 to 1:

10.

3. The hydrogenation reaction system according to claim 2, characterized in that: The height-to-diameter ratio of reactor I is 3 to 8, the height-to-diameter ratio of reactor II is 0.5 to 3.0, and the volume ratio of reactor I to reactor II is 1:1.5 to 1:

5.

4. The hydrogenation reaction system according to claim 1, characterized in that: The diameter ratio of the central tube to the cylinder is 1:2 to 1:

200.

5. The hydrogenation reaction system according to claim 1, characterized in that: The surface opening size of the central tube I is 1mm to 100mm; the surface opening area of ​​the central tube I is not less than the cross-sectional area of ​​the feed inlet I.

6. The hydrogenation reaction system according to claim 1, characterized in that: The surface opening size of the central tube II is 1mm to 100mm; the surface opening area of ​​the central tube II is not less than the cross-sectional area of ​​the discharge port II.

7. The hydrogenation reaction system according to claim 1, characterized in that: The opening areas of central tube I and central tube II are the same.

8. The hydrogenation reaction system according to claim 1, characterized in that: The reactor shell has an upper end cap at the top and a lower end cap at the bottom. The center of the inner wall of the upper end cap and the center of the inner wall of the lower end cap are fixedly welded together along the reactor axis.

9. The hydrogenation reaction system according to claim 1, characterized in that: The hydrogenation reaction system includes a feedstock mixing device for mixing liquid feedstock and hydrogen, selected from one or more of the following: static mixer, dissolved gas pump, mechanical stirring equipment, colloid mill, microporous plate nano / micro hydrogen dispersion assembly, microbubble generator, ceramic membrane nano / micro hydrogen dispersion assembly, or microchannel mixer.

10. The hydrogenation reaction system according to claim 1, characterized in that: The hydrogenation reaction system includes heat extraction equipment for removing heat from the effluent of reactor I and for exchanging heat from the feed of reactor II to the required reaction temperature of the material.

11. The hydrogenation reaction system according to claim 1, characterized in that: The hydrogenation reaction system includes a hydrogen supply line, which is directly connected to the feed mixing equipment to provide the hydrogen required for the hydrogenation reaction in reactor II.

12. The hydrogenation reaction system according to claim 1, characterized in that: The hydrogenation reaction system includes a gas-liquid separation device for separating the effluents from reactors I and II into gas and liquid components.

13. A method for hydrogenating maleic anhydride using a hydrogenation reaction system as described in any one of claims 1 to 12, characterized in that, The process includes the following: (1) A mixture of maleic anhydride solution and hydrogen is fed into the central tube I of reactor I through inlet I. The mixture diffuses through the openings on the wall of central tube I into the cylinder I filled with hydrogenation catalyst. A first-stage hydrogenation reaction occurs from bottom to top. The effluent from the first-stage hydrogenation reaction leaves reactor I through outlet I. (2) A mixture of the effluent from the first-stage hydrogenation reaction and supplementary hydrogen is fed into the cylinder II filled with hydrogenation catalyst through inlet II of reactor II. A second-stage hydrogenation reaction occurs from bottom to top. The effluent from the second-stage hydrogenation reaction after the reaction is completed diffuses through the openings on the wall of central tube II into central tube II. The effluent leaves reactor II through outlet II. The product is obtained by gas-liquid separation.

14. The method for hydrogenating maleic anhydride according to claim 13, characterized in that: The first mixed feed in step (1) is a liquid material with hydrogen as the dispersed phase and maleic anhydride solution as the continuous phase; the dispersion size of hydrogen is 100nm~1000μm.

15. The method for hydrogenating maleic anhydride according to claim 14, characterized in that: The first mixed feed in step (1) is a liquid phase material with hydrogen as the dispersed phase and maleic anhydride solution as the continuous phase; the dispersion size of hydrogen is 50μm to 600μm.

16. The method for hydrogenating maleic anhydride according to claim 13, characterized in that: The first mixing feed uses one or more of the following mixing equipment: static mixer, dissolved air pump, mechanical stirring equipment, colloid mill, microporous plate nano / micro hydrogen dispersion component, microbubble generator, ceramic membrane nano / micro hydrogen dispersion component, and microchannel mixer.

17. The method for hydrogenating maleic anhydride according to claim 13, characterized in that: The hydrogen gas used is hydrogen gas with a purity greater than 90% v.

18. The method for hydrogenating maleic anhydride according to claim 13, characterized in that: The volumetric flow rate ratio of hydrogen (Nm3 / h) in reactors I and II to maleic anhydride solution (m3 / h) in step (1) is 5:1 to 100:

1.

19. The method for hydrogenating maleic anhydride according to claim 18, characterized in that: The volumetric flow rate ratio of hydrogen (Nm3 / h) in reactors I and II to maleic anhydride solution (m3 / h) in step (1) is 10:1 to 50:

1.

20. The method for hydrogenating maleic anhydride according to claim 13, characterized in that: The hydrogenation reaction conditions in reactor I are as follows: reaction temperature is 40–200℃; reaction pressure is 0.5–10.0 MPa; and liquid hourly space velocity is 1–20.0 h⁻¹.

21. The method for hydrogenating maleic anhydride according to claim 20, characterized in that: The hydrogenation reaction conditions in reactor I are as follows: reaction temperature is 50–90℃; reaction pressure is 1–5.0 MPa; liquid hourly space velocity is 3.0–10.0 h⁻¹.

22. The method for hydrogenating maleic anhydride according to claim 13, characterized in that: The hydrogenation reaction conditions in reactor II are as follows: reaction temperature is 40–100℃; reaction pressure is 0.5–10.0 MPa; and liquid hourly space velocity is 0.1–5.0 h⁻¹.

23. The method for hydrogenating maleic anhydride according to claim 22, characterized in that: The hydrogenation reaction conditions in reactor II are as follows: reaction temperature is 50-70℃; reaction pressure is 1-5.0MPa; liquid hourly space velocity is 0.5-3.0h-1.

24. The method for hydrogenating maleic anhydride according to claim 13, characterized in that: The sum of the maleic anhydride hydrogenation conversion rates of reactors I and II is 100%, wherein the maleic anhydride hydrogenation conversion rate of reactor I is 10% to 99%, and the maleic anhydride hydrogenation conversion rate of reactor II is 1% to 90%, and the maleic anhydride hydrogenation conversion rate of reactor I is higher than that of reactor II.

25. The method for hydrogenating maleic anhydride according to claim 24, characterized in that: The sum of the maleic anhydride hydrogenation conversion rates of reactors I and II is 100%, wherein the maleic anhydride hydrogenation conversion rate of reactor I is 50-95%, the maleic anhydride hydrogenation conversion rate of reactor II is 5-50%, and the maleic anhydride hydrogenation conversion rate of reactor I is higher than that of reactor II.

26. The method for hydrogenating maleic anhydride according to claim 13, characterized in that: The hydrogenation catalyst is a supported nickel-based catalyst, wherein the catalyst support is one or more of SiO2, Al2O3, SiO2-Al2O3, TiO2, activated carbon or molecular sieve; the catalyst shape is one of spherical, strip-shaped, clover-shaped or toothed spherical.

27. The method for hydrogenating maleic anhydride according to claim 13, characterized in that: The liquid material obtained from the gas-liquid separation is partially recycled back to reactors I and II, and part of the material enters the subsequent succinic anhydride product fractionation unit, or all of the material enters the subsequent succinic anhydride product fractionation unit.

28. The method for hydrogenating maleic anhydride according to claim 27, characterized in that: The recycled material returned to reactor I accounts for 5 to 80 wt% of the fresh material at the inlet of reactor I; the recycled material returned to reactor II accounts for 1 to 30 wt% of the fresh material at the inlet of reactor I.

29. The method for hydrogenating maleic anhydride according to claim 28, characterized in that: The recycled material returned to reactor I accounts for 10-30 wt% of the fresh material at the inlet of reactor I; the recycled material returned to reactor II accounts for 5-20 wt% of the fresh material at the inlet of reactor I.

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