Up-flow maleic anhydride hydrogenation reaction system and method

Abstract

The invention discloses an up-flow maleic anhydride hydrogenation reaction system and method. The up-flow maleic anhydride hydrogenation reaction system comprises a reactor I and a reactor II, the reactor I is of a tubular reactor structure and comprises a barrel I, a feed port I is formed in the bottom of the barrel I, and a discharge port I is formed in the top of the barrel I; the height-diameter ratio of the reactor I is 1: 1-30: 1; the reactor II is of a shell-and-tube reactor structure and comprises a cylinder II, a central tube and a partition plate; holes are formed in the pipe wall of the central pipe, and partition plates are arranged in the central pipe in the radial direction; the bottom of the reactor II is provided with a feed port II, the feed port II is communicated with the lower cavity of the central tube, the top of the reactor II is provided with a discharge port II, and the discharge port II is communicated with the upper cavity of the central tube; the height-diameter ratio of the reactor II is (0.5: 1)-(10: 1); the effective volume of the reactor I is lower than that of the reactor II. The problems of centralized heat release, easy generation of local hot spots, serious side reaction and the like in the maleic anhydride hydrogenation reaction process are solved through two-stage reaction coupling, and high conversion rate and high selectivity in the maleic anhydride hydrogenation process are ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of succinic anhydride production, and specifically relates to an upflow maleic anhydride hydrogenation reaction system and method. Background Art

[0002] At present, the production methods of succinic anhydride are mainly divided into succinic acid dehydration method, biological fermentation method and maleic anhydride catalytic hydrogenation method. Among them, maleic anhydride catalytic hydrogenation method is the method with the highest conversion rate and the best product quality for producing succinic anhydride, and is most suitable for large-scale industrialization. However, the production of succinic anhydride by hydrogenation of maleic anhydride is a strongly exothermic reaction (△H=128kJ / mol). It is not easy to remove the reaction heat in time by conventional trickle bed hydrogenation and conventional liquid phase hydrogenation industry and reactor structure, so that the temperature of the reaction process cannot be controlled, resulting in local hot spots in the catalyst bed, serious side reactions, and catalyst bed hardening. It is difficult to take into account both the conversion rate and selectivity of the reaction process, and it is even more difficult to achieve a higher selectivity.

[0003] CN103570650A proposes a process flow for continuously producing succinic anhydride and succinic acid by hydrogenating maleic anhydride. The method adopts a two-stage hydrogenation reactor. The first-stage hydrogenation reactor is a fixed bed reactor in which hydrogen and reaction liquid enter from the bottom and exit from the top. The second-stage hydrogenation reactor is a trickle bed reactor in which hydrogen and reaction liquid enter from the top and exit from the bottom. The reaction heat is removed by an external circulation heat removal method, with the purpose of controlling the average operating temperature of the entire reactor and balancing the temperature in the reactor. In this method, the first-stage reactor adopts a flow mode in which hydrogen and reaction liquid flow upward in parallel. Based on the particularity of the large heat release of maleic anhydride hydrogenation reaction, conventional technology cannot ensure uniform mixing and distribution of materials, uniform reaction and solution of local hot spots; while the second-stage reactor adopts a trickle bed reactor flow mode in which hydrogen and reaction liquid flow downward in parallel, which makes it even more impossible to ensure timely removal of reaction heat and solution of local 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 adopts a two-stage low temperature and low pressure reaction process to prepare succinic anhydride. Two reactors are used, namely a first stage reactor and a second stage reactor, which are used in series; maleic anhydride, solvent and hydrogen enter the first stage reactor for partial catalytic selective hydrogenation. After the reaction, the remaining maleic anhydride, the generated succinic anhydride and solvent mixed liquid materials enter the second stage reactor for complete catalytic selective hydrogenation. The product of the second stage reactor is subjected to gas-liquid separation and distillation to obtain a succinic anhydride product. In this method, the two-stage reactor adopts a hydrogen and reaction liquid liquid phase hydrogenation method. Based on the particularity of the large heat release of maleic anhydride hydrogenation reaction, the conventional liquid phase hydrogenation mixing and reaction technology cannot ensure uniform mixing and distribution of materials, uniform reaction and solve the problem of local hot spots. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention discloses an upflow maleic anhydride hydrogenation reaction system and method. The present invention can effectively regulate the temperature rise and temperature distribution of the maleic anhydride hydrogenation reaction process through two-stage reaction coupling, solve the problems of concentrated heat release, easy generation of local hot spots, serious side reactions, etc. in the maleic anhydride hydrogenation reaction process, and ensure high conversion rate and high selectivity of the maleic anhydride hydrogenation process.

[0006] The upflow maleic anhydride hydrogenation reaction system of the present invention comprises a reactor I and a reactor II; Reactor I is a tubular reactor structure, comprising a barrel I, a feed port I is arranged at the bottom of barrel I, and a discharge port I is arranged at the top; the height-to-diameter ratio of reactor I is generally 1:1-30:1, preferably 3:1-15:1. Reactor II is a shell-and-tube reactor structure, comprising a barrel II, a central tube and a baffle, and the space between the central tube and barrel II is the shell space; a hole is opened on the tube wall of the central tube, barrel II and central tube are connected through the hole, a baffle is arranged in the radial direction inside the central tube, and the baffle divides the central tube into two cavities, an upper part and a lower part; a feed port II is arranged at the bottom of reactor II, and feed port II is connected to the lower cavity of the central tube, and a discharge port II is arranged at the top of reactor II, and discharge port II is connected to the upper cavity of the central tube; the height-to-diameter ratio of reactor II is 0.5:1-10:1, preferably 1:1-5:1.

[0007] The effective volume of reactor I is not greater than that of reactor II, and the ratio of the effective volume of reactor I to that of reactor II is 1:1 to 1:10, preferably 1:2 to 1:6. Note: The effective volume is defined as the volume of the catalyst filled in the reactor.

[0008] In the upflow maleic anhydride hydrogenation reaction system of the present invention, the partition of the reactor II is arranged horizontally. In principle, the partition can be arranged at any position of the central tube. The preferred position is to separate the volumes of the upper and lower chambers into 1:10 to 10:1.

[0009] In the upflow maleic anhydride hydrogenation reaction system of the present invention, holes are opened in part or all of the surface of the reactor II, and the hole sizes can be the same or different; the size of the hole opening on the surface of the central tube is generally 1mm to 100mm, and the hole area is not less than the cross-sectional area of ​​the feed port II.

[0010] In the upflow maleic anhydride hydrogenation reaction system of the present invention, the top of the reactor II is an upper head, the bottom is a lower head, and the center position of the inner wall of the upper head and the center position of the inner wall of the lower head are fixedly welded with a central tube along the axial direction of the reactor.

[0011] In the upflow maleic anhydride hydrogenation reaction system of the present invention, during the reaction process, the feed enters the lower cavity of the central tube from the feed port II, flows radially through the openings on the surface of the central tube and diffuses into the shell space of the reactor II, then flows axially from bottom to top through the catalyst bed filled in the shell space and simultaneously undergoes an upflow hydrogenation reaction, flows radially again after a period of residence time and diffuses into the central tube through the openings on the surface of the central tube, and is discharged from the discharge port II at the top of the central tube.

[0012] In the upflow maleic anhydride hydrogenation reaction system of the present invention, the shell spaces of the reactors I and II are filled with hydrogenation catalysts commonly used in the art; the catalyst types can be set as needed, and can be the same or different; the number of catalyst beds can also be set as needed.

[0013] The upflow maleic anhydride hydrogenation reaction system of the present invention further comprises a raw material mixing device for mixing liquid raw materials and hydrogen, such as a static mixer, an air dissolving pump, a mechanical stirring device, a colloid mill, a microporous plate nano / micro hydrogen dispersion component, a micro bubble generator, a ceramic membrane nano / micro hydrogen dispersion component, a microchannel mixer, and any other device having a liquid-liquid and / or gas-liquid mixing function. The raw material mixing device is generally arranged before the feed ports of reactors I and II. For example, the liquid raw materials (maleic anhydride, solvent) of maleic anhydride hydrogenation reaction and the hydrogen are mixed.

[0014] The upflow maleic anhydride hydrogenation reaction system of the present invention further comprises a temperature regulating device for regulating the temperature of the feed and discharge of the reactor I and the discharge of the reactor II, such as a heat exchanger, a heater or a cooler.

[0015] The upflow maleic anhydride hydrogenation reaction system of the present invention further comprises a supplementary hydrogen pipeline, which is generally directly connected to the raw material mixing device to provide hydrogen required for the hydrogenation reaction in the reactor II.

[0016] The upflow maleic anhydride hydrogenation reaction system of the present invention further includes a gas-liquid separation device for performing gas-liquid separation on the effluents of reactors I and II, which is generally accomplished through a gas-liquid separation tank, where gas is separated from the top of the separation tank and a liquid product is obtained from the bottom of the separation tank.

[0017] The present invention also provides a method for hydrogenating maleic anhydride, comprising the following contents: (1) A mixture of maleic anhydride solution and hydrogen enters reactor I through feed port I as a first mixed feed, and undergoes an upflow hydrogenation reaction in a reaction mode close to plug flow through a catalyst bed disposed in reactor I; (2) The mixture of the effluent from reactor I and the supplementary hydrogen enters the central tube from the feed port II of reactor II as the second mixed feed, diffuses into the shell space of reactor II through the openings on the surface of the central tube, and undergoes radial deflection-axial flow-radial deflection in sequence through the catalyst bed arranged in the shell space, and then diffuses into the central tube and finally leaves from the discharge port II.

[0018] In the method of the present invention, the first mixed feed described in step (1) is a liquid material with hydrogen as the dispersed phase and maleic anhydride solution as the continuous phase; the second mixed feed described in step (2) is a liquid material with hydrogen as the dispersed phase and a solution of maleic anhydride and succinic anhydride as the continuous phase; the dispersed size of hydrogen is generally 100nm to 1000μm, preferably 50μm to 600μm; generally, one or more mixing devices such as static mixer, dissolved air pump, mechanical stirring equipment, colloid mill, microporous plate nano / micro hydrogen dispersion component, micro bubble generator, ceramic membrane nano / micro hydrogen dispersion component, microchannel mixer, etc. are used.

[0019] 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 the maleic anhydride solution is generally 0.03 to 0.3 g / mL, preferably 0.05 to 0.30 g / mL.

[0020] In the method of the present invention, the hydrogen generally has a purity greater than 90 (v)%, preferably 99.9% pure hydrogen.

[0021] In the method of the present invention, the outer surface of the central tube is wrapped with one or more layers of wire mesh to prevent the catalyst particles from leaking along the openings on the surface of the central tube. The mesh aperture is generally smaller than the nominal diameter of the smallest cross section of the catalyst particles.

[0022] In the method of the present invention, the hydrogen (Nm 3 / h) and fresh raw materials (m 3 The volume flow rate ratio of maleic anhydride to solvent is 5:1 to 400:1, preferably 10:1 to 100:1.

[0023] In the method of the present invention, the hydrogenation reaction conditions of the reactor I are as follows: the reaction temperature is 40 to 200°C, preferably 50 to 90°C; the reaction pressure is generally 0.5 to 10.0 MPa, preferably 1 to 5.0 MPa; the liquid hourly space velocity is generally 1 to 30.0 h -1 , preferably 3.0~15.0h -1 .

[0024] In the method of the present invention, the hydrogenation reaction conditions of the 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; the liquid hourly space velocity is generally 0.1-5.0 h -1 , preferably 0.5~3.0h -1 .

[0025] In the method of the present invention, the sum of the maleic anhydride hydrogenation reaction conversion rates of the reactors I and II is 100%, wherein the maleic anhydride hydrogenation reaction conversion rate of the reactor I is generally 30% to 99%, preferably 50 to 98%, and the maleic anhydride hydrogenation reaction conversion rate of the reactor II is generally 1% to 70%, preferably 2 to 50%, and the maleic anhydride hydrogenation reaction conversion rate of the reactor I is higher than the maleic anhydride hydrogenation reaction conversion rate of the reactor II.

[0026] In the method of the present invention, the hydrogenation catalyst is preferably a supported nickel-based catalyst, wherein the catalyst carrier can be SiO 2 、Al 2 O 3 、SiO 2 -Al 2 O 3 、TiO 2 , activated carbon or molecular sieve, etc.; the catalyst shape can be one of spheres, strips, clover-leaf shapes, toothed spheres, etc., preferably spherical or toothed sphere catalysts.

[0027] In the method of the present invention, the liquid material obtained by the 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 not all of it can be recycled to the subsequent succinic anhydride product fractionation unit; if the reaction product is partially recycled, the recycled material recycled back to reactor I accounts for 1 to 50 wt% of the fresh material at the inlet of reactor I, preferably 5 to 30 wt%; the recycled material recycled back to reactor II accounts for 5 to 80 wt% of the fresh material at the inlet of reactor I, preferably 10 to 60 wt%.

[0028] In the method of the present invention, the material in the reactor I is the material in the early stage of maleic anhydride hydrogenation reaction. Due to the high maleic anhydride concentration and fast reaction rate, it is very easy to cause concentrated heat release, local hot spots and other problems, resulting in the problems of local catalyst coking and serious side reactions in the reactor on the one hand, and uneven reactions in the upper and lower parts of the reactor along the axis, that is, the reaction heat is concentrated in the lower part on the other hand; since the material in the reactor II is the material in the late stage of the reaction, the maleic anhydride concentration is low, the reaction rate is slow, and the mass transfer driving force is small, so a slightly lower space velocity is required to achieve the complete conversion of maleic anhydride, which is more likely to cause problems such as long local residence time and many side reactions.

[0029] In order to solve the above problems, the upflow maleic anhydride hydrogenation reaction system provided by the present invention has the following technical advantages: (1) by setting the flow mode in the reactor I to be upflow and close to the plug flow, that is, the reaction feed has a uniform speed in the axial direction without mixing, and is completely mixed in the radial direction, and the residence time of all the reaction feeds in the reactor I is almost the same. On the one hand, based on the absence of axial backmixing of the material, the reaction efficiency and conversion rate can be higher, and the side reactions are less; on the other hand, the material is stably pushed forward at a uniform speed to transfer the reaction heat in time, solve the problem of concentrated heat release and local hot spots, and make the reactor temperature more evenly distributed along the axial direction. (2) By setting the reactor II as a special shell-and-tube structure and setting a baffle in the central tube, the material can flow in the reactor II along the radial-axial, axial-axial, and axial-radial reaction paths. On the one hand, the position of the baffle in the central tube can be changed to adjust the effective residence time of each time period, so that the reaction materials in the late reaction period can maintain the optimal reaction residence time, and prevent the problem of too many side reactions caused by too long reaction time and too short reaction time causing maleic anhydride not to be 100% converted; the effective residence time here refers to the time when the reaction materials are fully in contact with the catalyst. On the other hand, based on the open-pore structure of the central tube surface, the reaction feed can be gradually diffused radially to the catalyst bed, and the reaction rate can be controlled to make the reaction more uniform and moderate. The reaction discharge can also be gradually removed during the reaction process to prevent the formation of local hot spots, which is conducive to controlling side reactions. (3) By setting the early-stage reaction materials and the late-stage reaction materials to adopt the structural forms of reactor I and reactor II respectively and the material flow mode adapted to the respective reaction characteristics, reactor I and reactor II are connected in series, and hydrogenation reactions occur in sequence. The two-stage reactions are coupled with each other, which ensures the efficient conversion of the entire maleic anhydride hydrogenation reaction while making the reaction more uniform and greatly reducing side reactions.

[0030] Note: The early stage of reaction described in this article refers to the stage when the maleic anhydride concentration in the maleic anhydride solution material in the reactor is greater than or equal to the succinic anhydride concentration, and the late stage of reaction refers to the reaction stage when the maleic anhydride concentration in the maleic anhydride solution material in the reactor is less than the succinic anhydride concentration. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The present invention is a schematic diagram of an upflow maleic anhydride hydrogenation reaction system and process.

[0032] Wherein, 1 is maleic anhydride solution, 2 is hydrogen, 3 is a mixer, 4 is feed for upflow maleic anhydride hydrogenation reaction system, 5 is reactor I, 6 is catalyst bed I, 7 is reaction discharge of reactor I, 8 is a heat collector, 9 is supplementary hydrogen, 10 is a mixer, 11 is reaction feed of reactor II, 12 is reactor II, 13 is a central tube, 14 is a surface opening of the central tube, 15 is an internal partition of the central tube, 16 is the shell space of reactor II, 17 is catalyst bed II, 18 is reaction discharge of reactor II, 19 is a heat collector, 20 is a gas-liquid separator, 21 is separated gas, and 22 is separated hydrogenation product. Implementation

[0033] The present invention will be described in detail below with reference to the accompanying drawings and embodiments, but the present invention is not limited thereto.

[0034] Attach Figure 1 The application process of an upflow maleic anhydride hydrogenation reaction system and process method of the present invention is described as follows: maleic anhydride solution 1 and hydrogen 2 are uniformly mixed in a mixer 3 to form an upflow maleic anhydride hydrogenation reaction system feed 4, which is introduced into the maleic anhydride hydrogenation reaction system. First, it enters reactor I 6 through the bottom feed port of reactor I 5, passes through catalyst bed I 6 from bottom to top, and undergoes upflow maleic anhydride hydrogenation reaction. After completing the primary hydrogenation reaction, the reaction discharge 7 leaves reactor I, is adjusted to a suitable temperature by heat collector 8, and then enters mixer 10 together with supplementary hydrogen 9 for uniform mixing, and enters reactor II 12 through the feed port as the feed of reactor II 12, and first diffuses radially to catalyst bed II 17 through the lower cavity of central tube 13, and undergoes hydrogenation reaction from bottom to top in catalyst bed II 17. After a period of residence time, the material diffuses radially to the upper cavity of central tube 13, and then leaves reactor II as the reaction discharge 18 of reactor II, and enters gas-liquid separator 20 after being cooled to a suitable temperature by heat collector 19, and separates gas 21 and liquid product 22.

[0035] The method of the present invention is applied to the maleic anhydride hydrogenation reaction process. Maleic anhydride raw material and γ-butyrolactone solvent are both commercially available, and their specific properties are shown in Table 1 and Table 2, respectively, and the catalyst properties are shown in Table 3.

[0036] Table 1 Maleic anhydride raw material properties Table 2 γ-butyrolactone solvent properties Table 3 Physical and chemical indicators of catalyst project index Appearance Bar Carrier <![CDATA[Al 2 THE 3 ]]> Catalyst type Nickel-based Nickel content, wt% 5～40 Comparative Example 1 The conventional fixed bed hydrogenation process is adopted, and two upflow hydrogenation reactors are connected in series, and maleic anhydride undergoes maleic anhydride hydrogenation reaction in the first reactor and the second reactor in sequence. First, the maleic anhydride raw material is dissolved in the γ-butyrolactone solvent and mixed evenly to prepare a maleic anhydride solution, which is mixed with hydrogen after being adjusted to the reactor inlet temperature, and enters from the bottom of the upflow hydrogenation reactor, and undergoes hydrogenation reaction from bottom to top through the catalyst bed. The obtained hydrogenated product is mixed with supplementary hydrogen after being adjusted in temperature, and enters from the bottom of the second upflow hydrogenation reactor, and undergoes hydrogenation reaction from bottom to top through the catalyst bed. After the hydrogenation reaction is completed, it leaves the reactor, and undergoes gas-liquid separation through a separator, and part of the separated material is recycled, and the other part enters the separation unit.

[0037] The operating conditions of the first hydrogenation reactor are as follows: The reactor inlet temperature was 50°C; The reaction pressure is 6.0~6.5MPaG; Reactor height-to-diameter ratio: 3.0 Volumetric air velocity: 2.5h -1 Maleic anhydride preparation concentration: 12g / mL Hydrogen (Nm 3 / h) and fresh raw materials (m 3 / h) (solution formed by maleic anhydride dissolved in γ-butyrolactone solvent) with a volume ratio of 100:1; The mass ratio of the reaction product circulating into the first reactor to the fresh raw material is 30%; The operation of the second hydrogenation reactor is as follows: The reactor inlet temperature was 50°C; The reaction pressure is 6.0~6.5MPaG; Volumetric air velocity: 1.5h -1 ; Reactor height-to-diameter ratio: 2.0; Hydrogen (Nm 3 / h) and fresh raw materials (m 3 / h) (solution formed by maleic anhydride dissolved in γ-butyrolactone solvent) with a volume ratio of 400:1; The mass ratio of the reaction product circulating into the second reactor to the fresh raw material is 35%; Under the reaction conditions, maleic anhydride and γ-butyrolactone solvents in Table 1 and Table 2 were used as raw materials and entered the first reactor and the second reactor for continuous hydrogenation reaction to obtain hydrogenated products. The reaction results are shown in Table 4.

[0038] Comparative Example 2 The maleic anhydride hydrogenation process is carried out in a conventional upflow fixed bed and downflow trickle bed in series, and maleic anhydride undergoes maleic anhydride hydrogenation reaction in the first reactor and the second reactor in turn. First, the maleic anhydride raw material is dissolved in the γ-butyrolactone solvent and mixed evenly to prepare a maleic anhydride solution, which is mixed with hydrogen after being adjusted to the reactor inlet temperature, enters from the bottom of the upflow hydrogenation reactor, and undergoes hydrogenation reaction from bottom to top through the catalyst bed. The obtained hydrogenated product is mixed with supplementary hydrogen after being adjusted in temperature, enters from the top of the downflow hydrogenation reactor, and undergoes hydrogenation reaction from top to bottom through the catalyst bed. After the hydrogenation reaction is completed, it leaves the reactor and undergoes gas-liquid separation through a separator. Part of the separated material is circulated, and the other part enters the separation unit.

[0039] The operating conditions of the first hydrogenation reactor are as follows: The reactor inlet temperature was 50°C; The reaction pressure is 6.0~6.5MPaG; Reactor height-to-diameter ratio: 3.0 Volumetric space velocity: 3.2h -1 Maleic anhydride preparation concentration: 12g / mL Hydrogen (Nm 3 / h) and fresh raw materials (m 3 / h) (solution formed by maleic anhydride dissolved in γ-butyrolactone solvent) with a volume ratio of 120:1; The mass ratio of the reaction product circulating into the first reactor to the fresh raw material is 30%; The operation of the second hydrogenation reactor is as follows: The reactor inlet temperature was 50°C; The reaction pressure is 6.0~6.5MPaG; Volumetric space velocity: 1.0h -1 ; Reactor height-to-diameter ratio: 2.0; Hydrogen (Nm 3 / h) and fresh raw materials (m 3 / h) (solution formed by maleic anhydride dissolved in γ-butyrolactone solvent) with a volume ratio of 400:1; The mass ratio of the reaction product circulating into the second reactor to the fresh raw material is 30%; Under the reaction conditions, maleic anhydride and γ-butyrolactone solvents in Table 1 and Table 2 were used as raw materials and entered the first reactor and the second reactor for continuous hydrogenation reaction to obtain hydrogenated products. The reaction results are shown in Table 4. Example

[0040] The method of the present invention is used to set a reactor I and a reactor II. First, a maleic anhydride (γ-butyrolactone solvent) solution and hydrogen gas prepared in advance with a certain concentration are mixed uniformly in an efficient mixer and then enter an upflow maleic anhydride hydrogenation reaction system, and then pass through reactors I and II in sequence to undergo hydrogenation reaction; when the reaction feed enters reactor I, an upflow hydrogenation reaction occurs from bottom to top through a catalyst bed I arranged in reactor I, and after the reaction effluent leaves reactor I, it is uniformly mixed with supplementary hydrogen gas after heat removal and temperature adjustment, and then enters reactor II, first enters the lower cavity of the central tube, and then radially diffuses into the catalyst bed II to undergo an upflow hydrogenation reaction, and after a period of reaction, radially diffuses into the upper cavity of the central tube again, and finally leaves reactor II for gas-liquid separation; after the reaction effluent is separated by gas and liquid, the separated gas is led out of the reaction system, and the separated liquid part enters a subsequent separation unit, and part is circulated back to the maleic anhydride hydrogenation reactor.

[0041] Reaction conditions of reactor I: Maleic anhydride solution concentration: 10% The reaction temperature is 50°C to 90°C; The reaction pressure is 2.5~3.0MPaG; Volumetric space velocity: 15.0h -1 ; Height-to-diameter ratio: 12.0; Hydrogen (Nm 3 / h) and fresh raw materials (m 3 / h) (solution formed by maleic anhydride dissolved in γ-butyrolactone solvent) with a volume ratio of 55:1; The mass ratio of the circulation amount of the reaction product entering the reactor I to the fresh raw material is 10%; Reaction conditions of reactor II: The reaction temperature is 50°C to 90°C; The reaction pressure is 2.0~2.5MPaG; Volumetric space velocity: 1.5h -1 ; Reactor II height-to-diameter ratio: 2.0; Hydrogen (Nm 3 / h) and fresh raw materials (m 3 / h) (solution formed by maleic anhydride dissolved in γ-butyrolactone solvent) with a volume ratio of 25:1; The mass ratio of the circulation amount of the reaction product entering the reactor II to the fresh raw material is 30%; Under the reaction conditions, the maleic anhydride and γ-butyrolactone solvents in Table 1 and Table 2 were used as raw materials and entered into the maleic anhydride hydrogenation system and hydrogenation method of the present invention for hydrogenation reaction to obtain hydrogenated products. The reaction results are shown in Table 4. Example 2

[0042] The reaction system and method are the same as in Example 1. The difference from the example is the concentration of maleic anhydride solution and the reaction conditions, which are as follows: Reaction conditions of reactor I: Maleic anhydride solution concentration: 15% The reaction temperature is 50°C to 80°C; The reaction pressure is 3.5~4.0MPaG; Volumetric space velocity: 12.0h -1 ; Reactor I height-to-diameter ratio: 10.0; Hydrogen (Nm 3 / h) and fresh raw materials (m 3 / h) (solution formed by maleic anhydride dissolved in γ-butyrolactone solvent) with a volume ratio of 55:1; The mass ratio of the circulation amount of the reaction product entering the reactor I to the fresh raw material is 20%; Reaction conditions of reactor II: The reaction temperature is 50°C to 90°C; The reaction pressure is 3.0~3.5MPaG; Volumetric space velocity: 1.2h -1 ; Reactor II height-to-diameter ratio: 1.5; Hydrogen (Nm 3 / h) and fresh raw materials (m 3 / h) (solution formed by maleic anhydride dissolved in γ-butyrolactone solvent) with a volume ratio of 20:1; The mass ratio of the circulation amount of the reaction product entering the reactor II to the fresh raw material is 35%; Under the reaction conditions, the maleic anhydride and γ-butyrolactone solvents in Table 1 and Table 2 were used as raw materials and entered into the maleic anhydride hydrogenation system and hydrogenation method of the present invention for hydrogenation reaction to obtain hydrogenated products. The reaction results are shown in Table 4. Example 3

[0043] The reaction system and method are the same as in Example 1. The difference from the example is the concentration of maleic anhydride solution and the reaction conditions, which are as follows: Reaction conditions of reactor I: Maleic anhydride solution concentration: 20% The reaction temperature is 50°C to 90°C; The reaction pressure is 3.5~4.0MPaG; Volumetric space velocity: 10.0h -1 ; Reactor I height-to-diameter ratio: 12.0; Hydrogen (Nm 3 / h) and fresh raw materials (m 3 / h) (solution formed by maleic anhydride dissolved in γ-butyrolactone solvent) with a volume ratio of 50:1; The mass ratio of the circulation amount of the reaction product entering the reactor I to the fresh raw material is 15%; Reaction conditions of reactor II: The reaction temperature is 50°C to 90°C; The reaction pressure is 3.0~3.5MPaG; Volumetric air velocity: 1.5h -1 ; Reactor II height-to-diameter ratio: 0.8; Hydrogen (Nm 3 / h) and fresh raw materials (m 3 / h) (solution formed by maleic anhydride dissolved in γ-butyrolactone solvent) with a volume ratio of 20:1; The mass ratio of the circulation amount of the reaction product entering the reactor II to the fresh raw material is 40%; Under the reaction conditions, the maleic anhydride and γ-butyrolactone solvents in Table 1 and Table 2 were used as raw materials and entered the upflow maleic anhydride hydrogenation system and process method of the present invention for hydrogenation reaction to obtain hydrogenated products. The reaction results are shown in Table 4.

[0044] Table 4 Reaction results Reaction results Comparative Example 1 Comparative Example 2 Example 1 Example 2 Example 3 Reactor I radial temperature difference, ℃ 5.6～6.8 5.5～6.7 0.9～1.7 1.2～2.2 1.4～2.5 Reactor II radial temperature difference, ℃ 3.6～4.4 3.2～4.0 0.2～0.5 0.3～0.6 0.4～0.8 Total conversion, wt% 99.8～99.9 99.7～99.9 99.8～99.9 99.8～99.9 99.8～99.9 Total selectivity, % 95.3～96.4 95.6～96.9 98.6～99.7 98.4～99.3 98.2～99.1

[0045] It can be seen from the effects of this embodiment and the comparative example that the upflow maleic anhydride hydrogenation reaction system and process method of the present invention are used to make the reaction feed pass through reactor I and reactor II in sequence to undergo primary and secondary hydrogenation reactions, and obtain the succinic anhydride product through gas-liquid separation, wherein reactor I is the material in the early stage of the reaction, and reacts in a plug flow in the upflow reactor I, while reactor II is the material in the late stage of the reaction, and reacts in an axial radial alternating return flow in the shell and tube reactor II, and the coupling between the two-stage reactions can effectively regulate the temperature rise and temperature distribution in the maleic anhydride hydrogenation reaction process, solve the problems of concentrated heat release, easy generation of local hot spots, serious side reactions, etc. in the maleic anhydride hydrogenation reaction process, and ensure high conversion rate and high selectivity in the maleic anhydride hydrogenation process.

Claims

1. An upflow maleic anhydride hydrogenation reaction system, characterized in that: It includes reactor I and reactor II; Reactor I is of a tubular reactor structure, including cylinder I, with a feed inlet I arranged at the bottom of cylinder I and a discharge outlet I arranged at the top; The height-diameter ratio of reactor I is 1:1 to 30:1, preferably 3:1 to 15:

1. Reactor II is of a shell-and-tube reactor structure, including cylinder II, a central tube and a partition plate. The space between the central tube and cylinder II is the shell space; There are openings on the tube wall of the central tube, and cylinder II and the central tube are connected through the openings. A partition plate is arranged along the radial direction inside the central tube, and the partition plate divides the central tube into two upper and lower cavities; A feed inlet II is arranged at the bottom of reactor II, and feed inlet II is communicated with the lower cavity of the central tube. A discharge outlet II is arranged at the top of reactor II, and discharge outlet II is communicated with the upper cavity of the central tube; The height-diameter ratio of reactor II is 0.5:1 to 10:1, preferably 1:1 to 5:1; The effective volume of reactor I is not greater than the effective volume of reactor II, and the ratio of the effective volumes of reactor I and reactor II is 1:1 to 1:10, preferably 1:2 to 1:

6.

2. The system according to claim 1, characterized in that: The partition plate of reactor II is horizontally arranged, and the preferred position is to divide the volumes of the upper and lower cavities into 1:10 to 10:

1.

3. The system according to claim 1, characterized in that: Some or all areas on the surface of reactor II are provided with openings, and the sizes of the openings are the same or different; The size of the openings on the surface of the central tube is 1 mm to 100 mm, and the opening area is not less than the cross-sectional area of feed inlet II.

4. The system according to claim 1, characterized in that: The top of reactor II is an upper head, and the bottom is a lower head. The center position of the inner wall of the upper head and the center position of the inner wall of the lower head are fixedly welded along the axial direction of the reactor to the central tube.

5. The system according to claim 1, characterized in that: The feed enters the lower cavity of the central tube through feed inlet II, undergoes radial flow through the openings on the surface of the central tube and diffuses into the shell space of reactor II, then flows axially from bottom to top through the catalyst bed filled in the shell space and undergoes an upflow hydrogenation reaction. After a certain residence time, it undergoes radial flow again and diffuses into the central tube through the openings on the surface of the central tube, and is discharged from the discharge outlet II at the top of the central tube.

6. The system according to claim 1, characterized in that: The shell spaces of reactor I and reactor II are filled with hydrogenation catalysts commonly used in the art.

7. The system according to claim 1, characterized in that: It includes a raw material mixing device for mixing liquid-phase raw materials and hydrogen, specifically selected from one or more of a static mixer, a gas dissolution pump, a mechanical stirring device, a colloid mill, a microporous plate nano / micron hydrogen dispersion component, a microbubble generator, a ceramic membrane nano / micron hydrogen dispersion component, and a microchannel mixer; The raw material mixing device is arranged in front of the feed inlets of reactor I and II.

8. The system according to claim 1, characterized in that: It includes a temperature control device for regulating the temperature of the feedstock and effluent of Reactor I and the effluent of Reactor II.

9. The system according to claim 1, characterized in that: it includes a supplementary hydrogen pipeline which is directly connected to the raw material mixing device and is used to provide the hydrogen required for the hydrogenation reaction in Reactor II.

10. The system according to claim 1, characterized in that: it includes a gas-liquid separation device for separating the gas and liquid of the effluents from Reactors I and II.

11. A maleic anhydride hydrogenation method, characterized in that it includes the following: The mixed material of maleic anhydride solution and hydrogen enters Reactor I as the first mixed feed through Feed Port I, and undergoes an up-flow hydrogenation reaction in the catalyst bed layer arranged in Reactor I in a reaction mode close to plug flow; The mixed material of the effluent from Reactor I and supplementary hydrogen enters the central tube as the second mixed feed through Feed Port II of Reactor II, diffuses to the shell space of Reactor II through the openings on the surface of the central tube, successively undergoes radial baffle - axial flow - radial baffle in the catalyst bed layer arranged in the shell space, and then diffuses into the central tube, and finally leaves through Discharge Port II.

12. The method according to claim 11, 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 second mixed feed in step (2) is a liquid-phase material with hydrogen as the dispersed phase and the solution of maleic anhydride and succinic anhydride as the continuous phase; the dispersed size of hydrogen is 100 nm to 1000 μm.

13. The method according to claim 11, characterized in that: 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 the maleic anhydride solution is 0.03 - 0.3 g / mL.

14. The method according to claim 11, characterized in that: One or more layers of wire meshes are wrapped on the outer surface of the central tube to prevent the catalyst particles from leaking along the openings on the surface of the central tube, and the aperture of the wire mesh is smaller than the nominal diameter of the smallest cross-section of the catalyst particles.

15. The method according to claim 11, characterized in that: The volume flow ratio of hydrogen (Nm 3 / h) in Reactors I and II to the fresh feed (m 3 / h) (the sum of maleic anhydride and solvent) is 5:1 to 400:

1.

16. The method according to claim 11, characterized in that: The hydrogenation reaction conditions of the described reactor I are as follows: the reaction temperature is 40 to 200 °C, preferably 50 to 90 °C; the reaction pressure is 0.5 to 10.0 MPa, preferably 1 to 5.0 MPa; the liquid hourly space velocity is 1 to 30.0 h -1 , preferably 3.0 to 15.0 h -1 .

17. The method according to claim 11, characterized in that: The hydrogenation reaction conditions of the described Reactor II are as follows: the reaction temperature is 40 to 100 °C, preferably 50 to 70 °C; the reaction pressure is 0.5 to 10.0 MPa, preferably 1 to 5.0 MPa; the liquid hourly space velocity is 0.1 to 5.0 h -1 , preferably 0.5 to 3.0 h -1 .

18. The method according to claim 11, characterized in that: 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 30% - 99%, preferably 50 - 98%, the maleic anhydride hydrogenation reaction conversion rate of Reactor II is 1% - 70%, preferably 2 - 50%, and the maleic anhydride hydrogenation reaction conversion rate of Reactor I is higher than that of Reactor II.

19. The method according to claim 11, characterized in that: The hydrogenation catalyst described above is preferably a supported nickel-based catalyst, and the catalyst carrier thereof is SiO 2 , Al 2 O 3 , SiO 2 - Al 2 O 3 , TiO 2 , activated carbon or molecular sieve, etc., or one or more thereof; the catalyst shape is one of spherical, bar-shaped, clover-shaped, and tooth-shaped spherical.

20. The method according to claim 11, characterized in that: The liquid material obtained by gas-liquid separation is partially recycled back to Reactors I and II, and part of the material goes to the subsequent succinic anhydride product fractionation unit; or it is not recycled and all goes to the subsequent succinic anhydride product fractionation unit.

21. According to the method described in claim 21, it is characterized in that: The recycled material recycled back to Reactor I accounts for 1-50 wt%, preferably 5-30 wt% of the fresh material at the inlet of Reactor I; the recycled material recycled back to Reactor II accounts for 5-80 wt%, preferably 10-60 wt% of the fresh material at the inlet of Reactor I.

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