A method and system for producing succinic acid from butane and / or benzene

Abstract

The application provides a method and system for producing succinic acid from butane and / or benzene, which comprises the following steps: (1) butane and / or benzene is subjected to an oxidation reaction with an oxygen-containing gas in an oxidation reaction unit to obtain an oxidation reaction product; (2) the oxidation reaction product is subjected to absorption-distillation in a maleic anhydride separation unit comprising an absorption tower and a rectifying tower to obtain a maleic anhydride solution; (3) the maleic anhydride solution is subjected to a hydrogenation reaction in a maleic anhydride hydrogenation reaction unit to obtain a hydrogenation product; (4) the hydrogenation product is subjected to separation in a succinic anhydride separation unit to obtain succinic anhydride and a solvent, and the separated solvent is recycled to step (2) as an absorbent; and (5) the succinic anhydride is subjected to hydrolysis and crystallization in a succinic anhydride hydrolysis unit to obtain a succinic acid product. The maleic anhydride separation unit of the method is simpler than a traditional process flow, and the equipment is saved, the investment is saved, the succinic anhydride separation unit is easy to operate and control, the quality of the succinic acid product is stable, and the quality is high.

Description

TECHNICAL FIELD

[0001] The present application relates to a system and method for producing succinic acid from butane and / or benzene. BACKGROUND

[0002] Succinic acid has a molecular formula of C4H6O4 and a molecular weight of 118.09. It can react with a base, undergo esterification and reduction, and generate succinic anhydride by dehydration under heat. It can also undergo nucleophilic substitution, in which the hydroxyl group is replaced by a halogen atom, an amine compound, an acyl group, etc. It is an important fine chemical product and an organic synthesis intermediate. Succinic acid and its derivatives are useful platform chemicals that are widely used in the manufacture of polymers, fuel additives, inks, cosmetics, and as additives in food and pharmaceuticals.

[0003] The main methods for producing succinic acid include microbial fermentation, electrochemical synthesis, and catalytic hydrogenation of maleic anhydride. The microbial fermentation method for preparing succinic acid is complex, has a large amount of wastewater discharge, and has high production and separation costs. The conversion rate of succinic acid produced by the electrochemical synthesis method is not high, the power consumption is large, the electrolytic cell is difficult to maintain, the electrode is severely corroded, and there is a large amount of wastewater discharge, which is not conducive to large-scale production. The catalytic hydrogenation method is to make maleic anhydride or maleic acid undergo hydrogenation reaction under the action of a catalyst to generate succinic acid. This method has the advantages of high conversion rate, high product purity, no obvious side reactions, and environmental friendliness, and is the most widely used method for synthesizing succinic acid in industry.

[0004] The production methods of maleic anhydride in China can be divided into benzene oxidation method and n-butane oxidation method according to the raw material route. With the development of large-scale and intensive production of maleic anhydride, the post-treatment of maleic anhydride tends to use solvent absorption and desorption technology process. Typical solvent absorption and desorption processes include the Henschel process, the Conser process, and the ALMA process. The first two processes use dibutyl phthalate (DBP) as a solvent, and the latter uses diisobutyl hexahydrophthalate (DIBE) as a solvent. Regardless of the process, the crude maleic anhydride after absorption and desorption still needs to be purified by multiple rectifications to obtain refined maleic anhydride products. Moreover, multiple separation towers are operated under reduced pressure, which requires large equipment investment, complex process, and long process.

[0005] For enterprises with carbon four resources or benzene resources, it is urgent to optimize and improve the process for producing succinic acid from butane or benzene as raw materials. SUMMARY

[0006] To solve the problems in the prior art, the present application provides a process and method for producing succinic acid from butane / benzene as raw materials. The process and method have the characteristics of simple process, low investment, strong applicability, and easy control.

[0007] According to the first aspect of the present application, the present application provides a method for producing succinic acid from butane and / or benzene, which comprises:

[0008] (1) butane and / or benzene is oxidized with an oxygen-containing gas in an oxidation reaction unit to obtain an oxidation reaction product;

[0009] (2) the oxidation reaction product is subjected to absorption-distillation in a maleic anhydride separation unit comprising an absorption tower and a distillation tower to obtain a maleic anhydride solution;

[0010] (3) the maleic anhydride solution is subjected to hydrogenation reaction in a maleic anhydride hydrogenation reaction unit to obtain a hydrogenation product;

[0011] (4) the hydrogenation product is separated in a succinic anhydride separation unit to obtain succinic anhydride and solvent, and the separated solvent is optionally recycled to step (2) as an absorbent;

[0012] (5) the succinic anhydride is subjected to hydrolysis and crystallization in a succinic anhydride hydrolysis unit to obtain a succinic acid product.

[0013] According to the second aspect of the present application, the present application provides a system for producing succinic acid from butane and / or benzene, which comprises:

[0014] connected in series along the material flow direction: an oxidation reaction unit, a maleic anhydride separation unit comprising an absorption tower and a distillation tower connected in series, a maleic anhydride hydrogenation reaction unit, a succinic anhydride separation unit, and a succinic anhydride hydrolysis unit;

[0015] wherein butane and / or benzene is oxidized with an oxygen-containing gas in the oxidation reaction unit to obtain an oxidation reaction product, which is subjected to absorption-distillation in the maleic anhydride separation unit to obtain a maleic anhydride solution; the maleic anhydride solution is subjected to hydrogenation reaction in the maleic anhydride hydrogenation reaction unit to obtain a hydrogenation product; the hydrogenation product is separated in the succinic anhydride separation unit to obtain succinic anhydride and solvent; and the succinic anhydride is subjected to hydrolysis and crystallization in the succinic anhydride hydrolysis unit to obtain a succinic acid product.

[0016] In the present application, butane / benzene and an oxygen-containing gas such as air enter the oxidation reaction unit; the oxidation reaction product enters the maleic anhydride separation unit to obtain a maleic anhydride solution through absorption-distillation; the maleic anhydride solution enters the maleic anhydride hydrogenation reaction unit; the maleic anhydride hydrogenation product is subjected to separation in the succinic anhydride separation unit to obtain succinic anhydride and solvent, and the solvent is recycled to the maleic anhydride separation unit; and the succinic anhydride enters the hydrolysis-crystallization unit to obtain a succinic acid product. The method of the present application has the advantages of simple maleic anhydride separation unit, saving of equipment, low investment, easy operation of the succinic anhydride separation unit, easy control, stable quality of the succinic acid product, and high quality.

[0017] Specifically, the method of the present application has the following advantages:

[0018] (1) The present application provides a process for producing succinic acid from butane / benzene for enterprises with butane or benzene resources. The succinic anhydride separation unit is simpler than the traditional process flow, saves equipment, and reduces investment.

[0019] (2) The succinic anhydride separation unit of the present application is easy to operate and control, which makes the quality of succinic acid product stable and high.

[0020] (3) Using the method of the present application, the solvent used in the succinic anhydride separation unit can be a byproduct produced by the present method, and the solvent is recycled, so there is no need to purchase solvent from outside, which saves investment and is independent in process and has strong practicality.

[0021] (4) The method of the present application has the characteristics of simple process, low investment, strong applicability, easy control, etc.

[0022] (5) Using the method of the present application, the succinic anhydride separation unit does not need to operate under vacuum, which not only saves equipment investment, but also saves energy consumption.

[0023] (6) Using the method of the present application, the succinic anhydride separation unit can meet the requirements by adjusting the operating conditions of the absorbent at any time according to the required solution concentration or solvent of the subsequent succinic anhydride hydrogenation reaction, which realizes controllable operation in the whole process in industry. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a method for producing succinic acid from butane / benzene according to an embodiment of the present application.

[0025] Figure 2 is a method for producing succinic acid from butane / benzene according to an embodiment of the present application.

[0026] Figure 3 is a flow diagram of a succinic anhydride hydrogenation reaction unit according to a preferred embodiment of the present application.

[0027] Figure 4 is a flow diagram of a succinic anhydride hydrogenation reaction unit according to a preferred embodiment of the present application. DETAILED DESCRIPTION

[0028] The endpoints of the ranges and any values disclosed herein are not limited to the precise values stated. The ranges or values should be construed to be approximations that allow for significant variation. Various ranges of values that are explicitly delineated in the specification as supplied herein constitute examples of the minimum and maximum values for the range. The minimum and maximum values of each range are inclusive of the values between them. The endpoints of the ranges and any values disclosed herein are not limited to the precise values stated. The ranges or values should be construed to be approximations that allow for significant variation. Various ranges of values that are explicitly delineated in the specification as supplied herein constitute examples of the minimum and maximum values for the range. The minimum and maximum values of each range are inclusive of the values between them.

[0029] The following specific description of the present application is made in conjunction with specific drawings and examples. It is necessary to point out that the following examples are only used to further illustrate the present application and cannot be understood as limiting the scope of protection of the present application. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present application still fall within the scope of protection of the present application.

[0030] The present application is a method for producing succinic acid from butane and / or benzene, which comprises:

[0031] (1) butane and / or benzene is oxidized with an oxygen-containing gas in an oxidation reaction unit to obtain an oxidation reaction product;

[0032] (2) the oxidation reaction product is introduced into a maleic anhydride separation unit comprising an absorption tower and a rectification tower to obtain a maleic anhydride solution through absorption-rectification;

[0033] (3) the maleic anhydride solution is introduced into a maleic anhydride hydrogenation reaction unit to obtain a hydrogenation product through hydrogenation reaction;

[0034] (4) the hydrogenation product is introduced into a succinic anhydride separation unit to separate succinic anhydride and solvent, and the separated solvent is recycled to step (2) as an absorbent;

[0035] (5) the succinic anhydride is introduced into a succinic anhydride hydrolysis unit to obtain a succinic acid product through hydrolysis-crystallization.

[0036] The present application does not have special requirements for the oxygen-containing gas, and common oxygen-containing gases used for oxidation can be used in the present application, such as air and / or oxygen.

[0037] The present application specifically comprises the following steps:

[0038] (1) butane / benzene and air are introduced into an oxidation reaction unit;

[0039] (2) the oxidation reaction product is introduced into a maleic anhydride separation unit to obtain a maleic anhydride solution through absorption-rectification;

[0040] (3) the maleic anhydride solution is introduced into a maleic anhydride hydrogenation reaction unit;

[0041] (4) the hydrogenation product is introduced into a succinic anhydride separation unit to obtain succinic anhydride and solvent, and the separated solvent is recycled to step (2);

[0042] (5) the separated succinic anhydride is introduced into a hydrolysis unit to obtain a succinic acid product through hydrolysis-crystallization.

[0043] According to the present application, in step (1), butane / benzene and an oxygen-containing gas such as air are introduced into an oxidation reaction unit, and the design and operating conditions of the oxidation reaction unit are not specifically limited and can be determined by those skilled in the art based on professional knowledge and existing technology.

[0044] According to the present application, in the step (2), the maleic anhydride separation unit mainly comprises an absorption tower, a rectification tower, and other devices such as heat exchangers, pumps, tanks, pipelines, etc. The cooled oxidation reaction product is fed into the absorption tower from the bottom of the tower, the solvent is fed into the absorption tower from the top of the tower, the overhead material of the absorption tower is sent to the outside of the boundary area, the rich solvent obtained from the bottom of the absorption tower is fed into the rectification tower, the overhead material of the rectification tower is sent to the outside of the boundary area, and the bottom material of the rectification tower is sent to the maleic anhydride hydrogenation reaction unit.

[0045] According to the present application, in the step (2), the overhead material of the rectification tower can also be sent to the outside of the boundary area, the maleic anhydride solvent mixture is taken out from the side line of the tower and sent to the maleic anhydride hydrogenation reaction unit, and the bottom material of the tower is sent to the solvent purification unit.

[0046] According to the present application, in the step (2), the operation pressure of the absorption tower is preferably 0.0-1.0 MPag, the operation temperature is 40-120℃, and the number of theoretical plates is 5-50.

[0047] According to the present application, in the step (2), the operation pressure of the rectification tower is preferably 0.0-1.0 MPag, the operation temperature is 40-150℃, and the number of theoretical plates is 5-100.

[0048] According to the present application, in the step (2), a fresh absorption agent is preferably supplemented and fed into the top of the absorption tower.

[0049] According to the present application, in the step (2), the absorption agent is preferably a solvent required for the maleic anhydride hydrogenation reaction, such as one or more than one mixed solvent selected from the group consisting of γ-butyrolactone, dibutyl phthalate, diisobutyl hexahydrophthalate, tetrahydrofuran, aromatic hydrocarbons, ethyl acetate, tetracarboxylic acid ester, ethanol, isopropyl alcohol, hexane, cyclohexane, propylene oxide, benzene, xylene, chlorobenzene, dichlorobenzene, and part of ketone and ether solvents, and more preferably γ-butyrolactone and tetrahydrofuran.

[0050] According to the present application, in the step (2), the solvent ratio of the absorption agent to maleic anhydride is not specifically limited, and can be determined by a person skilled in the art according to professional knowledge and prior art.

[0051] According to the present application, in the step (2), a part of the bottom material of the absorption tower is separated, cooled to 30-80℃, and then partially returned to the absorption tower and partially sent to the rectification tower.

[0052] According to the present application, in the step (2), the overhead material of the absorption tower is cooled to 20-50℃ by a heat exchanger, and then passed through a gas-liquid separator, the gas phase is sent to the outside of the boundary area, and the liquid phase is sent to the rectification tower.

[0053] According to the application, in the step (4), the succinic anhydride separation unit mainly comprises a light-removing column and a heavy-removing column. The material from the maleic anhydride hydrogenation reaction unit enters the light-removing column, the light-removing column bottom material enters the heavy-removing column, the heavy-removing column top product is the solvent, the heavy-removing column side line product is the succinic anhydride, and the heavy-removing column bottom product is the heavy component.

[0054] According to the application, in the step (4), the succinic anhydride separation unit further comprises a solvent recovery column. The material from the maleic anhydride hydrogenation reaction unit enters the light-removing column, the light-removing column bottom material enters the solvent recovery column, the solvent recovery column top product is the solvent, the solvent recovery column bottom material enters the heavy-removing column, the heavy-removing column top product is the succinic anhydride, and the heavy-removing column bottom product is the heavy component.

[0055] According to the preferred embodiment of the application, in the step (4), the succinic anhydride separation unit comprises a light-removing column, a heavy-removing column and a solvent recovery column connected in series, the hydrogenation product enters the light-removing column, the light-removing column bottom material enters the heavy-removing column, the heavy-removing column top product is the solvent, the heavy-removing column side line product is the succinic anhydride, and the heavy-removing column bottom product enters the solvent recovery column.

[0056] According to the preferred embodiment of the application, the light component is discharged from the light-removing column 8 top, the light-removing column bottom material enters the heavy-removing column 9, the by-product is discharged from the heavy-removing column 9 top, the heavy component is discharged from the heavy-removing column bottom, and the succinic anhydride is discharged from the side line.

[0057] In the application, the light component refers to the dissolved hydrogen, a small amount of solvent such as γ-butyrolactone and tetrahydrofuran, etc.

[0058] In the application, the purpose of the light-removing column is to remove hydrogen, a small amount of solvent such as γ-butyrolactone and tetrahydrofuran, etc. There is no special requirement for its setting and operating conditions, as long as the purpose of the application can be achieved.

[0059] In the application, the purpose of the heavy-removing column is to remove the solvent from the top and the heavy component from the bottom, and the succinic anhydride is discharged from the side line. There is no special requirement for its setting and operating conditions, as long as the purpose of the application can be achieved.

[0060] In the application, there is no special requirement for the operating conditions of the light-removing column. The commonly used operating conditions of the light-removing column are suitable for the application. In the step (4), the operating pressure of the light-removing column is preferably 0.5-20 KPa, preferably 6-15 KPa; the operating temperature is 30-150 ℃, preferably 80-130 ℃; and the theoretical plate number is 10-80.

[0061] The application has no special requirements for the operating conditions of the heavy component removal column, and the commonly used operating conditions of the light component removal column are suitable for the application. For the application, in the step (4), the operating pressure of the heavy component removal column is preferably 0.5-20 KPa, preferably 3-15 KPa; the operating temperature is 30-150℃, preferably 100-130℃; and the number of theoretical plates is 10-80.

[0062] According to the application, in the step (4), the operating pressure of the solvent recovery column is 0.5-20 KPa, the operating temperature is 30-150℃, and the number of theoretical plates is 10-80.

[0063] According to the application, in the step (4), the separated solvent is preferably heat-exchanged to the absorption temperature and then recycled to the step (2) for use in the absorption column.

[0064] According to the application, in the step (5), the hydrolysis unit is not specifically limited, and can be determined by those skilled in the art according to professional knowledge and prior art.

[0065] According to a preferred embodiment of the application, in the maleic anhydride separation unit, the operating conditions of the absorption column include: the pressure is 0.0-1.0 MPag, the temperature is 40-120℃, and the number of theoretical plates is 5-50; the absorbent is selected from one or more than one of γ-butyrolactone, dibutyl phthalate, diisobutyl hexahydrophthalate, tetrahydrofuran, aromatic hydrocarbon, ethyl acetate, four-carbon dibasic acid ester, ethanol, isopropyl alcohol, hexane, cyclohexane, propylene oxide, benzene, xylene, chlorobenzene, dichlorobenzene, ketone and ether, and more preferably γ-butyrolactone and / or tetrahydrofuran.

[0066] According to a preferred embodiment of the application, the operating conditions of the rectification column include: the pressure is 0.0-1.0 MPag, the temperature is 40-150℃, and the number of theoretical plates is 5-100.

[0067] According to a preferred embodiment of the application, in the step (2), part of the material in the tower bottom of the absorption column is cooled to 30-80℃ and then returned to the absorption column.

[0068] According to a preferred embodiment of the application, in the step (2), the material in the tower top of the absorption column is cooled to 20-50℃ by a heat exchanger, and then sent to a gas-liquid separator, the gas phase is sent out of the area, and the liquid phase is sent to the rectification column.

[0069] The application does not specifically limit the maleic anhydride hydrogenation reaction unit, and those skilled in the art can determine it according to professional knowledge and prior art. According to a preferred embodiment of the application, the hydrogenation reaction in the step (3) includes:

[0070] I) the maleic anhydride solution is divided into two streams, one of which is mixed with the liquid phase material from the second-stage hydrogenation reaction with or without cooling, and then enters the first-stage hydrogenation reactor from the liquid phase feed port of the first-stage hydrogenation reactor to contact hydrogen to perform hydrogenation;

[0071] II) the first-stage hydrogenation product is sequentially cooled, gas-liquid separation is performed, the gas phase from the gas-liquid separation enters the second-stage hydrogenation reactor from the gas phase feed port of the second-stage hydrogenation reactor, and the liquid phase from the gas-liquid separation is mixed with the other stream of the maleic anhydride solution, and then enters the second-stage hydrogenation reactor from the liquid phase feed port of the second-stage reactor to convert all the maleic anhydride into succinic anhydride by hydrogenation reaction;

[0072] III) the second-stage hydrogenation product is subjected to gas-liquid separation to obtain a gas phase and a liquid phase material from the second-stage hydrogenation reaction, and part of the liquid phase material from the second-stage hydrogenation reaction is returned to step I), and optionally part or all of the gas phase of the second-stage hydrogenation product is used as recycled hydrogen;

[0073] IV) the remaining liquid phase material from the second-stage hydrogenation reaction is sent to a succinic anhydride separation unit.

[0074] In the present application, the hydrogen raw material can be fresh hydrogen or recycled hydrogen. In the present application, the hydrogen raw material in step I) is preferably a mixture of recycled hydrogen and make-up hydrogen 22.

[0075] According to a preferred embodiment of the present application, the liquid phase material from the second-stage hydrogenation reaction in step I) is cooled material.

[0076] According to a preferred embodiment of the present application, the liquid phase material from the second-stage hydrogenation reaction in step I) is cooled to 30-80°C, preferably to 40-60°C.

[0077] In the present application, there is no special requirement for the operating conditions of the second-stage hydrogenation reactor. According to a preferred embodiment of the present application, in step II), the operating conditions of the second-stage hydrogenation reactor 5 include: a temperature of 30-100°C, preferably 40-80°C, for example 40°C, 41°C, 42°C, 43°C, 44°C, 45°C, 46°C, 47°C, 48°C, 49°C, 50°C, and the like; and / or a pressure of 0.1-10 MPa, preferably 0.5-5 MPa; and / or a space velocity of 0.1-5 h -1 .

[0078] In the present application, there is no special requirement for the composition of the maleic anhydride solution. In the present application, the maleic anhydride solution is preferably a mixture of maleic anhydride and a solvent, and the type of the solvent is not particularly limited. In the present application, the solvent is more preferably one or more of acetic anhydride, γ-butyrolactone, dioxane, tetrahydrofuran, aromatic hydrocarbon, ethyl acetate, four-carbon dibasic acid ester, ethanol, isopropyl alcohol, hexane, cyclohexane, propylene oxide, ketone, and ether.

[0079] According to a preferred embodiment of the present application, the concentration of maleic anhydride in the maleic anhydride solution is 1-90 wt%, preferably 10-40 wt%.

[0080] According to the method of the present application, the concentration of maleic anhydride in the incoming maleic anhydride solution can not be too low, thereby reducing the amount of solvent used and reducing the energy consumption for subsequent solvent recovery. According to a preferred embodiment of the present application, the proportion of each of the one stream and the other stream is 5-95 wt%, preferably the proportion of the one stream is 20-60 wt% and the proportion of the other stream is 40-80 wt%.

[0081] According to a preferred embodiment of the present application, the molar ratio of the total amount of hydrogen to the total amount of maleic anhydride in the maleic anhydride solution is 5-100, preferably 10-40. This can effectively remove the reaction heat and improve the utilization rate of the catalyst.

[0082] According to a preferred embodiment of the present application, the operating conditions of the first hydrogenation reactor include a temperature of 30-100°C, preferably 40-80°C, for example 40°C, 41°C, 42°C, 43°C, 44°C, 45°C, 46°C, 47°C, 48°C, 49°C, 50°C, and the like. This can effectively remove the reaction heat and improve the utilization rate of the catalyst.

[0083] According to a preferred embodiment of the present application, the operating conditions of the first hydrogenation reactor include a reaction pressure of 0.1-10 MPa, preferably 0.5-5 MPa.

[0084] According to a preferred embodiment of the present application, the operating conditions of the first hydrogenation reactor include a space velocity of 0.5-5 h -1 .

[0085] According to a preferred embodiment of the present application, as shown in Figure 4 , the method further comprises:

[0086] The gas phase obtained by gas-liquid separation of the second hydrogenation product is cooled in the second cooler 11 and then subjected to third gas-liquid separation in the third gas-liquid separator 12, and the gas phase obtained is partially or entirely returned to the first hydrogenation reactor 2 as recycle hydrogen; optionally, the liquid phase obtained by the third gas-liquid separation is returned to the second gas-liquid separator 6 for gas-liquid separation.

[0087] According to a preferred embodiment of the present application, the temperature for cooling the gas phase obtained by gas-liquid separation of the second hydrogenation product is 30-80°C.

[0088] According to a preferred embodiment of the present application, 20-90 wt% of the liquid phase material of the second hydrogenation reaction is returned to step I) as raw material, and the remainder is sent to the light-removing column.

[0089] The maleic anhydride hydrogenation method of the present application can effectively remove the heat released in the reaction, and is flexible and easy to control. In the method of the present application, the concentration of maleic anhydride in the incoming maleic anhydride solution can not be too low, thereby reducing the solvent usage and lowering the energy consumption of subsequent solvent recovery.

[0090] The maleic anhydride hydrogenation method of the present application has good gas-liquid-solid contact, high effective utilization rate of catalyst, and low investment.

[0091] The maleic anhydride hydrogenation method of the present application has mild reaction operating conditions, low temperature rise of the reaction bed, and can be operated at about 40℃, which is conducive to improving the selectivity of the catalyst and prolonging the service life of the catalyst. In the method of the present application, the light removal column and the heavy removal column are operated in combination to obtain the succinic anhydride product, and the process is simple, easy to operate and control, and the succinic anhydride product has high purity.

[0092] The maleic anhydride hydrogenation reaction of the present application has the following advantages:

[0093] (1) The maleic anhydride solution is divided into two streams in the present application, which are mixed with different materials and then enter two hydrogenation reactors, so that the content of maleic anhydride entering the reactor is reduced, the heat released in the reaction can be effectively removed, the operation is flexible and easy to control.

[0094] (2) In the method of the present application, the concentration of maleic anhydride in the incoming maleic anhydride solution can not be too low, thereby reducing the solvent usage and lowering the energy consumption of subsequent solvent recovery.

[0095] (3) In the present application, after the first-stage reaction, the gas phase is separated by cooling and gas-liquid separation, and the gas phase is introduced into the second-stage reactor, which is conducive to effectively removing the reaction heat generated in the second-stage reaction.

[0096] (4) In the present application, a gas-liquid separation is provided after the first-stage reactor, and the gas phase and the liquid phase are introduced into the reactor, respectively, and preferably through a distribution device, so that the materials entering the reactor are more fully contacted, the gas-liquid-solid contact is good, the effective utilization rate of the catalyst is high, and the investment is low.

[0097] (5) The reaction operating conditions of the present application are mild, and the reactor can be operated at 40℃, which greatly reduces the reaction severity and the temperature rise of the reaction bed, which is conducive to improving the selectivity of the catalyst and prolonging the service life of the catalyst.

[0098] (6) In the method of the present application, the light removal column and the heavy removal column are operated in combination to obtain the succinic anhydride product, and the process is simple, easy to operate and control, and the succinic anhydride product has high purity.

[0099] According to a preferred embodiment of the present application, 0.5-2% by weight of the gas phase material of the second-stage hydrogenation reaction is taken out as fuel gas, and the rest is used as the circulating hydrogen gas.

[0100] According to the preferred embodiment of the present application, part or all of the gas phase obtained by gas-liquid separation of the second-stage hydrogenation product is recycled to the first-stage hydrogenation reactor as recycled hydrogen, and the rest is used as vent gas, and part of the liquid phase material obtained by gas-liquid separation of the second-stage hydrogenation product is recycled to the first-stage hydrogenation reactor as raw material.

[0101] The reaction operating conditions of the present application are mild, the temperature rise of the reaction bed is low, the reaction heat generated in the second-stage reaction can be effectively removed, which is beneficial to improve the selectivity of the catalyst and prolong the service life of the catalyst. The process and method of the present application have the characteristics of simple flow, low investment, strong applicability, easy control, etc.

[0102] Preferably, the catalysts filled in the first-stage hydrogenation reactor and the second-stage hydrogenation reactor are not limited, and any maleic anhydride hydrogenation catalysts can be used, such as the catalysts described in Chinese Patent Application CN202011118431.X and Chinese Patent Application CN202011120495.3.

[0103] According to the preferred embodiment of the present application, when the gas phase and the liquid phase enter the first-stage reactor and the second-stage reactor, they pass through the distributor and then contact with the catalyst.

[0104] According to the preferred embodiment of the present application, preferably, after the second-stage hydrogenation product is subjected to gas-liquid separation, the gas phase material can be cooled by a heat exchanger, and the cooling temperature is preferably 30-80℃, and then the cooled material is subjected to a step of gas-liquid separation again, the gas phase is recycled to step II), and the liquid phase is returned to the previous gas-liquid separator.

[0105] According to the preferred embodiment of the present application, preferably, after the second-stage hydrogenation product is subjected to gas-liquid separation, about 0.5%-2% of the material of the gas phase is taken out as fuel gas, and the rest of the gas phase is cooled and then recycled to the first-stage hydrogenation reactor, mixed with the fresh hydrogen gas, and then enters the first-stage hydrogenation reactor.

[0106] According to the preferred embodiment of the present application, preferably, after the second-stage hydrogenation product is subjected to gas-liquid separation, 10%-80% of the liquid phase reaction product is sent to a light-removing tower, and the remaining liquid phase reaction product is cooled to 40-80℃ by a cooler, and then mixed with a maleic anhydride solution and enters the first-stage hydrogenation reactor for recycling.

[0107] According to a preferred embodiment of the present application, in step I), the proportion of one stream is 20-60% by weight, and the proportion of the other stream is 40-80% by weight.

[0108] According to a preferred embodiment of the present application, the molar ratio of the total hydrogen amount to the total maleic anhydride in the maleic anhydride solution is 10-40.

[0109] As shown in Figure 3 The present application provides a maleic anhydride hydrogenation reaction, which comprises:

[0110] (1) the succinic anhydride solution 21 is divided into two streams by the distributor 1, one of which is mixed with the liquid phase material from the second stage hydrogenation reaction and enters the first stage hydrogenation reactor 2 from the upper liquid phase inlet of the first stage hydrogenation reactor 2 to contact with hydrogen gas entering the first stage hydrogenation reactor 2 from the top gas phase inlet of the first stage hydrogenation reactor 2;

[0111] (2) the first stage hydrogenation product is sequentially cooled, gas-liquid separated, and the gas phase from the gas-liquid separation enters the second stage hydrogenation reactor 5 from the top gas phase inlet of the second stage hydrogenation reactor 5, and the liquid phase from the gas-liquid separation is mixed with the other stream of succinic anhydride solution and enters the second stage hydrogenation reactor 5 from the upper liquid phase inlet of the second stage hydrogenation reactor 5 to react with hydrogen gas to convert all succinic anhydride into butane diacid anhydride;

[0112] (3) the second stage hydrogenation product is gas-liquid separated to obtain a gas phase and a liquid phase material from the second stage hydrogenation reaction, and part of the liquid phase material from the second stage hydrogenation reaction is returned to step 1, and part or all of the gas phase of the second stage hydrogenation product is optionally used as recycled hydrogen gas;

[0113] (4) the remaining liquid phase material from the second stage hydrogenation reaction is sent to the light component removal column 8, and the light components are removed from the top of the light component removal column 8, and the column bottom material is sent to the heavy component removal column 9;

[0114] (5) butane diacid anhydride is removed from the side line of the heavy component removal column 9, by-products including solvents such as γ-butyrolactone are removed from the top of the heavy component removal column 9, and heavy components including polymers are removed from the column bottom.

[0115] As shown in Figure 1 , the present application provides a system for producing succinic acid from butane and / or benzene, which comprises:

[0116] connected in series along the material flow direction: an oxidation reaction unit, a succinic anhydride separation unit comprising an absorption column 13 and a rectification column 14 connected in series, a succinic anhydride hydrogenation reaction unit, a butane diacid anhydride separation unit, and a butane diacid anhydride hydrolysis unit;

[0117] wherein butane and / or benzene and an oxygen-containing gas are subjected to an oxidation reaction in the oxidation reaction unit, and the product enters the succinic anhydride separation unit to be subjected to absorption-rectification to obtain a succinic anhydride solution; the succinic anhydride solution enters the succinic anhydride hydrogenation reaction unit to be subjected to a hydrogenation reaction to obtain a hydrogenation product; the hydrogenation product enters the butane diacid anhydride separation unit to be separated to obtain butane diacid anhydride and a solvent; and the butane diacid anhydride enters the butane diacid anhydride hydrolysis unit to be subjected to hydrolysis and crystallization to obtain a succinic acid product.

[0118] The present application does not have special requirements for the oxidation reaction unit, the butane diacid anhydride separation unit, and the hydrolysis unit, and those skilled in the art can judge and select according to common sense and knowledge.

[0119] According to a preferred embodiment of the present application, asFigure 3 As shown in the figure, the maleic anhydride hydrogenation reaction unit comprises:

[0120] A first hydrogenation reactor 2, a first reaction product cooler 3 and a first gas-liquid separator 4 are connected in series along the material flow direction; a second hydrogenation reactor 5 is connected in series with the first gas-liquid separator 4 through a gas phase inlet and a liquid phase inlet; and a second gas-liquid separator 6 is connected in series with the second hydrogenation reactor.

[0121] A liquid phase raw material supply pipeline is connected to the liquid phase inlet of the first hydrogenation reactor 2 and the liquid phase inlet of the second hydrogenation reactor 5.

[0122] According to a preferred embodiment of the present application, as shown in the figure, Figures 1-2 The maleic anhydride separation unit comprises a light-removing column 8 and a heavy-removing column 9 connected in series; the feed inlet of the light-removing column is connected to the liquid phase outlet of the second gas-liquid separator; the light-removing column is provided with a top outlet and a column bottom outlet; the feed inlet of the heavy-removing column is connected to the column bottom outlet of the light-removing column; the heavy-removing column is provided with a top outlet, a bottom outlet and a side outlet.

[0123] As shown in the figure, Figure 2 The maleic anhydride separation unit comprises a light-removing column 8, a heavy-removing column 9 and a solvent recovery column 10 connected in series; the feed inlet of the light-removing column is connected to the liquid phase outlet of the second gas-liquid separator; the light-removing column is provided with a top outlet and a column bottom outlet; the feed inlet of the heavy-removing column is connected to the column bottom outlet of the light-removing column; the heavy-removing column is provided with a top outlet and a column bottom outlet; the feed inlet of the solvent recovery column is connected to the column bottom outlet of the heavy-removing column; and the solvent recovery column comprises a column bottom outlet and a top outlet.

[0124] According to a preferred embodiment of the present application, as shown in the figure, Figures 3-4 In the maleic anhydride hydrogenation reaction unit, the first reaction product cooler 3 and the first gas-liquid separator 4 are connected in series at the end of the column bottom outlet of the first hydrogenation reactor 2.

[0125] According to a preferred embodiment of the present application, as shown in the figure, Figures 3-4 In the maleic anhydride hydrogenation reaction unit, the second gas-liquid separator 6 is connected in series with the column bottom outlet of the second hydrogenation reactor 5.

[0126] According to a preferred embodiment of the present application, as shown in the figure, Figures 3-4 In the maleic anhydride hydrogenation reaction unit, the first hydrogenation reactor 2 comprises a top gas phase inlet, an upper liquid phase inlet and a column bottom outlet.

[0127] According to a preferred embodiment of the present application, as shown in the figure,Figures 3-4 As shown in the figure, in the maleic anhydride hydrogenation reaction unit, the two-stage hydrogenation reactor 5 comprises a top gas phase feed inlet and an upper liquid phase feed inlet as well as a bottom discharge outlet.

[0128] According to a preferred embodiment of the present application, as shown in the figure, Figures 3-4 As shown in the figure, in the maleic anhydride hydrogenation reaction unit, the top gas phase outlet of the first-stage gas-liquid separator 4 is in communication with the top gas phase feed inlet of the two-stage hydrogenation reactor 5 through a pipeline.

[0129] According to a preferred embodiment of the present application, as shown in the figure, Figures 3-4 As shown in the figure, the bottom liquid phase outlet of the first-stage gas-liquid separator 4 is in communication with the upper liquid phase feed inlet of the two-stage hydrogenation reactor 5 through a pipeline.

[0130] According to a preferred embodiment of the present application, as shown in the figure, Figures 3-4 As shown in the figure, the top gas phase outlet of the two-stage gas-liquid separator 6 is in communication with the top gas phase feed inlet of the first-stage hydrogenation reactor 2 through a pipeline.

[0131] According to a preferred embodiment of the present application, as shown in the figure, Figures 3-4 As shown in the figure, the bottom liquid phase outlet of the two-stage gas-liquid separator 6 is in communication with the upper liquid phase feed inlet of the first-stage hydrogenation reactor 2 through a pipeline.

[0132] According to a preferred embodiment of the present application, as shown in the figure, Figure 3 As shown in the figure, a circulating material cooler 7 is preferably arranged on the pipeline in communication between the bottom liquid phase outlet of the two-stage gas-liquid separator 6 and the upper liquid phase feed inlet of the first-stage hydrogenation reactor 2.

[0133] According to a preferred embodiment of the present application, as shown in the figure, Figure 4 As shown in the figure, a circulating gas cooler 10 is preferably arranged on the pipeline in communication between the top gas phase outlet of the two-stage gas-liquid separator 6 and the top gas phase feed inlet of the first-stage hydrogenation reactor 2.

[0134] According to a preferred embodiment of the present application, the maleic anhydride hydrogenation reaction unit further comprises a distributor 1 for distributing the liquid phase raw material into two streams to be supplied to the first-stage hydrogenation reactor 2 and the two-stage hydrogenation reactor 5 as needed.

[0135] According to a preferred embodiment of the present application, as shown in the figure, Figure 3 As shown in the figure, a two-stage cooler 11 and a third gas-liquid separator 12 are arranged in series at the top gas phase outlet end of the two-stage gas-liquid separator 6, the gas phase outlet of the third gas-liquid separator 12 is in communication with the top gas phase feed inlet of the first-stage hydrogenation reactor 2 through a pipeline; the bottom liquid phase outlet of the third gas-liquid separator 12 is in communication with the liquid phase feed inlet of the two-stage gas-liquid separator 6.

[0136] According to a preferred embodiment of the present application, a circulation gas cooler 10 is arranged in a communication pipeline between the gas phase outlet of the third gas-liquid separator 12 and the top gas phase feed inlet of the first-stage hydrogenation reactor 2.

[0137] As shown in Figure 4 the maleic anhydride hydrogenation reaction unit of the present application comprises:

[0138] a first-stage hydrogenation reactor 2, a first-stage reaction product cooler 3 and a first-stage gas-liquid separator 4 connected in series along the material flow direction; a second-stage hydrogenation reactor 5 connected in communication with the gas phase outlet of the first-stage gas-liquid separator 4 through a gas phase inlet and connected in communication with the liquid phase outlet of the first-stage gas-liquid separator 4 through a liquid phase inlet; and a second-stage gas-liquid separator 6 connected in series communication with the second-stage hydrogenation reactor 5;

[0139] a liquid phase raw material supply pipeline connected in communication with the upper liquid phase feed inlet of the first-stage hydrogenation reactor 2 and the upper liquid phase feed inlet of the second-stage hydrogenation reactor 5.

[0140] The maleic anhydride hydrogenation reaction unit of the present application can effectively remove the heat released during the reaction, is flexible to operate, easy to control, has good gas-liquid-solid contact, high effective utilization rate of catalyst and low investment. The use of the maleic anhydride hydrogenation reaction unit of the present application can reduce the temperature rise of the reaction bed, which is conducive to improving the selectivity of the catalyst and prolonging the service life of the catalyst.

[0141] According to a preferred embodiment of the present application, the first-stage reaction product cooler 3 and the first-stage gas-liquid separator 4 are connected in series at the end of the bottom discharge outlet of the first-stage hydrogenation reactor 2.

[0142] According to a preferred embodiment of the present application, the second-stage gas-liquid separator 6 is connected in series communication with the bottom discharge outlet of the second-stage hydrogenation reactor 5.

[0143] According to a preferred embodiment of the present application, the first-stage hydrogenation reactor 2 comprises a top gas phase feed inlet, an upper liquid phase feed inlet and a bottom discharge outlet.

[0144] According to a preferred embodiment of the present application, the second-stage hydrogenation reactor 5 comprises a top gas phase feed inlet, an upper liquid phase feed inlet and a bottom discharge outlet.

[0145] According to a preferred embodiment of the present application, the feed inlet of the light-removing column 8 is connected in communication with the liquid phase discharge outlet of the second-stage gas-liquid separator 6, and the light-removing column 8 is provided with a top outlet and a column still discharge outlet.

[0146] According to a preferred embodiment of the present application, the feed inlet of the heavy-removing column 9 is connected in communication with the column still discharge outlet of the light-removing column 8, and the heavy-removing column 9 is provided with a top outlet, a bottom outlet and a side line discharge outlet.

[0147] According to a preferred embodiment of the present application, the top gas phase outlet of the first stage gas-liquid separator 4 is in communication with the top gas phase inlet of the second stage hydrogenation reactor 5 through a pipeline.

[0148] According to a preferred embodiment of the present application, the bottom liquid phase outlet of the first stage gas-liquid separator 4 is in communication with the upper liquid phase inlet of the second stage hydrogenation reactor 5 through a pipeline.

[0149] According to a preferred embodiment of the present application, the top gas phase outlet of the second stage gas-liquid separator 6 is in communication with the top gas phase inlet of the first stage hydrogenation reactor 2 through a pipeline.

[0150] According to a preferred embodiment of the present application, the bottom liquid phase outlet of the second stage gas-liquid separator 6 is in communication with the upper liquid phase inlet of the first stage hydrogenation reactor 2 and the light removal column feed inlet respectively through pipelines. Thus, the heat released by the reaction can be effectively removed, and the catalyst utilization rate is improved.

[0151] According to a preferred embodiment of the present application, a circulating material cooler 7 is preferably arranged on the pipeline for communication between the bottom liquid phase outlet of the second stage gas-liquid separator 6 and the upper liquid phase inlet of the first stage hydrogenation reactor 2. Thus, the heat released by the reaction can be effectively removed, and the catalyst utilization rate is improved.

[0152] According to a preferred embodiment of the present application, a circulating gas cooler 10 is preferably arranged on the pipeline for communication between the top gas phase outlet of the second stage gas-liquid separator 6 and the top gas phase inlet of the first stage hydrogenation reactor 2. Thus, the heat released by the reaction can be effectively removed, and the catalyst utilization rate is improved.

[0153] According to a preferred embodiment of the present application, the system further comprises a distributor 1 for distributing the liquid phase raw material into two streams for supplying the first stage hydrogenation reactor 2 and the second stage hydrogenation reactor 5 as needed.

[0154] According to a preferred embodiment of the present application, as shown in Figure 1 the top gas phase outlet end of the second stage gas-liquid separator 6 is sequentially provided with a second stage cooler 11 and a third gas-liquid separator 12, the gas phase outlet of the third gas-liquid separator 12 is in communication with the top gas phase inlet of the first stage hydrogenation reactor 2 through a pipeline; the bottom liquid phase outlet of the third gas-liquid separator 12 is in communication with the liquid phase inlet of the second stage gas-liquid separator 6; thus, the heat released by the reaction can be effectively removed, and the catalyst utilization rate is improved.

[0155] According to a preferred embodiment of the present application, a circulating gas cooler 10 is preferably arranged on the pipeline for communication between the gas phase outlet of the third gas-liquid separator 12 and the top gas phase inlet of the first stage hydrogenation reactor 2.

[0156] The following examples employ the following catalyst:

[0157] Chinese patent application CN202011118431.X - Example 1

[0158] (1) 50.00 g of basic nickel carbonate (nickel content 45 wt.%, 9.16 g of Cu(NO3)2·3H2O, 49.91 g of ethylenediaminetetraacetic acid, 500 g of deionized water, and 100 g of 25 wt.% ammonia water were weighed and mixed, and ammonia gas was introduced to adjust the pH of the solution to 10.5. The solution was stirred at 45°C until all the solids were dissolved to obtain a nickel-copper ammonia complex solution;

[0159] (2) 458.31 g of silica sol was mixed with the nickel-copper ammonia complex solution obtained in step (1) to obtain a mixed solution;

[0160] (3) The mixed solution was aged at a temperature of 60°C for 14 h under stirring, and then dried at 120°C for 12 h to obtain a catalyst precursor;

[0161] (4) The catalyst precursor was saturatedly impregnated with a cerium nitrate solution containing 11.41 g of Ce(NO3)3·6H2O to obtain a base catalyst;

[0162] (5) The base catalyst was dried at 115°C for 12 h, and then calcined at 400°C for 4 h to obtain a catalyst S1.

[0163] Based on the total weight of the catalyst S1, the catalyst S1 contains 19 wt.% of NiO, 2 wt.% of CuO, 3 wt.% of CeO2, and 76 wt.% of SiO2.

[0164] CN202011120495.3 - Example 1

[0165] (1) 10.90 g of Ni(NO3)3·6H2O and 5.04 g of Ce(NO3)3·6H2O cerium were weighed, dissolved in water and diluted to 50.0 ml, and then 50 g of a carrier SiO2 (specific surface area 300 m2 / g, water absorption 1.0 mL / g) was impregnated in the mixed solution of nickel nitrate-cerium nitrate, stirred uniformly, and aged for 4 hours, then dried at 120°C for 12 hours, and finally calcined at 450°C in air for 4 hours to obtain a composite oxide carrier E;

[0166] (2) The composite oxide support E was added to 100 ml of an exothermic Ru metal solution with a Ru content of 0.02 g / L. Under stirring conditions, 25% ammonia water was added dropwise to adjust the pH value of the solution and maintain it at 9. After reacting at 55°C for 6 hours, the solution was filtered, dried at 110°C for 12 hours, and finally calcined in air at 500°C for 4 hours to obtain the finished catalyst S1.

[0167] The catalyst S1 contains, based on the mass of the catalyst support SiO2, Ni in the catalyst is 7% of the mass of the support, CeO2 is 4% of the mass of the support, and Ru is 0.4% of the mass of the support.

[0168] Example 1

[0169] use Figure 1 The diagram illustrates a method for producing succinic acid from butane.

[0170] Butane and air are mixed and fed into the oxidation reaction unit. The reaction product enters the absorber of the maleic anhydride separation unit, starting from the bottom. γ-Butyrolactone is used as the solvent, entering the absorber from the top. The absorber has 18 theoretical plates, operates at 75°C and 0.06 MPa. Tail gas is collected from the top of the absorber, and the solvent-rich bottom product enters the distillation column. The distillation column has 20 theoretical plates, operates at 95°C and 0.003 MPa. Light components are collected from the top of the distillation column, and the bottom product is sent to the maleic anhydride hydrogenation reaction unit.

[0171] The maleic anhydride hydrogenation reaction unit employs a two-stage hydrogenation reactor with a hydrogen to maleic anhydride molar ratio of 12 and a space velocity of 2.5 h⁻¹ in the first-stage hydrogenation reactor. -1 The reaction temperature was 40℃, and the reaction pressure was 1.5MPa. The products of the first-stage hydrogenation reaction were cooled to 40℃, and after gas-liquid separation, the gas and liquid phases entered the second-stage hydrogenation reactor separately from the top of the first-stage reactor. The space velocity in the second-stage hydrogenation reactor was 1 h⁻¹. -1 The reaction temperature was 45℃, and the reaction pressure was 1.3MPa. After the products of the second-stage hydrogenation reaction passed through a gas-liquid separator, 1% by volume of the gas phase was vented, and the remaining gas phase, along with the replenished fresh hydrogen, was sent to the first-stage hydrogenation reactor. The liquid phase after gas-liquid separation was used as follows: 65% of the liquid phase was sent to the light component removal tower, and the remaining 35% of the liquid phase, after being heated to 40℃, was mixed with the maleic anhydride solution and then entered the first-stage hydrogenation reactor. The catalysts packed in both the first and second-stage reactors were Ni-active catalysts; the specific composition is described in Chinese Patent CN202011118431.X - Example 1.

[0172] After two hydrogenation reactions, the total conversion rate of maleic anhydride was 99.91%, and the total selectivity of succinic anhydride was 99.85%.

[0173] The material from the succinic anhydride hydrogenation reaction unit enters the succinic anhydride separation unit, first passes through the light component removal tower to separate out the light components, and the tower bottom material is sent to the heavy component removal tower. The γ-butyrolactone is collected from the top of the heavy component removal tower and returned to the absorption tower of the succinic anhydride separation unit for recycling. The heavy components are collected from the tower bottom of the heavy component removal tower, and the succinic anhydride is collected from the side line and sent to the succinic anhydride hydrolysis unit.

[0174] The theoretical plate number of the light component removal tower is 26, the tower top pressure is 10 KPa, and the operating temperature is 100°C. The theoretical plate number of the heavy component removal tower is 25, the tower top pressure is 3 KPa, and the operating temperature is 105°C. The purity of the obtained succinic anhydride is 99.9%.

[0175] The operating pressure of the hydrolysis kettle of the hydrolysis unit is 0.12 MPa, and the operating temperature is 80°C. After centrifugal separation and drying, the succinic acid product is obtained. The purity of the succinic acid product is 99.9%.

[0176] Comparative Example 1

[0177] The butane and air are mixed and enter the oxidation reaction unit. The reaction product enters the absorption tower of the succinic anhydride separation unit from the tower bottom. The solvent used is dibutyl phthalate. The solvent enters the absorption tower from the top. The absorption tower has a total of 20 theoretical plates, the operating temperature is 90°C, and the operating pressure is 0.05 MPag. The tail gas is collected from the top of the absorption tower and sent outside the boundary. The rich solvent from the tower bottom enters the stripping tower. The stripping tower has a total of 25 theoretical plates, the operating temperature is 142°C, and the operating pressure is 12 KPa. The material from the top of the stripping tower is sent to the light component tower. The material from the tower bottom of the stripping tower is sent to the absorption tower for recycling. The light component tower has a total of 20 theoretical plates, the operating temperature is 40°C, and the operating pressure is 8 KPa. The material from the top of the light component tower is sent outside the boundary. The material from the tower bottom is sent to the product refining tower. The product refining tower has a total of 25 plates, the operating temperature is 132°C, and the operating pressure is 10 KPa. The succinic anhydride product is collected from the side line of the upper part of the product refining tower and sent to the succinic anhydride hydrogenation reaction unit. The tower bottom material is returned to the absorption tower after heat exchange to 50°C for recycling.

[0178] The operating conditions of the succinic anhydride hydrogenation reaction unit are the same as in Example 1. The difference is that a stream of γ-butyrolactone / dioxane is introduced from outside as the solvent. After two-stage hydrogenation reaction, the total conversion rate of succinic anhydride is 99.50%, and the total selectivity of succinic anhydride is 99%.

[0179] The succinic anhydride separation unit and the hydrolysis unit are the same as in Example 1. The purity of the succinic acid product is 99.5%.

[0180] The succinic anhydride separation unit is complex to operate, and an additional absorbent needs to be introduced, which increases the process cost. The total conversion rate obtained is not as good as that of the method of the present application.

[0181] Example 2

[0182] The succinic anhydride hydrogenation reaction unit is used Figure 3A method for producing succinic acid from butane as raw material is shown.

[0183] The oxidation reaction-separation is carried out according to the method of Example 1 to obtain a maleic anhydride solution with a content of 10% by weight of maleic anhydride, and the solvent is γ-butyrolactone.

[0184] The hydrogenation reaction of maleic anhydride is carried out as shown in the formula. Figure 1 The maleic anhydride solution is divided into two streams in a proportion of 50% by weight and 50% by weight, one of which is mixed with the recycled second-stage hydrogenation reaction product and then introduced into the first-stage hydrogenation reactor from the upper part of the reactor. The other is mixed with the first-stage hydrogenation reaction product and then introduced into the second-stage hydrogenation reactor from the upper part of the reactor. The total amount of hydrogen gas, including the circulating hydrogen gas and the supplemented fresh hydrogen gas, is 10 times the molar ratio of the total maleic anhydride in the maleic anhydride solution.

[0185] In the first-stage hydrogenation reactor, the space velocity is 2.5h -1 -1, the reaction temperature is 40°C, and the reaction pressure is 1.5 MPa. The first-stage hydrogenation reaction product is cooled to 40°C, and after gas-liquid separation, the gas phase is introduced into the second-stage hydrogenation reactor from the top of the reactor, and the liquid phase is mixed with another part of the maleic anhydride solution and then introduced into the second-stage hydrogenation reactor from the upper part of the reactor. The space velocity in the second-stage hydrogenation reactor is 1h -1 -1, the reaction temperature is 42°C, and the reaction pressure is 1.3 MPa. After the second-stage hydrogenation reaction product passes through the gas-liquid separator, the gas phase is sent into the first-stage hydrogenation reactor together with the supplemented fresh hydrogen gas, and 65% by weight of the liquid phase is taken to the subsequent light removal tower and heavy removal tower, and 35% by weight of the liquid phase is returned to the first-stage hydrogenation reactor. The mixture is heated to 40°C and then introduced into the first-stage hydrogenation reactor.

[0186] The catalysts loaded in the first-stage and second-stage reactors are both Ni active component catalysts, as described in detail in Chinese Patent Application CN202011118431.X-Example 1.

[0187] After the two-stage reaction, the total conversion rate of maleic anhydride is 99.91%, and the total selectivity of succinic anhydride is 99.83%.

[0188] The separation and hydrolysis are carried out according to the method of Example 1 to obtain a succinic acid product with a purity of more than 99.9%.

[0189] Example 3

[0190] The hydrogenation reaction of maleic anhydride is carried out as shown in the formula. Figure 4 A method for producing succinic acid from butane as raw material is shown.

[0191] The oxidation reaction-separation is carried out according to the method of Example 1 to obtain a maleic anhydride solution with a content of 25% by weight of maleic anhydride, and the solvent is hexane.

[0192] The hydrogenation reaction of maleic anhydride is carried out as shown in the formula. Figure 1The method for hydrogenating maleic anhydride, as shown, involves dividing the maleic anhydride solution into two streams at a ratio of 40 wt% and 60 wt%. The 40 wt% maleic anhydride solution is mixed with the product of the second-stage hydrogenation reaction and then enters the first-stage hydrogenation reactor from the top of the reactor. The 60 wt% maleic anhydride solution is mixed with the product of the first-stage hydrogenation reaction and then enters the second-stage hydrogenation reactor from the top of the reactor. The molar ratio of the total amount of recycled hydrogen and replenished fresh hydrogen to the total maleic anhydride in the incoming maleic anhydride solution is 40.

[0193] In a single-stage hydrogenation reactor, the space velocity (SPV) is 3 h⁻¹. -1 The reaction temperature was 40℃, and the reaction pressure was 1.7MPa. The products of the first-stage hydrogenation reaction were cooled to 42℃, and after gas-liquid separation, the gas phase entered the second-stage hydrogenation reactor from the top of the reactor, while the liquid phase, after mixing with part of the maleic anhydride solution, entered the second-stage hydrogenation reactor. The space velocity in the second-stage hydrogenation reactor was 0.8 h⁻¹. -1 The reaction temperature is 45℃ and the reaction pressure is 1.5MPa. After the product of the second-stage hydrogenation reaction passes through a gas-liquid separator, the gas phase is cooled again to 40℃ and then passed through a gas-liquid separator. The gas phase, along with the replenished fresh hydrogen, is sent to the first-stage hydrogenation reactor. 50% by weight of the liquid phase from the gas-liquid separator is sent to the light-weight removal tower, and another 50% by weight of the liquid phase is returned to the first-stage hydrogenation reactor. After mixing with some maleic anhydride solution, the mixture is heated to 40℃ and then enters the first-stage hydrogenation reactor.

[0194] The catalysts packed in the first and second stage reactors are both Ni active component catalysts, as detailed in Chinese patent application CN202011120495.3 - Example 1.

[0195] After two stages of reaction, the total conversion rate of maleic anhydride was 99.89%, and the total selectivity of succinic anhydride was 99.78%.

[0196] Separation and hydrolysis according to the method in Example 1 can yield a product with a purity of succinic acid of 99.9% or higher.

[0197] Example 4

[0198] use Figure 3 The diagram illustrates a method for producing succinic acid from butane.

[0199] The absorbent was adjusted to dioxane, and an oxidation reaction-separation was performed according to the method in Example 1 to obtain a maleic anhydride solution with a maleic anhydride content of 18% by weight.

[0200] use ​The maleic anhydride solution is divided into two streams in a ratio of 20% and 80%, wherein the 20% maleic anhydride solution is mixed with the second-stage hydrogenation reaction product and then introduced into the first-stage hydrogenation reactor from the upper part of the reactor, and the 80% maleic anhydride solution is mixed with the first-stage hydrogenation reaction product and then introduced into the second-stage hydrogenation reactor from the upper part of the reactor. The total hydrogen gas amount of the circulating hydrogen gas and the supplemented fresh hydrogen gas is 30 times the molar ratio of the total maleic anhydride in the maleic anhydride solution.

[0201] In the first-stage hydrogenation reactor, the first-stage hydrogenation reactor space velocity is 1.8h -1 , the reaction temperature is 40℃, and the reaction pressure is 1.3MPa. The first-stage hydrogenation reaction product is cooled to 45℃, and after gas-liquid separation, the gas phase is introduced into the second-stage hydrogenation reactor from the top of the reactor, and the liquid phase is mixed with part of the maleic anhydride solution and then introduced into the second-stage hydrogenation reactor. The second-stage hydrogenation reactor space velocity is 1.2h -1 , the reaction temperature is 48℃, and the reaction pressure is 1.2MPa. After the second-stage hydrogenation reaction product passes through the gas-liquid separator, the gas phase is sent into the first-stage hydrogenation reactor together with the supplemented fresh hydrogen gas, and 60% of the liquid phase is sent to the subsequent separation unit, and 40% of the liquid phase is returned to the first-stage hydrogenation reactor, mixed with the maleic anhydride solution, and then heated to the reaction temperature before being introduced into the first-stage hydrogenation reactor.

[0202] The catalysts loaded in the first-stage and second-stage reactors are both Ni active component catalysts, and the specific catalysts are described in Chinese Patent Application CN202011118431.X-Example 1.

[0203] After the two-stage reaction, the total conversion rate of maleic anhydride is 99.83%, and the total selectivity of succinic anhydride is 99.85%.

[0204] According to the separation and hydrolysis method of Example 1, a product with a purity of succinic acid of more than 99.9% can be obtained.

[0205] The preferred embodiments of the present application are described in detail above, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including the combination of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as disclosed by the present application and fall within the protection scope of the present application.

Claims

1. A method for producing succinic acid from butane and / or benzene, characterized in that, The method includes: (1) Butane and / or benzene react with oxygen-containing gas in an oxidation reaction unit to obtain oxidation reaction products; (2) The oxidation reaction products enter the maleic anhydride separation unit, which includes an absorption tower and a distillation tower, and are absorbed and distilled to obtain a maleic anhydride solution; (3) The maleic anhydride solution enters the maleic anhydride hydrogenation reaction unit to carry out the hydrogenation reaction and obtain the hydrogenation product; (4) The hydrogenation product enters the succinic anhydride separation unit, where succinic anhydride and solvent are separated. (5) Succinic anhydride enters the succinic anhydride hydrolysis unit for hydrolysis and crystallization to obtain succinic acid product; The hydrogenation reaction in step (3) includes: I) The maleic anhydride solution is divided into two streams. One stream is mixed with the liquid phase material of the second-stage hydrogenation reaction, which is either cooled or uncooled. The mixture then enters the first-stage hydrogenation reactor from the liquid phase inlet of the first-stage hydrogenation reactor to contact with hydrogen for hydrogenation. II) The hydrogenation products of the first stage are cooled and cooled down sequentially, and the gas phase of the gas-liquid separation is completely fed into the second stage hydrogenation reactor from the gas phase inlet. The liquid phase of the gas-liquid separation is mixed with another maleic anhydride solution and then fed into the second stage hydrogenation reactor from the liquid phase inlet, thus converting all the maleic anhydride hydrogenation reaction into succinic anhydride. III) The products of the second-stage hydrogenation are subjected to gas-liquid separation to obtain a gas phase and a liquid phase from the second-stage hydrogenation reaction. Part of the liquid phase from the second-stage hydrogenation reaction is returned to step I). IV) The remaining liquid phase material from the two hydrogenation reactions is sent to the succinic anhydride separation unit; The molar ratio of total hydrogen to total maleic anhydride in the maleic anhydride solution is 10~40.

2. The method according to claim 1, wherein, Within the maleic anhydride separation unit: The operating conditions for the absorption tower include: pressure of 0.0~1.0MPag, temperature of 40~120℃, and theoretical plate number of 5~50. The absorbent is selected from one or more of the following solvents: γ-butyrolactone, dibutyl phthalate, diisobutyl hexahydrophthalate, tetrahydrofuran, aromatic hydrocarbons, ethyl acetate, tetracarbon diester, ethanol, isopropanol, hexane, cyclohexane, propylene oxide, benzene, xylene, chlorobenzene, dichlorobenzene, ketones, and ethers. The operating conditions for the distillation column include: pressure of 0.0~1.0 MPa, temperature of 40~150℃, and theoretical plate number of 5~100.

3. The method according to claim 1, wherein, Within the maleic anhydride separation unit: the absorbent is selected from γ-butyrolactone and / or tetrahydrofuran.

4. The method according to claim 1, wherein, In step (2), After a portion of the material in the absorber bottoms is cooled to 30-80°C, part is returned to the absorber and part is sent to the distillation column; and / or The material at the top of the absorption tower is cooled to 20~50℃ by a heat exchanger, and then passed through a gas-liquid separator. The gas phase is sent outside the boundary, and the liquid phase is sent to the distillation tower.

5. The method according to claim 1, wherein, In step (4), The solvent obtained from the separation is returned to step (2) for recycling as an absorbent; and / or The succinic anhydride separation unit includes: a light component removal tower and a heavy component removal tower connected in series. The hydrogenation product enters the light component removal tower, the bottom material of the light component removal tower enters the heavy component removal tower, the solvent is collected from the top of the heavy component removal tower, the succinic anhydride is collected from the side stream of the tower, and the heavy component is collected from the bottom of the tower.

6. The method according to claim 5, wherein, In step (4), The succinic anhydride separation unit includes: a light component removal tower, a heavy component removal tower, and a solvent recovery tower connected in series. The hydrogenation product enters the light component removal tower, the bottom material of the light component removal tower enters the heavy component removal tower, the heavy component collected from the bottom of the heavy component removal tower enters the solvent recovery tower, and the succinic anhydride is collected from the top of the solvent recovery tower.

7. The method according to claim 6, wherein, Operating conditions for the light-light product removal tower include: pressure of 0.5~20 kPa, temperature of 30~150℃, and theoretical plate number of 10~80; and / or The operating conditions for the deweight removal tower include: pressure of 0.5~20 kPa, temperature of 30~150℃, and theoretical plate number of 10~80; and / or The operating conditions for the solvent recovery tower include: pressure of 0.5~20 kPa, temperature of 30~150℃, and theoretical plate number of 10~80.

8. The method according to claim 1, wherein, In step III), part or all of the gaseous phase of the two-stage hydrogenation product is used as recycled hydrogen; and / or The hydrogen feedstock in step I) is a mixture of recycled hydrogen and supplementary hydrogen; and / or The liquid phase material in the two-stage hydrogenation reaction described in step I) is a cooled material.

9. The method according to claim 8, wherein, The liquid phase material in the two-stage hydrogenation reaction described in step I) is a material cooled to 30~80℃.

10. The method according to claim 9, wherein, The liquid phase material in the two-stage hydrogenation reaction described in step I) is a material cooled to 40~60℃.

11. The method according to any one of claims 1-10, wherein, In step II), the operating conditions of the two-stage hydrogenation reactor include: a temperature of 30–100 °C; and / or a pressure of 0.1–10 MPa; and / or a space velocity of 0.1–5 h⁻¹. -1 ; and / or In step I), One share accounts for 20-60% by weight, and the other share accounts for 40-80% by weight; and / or The operating conditions for a single-stage hydrogenation reactor include: a temperature of 30–100 °C; and / or a reaction pressure of 0.1–10 MPa; and / or a space velocity of 0.5–5 h⁻¹. -1 .

12. The method according to claim 11, wherein, In step II), the operating conditions of the two-stage hydrogenation reactor include: a temperature of 40–80°C; and / or a pressure of 0.5–5 MPa; and / or In step I), The operating conditions for a single-stage hydrogenation reactor include: a temperature of 40-80℃; and / or a reaction pressure of 0.5-5MPa.

13. A system for producing succinic acid from butane and / or benzene, characterized in that, The system includes: Along the material flow direction, the following are connected in series: oxidation reaction unit, maleic anhydride separation unit including absorption tower (13) and distillation tower (14) connected in series, maleic anhydride hydrogenation reaction unit, succinic anhydride separation unit, and succinic anhydride hydrolysis unit; In this process, butane and / or benzene undergo an oxidation reaction with oxygen-containing gas in the oxidation reaction unit, and then enter the maleic anhydride separation unit for absorption-distillation to obtain a maleic anhydride solution. The maleic anhydride solution enters the maleic anhydride hydrogenation reaction unit for hydrogenation to obtain a hydrogenation product. The hydrogenation product enters the succinic anhydride separation unit to separate succinic anhydride and solvent. The succinic anhydride enters the succinic anhydride hydrolysis unit for hydrolysis and crystallization to obtain succinic acid product. The maleic anhydride hydrogenation reaction unit includes: Along the material flow direction, a first-stage hydrogenation reactor (2), a first-stage reaction product cooler (3), and a first-stage gas-liquid separator (4) are connected in series. A second-stage hydrogenation reactor (5) is connected to the gas phase outlet of the first-stage gas-liquid separator (4) through a gas phase inlet and to the liquid phase outlet of the first-stage gas-liquid separator (4) through a liquid phase inlet. A second-stage gas-liquid separator (6) is connected in series with the second-stage hydrogenation reactor. The liquid phase feedstock supply pipeline is connected to the liquid phase inlet of the first-stage hydrogenation reactor (2) and the liquid phase inlet of the second-stage hydrogenation reactor (5).

14. The system according to claim 13, wherein, The succinic anhydride separation unit includes: Lightweight removal tower (8) and heavyweight removal tower (9) connected in series. The feed inlet of the light-light removal tower is connected to the liquid phase outlet of the two-stage gas-liquid separator, and the light-light removal tower is provided with a top outlet and a bottom outlet; The feed inlet of the heavy removal tower is connected to the outlet of the bottom of the light removal tower, and the heavy removal tower is provided with a top outlet, a bottom outlet and a side sampling outlet.

15. The system according to claim 13, wherein, The succinic anhydride separation unit includes: A light-light removal tower (8), a heavy-light removal tower (9), and a solvent recovery tower connected in series; The feed inlet of the light-light removal tower is connected to the liquid phase outlet of the two-stage gas-liquid separator, and the light-light removal tower is provided with a top outlet and a bottom outlet; The feed inlet of the heavy removal tower is connected to the bottom outlet of the light removal tower, and the heavy removal tower is provided with a top outlet and a bottom outlet; The inlet of the solvent recovery tower is connected to the outlet of the bottom of the de-weighting tower, and the solvent recovery tower includes a bottom outlet and a top outlet.

16. The system according to claim 13, wherein, In the maleic anhydride hydrogenation reaction unit, A reaction product cooler (3) and a gas-liquid separator (4) are connected in series at the bottom outlet of the hydrogenation reactor (2); and / or The two-stage gas-liquid separator (6) is connected in series with the bottom outlet of the two-stage hydrogenation reactor (5); and / or The hydrogenation reactor (2) includes a top gas phase inlet, an upper liquid phase inlet, and a bottom outlet; and / or The two-stage hydrogenation reactor (5) includes a top gas phase inlet, an upper liquid phase inlet, and a bottom outlet.

17. The system according to claim 13, wherein, In the maleic anhydride hydrogenation reaction unit, The top gas phase outlet of the first-stage gas-liquid separator (4) is connected to the top gas phase inlet of the second-stage hydrogenation reactor (5) via a pipeline; and / or The bottom liquid phase outlet of the first-stage gas-liquid separator (4) is connected to the upper liquid phase inlet of the second-stage hydrogenation reactor (5) via a pipeline; and / or The top gas phase outlet of the two-stage gas-liquid separator (6) is connected to the top gas phase inlet of the first-stage hydrogenation reactor (2) via a pipeline; and / or The bottom liquid phase outlet of the two-stage gas-liquid separator (6) is connected to the upper liquid phase inlet of the first-stage hydrogenation reactor (2) via a pipeline.

18. The system according to claim 17, wherein, In the maleic anhydride hydrogenation reaction unit, A circulating material cooler (7) is installed on the connecting pipeline between the bottom liquid phase outlet of the second-stage gas-liquid separator (6) and the upper liquid phase inlet of the first-stage hydrogenation reactor (2).

19. The system according to claim 17, wherein, In the maleic anhydride hydrogenation reaction unit, A circulating gas cooler (10) is installed on the connecting pipeline between the top gas phase outlet of the two-stage gas-liquid separator (6) and the top gas phase inlet of the first-stage hydrogenation reactor (2).

20. The system according to any one of claims 13-19, wherein, The maleic anhydride hydrogenation reaction unit also includes a distributor (1) for distributing the liquid raw material into two streams as needed to supply the first-stage hydrogenation reactor (2) and the second-stage hydrogenation reactor (5). A second-stage cooler (11) and a third gas-liquid separator (12) are connected in series at the top gas phase outlet of the second-stage gas-liquid separator (6). The gas phase outlet of the third gas-liquid separator (12) is connected to the top gas phase inlet of the first-stage hydrogenation reactor (2) through a pipeline. The bottom liquid phase outlet of the third gas-liquid separator (12) is connected to the liquid phase inlet of the second-stage gas-liquid separator (6).

21. The system according to claim 20, wherein, A circulating gas cooler (10) is installed on the connecting pipeline between the gas phase outlet of the third gas-liquid separator (12) and the top gas phase inlet of the first-stage hydrogenation reactor (2).

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