A device and method for producing succinic acid by oxidation-hydrogenolysis of butane and / or benzene

Abstract

The application provides a device and method for producing succinic acid by oxidizing and hydrolyzing butane and / or benzene as raw materials, the device comprising: an oxidation separation system, a maleic anhydride hydrogenation separation system and a succinic anhydride hydrolysis system connected in series along the material flow direction; wherein butane and / or benzene and oxygen-containing gas are subjected to oxidation reaction in the oxidation separation system and separated to obtain maleic anhydride material; the maleic anhydride material enters the maleic anhydride hydrogenation separation system to perform hydrogenation reaction and is separated to obtain succinic anhydride; and the succinic anhydride enters the succinic anhydride hydrolysis system to perform hydrolysis and crystallization, thereby obtaining succinic acid product. The application provides a process for producing succinic acid from butane / benzene for enterprises with butane or benzene resources, and the application preferably adopts two-stage hydrogenation reactors and circulates part of the material at the outlet of the second reactor to the first reactor, so that the content of maleic anhydride in the first reaction feed can be effectively diluted and the reaction heat generated in the first reaction can be taken away due to the fact that the material does not contain maleic anhydride.

Description

TECHNICAL FIELD

[0001] The present application relates to a device and method for producing succinic acid by oxidative hydrolysis of butane and / or benzene. BACKGROUND

[0002] Succinic acid, also known as succinic acid, exists not only in succinate but also in various plants and human and animal tissues. It is a colorless or white solid with no smell and acidic taste. Succinic acid is an important organic chemical raw material and intermediate, mainly used in pharmaceuticals, pesticides, food, synthetic plastics, rubber, protective coatings, dyes and other industries. In addition, succinic acid can also derive many downstream products, such as 1,4-butanediol (BDO), tetrahydrofuran (THF), gamma-butyrolactone (GBL), N-methyl pyrrolidone (NMP) and the like. With the rise of degradable plastic PBS resin in the world, the largest consumer market of succinic acid products in the future should be used for the synthesis of degradable plastic PBS resin. At present, there are few large-scale succinic acid production enterprises in the international aspect, with a production capacity of about 50,000 tons per year. The existing succinic acid production enterprises in China have small production scale, and the maximum single-line capacity is only 1000 tons.

[0003] There are many methods for producing succinic acid. Currently, the main industrialized methods include electrolytic reduction, catalytic hydrogenation of succinic anhydride, and biological fermentation. Due to the problems such as high power consumption, easy damage of ion membrane, serious corrosion of electrode, difficult maintenance of electrolytic cell, large sewage discharge and large occupation area, the electrochemical method is difficult to meet the requirements of rapid growth of succinic acid demand at present. The biological fermentation method is reported more in France, and the domestic biological fermentation method for producing succinic acid started late and has not been applied to actual production.

[0004] The catalytic hydrogenation method of succinic anhydride for producing succinic acid has the advantages of high conversion rate, high product purity, no obvious side reaction, and environmental friendliness, and is the most widely used method for synthesizing succinic acid in industry. The common process for producing succinic acid by catalytic hydrogenation of succinic anhydride is a two-step method, i.e. succinic anhydride is first catalytically hydrogenated to generate succinic anhydride, and then succinic anhydride is hydrolyzed to generate succinic acid.

[0005] For the raw material succinic anhydride, the domestic production method can be divided into benzene oxidation method and n-butane oxidation method according to the raw material route. For the catalytic hydrogenation process of succinic anhydride, since the hydrogenation of succinic anhydride to generate succinic anhydride is a strong exothermic reaction (ΔH = -128 kJ / mol), the adiabatic temperature rise is large, which easily causes the polymerization and coking of organic matter on the surface of the catalyst, reduces the activity of the catalyst, and at the same time, easily causes the sharp rise of the temperature of the catalyst bed, and the occurrence of the temperature runaway phenomenon. Therefore, how to take effective measures to reduce the reaction heat is the key and difficulty of the succinic anhydride hydrogenation process.

[0006] CN103570650A discloses a process for continuous production of succinic anhydride and succinic acid by hydrogenation of maleic anhydride, which adopts two-stage hydrogenation reactors. At the outlet of the first-stage hydrogenation reactor, part of the reaction liquid enters the second-stage hydrogenation reactor after heat exchange, and the rest of the reaction liquid is mixed with the raw material maleic anhydride solution and then re-enters the first-stage hydrogenation reactor device. The material at the outlet of the first-stage reactor still contains a certain amount of maleic anhydride, which is recycled to the inlet of the first-stage reactor again, so that the amount of maleic anhydride entering the first-stage reactor does not decrease significantly, and therefore the heat removal effect of the reactor is limited.

[0007] CN105801536A discloses a method for preparing succinic anhydride by selective hydrogenation of maleic anhydride in liquid phase, which adopts two-stage reactors in series and uses hydrogen as the heat removal medium. Hydrogen is introduced into the first-stage reactor and the second-stage reactor, separated by a gas-liquid separator after the heat is removed, and then recycled. The molar ratio of the recycled hydrogen to maleic anhydride is 30-200:1. This method can achieve a certain heat removal effect, but the amount of recycled hydrogen is relatively large, which leads to high energy consumption of the hydrogen compressor, and the amount of hydrogen entering the reactor is large, which requires an increase in the volume of the reactor, resulting in high investment and energy consumption.

[0008] Therefore, it is urgent to develop a succinic acid production process that can effectively remove the heat generated by the hydrogenation reaction of maleic anhydride and reduce the problems of high investment and high energy consumption. SUMMARY

[0009] To solve the problems of the prior art, the present application provides a device and method for producing succinic acid from butane / benzene as raw materials, which have the characteristics of simple process, low investment, strong applicability, easy control, etc.

[0010] The present application provides a device for producing succinic acid by oxidation, hydrogenation and hydrolysis of butane and / or benzene as raw materials, which comprises: an oxidation separation system, a maleic anhydride hydrogenation separation system and a succinic anhydride hydrolysis system connected in series along the material flow direction; wherein butane and / or benzene and an oxygen-containing gas undergo an oxidation reaction in the oxidation separation system and are separated to obtain maleic anhydride material; the maleic anhydride material enters the maleic anhydride hydrogenation separation system to undergo a hydrogenation reaction and is separated to obtain succinic anhydride; and the succinic anhydride enters the succinic anhydride hydrolysis system to undergo hydrolysis and crystallization, thereby obtaining succinic acid product.

[0011] Preferably, the maleic anhydride hydrogenation separation system comprises a maleic anhydride hydrogenation system and a hydrogenation product separation system.

[0012] Preferably, the maleic anhydride hydrogenation system comprises:

[0013] a first hydrogenation reactor comprising a lower and / or bottom gas phase inlet, a lower and / or bottom liquid phase feed inlet, a top and / or upper outlet; and a first reaction product cooler and a first gas-liquid separator connected in series to the outlet of the first hydrogenation reactor;

[0014] a second hydrogenation reactor in series communication with the first gas-liquid separator, the second hydrogenation reactor comprising a lower and / or bottom gas phase inlet, a lower and / or bottom liquid phase feed inlet, a top and / or upper outlet;

[0015] a second gas-liquid separator in series communication with the outlet of the second hydrogenation reactor;

[0016] a liquid phase feed line in communication with the liquid phase inlet of the first hydrogenation reactor and the liquid phase inlet of the second hydrogenation reactor.

[0017] Preferably, the hydrogenation product separation system comprises:

[0018] a light ends column and a heavy ends column in series communication;

[0019] the inlet of the light ends column is in communication with the liquid phase outlet of the second gas-liquid separator, the light ends column is provided with a top outlet and a column bottom outlet;

[0020] the inlet of the heavy ends column is in communication with the column bottom outlet of the light ends column, the heavy ends column is provided with a top outlet, a bottom outlet and a side draw outlet.

[0021] Preferably, in the maleic anhydride hydrogenation system,

[0022] the top gas phase outlet of the first gas-liquid separator is in communication with the lower and / or bottom gas phase inlet of the second hydrogenation reactor by a line; and / or

[0023] the bottom liquid phase outlet of the first gas-liquid separator is in communication with the lower and / or bottom liquid phase inlet of the second hydrogenation reactor by a line; and / or

[0024] the top gas phase outlet of the second gas-liquid separator is in communication with the lower and / or bottom gas phase inlet of the first hydrogenation reactor by a line; and / or

[0025] the bottom liquid phase outlet of the second gas-liquid separator is in communication with the lower and / or bottom liquid phase inlet of the first hydrogenation reactor by a line.

[0026] Preferably, in the maleic anhydride hydrogenation system,

[0027] A circulation material cooler is arranged on a communication pipeline between the bottom liquid phase outlet of the two-stage gas-liquid separator and the lower liquid phase feed inlet and / or the bottom liquid phase feed inlet of the first-stage hydrogenation reactor;

[0028] Preferably, a two-stage cooler or a two-stage cooler and a third gas-liquid separator are arranged in sequence at the top gas phase outlet end of the two-stage gas-liquid separator, the gas phase outlet of the third gas-liquid separator is communicated with the lower gas phase inlet and / or the bottom gas phase inlet of the first-stage hydrogenation reactor through a pipeline; the bottom liquid phase outlet of the third gas-liquid separator is communicated with the liquid phase feed inlet of the two-stage gas-liquid separator;

[0029] The maleic anhydride hydrogenation system further comprises a distributor for distributing the liquid phase raw material into two streams to supply the first-stage hydrogenation reactor and the second-stage hydrogenation reactor.

[0030] Preferably, the oxidation separation system comprises an oxidation reaction system and a maleic anhydride separation system, the maleic anhydride separation system comprises an absorption tower and a rectification tower communicated in sequence, and the maleic anhydride solution separated by using the absorption tower and the rectification tower is directly used as the raw material of the maleic anhydride hydrogenation separation system, so that the maleic anhydride hydrogenation can be performed without additional introduction of a solvent.

[0031] The present application provides a method for producing succinic acid by using butane and / or benzene as raw materials through oxidation, hydrogenation and hydrolysis, the method is performed in the device described in the present application, and the method comprises the following steps: butane and / or benzene and an oxygen-containing gas are subjected to an oxidation reaction in an oxidation separation system and separated to obtain a maleic anhydride material; the maleic anhydride material is introduced into a maleic anhydride hydrogenation separation system to perform a hydrogenation reaction and separated to obtain succinic anhydride; and the succinic anhydride is introduced into a succinic anhydride hydrolysis system to perform hydrolysis and crystallization, so as to obtain a succinic acid product.

[0032] Preferably, the maleic anhydride hydrogenation separation system performs two-stage hydrogenation, and the maleic anhydride hydrogenation method comprises the following steps:

[0033] (1) the maleic anhydride solution from the oxidation separation system is divided into two streams, one of which is mixed with a liquid phase material subjected to a partial two-stage hydrogenation reaction after being cooled or without cooling, and then introduced into the first-stage hydrogenation reactor from the bottom liquid phase feed inlet and / or the lower liquid phase feed inlet of the first-stage hydrogenation reactor to contact with hydrogen gas to perform hydrogenation, and the hydrogen gas is introduced into the first-stage hydrogenation reactor from the bottom gas phase inlet and / or the lower gas phase inlet of the first-stage hydrogenation reactor;

[0034] (2) the first-stage hydrogenation product is sequentially subjected to cooling, gas-liquid separation, and the gas phase of the gas-liquid separation is introduced into the second-stage hydrogenation reactor from the bottom gas phase inlet and / or the lower gas phase inlet of the second-stage hydrogenation reactor, and the liquid phase of the gas-liquid separation is mixed with the other stream of the maleic anhydride solution and then introduced into the second-stage hydrogenation reactor from the bottom liquid phase feed inlet and / or the lower liquid phase feed inlet of the second-stage hydrogenation reactor;

[0035] (3) the second hydrogenation product is subjected to gas-liquid separation to obtain a gas phase and a liquid phase material of the second hydrogenation reaction, and the gas phase is used as the recycle hydrogen gas partially or wholly.

[0036] Preferably, the hydrogen gas raw material of step (1) is a mixed hydrogen gas raw material of the recycle hydrogen gas and the make-up hydrogen gas; and / or

[0037] The liquid phase material of the second hydrogenation reaction of step (1) is a cooled material.

[0038] More preferably, the liquid phase material of the second hydrogenation reaction of step (1) is a material cooled to 30-80°C, preferably to 40-60°C.

[0039] Preferably, the maleic anhydride hydrogenation method further comprises:

[0040] The gas phase obtained by subjecting the second hydrogenation product to gas-liquid separation is cooled and then subjected to a third gas-liquid separation, and the gas phase obtained is used as the recycle hydrogen gas partially or wholly mixed with the make-up hydrogen gas as the hydrogen gas raw material of the first hydrogenation reactor; and the liquid phase obtained is optionally returned to the second gas-liquid separator for gas-liquid separation;

[0041] Preferably, the temperature for cooling the gas phase obtained by subjecting the second hydrogenation product to gas-liquid separation is 30-80°C.

[0042] Preferably, in step (1),

[0043] The maleic anhydride solution is a mixture of maleic anhydride and a solvent, and the solvent is one or more of acetic anhydride, γ-butyrolactone, dioxane, tetrahydrofuran, aromatic hydrocarbon, ethyl acetate, tetracarboxylic acid ester, ethanol, isopropanol, hexane, cyclohexane, propylene oxide, ketone and ether; and / or

[0044] The concentration of maleic anhydride in the maleic anhydride solution is 1-90% by weight, preferably 10-40% by weight; and / or

[0045] The proportion of each of the two streams is 5-95% by weight; preferably the proportion of one stream is 20-50% by weight and the proportion of the other stream is 50-80% by weight; and / or

[0046] The molar ratio of the total hydrogen gas amount to the total maleic anhydride in the maleic anhydride solution is 5-100, preferably 10-40; and / or

[0047] The operating conditions of the first-stage hydrogenation reactor include: a temperature of 30-100℃, preferably 40-80℃, for example 40℃, 41℃, 42℃, 43℃, 44℃, 45℃, 46℃, 47℃, 48℃, 49℃, 50℃, and the like, and each of the reaction temperatures is applicable to the present application; and / or a reaction pressure of 0.1-10 MPa, preferably 0.5-5 MPa, and more preferably 1-2 MPa; and / or a space velocity of 0.5-5 h -1 ;

[0048] In step (2), the operating conditions of the second-stage hydrogenation reactor include:

[0049] a temperature of 30-120℃, preferably 40-100℃, for example 40℃, 41℃, 42℃, 43℃, 44℃, 45℃, 46℃, 47℃, 48℃, 49℃, 50℃, and the like, and each of the reaction temperatures is applicable to the present application; and / or a pressure of 0.1-10 MPa, preferably 0.5-5 MPa, and more preferably 1.2-1.5 MPa; and / or a space velocity of 0.5-5 h -1 .

[0050] Preferably, the oxidation separation system comprises an oxidation reaction system and a maleic anhydride separation system, and the maleic anhydride separation system comprises an absorption tower and a rectification tower connected in series, and the maleic anhydride solution separated by the absorption tower and the rectification tower is directly used as the raw material of the maleic anhydride hydrogenation separation system, and the maleic anhydride hydrogenation can be performed without additional introduction of solvent.

[0051] Preferably, in the maleic anhydride separation system:

[0052] The operating conditions of the absorption tower include: a pressure of 0.0-1.0 MPag, a temperature of 40-120℃, and a theoretical plate number of 5-50;

[0053] The absorbent is selected from one or more than one of γ-butyrolactone, dibutyl phthalate, diisobutyl hexahydrophthalate, tetrahydrofuran, aromatic hydrocarbon, ethyl acetate, tetracarboxylic acid ester, ethanol, isopropyl alcohol, hexane, cyclohexane, propylene oxide, benzene, xylene, chlorobenzene, dichlorobenzene, ketone and ether, and more preferably γ-butyrolactone and / or tetrahydrofuran;

[0054] The operating conditions of the rectification tower include: a pressure of 0.0-1.0 MPag, a temperature of 40-150℃, and a theoretical plate number of 5-100;

[0055] Part of the material in the tower bottom of the absorption tower is cooled to 30-80℃ and then returned to the absorption tower; and / or

[0056] The material in the tower top of the absorption tower is cooled to 20-50℃ by a heat exchanger, and then separated by a gas-liquid separator, and the gas phase is sent out of the boundary area, and the liquid phase is sent to the rectification tower.

[0057] Preferably, in the hydrogenation product separation system:

[0058] The operating conditions of the light removal column include: pressure of 0.5-20 KPa, temperature of 30-150℃, and theoretical plate number of 10-80; and / or the operating conditions of the heavy removal column include: pressure of 0.5-20 KPa, temperature of 30-150℃, and theoretical plate number of 10-80.

[0059] The method of the present application has the following features:

[0060] (1) The present application provides a process for producing succinic acid from butane / benzene for enterprises having butane or benzene resources. The present application preferably adopts two-stage hydrogenation reactors, and part of the material at the outlet of the second reactor is recycled to the first reactor. Since the material does not contain maleic anhydride, the content of maleic anhydride in the feed of the first reaction can be effectively diluted, and the reaction heat generated in the first reaction can be removed.

[0061] (2) The present application preferably separates the gas phase after cooling after the first reaction, and the gas phase is all introduced into the second reactor, which can effectively remove the reaction heat generated in the second reaction. After the first reactor, a gas-liquid separation is arranged, and the gas phase and the liquid phase are introduced into the reactor respectively, and pass through a gas-liquid distributor, so that the material introduced into the reactor is more fully contacted, the gas-liquid-solid contact is good, the effective utilization rate of the catalyst is high, and the investment is saved.

[0062] (3) By using the present application, succinic anhydride is obtained through the light removal column and the heavy removal column, the purity of the succinic anhydride product is high, and the purity of the succinic acid product obtained by hydrolysis is good, and the whole process operation is easy to control.

[0063] (4) The device and method of the present application have the characteristics of simple process, low investment, strong applicability, easy control, etc. BRIEF DESCRIPTION OF DRAWINGS

[0064] Figure 1 is a schematic diagram of the method of a preferred embodiment of the present application.

[0065] Figure 2 is a schematic diagram of the method of a preferred embodiment of the present application.

[0066] Figure 3 is a schematic diagram of a maleic anhydride hydrogenation method of the present application.

[0067] Figure 4 is a schematic diagram of a maleic anhydride hydrogenation method of the present application.

[0068] BRIEF DESCRIPTION OF DRAWINGS

[0069] 1 distributor; 2 primary hydrogenation reactor; 3 primary reaction product cooler; 4 primary gas-liquid separator; 5 secondary hydrogenation reactor; 6 secondary gas-liquid separator; 7 recycle material cooler; 8 secondary cooler; 9 third gas-liquid separator; 11 succinic anhydride solution; 12 reaction product; 13 make-up hydrogen DETAILED DESCRIPTION

[0070] The endpoints of the ranges and any values described herein are not limited to the precise values stated. The ranges and values should be construed to be roughly about the ranges and values. For values described herein, the endpoints of the ranges are not included, unless the context clearly indicates otherwise. The ranges and individual points within the ranges can be combined to form new ranges, which are also within the scope of the present disclosure.

[0071] The following examples are provided to further illustrate the present application, and are not intended to limit the scope of the present application. It is to be understood that variations and modifications of the specific examples, forms, and embodiments disclosed can be made by those skilled in the art, and are also intended to fall within the scope of the present application.

[0072] As shown in Figure 1 , the present application provides a device for producing succinic acid by oxidizing and hydrolyzing butane and / or benzene, which comprises: an oxidation separation system, a succinic anhydride hydrogenation separation system and a succinic anhydride hydrolysis system connected in series along the material flow direction; wherein butane and / or benzene and an oxygen-containing gas are subjected to an oxidation reaction in the oxidation separation system and separated to obtain succinic anhydride material; the succinic anhydride material enters the succinic anhydride hydrogenation separation system to undergo a hydrogenation reaction and is separated to obtain succinic anhydride; and the succinic anhydride enters the succinic anhydride hydrolysis system to undergo hydrolysis and crystallization to obtain succinic acid product.

[0073] According to a preferred embodiment of the present application, as shown in Figure 1 , Figure 2 , Figure 3 and Figure 4 , the succinic anhydride hydrogenation separation system comprises: a succinic anhydride hydrogenation system and a hydrogenation product separation system; and according to a preferred embodiment of the present application, as shown in Figure 3 and Figure 4 , the succinic anhydride hydrogenation system comprises:

[0074] a primary hydrogenation reactor, the primary hydrogenation reactor comprising a lower gas phase inlet and / or a bottom gas phase inlet, a lower liquid phase inlet and / or a bottom liquid phase inlet, a top outlet and / or an upper outlet; and a primary reaction product cooler and a primary gas-liquid separator connected in series at the outlet end of the primary hydrogenation reactor;

[0075] a second-stage hydrogenation reactor, which is in series communication with the first-stage gas-liquid separator, and which comprises a lower gas phase inlet and / or a bottom gas phase inlet, a lower liquid phase feed inlet and / or a bottom liquid phase feed inlet, a top outlet and / or an upper outlet;

[0076] a second-stage gas-liquid separator, which is in series communication with the second-stage hydrogenation reactor outlet;

[0077] a liquid phase raw material supply pipeline, which is in communication with the liquid phase feed inlet of the first-stage hydrogenation reactor and the liquid phase feed inlet of the second-stage hydrogenation reactor.

[0078] The present application has no special requirements for the settings and operating conditions of the hydrogenation product separation system, and can be adjusted as needed, such as Figure 1 and Figure 2 According to a preferred embodiment of the present application, the hydrogenation product separation system comprises:

[0079] a light component removal column and a heavy component removal column in series communication; the feed inlet of the light component removal column is in communication with the liquid phase outlet of the second-stage gas-liquid separator, and the light component removal column is provided with a top outlet and a column bottom outlet; the feed inlet of the heavy component removal column is in communication with the column bottom outlet of the light component removal column, and the heavy component removal column is provided with a top outlet, a bottom outlet and a side outlet.

[0080] According to the present application, the hydrogenation product separation system mainly comprises a light component removal column and a heavy component removal column. The material from the maleic anhydride hydrogenation reaction system enters the light component removal column, the column bottom material of the light component removal column enters the heavy component removal column, the solvent is collected at the top of the heavy component removal column, the required succinic anhydride is collected at the side outlet of the heavy component removal column, and the heavy components generated by polymerization are collected at the column bottom.

[0081] In the present application, the light components refer to dissolved hydrogen, a small amount of solvent such as γ-butyrolactone and tetrahydrofuran, etc.

[0082] In the present application, the purpose of the light component removal column is to remove hydrogen, a small amount of solvent such as γ-butyrolactone and tetrahydrofuran, etc. There are no special requirements for its settings and operating conditions, as long as the purpose of the present application can be achieved.

[0083] In the present application, the purpose of the heavy component removal column is to remove the solvent from the top and the heavy components generated by polymerization from the column bottom, and the required succinic anhydride is collected at the side outlet. There are no special requirements for its settings and operating conditions, as long as the purpose of the present application can be achieved.

[0084] According to a preferred embodiment of the present application, preferably, the top gas phase outlet of the first-stage gas-liquid separator is in communication with the lower gas phase inlet and / or the bottom gas phase inlet of the second-stage hydrogenation reactor through a pipeline.

[0085] According to the preferred embodiment of the present application, preferably, the bottom liquid phase outlet of the first-stage gas-liquid separator is communicated with the lower liquid phase inlet and / or the bottom liquid phase inlet of the first-stage hydrogenation reactor through a pipeline.

[0086] According to the preferred embodiment of the present application, preferably, the top gas phase outlet of the second-stage gas-liquid separator is communicated with the lower gas phase inlet and / or the bottom gas phase inlet of the first-stage hydrogenation reactor through a pipeline.

[0087] According to the preferred embodiment of the present application, preferably, the bottom liquid phase outlet of the second-stage gas-liquid separator is communicated with the lower liquid phase inlet and / or the bottom liquid phase inlet of the first-stage hydrogenation reactor through a pipeline.

[0088] According to the preferred embodiment of the present application, preferably, a circulating material cooler is arranged on the pipeline for communicating the bottom liquid phase outlet of the second-stage gas-liquid separator with the lower liquid phase inlet and / or the bottom liquid phase inlet of the first-stage hydrogenation reactor.

[0089] According to the preferred embodiment of the present application, preferably, as shown in Figure 4 the second-stage cooler is arranged at the end of the top gas phase outlet of the second-stage gas-liquid separator, or the second-stage cooler and a third gas-liquid separator are arranged in sequence, the gas phase outlet of the third gas-liquid separator is communicated with the lower gas phase inlet and / or the bottom gas phase inlet of the first-stage hydrogenation reactor through a pipeline, and the bottom liquid phase outlet of the third gas-liquid separator is communicated with the liquid phase inlet of the second-stage gas-liquid separator.

[0090] According to the preferred embodiment of the present application, preferably, the maleic anhydride hydrogenation system further comprises a distributor for distributing the liquid phase raw material into two streams for supplying the first-stage hydrogenation reactor and the second-stage hydrogenation reactor.

[0091] According to the present application, butane / benzene and oxygen-containing gas such as air enter an oxidation separation system, which is not limited in design and operating conditions as long as the oxidation reaction and separation operation can be realized, and is determined by the person skilled in the art according to the professional knowledge and prior art. As shown in Figure 2 the oxidation separation system, for example, comprises an oxidation reaction system (including an oxidation reactor) and a maleic anhydride separation system, which, for example, comprises an absorption tower, a stripping tower, a light component tower and a product refining tower, and according to the preferred embodiment of the present application, the oxidation separation system comprises an oxidation reaction system and a maleic anhydride separation system, the maleic anhydride separation system comprises an absorption tower and a rectifying tower communicated in series, and the maleic anhydride solution separated by the absorption tower and the rectifying tower is directly used as the raw material of the maleic anhydride hydrogenation separation system, and the maleic anhydride hydrogenation can not introduce additional solvent.

[0092] According to the present invention, the maleic anhydride separation system mainly includes an absorption tower and a distillation tower. Other equipment, such as heat exchangers, pumps, tanks, pipelines, etc., are not specifically required and can be determined by those skilled in the art based on the circumstances and existing technology. The oxidation reaction products cooled by the heat exchange enter the absorption tower from the bottom, the solvent enters the absorption tower from the top, the top material of the absorption tower is sent outside the boundary, the solvent-rich material obtained from the bottom of the absorption tower enters the distillation tower, the top material of the distillation tower is collected and sent outside the boundary, and the bottom material is sent to the maleic anhydride hydrogenation separation system.

[0093] In this invention, there are no special requirements for the oxidation reaction system and the succinic anhydride hydrolysis system; those skilled in the art can determine them based on common sense and professional knowledge.

[0094] According to the present invention, the distillation column may also have its top material collected and sent outside the boundary area, and its side stream of maleic anhydride solvent mixture collected and sent to the maleic anhydride hydrogenation reaction system, while the bottom material undergoes the next crystallization step.

[0095] like Figure 1 As shown, this invention provides a method for producing succinic acid by oxidative hydrogenation and hydrolysis using butane and / or benzene as raw materials. The method is carried out in the apparatus described in this invention. The method includes: butane and / or benzene reacting with oxygen-containing gas in an oxidative separation system to obtain maleic anhydride material; the maleic anhydride material entering a maleic anhydride hydrogenation separation system to undergo a hydrogenation reaction and be separated to obtain succinic anhydride; and the succinic anhydride entering a succinic anhydride hydrolysis system to undergo hydrolysis and crystallization to obtain succinic acid product.

[0096] This invention does not have any special requirements for the oxygen-containing gas; any commonly used oxygen-containing gas can be used in this invention, such as air and / or oxygen.

[0097] According to the present invention, the preferred operating pressure of the absorption tower is 0.0 to 1.0 MPa, the operating temperature is 40 to 120°C, and the theoretical number of trays is 5 to 50.

[0098] According to the present invention, the preferred operating pressure of the distillation column is 0.0 to 1.0 MPa, the operating temperature is 40 to 150°C, and the theoretical number of plates is 5 to 100.

[0099] According to the present invention, it is preferable that a fresh absorbent is added to the top of the absorption tower.

[0100] According to the present invention, the absorbent is preferably a solvent required for the hydrogenation reaction of maleic anhydride, such as one or more mixed solvents selected from γ-butyrolactone, dibutyl phthalate, diisobutyl hexahydrophthalate, tetrahydrofuran, aromatic hydrocarbons, ethyl acetate, tetracarbon diester, ethanol, isopropanol, hexane, cyclohexane, propylene oxide, benzene, xylene, chlorobenzene, dichlorobenzene, and some ketones and ethers, more preferably γ-butyrolactone and tetrahydrofuran.

[0101] According to the application, the solvent ratio of the absorbent to maleic anhydride is not specifically limited, and can be determined by those skilled in the art according to professional knowledge and prior art.

[0102] According to the application, optionally, a part of the material in the tower bottom of the absorption tower is returned to the absorption tower after being cooled to 30-80 DEG C.

[0103] According to the application, optionally, the material in the tower top of the absorption tower is cooled to 20-50 DEG C. through a heat exchanger, and then is sent to a gas-liquid separator, the gas phase is sent out of the area, and the liquid phase is sent to the rectification tower.

[0104] In the application, the absorption tower and the rectification tower are cooperatively operated to separate the maleic anhydride solution required by the application, so that the whole process flow of the method of the application is flexible and controllable.

[0105] The application does not have special requirements for the operating conditions of the light-removing tower, and the commonly used operating conditions of the light-removing tower are suitable for the application. For the application, preferably, in the step (4), the operating pressure of the light-removing tower is 0.5-20 KPa, preferably 6-15 KPa; the operating temperature is 30-150 DEG C, preferably 80-130 DEG C; and the number of theoretical plates is 10-80.

[0106] The application does not have special requirements for the operating conditions of the heavy-removing tower, and the commonly used operating conditions of the light-removing tower are suitable for the application. For the application, preferably, in the step (4), the operating pressure of the heavy-removing tower is 0.5-20 KPa, preferably 3-15 KPa; the operating temperature is 30-150 DEG C, preferably 80-130 DEG C; and the number of theoretical plates is 10-80.

[0107] According to the application, preferably, the separated solvent needs to be heated to the absorption temperature and then is recycled to the absorption tower in the step (2) for recycling.

[0108] According to the application, the operating conditions of the hydrolysis system are not specifically limited, and can be determined by those skilled in the art according to professional knowledge and prior art.

[0109] According to a preferred embodiment of the application, the operating conditions of the absorption tower include: the pressure is 0.0-1.0 MPag, the temperature is 40-120 DEG C, and the number of theoretical plates is 5-50; the absorbent is selected from one or more than one of gamma-butyrolactone, dibutyl phthalate, diisobutyl hexahydrophthalate, tetrahydrofuran, aromatic hydrocarbon, ethyl acetate, four-carbon dibasic acid ester, ethanol, isopropyl alcohol, hexane, cyclohexane, propylene oxide, benzene, dimethylbenzene, chlorobenzene, dichlorobenzene, ketone and ether, and more preferably gamma-butyrolactone and / or tetrahydrofuran; and the operating conditions of the rectification tower include: the pressure is 0.0-1.0 MPag, the temperature is 40-150 DEG C, and the number of theoretical plates is 5-100.

[0110] According to a preferred embodiment of the present application, part of the material in the tower of the absorption tower is cooled to 30-80°C and returned to the absorption tower, the material at the top of the absorption tower is cooled to 20-50°C 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.

[0111] According to a preferred embodiment of the present application, the present application specifically comprises the following steps: butane / benzene and air enter an oxidation reaction system to obtain maleic anhydride; the maleic anhydride enters a maleic anhydride hydrogenation reaction system to obtain succinic anhydride; and the succinic anhydride enters a hydrolysis system to obtain succinic acid product.

[0112] According to the present application, butane / benzene and air enter an oxidation reaction system, and after oxidation reaction and separation, maleic anhydride product is obtained and sent to a maleic anhydride hydrogenation reaction system. The present application does not make specific limitations on the oxidation reaction system, and those skilled in the art can determine it according to professional knowledge and existing technology.

[0113] According to the present application, the maleic anhydride hydrogenation reaction system mainly comprises a first-stage hydrogenation reactor, a second-stage hydrogenation reactor, a light-removing tower, a heavy-removing tower, etc. Other devices such as heat exchangers, pumps, tanks, compressors, etc. are not specifically required, and those skilled in the art can determine them according to the situation and existing technology.

[0114] According to the present application, maleic anhydride or maleic anhydride solution can be separated from the oxidation separation system. If maleic anhydride is separated, the separated maleic anhydride is mixed with solvent from outside (the solvent mixed with maleic anhydride can be one or more than one of acetic anhydride, γ-butyrolactone, dioxane, tetrahydrofuran, aromatic hydrocarbon, ethyl acetate, four-carbon dibasic acid ester, ethanol, isopropyl alcohol, hexane, cyclohexane, propylene oxide, and part of ketone and ether solvents, etc.), and the mixture is prepared into maleic anhydride solution. The maleic anhydride solution is mixed with part of the second-stage hydrogenation reaction, and then enters the reactor from the first-stage hydrogenation reactor. Fresh hydrogen gas and circulating gas material are mixed, and then enter the reactor from the first-stage hydrogenation reactor. Through contact with the catalyst, hydrogenation reaction occurs, and maleic anhydride is completely / partially converted into succinic anhydride. The reaction temperature of the first-stage hydrogenation reactor is 30-100°C, preferably 40-80°C. The reaction pressure is 0.1-10 MPa, preferably 0.5-5 MPa. The molar ratio of circulating hydrogen gas and fresh hydrogen gas to the maleic anhydride is 5-100, preferably 10-40.

[0115] According to the present application, the oxidation separation system is preferably an absorption tower and a rectification tower which can separate the maleic anhydride solution required by the maleic anhydride hydrogenation reaction of the present application.

[0116] According to the preferred embodiment of the present application, the first-stage hydrogenation product is cooled by a heat exchanger first, and then separated by a gas-liquid separator. The gas phase is all introduced into the reactor from the top of the second-stage hydrogenation reactor, and the liquid phase is all introduced into the second-stage hydrogenation reactor from the upper part of the second-stage hydrogenation reactor to contact with the catalyst to occur hydrogenation reaction, and all maleic anhydride is converted into succinic anhydride. The reaction temperature of the second-stage hydrogenation reactor is 30-120℃, preferably 50-100℃. The reaction pressure is 0.1-10MPa, preferably 0.5-5MPa.

[0117] According to the preferred embodiment of the present application, after the second-stage hydrogenation reaction product is separated by a gas-liquid separator, the gas phase is mixed with fresh hydrogen after being heated to the reaction temperature, and then introduced into the first-stage hydrogenation reactor for recycling. Part of the liquid phase is sent to the light component removal column, and part of the liquid phase is recycled to the first-stage hydrogenation reactor after being heated, and then mixed with the maleic anhydride solution to enter the first-stage hydrogenation reactor. Preferably, 10%-80% of the liquid phase reaction product is sent to the light component removal column, and the rest of the liquid phase is returned to the first-stage reactor for recycling.

[0118] According to the preferred embodiment of the present application, the light components are collected from the top of the light component removal column, and the column bottom material is sent to the heavy component removal column. The solvent is collected from the top of the heavy component removal column, part of which is used as the solvent for dissolving maleic anhydride, and part of which is collected as a byproduct. Succinic anhydride is collected from the side line of the heavy component removal column and sent to the subsequent hydrolysis system. The heavy components are collected from the column bottom of the heavy component removal column. The operating pressure of the light component removal column is 0.5-20KPa, the operating temperature is 30-150℃, and the theoretical plate number is 10-80. The operating pressure of the heavy component removal column is 0.5-20KPa, the operating temperature is 30-150℃, and the theoretical plate number is 10-80. Succinic anhydride is collected from the side line of the heavy component removal column, preferably from the distillation section.

[0119] According to the preferred embodiment of the present application, the column bottom material of the light component removal column is first sent to the solvent recovery column. The solvent is collected from the top of the solvent recovery column, part of which is used as the solvent for dissolving maleic anhydride, and part of which is collected as a byproduct. The column bottom material is sent to the heavy component removal column. Succinic anhydride is collected from the top of the heavy component removal column, and the heavy components are collected from the column bottom. The operating pressure of the solvent recovery column is 0.5-20KPa, the operating temperature is 30-150℃, and the theoretical plate number is 10-80.

[0120] According to the preferred embodiment of the present application, 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 patents CN202011118431.X and CN202011120495.3.

[0121] According to the preferred embodiment of the present application, after the second-stage hydrogenation reaction product is separated by a gas-liquid separator, the gas phase material is first cooled by a heat exchanger, and the cooling temperature is preferably 30-80℃. The cooled material is then subjected to gas-liquid separation, the gas phase is recycled to the first-stage reactor for use, and the liquid phase is returned to the previous gas-liquid separator.

[0122] According to the preferred embodiment of the present application, after the two-stage hydrogenation product is subjected to gas-liquid separation, about 0.5% to 2% of the material in the gas phase is collected as fuel gas, and the remaining gas phase is recycled to the first-stage hydrogenation reactor, mixed with supplemental fresh hydrogen gas, and then introduced into the first-stage hydrogenation reactor.

[0123] According to the preferred embodiment of the present application, succinic anhydride is converted into succinic acid by hydrolysis-crystallization or the like. The present application does not limit the specific hydrolysis-crystallization method, which can be determined by those skilled in the art based on their professional knowledge and the prior art.

[0124] According to the preferred embodiment of the present application, the succinic anhydride hydrogenation method comprises performing two-stage hydrogenation reactions,

[0125] (1) the succinic anhydride solution is divided into two streams, one of which is mixed with the liquid-phase material from the partially cooled or uncooled two-stage hydrogenation reaction, and then introduced into the first-stage hydrogenation reactor from the bottom liquid-phase inlet and / or the lower liquid-phase inlet to contact hydrogen gas and perform hydrogenation, wherein the hydrogen gas is introduced into the first-stage hydrogenation reactor from the bottom gas-phase inlet and / or the lower gas-phase inlet;

[0126] (2) the first-stage hydrogenation product is sequentially subjected to cooling, gas-liquid separation, and the gas phase from the gas-liquid separation is introduced into the two-stage hydrogenation reactor from the bottom gas-phase inlet and / or the lower gas-phase inlet, and the liquid phase from the gas-liquid separation is mixed with the other stream of succinic anhydride solution and then introduced into the two-stage hydrogenation reactor from the bottom liquid-phase inlet and / or the lower liquid-phase inlet;

[0127] (3) the two-stage hydrogenation product is subjected to gas-liquid separation to obtain the gas phase and the liquid-phase material from the two-stage hydrogenation reaction, and the gas phase is optionally used as part or all of the recycled hydrogen gas.

[0128] The succinic anhydride hydrogenation method of the present application can effectively remove the heat generated during the reaction, is flexible and easy to control, the concentration of succinic anhydride in the succinic anhydride solution can not be too low, thereby reducing the amount of solvent used and reducing the energy consumption for subsequent solvent recovery, the gas-liquid-solid contact is good, the effective utilization rate of the catalyst is high, and the investment is saved, the reaction operating conditions are mild, the temperature rise of the reaction bed is low, the succinic anhydride hydrogenation reaction can be performed at about 40°C, which is conducive to improving the selectivity of the catalyst and prolonging the service life of the catalyst.

[0129] According to the preferred embodiment of the present application, the hydrogen gas raw material in step (1) is a mixed hydrogen gas raw material of recycled hydrogen gas and supplemental hydrogen gas.

[0130] According to the preferred embodiment of the present application, preferably, the liquid-phase material from the two-stage hydrogenation reaction in step (1) is cooled material. This can effectively remove heat and improve the effective utilization rate of the catalyst, thereby prolonging the service life of the catalyst.

[0131] According to the preferred embodiment of the present application, preferably, the liquid phase material of the two-stage hydrogenation reaction in step (1) is cooled to 30-80°C, preferably 40-60°C. This can effectively remove heat and improve the effective utilization of the catalyst, prolonging the service life of the catalyst.

[0132] According to the preferred embodiment of the present application, preferably, the method further comprises:

[0133] The gas phase obtained by gas-liquid separation of the two-stage hydrogenation product is cooled and then subjected to a third gas-liquid separation, and the gas phase obtained is partially or entirely mixed with the make-up hydrogen gas as the hydrogen gas raw material for the first-stage hydrogenation reactor; optionally, the liquid phase obtained is returned to the two-stage gas-liquid separator for gas-liquid separation. This can effectively remove heat and improve the effective utilization of the catalyst, prolonging the service life of the catalyst.

[0134] According to the preferred embodiment of the present application, preferably, the temperature for cooling the gas phase obtained by gas-liquid separation of the two-stage hydrogenation product is 30-80°C. This can effectively remove heat and improve the effective utilization of the catalyst, prolonging the service life of the catalyst.

[0135] According to the preferred embodiment of the present application, preferably, the maleic anhydride solution has no special requirements and can be a commonly used maleic anhydride raw material. For the present application, the maleic anhydride solution is preferably a mixture of maleic anhydride and a solvent, and the type of the solvent has no special requirements. For the present application, the solvent is preferably one or more of acetic anhydride, γ-butyrolactone, dioxane, tetrahydrofuran, aromatic hydrocarbon, ethyl acetate, tetracarboxylic acid ester, ethanol, isopropyl alcohol, hexane, cyclohexane, propylene oxide, ketone and ether.

[0136] The method of the present application can be used for a maleic anhydride solution with a relatively high concentration of maleic anhydride, thereby reducing the amount of solvent used and reducing the energy consumption for subsequent solvent recovery. According to the preferred embodiment of the present application, preferably, the concentration of maleic anhydride in the maleic anhydride solution is 1-90% by weight, preferably 10-40% by weight.

[0137] According to the preferred embodiment of the present application, preferably, the proportion of one stream to the other is each 5-95% by weight; preferably, the proportion of one stream is 20-50% by weight and the proportion of the other stream is 50-80% by weight. This can effectively remove heat and improve the effective utilization of the catalyst, prolonging the service life of the catalyst.

[0138] According to the preferred embodiment of the present application, preferably, the molar ratio of the total hydrogen gas amount to the total maleic anhydride in the maleic anhydride solution is 5-100, preferably 10-40.

[0139] According to the preferred embodiment of the present application, preferably, the operating conditions of the first-stage 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, in sequence, each reaction temperature being applicable to the present application; and / or a reaction pressure of 0.1-10 MPa, preferably 0.5-5 MPa; and / or a space velocity of 0.5-5 h -1 . Thus, the heat can be effectively removed, the effective utilization of the catalyst can be improved, and the service life of the catalyst can be prolonged.

[0140] According to the preferred embodiment of the present application, preferably, the operating conditions of the second-stage 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, in sequence, each reaction temperature being applicable to the present application; and / or a pressure of 0.1-10 MPa, preferably 0.5-5 MPa; and / or a space velocity of 0.5-5 h -1 . Thus, the heat can be effectively removed, the effective utilization of the catalyst can be improved, and the service life of the catalyst can be prolonged.

[0141] According to the preferred embodiment of the present application, preferably, 20-90% by weight of the liquid-phase material of the second-stage hydrogenation reaction is returned to step (1) as a raw material, and the rest is sent to a subsequent separation system as a liquid-phase product. Thus, the heat can be effectively removed, the effective utilization of the catalyst can be improved, and the service life of the catalyst can be prolonged.

[0142] According to the preferred embodiment of the present application, preferably, 0.5-2% by volume of the gas-phase material of the second-stage hydrogenation reaction is produced as fuel gas, and the rest is used as the circulating hydrogen gas. Thus, the heat can be effectively removed, the effective utilization of the catalyst can be improved, and the service life of the catalyst can be prolonged.

[0143] According to the present application, as shown in Figure 3 , the hydrogenation of maleic anhydride specifically includes:

[0144] (1) The maleic anhydride solution is divided into two streams, one of which is mixed with the liquid-phase material of the second-stage reaction and then enters the first-stage hydrogenation reactor from the bottom / lower part of the reactor, and the other stream of the maleic anhydride solution is mixed with the liquid-phase material of the first-stage reaction and then enters the second-stage hydrogenation reactor from the bottom / lower part of the reactor;

[0145] (2) The circulating hydrogen gas is mixed with the additional fresh hydrogen gas and then enters the first-stage hydrogenation reactor from the bottom of the reactor, and reacts with the maleic anhydride to convert the maleic anhydride into succinic anhydride by full / partial reaction;

[0146] (3) The one-stage hydrogenation product is cooled by a cooler, then separated into gas and liquid phases by a gas-liquid separator, the gas phase is all introduced into the second-stage hydrogenation reactor from the bottom 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 from the bottom or lower part of the reactor to react with hydrogen to convert all the maleic anhydride into succinic anhydride;

[0147] (4) After the second-stage hydrogenation reaction product is separated into gas and liquid phases, the gas phase is cooled to the reaction temperature and then recycled to step (2), and part of the liquid phase is introduced into a subsequent system, and part of the liquid phase is cooled and then mixed with the maleic anhydride solution and introduced into the one-stage hydrogenation reactor.

[0148] According to the present application, in the aforementioned step (3), after the one-stage hydrogenation product is separated into gas and liquid phases, the gas phase is all introduced into the second-stage hydrogenation reactor from the bottom 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 from the bottom or lower part of the reactor, and after the two-stage hydrogenation reaction, all the maleic anhydride is converted into succinic anhydride.

[0149] According to the present application, in the aforementioned step (4), after the second-stage hydrogenation reaction product is separated into gas and liquid phases, the gas phase material can be further cooled by a heat exchanger, and the cooling temperature is preferably 30-80℃, and then the cooled material is further separated into gas and liquid phases, the gas phase is recycled to step (2), and the liquid phase is returned to the previous gas-liquid separator.

[0150] According to the present application, in the aforementioned step (4), after the second-stage hydrogenation reaction product is separated into gas and liquid phases, preferably about 0.5%-2% of the material of the gas phase is introduced into a fuel gas, and the rest is recycled to the one-stage hydrogenation reactor, mixed with the fresh hydrogen gas, and then introduced into the one-stage hydrogenation reactor.

[0151] According to the present application, in the aforementioned step (4), after the second-stage hydrogenation reaction product is separated into gas and liquid phases, preferably 10%-80% of the liquid phase reaction product is sent to a subsequent separation system, and the remaining liquid phase reaction product is first cooled to 40-80℃ by a cooler, then mixed with the maleic anhydride solution, and then introduced into the one-stage hydrogenation reactor from the bottom or lower part of the reactor.

[0152] In the present application, the catalysts filled in the one-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 CN202011118431.X and Chinese patent CN202011120495.3.

[0153] In the present application, in the steps (1)-(3), the gas phase and the liquid phase are introduced into the one-stage reactor and the second-stage reactor through a distributor before contacting with the catalyst.

[0154] The maleic anhydride hydrogenation reaction method of the present application has the following characteristics:

[0155] (1) The present application divides the maleic anhydride solution into two streams, which are mixed with different materials respectively and then enter two hydrogenation reactors, so that the content of maleic anhydride entering the reactor is reduced, the heat released by the reaction can be effectively removed, the operation is flexible and easy to control.

[0156] (2) By using the method of the present application, the concentration of maleic anhydride in the incoming maleic anhydride solution can not be too low, which reduces the amount of solvent used and reduces the energy consumption of subsequent solvent recovery.

[0157] (3) After the first-stage reaction, the present application performs gas-liquid separation after cooling, and the gas phase enters the second-stage reactor, which is beneficial to effectively remove the reaction heat generated in the second-stage reaction.

[0158] (4) The present application is characterized in that the reaction materials enter from the bottom of the reactor, and after the first-stage reactor, a gas-liquid separation is provided, and the gas phase and the liquid phase enter the reactor respectively, 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 saved.

[0159] (5) The reaction operating conditions of the present application are mild, the reaction temperature is 40-50℃, the reaction temperature is greatly reduced, the reaction bed temperature rise is low, which is beneficial to improve the selectivity of the catalyst and prolong the service life of the catalyst.

[0160] According to a preferred embodiment of the present application, the following example of the maleic anhydride hydrogenation method is carried out by using the flow shown in Figure 3 or Figure 4 , wherein 1 is a distributor, 2 is a first-stage hydrogenation reactor, 3 is a first-stage reaction product cooler, 4 is a first-stage gas-liquid separator, 5 is a second-stage hydrogenation reactor, 6 is a second-stage gas-liquid separator, 7 is a circulating material cooler, 8 is a second-stage cooler, 9 is a third gas-liquid separator, 11 is a maleic anhydride solution, 12 is a reaction product, and 13 is supplemental hydrogen.

[0161] (1) The maleic anhydride solution 11 is divided into two streams by the raw material distributor 1, wherein one stream is mixed with part of the liquid phase material of the second-stage hydrogenation reaction which has been cooled or not cooled (the cooling is carried out in the circulating material cooler 7) and then enters the first-stage hydrogenation reactor 2 from the bottom liquid inlet and / or the lower liquid inlet to contact hydrogen (containing supplemental hydrogen 13 and circulating hydrogen) for hydrogenation, and the hydrogen enters the first-stage hydrogenation reactor from the bottom gas inlet and / or the lower gas inlet;

[0162] (2) The first-stage hydrogenation product is sequentially cooled in the first-stage reaction product cooler 3, gas-liquid separated in the first-stage gas-liquid separator 4, and the gas phase of the gas-liquid separation enters the second-stage hydrogenation reactor 5 from the bottom gas inlet and / or the lower gas inlet, and the liquid phase of the gas-liquid separation is mixed with another stream of the maleic anhydride solution and then enters the second-stage hydrogenation reactor 5 from the bottom liquid inlet and / or the lower liquid inlet.

[0163] (3) The second-stage hydrogenation product enters a second-stage gas-liquid separator 6 for gas-liquid separation to obtain a gas phase and a liquid-phase material of the second-stage hydrogenation reaction (another part as the reaction product 12) described in step (1), and the gas phase is optionally used as part or all of the circulating hydrogen.

[0164] Alternatively, as shown in Figure 4 , the second-stage hydrogenation product enters a second-stage cooler 8 for cooling and then enters a third gas-liquid separator 9 for gas-liquid separation, and the gas phase obtained is mixed with the make-up hydrogen 13 as the hydrogen raw material of the first-stage hydrogenation reactor; optionally, the liquid phase obtained is returned to the second-stage gas-liquid separator 6 for gas-liquid separation; preferably, the temperature for cooling the gas phase obtained by gas-liquid separation of the second-stage hydrogenation product in the second-stage cooler 8 is 30-80°C. Thus, the heat can be effectively removed, and the catalytic efficiency can be improved.

[0165] The following examples use the following catalyst:

[0166] Chinese patent application CN202011118431.X - Example 1

[0167] (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 are mixed, and ammonia gas is introduced to adjust the pH of the solution to 10.5, and the solution is stirred at 45°C until all the solids are dissolved to obtain a nickel-copper ammonia complex solution;

[0168] (2) 458.31 g of silica sol is mixed with the nickel-copper ammonia complex solution obtained in step (1) to obtain a mixed solution;

[0169] (3) The mixed solution is 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;

[0170] (4) The catalyst precursor is saturatedly impregnated with a cerium nitrate solution containing 11.41 g of Ce(NO3)3·6H2O to obtain a matrix catalyst;

[0171] (5) The matrix catalyst is dried at 115°C for 12 h and then calcined at 400°C for 4 h to form a catalyst S1.

[0172] 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.

[0173] Chinese patent application CN202011120495.3 - Example 1

[0174] (1) Weigh 10.90g of Ni(NO3)3·6H2O and 5.04g of Ce(NO3)3·6H2O, dissolve them in water and make up to 50.0ml. Then, 50g of carrier SiO2 (specific surface area 300m2 / g, water absorption rate 1.0mL / g) is immersed in a nickel nitrate-cerium nitrate mixed solution, stirred evenly, and allowed to stand for aging for 4 hours. Then, it is dried at 120℃ for 12 hours and finally calcined in air at 450℃ for 4 hours to obtain composite oxide carrier E.

[0175] (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.

[0176] 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.

[0177] Example 1

[0178] use Figure 2 The diagram illustrates a method for producing succinic acid from butane.

[0179] Butane and air are mixed and enter the oxidation separation system. The catalyst used in the oxidation reaction is detailed in Chinese Patent CN201710053664.8 - Example 1. The reaction product, after being cooled by heat exchange, enters the absorption tower from the bottom. Dibutyl phthalate is used as the solvent, entering the absorption tower from the top. The absorption tower has 20 theoretical plates, operating at 90°C and 0.05 MPa. Tail gas is collected from the top of the absorption tower and sent outside the boundary. The solvent-rich bottom of the absorption tower enters the stripping tower. The stripping tower has 25 theoretical plates, operating at 142°C and 12 kPa. The top material of the stripping tower is sent to the light component tower, and the bottom material is sent to the absorption tower for recycling. The light component tower has 20 theoretical plates, operating at 40°C and 8 kPa. The top material of the light component tower is sent outside the boundary, and the bottom material is sent to the product refining tower. The product refining tower has 25 trays, an operating temperature of 132℃, and an operating pressure of 10 kPa. The maleic anhydride product is collected from the upper side stream of the product refining tower and sent to the maleic anhydride hydrogenation separation system. The bottom material is returned to the absorption tower for recycling after being heated to 50℃.

[0180] The hydrogenation separation system of maleic anhydride adopts two-stage hydrogenation reactors. A stream of γ-butyrolactone is introduced from the outside as a solvent, mixed with the circulating solvent and maleic anhydride to form a 10 wt% maleic anhydride solution, which is sent to the upper part of the first-stage hydrogenation reactor after being heated to 40°C. Fresh hydrogen gas and circulating hydrogen gas are mixed and introduced into the top of the first-stage hydrogenation reactor, with a hydrogen to maleic anhydride molar ratio of 12. The space velocity of the first-stage hydrogenation reactor is 2.5 h -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 and the liquid phase are introduced into the second-stage hydrogenation reactor from the top of the reactor. The space velocity of the second-stage hydrogenation reactor is 1 h -1 , the reaction temperature is 45°C, and the reaction pressure is 1.3 MPa. After the second-stage hydrogenation reaction product passes through the gas-liquid separator, 1% of the gas phase is vented, and the remaining gas phase is sent into the first-stage hydrogenation reactor together with the fresh hydrogen gas. The liquid phase after gas-liquid separation is sent to the light-removing tower at 65 wt%, and the liquid phase after heat exchange to 40°C is mixed with the maleic anhydride solution and introduced into the first-stage hydrogenation reactor. The catalysts loaded in the first-stage and second-stage reactors are both Ni active component catalysts, and the specific composition is shown in Chinese Patent CN202011118431.X-Example 1.

[0181] After two-stage hydrogenation reaction, the total conversion rate of maleic anhydride is 99.91%, and the total selectivity of succinic anhydride is 99.80%.

[0182] The material from the maleic anhydride hydrogenation reaction system enters the succinic anhydride separation system, first passes through the light-removing tower to separate out the light components, and the tower bottom material is sent to the heavy-removing tower. γ-Butyrolactone is collected at the top of the heavy-removing tower and is recycled as a solvent for dissolving maleic anhydride. Heavy components are collected at the bottom of the heavy-removing tower, and succinic anhydride is collected from the side line and sent to the succinic anhydride hydrolysis system.

[0183] The light-removing tower has 26 theoretical plates, the tower top pressure is 10 KPa, and the operating temperature is 100°C. The heavy-removing tower has 25 theoretical plates, the tower top pressure is 3 KPa, and the operating temperature is 105°C. The obtained succinic anhydride has a purity of 99.9%.

[0184] The hydrolysis system operates at a pressure of 0.12 MPa and a temperature of 80°C in the hydrolysis kettle. After centrifugal separation and drying, succinic acid product is obtained. The purity of succinic acid product is 99.9%.

[0185] Example 2

[0186] According to the method of Example 1, except that the separation stage in the oxidation separation system adopts an absorption tower-distillation tower separation to obtain a maleic anhydride solution.

[0187] The butane and air are mixed and subjected to oxidation reaction. The reaction product enters an absorption tower, enters from the tower kettle, and the solvent is γ-butyrolactone, enters the absorption tower from the top, and the tail gas is taken out from the top of the absorption tower. The rich solvent from the tower kettle enters a rectification tower. The light components are taken out from the top of the rectification tower, and the material in the tower kettle is a maleic anhydride solution.

[0188] The operation conditions of the absorption tower include that the pressure is 0.0-1.0 MPag, the temperature is 40-120℃, and the theoretical plate number is 5-50.

[0189] The operation conditions of the rectification tower include that the pressure is 0.0-1.0 MPag, the temperature is 40-150℃, and the theoretical plate number is 5-100.

[0190] Under the above operation conditions, the operation conditions and the type of absorbent are adjusted to obtain a maleic anhydride solution with a solvent of γ-butyrolactone and a maleic anhydride content of 10% by weight.

[0191] The maleic anhydride hydrogenation reaction method shown in the drawing is used. Figure 3 The maleic anhydride solution is divided into two streams in a proportion of 50% by weight and 50% by weight. One of the streams is mixed with the recycled second-stage hydrogenation reaction product and then enters the first-stage hydrogenation reactor from the lower part of the reactor. The other stream is mixed with the first-stage hydrogenation reaction product and then enters the second-stage hydrogenation reactor from the lower part of the reactor. The total hydrogen gas amount of 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.

[0192] In the first-stage hydrogenation reactor, the space velocity of the first-stage hydrogenation reactor is 2.5h -1 -1, the reaction temperature is 40℃, and the reaction pressure is 1.5 MPa. The first-stage hydrogenation reaction product is cooled to 40℃, and after gas-liquid separation, the gas phase is all introduced into the second-stage hydrogenation reactor from the bottom 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 from the lower part of the reactor. The space velocity of the second-stage hydrogenation reactor is 1h -1 -1, the reaction temperature is 42℃, and the reaction pressure is 1.3 MPa. After the second-stage hydrogenation reaction product passes through a gas-liquid separator, 1% by volume of the gas phase is vented, and the remaining gas phase is cooled to 40℃ and then introduced into the first-stage hydrogenation reactor from the bottom of the reactor together with the supplemented fresh hydrogen gas. After the second-stage hydrogenation reaction product is subjected to gas-liquid separation, 65% by weight of the liquid phase is sent to the subsequent separation system, and 35% by weight of the liquid phase is mixed with the maleic anhydride solution, which is then heated to 40℃ and then introduced into the first-stage hydrogenation reactor.

[0193] The catalysts filled in the first-stage and second-stage hydrogenation reactors are both Ni active component catalysts, and the specific composition is shown in Chinese Patent CN202011118431.X-Example 1.

[0194] After the two-stage reaction, the total conversion rate of maleic anhydride is 99.92%, and the total selectivity of succinic anhydride is 99.83%.

[0195] By separating and hydrolyzing according to the method in Example 1, a product with a purity of succinic acid of 99.9% or higher can be obtained.

[0196] Example 3

[0197] Following the method of Example 2, butane and air were oxidized and separated, except that the operating conditions and the type of absorbent were adjusted to obtain a maleic anhydride solution with hexane as the solvent and a maleic anhydride content of 25% by weight.

[0198] use Figure 4 The 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 bottom 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 bottom 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.

[0199] 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 1.7 MPa. 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 bottom of the reactor. The liquid phase, after mixing with another portion of the maleic anhydride solution, also entered the second-stage hydrogenation reactor from the bottom of the 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 passes through a gas-liquid separator. The gas phase, along with the replenished fresh hydrogen, is sent into the first-stage hydrogenation reactor. 50% by weight of the liquid phase from gas-liquid separator B is sent to the light phase 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.

[0200] The catalysts packed in the first and second stage hydrogenation reactors are all Ni active component catalysts, and the specific composition can be found in Chinese Patent CN202011120495.3-Example 1.

[0201] After two stages of reaction, the total conversion rate of maleic anhydride was 99.80%, and the total selectivity of succinic anhydride was 99.71%.

[0202] By separating and hydrolyzing according to the method in Example 1, a product with a purity of succinic acid of 99.9% or higher can be obtained.

[0203] Example 4

[0204] The butane and air were oxidized and separated according to the method of Example 2, except that the operating conditions and the type of absorbent were adjusted, and the solvent was dioxane, and the maleic anhydride solution contained 18% by weight of maleic anhydride;

[0205] The reaction method of maleic anhydride hydrogenation shown in the above formula was used, and the maleic anhydride solution was divided into two streams in a ratio of 20% by weight and 80% by weight. The 20% by weight of the maleic anhydride solution was mixed with the second-stage hydrogenation reaction product and then introduced into the first-stage hydrogenation reactor from the bottom of the reactor. The 80% by weight of the maleic anhydride solution was mixed with the first-stage hydrogenation reaction product and then introduced into the second-stage hydrogenation reactor from the bottom of the reactor. The total amount of the circulating hydrogen and the fresh hydrogen supplement was 30 times the molar ratio of the total maleic anhydride in the maleic anhydride solution. Figure 3

[0206] In the first-stage hydrogenation reactor, the space velocity of the first-stage hydrogenation reactor was 1.8h -1 -1, the reaction temperature was 40℃, and the reaction pressure was 1.2MPa. The first-stage hydrogenation reaction product was cooled to 45℃, and then the gas phase was introduced into the second-stage hydrogenation reactor from the bottom of the reactor after gas-liquid separation. The liquid phase was mixed with another part of the maleic anhydride solution and then introduced into the second-stage hydrogenation reactor from the bottom of the reactor. In the second-stage hydrogenation reactor, the space velocity was 1.2h -1 -1, the reaction temperature was 48℃, and the reaction pressure was 1.2MPa. After the second-stage hydrogenation reaction product passed through the gas-liquid separator, 1% by volume of the gas phase was discharged, and the remaining gas phase was introduced into the first-stage hydrogenation reactor together with the fresh hydrogen supplement. 60% by weight of the liquid phase was sent to the subsequent separation system, and 40% by weight of the liquid phase was returned to the first-stage hydrogenation reactor. The liquid phase was mixed with the maleic anhydride solution and then heated to the reaction temperature, and then introduced into the first-stage hydrogenation reactor.

[0207] The catalysts filled in the first-stage and second-stage hydrogenation reactors were both Ni active component catalysts, and the specific composition was shown in Example 1 of Chinese Patent CN202011118431.X.

[0208] After the two-stage reaction, the total conversion rate of maleic anhydride was 99.86%, and the total selectivity of succinic anhydride was 99.81%.

[0209] 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.

[0210] The preferred embodiments of the application are described in detail above, but the application is not limited thereto. Within the technical concept of the application, various simple modifications can be made to the technical solutions of the 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 application and fall within the protection scope of the application.​

Claims

1. An apparatus for producing succinic acid by oxidative hydrogenation and hydrolysis of butane and / or benzene as raw materials, characterized in that, The device comprises, in the direction of the material flow, an oxidation separation system, a maleic anhydride hydrogenation separation system and a succinic anhydride hydrolysis system connected in series; wherein butane and / or benzene and an oxygen-containing gas are subjected to an oxidation reaction in the oxidation separation system and separated to obtain maleic anhydride material; the maleic anhydride material enters the maleic anhydride hydrogenation separation system to undergo a hydrogenation reaction and is separated to obtain succinic anhydride; the succinic anhydride enters the succinic anhydride hydrolysis system to undergo hydrolysis and crystallization to obtain succinic acid product; The maleic anhydride hydrogenation separation system comprises a maleic anhydride hydrogenation system and a hydrogenation product separation system; The maleic anhydride hydrogenation system comprises: A first hydrogenation reactor, the first hydrogenation reactor comprises a lower gas phase inlet and / or a bottom gas phase inlet, a lower liquid phase feed inlet and / or a bottom liquid phase feed inlet, a top outlet and / or an upper outlet; and a first reaction product cooler and a first gas-liquid separator connected in series at the outlet of the first hydrogenation reactor; A second hydrogenation reactor, the second hydrogenation reactor is connected in series with the first gas-liquid separator, and the second hydrogenation reactor comprises a lower gas phase inlet and / or a bottom gas phase inlet, a lower liquid phase feed inlet and / or a bottom liquid phase feed inlet, a top outlet and / or an upper outlet; A second gas-liquid separator, the second gas-liquid separator is connected in series with the outlet of the second hydrogenation reactor; A liquid phase raw material supply pipeline is connected with the liquid phase feed inlet of the first hydrogenation reactor and the liquid phase feed inlet of the second hydrogenation reactor; The top gas phase outlet of the second gas-liquid separator is connected with the lower gas phase inlet and / or the bottom gas phase inlet of the first hydrogenation reactor through a pipeline; The bottom liquid phase outlet of the second gas-liquid separator is connected with the lower liquid phase feed inlet and / or the bottom liquid phase feed inlet of the first hydrogenation reactor through a pipeline.

2. The apparatus of claim 1, wherein, The hydrogenation product separation system comprises: A light-removing column and a heavy-removing column connected in series; The feed inlet of the light-removing column is connected with the liquid phase outlet of the second gas-liquid separator, and 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 with the column bottom outlet of the light-removing column, and the heavy-removing column is provided with a top outlet, a bottom outlet and a side line outlet.

3. The apparatus of claim 2, wherein, In the maleic anhydride hydrogenation system, The top gas phase outlet of the first gas-liquid separator is connected with the lower gas phase inlet and / or the bottom gas phase inlet of the second hydrogenation reactor through a pipeline; and / or The bottom liquid phase outlet of the first gas-liquid separator is connected with the lower liquid phase feed inlet and / or the bottom liquid phase feed inlet of the second hydrogenation reactor through a pipeline.

4. The apparatus of claim 3, wherein, In the maleic anhydride hydrogenation system, A circulating material cooler is arranged on the pipeline connecting the bottom liquid phase outlet of the second gas-liquid separator with the lower liquid phase feed inlet and / or the bottom liquid phase feed inlet of the first hydrogenation reactor; The maleic anhydride hydrogenation system further comprises a distributor for distributing the liquid phase raw material into two streams to supply the first hydrogenation reactor and the second hydrogenation reactor as needed.

5. The apparatus of claim 4, wherein, A second cooler is arranged at the top gas phase outlet end of the second gas-liquid separator, or a second cooler and a third gas-liquid separator are arranged in series, and the gas phase outlet of the third gas-liquid separator is communicated with the lower gas phase inlet and / or the bottom gas phase inlet of the first hydrogenation reactor through a pipeline; the bottom liquid phase outlet of the third gas-liquid separator is communicated with the liquid phase feed inlet of the second gas-liquid separator.

6. The apparatus of any of claims 1-5, wherein, The oxidation separation system comprises an oxidation reaction system and a maleic anhydride separation system, and the maleic anhydride separation system comprises an absorption tower and a rectification tower which are communicated in series, and the maleic anhydride solution separated by the absorption tower and the rectification tower is directly used as a raw material of a maleic anhydride hydrogenation separation system, and the maleic anhydride hydrogenation can be performed without additional introduction of a solvent.

7. A process for the production of succinic acid by oxidative hydrohydrogenolysis from butane and / or benzene, characterized in that, The method is performed in the device of any one of claims 1-6, and the method comprises: butane and / or benzene and an oxygen-containing gas are subjected to an oxidation reaction and separation in an oxidation separation system to obtain a maleic anhydride material; the maleic anhydride material is subjected to a hydrogenation reaction in a maleic anhydride hydrogenation separation system and is separated to obtain succinic anhydride; the succinic anhydride is subjected to hydrolysis and crystallization in a succinic anhydride hydrolysis system to obtain succinic acid products; The second hydrogenation is performed in the maleic anhydride hydrogenation separation system, and the maleic anhydride hydrogenation method comprises: (1) the maleic anhydride solution from the oxidation separation system is divided into two streams, one of which is mixed with a liquid phase material subjected to a partial second hydrogenation reaction after being cooled or without cooling, and then enters the first hydrogenation reactor from the bottom liquid phase inlet and / or the lower liquid phase inlet of the first hydrogenation reactor to contact with hydrogen gas for hydrogenation, and the hydrogen gas enters the first hydrogenation reactor from the bottom gas phase inlet and / or the lower gas phase inlet of the first hydrogenation reactor; (2) the first hydrogenation product is sequentially subjected to cooling, gas-liquid separation, and the gas phase of the gas-liquid separation enters the second hydrogenation reactor from the bottom gas phase inlet and / or the lower gas phase inlet of the second hydrogenation reactor, and the liquid phase of the gas-liquid separation is mixed with the other stream of the maleic anhydride solution and then enters the second hydrogenation reactor from the bottom liquid phase inlet and / or the lower liquid phase inlet of the second hydrogenation reactor; (3) the second hydrogenation product is subjected to gas-liquid separation to obtain a gas phase and a liquid phase material subjected to the second hydrogenation reaction, and the gas phase is partially or entirely used as the circulating hydrogen gas.

8. The method of claim 7, wherein, In the maleic anhydride hydrogenation method, the hydrogen gas raw material of step (1) is a mixed hydrogen gas raw material of the circulating hydrogen gas and the supplemental hydrogen gas; and / or the liquid phase material subjected to the second hydrogenation reaction of step (1) is a material cooled to 30-80°C.

9. The method of claim 8, wherein, In the maleic anhydride hydrogenation method, the liquid phase material subjected to the second hydrogenation reaction of step (1) is a material cooled to 40-60°C.

10. The method of claim 8, wherein, In the maleic anhydride hydrogenation method, the liquid phase material subjected to the second hydrogenation reaction of step (1) is a material cooled to 40-60°C.

11. The method of claim 7, wherein, The maleic anhydride hydrogenation method further comprises: the gas phase obtained by subjecting the second hydrogenation product to gas-liquid separation is cooled and then subjected to a third gas-liquid separation, the gas phase obtained is partially or entirely mixed with the supplemental hydrogen gas as the hydrogen gas raw material of the first hydrogenation reactor, and the liquid phase obtained is returned to the second gas-liquid separator for gas-liquid separation.

12. The method of claim 11, wherein, The temperature for cooling the gas phase obtained by subjecting the second hydrogenation product to gas-liquid separation is 30-80°C.

13. The method of claim 7, wherein, In step (1), The maleic anhydride solution is a mixture of maleic anhydride and a solvent, and the solvent is one or more of acetic anhydride, gamma-butyrolactone, dioxane, tetrahydrofuran, aromatic hydrocarbon, ethyl acetate, tetracarbon diacid ester, ethanol, isopropyl alcohol, hexane, cyclohexane, propylene oxide, ketone and ether; and / or The concentration of maleic anhydride in the maleic anhydride solution is 1-90% by weight; and / or The proportion of each of the two streams is 5-95% by weight; and / or The molar ratio of the total amount of hydrogen to the total maleic anhydride in the maleic anhydride solution is 5-100; and / or The operating conditions of the first 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 ; In step (2), the operating conditions of the two-stage hydrogenation reactor include: temperature is 30-120°C; and / or pressure is 0.1-10 MPa; and / or space velocity is 0.5-5 h -1 .

14. The method of claim 13, wherein, In step (1), The concentration of maleic anhydride in the maleic anhydride solution is 10-40% by weight; and / or The proportion of one stream is 20-50% by weight, and the proportion of the other stream is 50-80% by weight; and / or The molar ratio of the total amount of hydrogen to the total maleic anhydride in the maleic anhydride solution is 10-40; and / or The operating conditions of the one-stage hydrogenation reactor include: the temperature is 40-80℃; and / or the reaction pressure is 0.5-5MPa; In step (2), the operating conditions of the two-stage hydrogenation reactor include: the temperature is 40-100℃.

15. The method of any of claims 7-14, wherein, The oxidation separation system comprises an oxidation reaction system and a maleic anhydride separation system, and the maleic anhydride separation system comprises an absorption tower and a rectification tower connected in series, and the maleic anhydride solution separated by the absorption tower and the rectification tower is directly used as the raw material of the maleic anhydride hydrogenation separation system, and the maleic anhydride hydrogenation can not introduce additional solvent; In the maleic anhydride separation system: The operating conditions of the absorption tower include: the pressure is 0.0-1.0MPag, the temperature is 40-120℃, and the theoretical plate number is 5-50; The absorbent is selected from one or more of gamma-butyrolactone, dibutyl phthalate, diisobutyl hexahydrophthalate, tetrahydrofuran, ethyl acetate, tetracarbon diacid ester, ethanol, isopropyl alcohol, hexane, cyclohexane, propylene oxide, benzene, xylene, chlorobenzene, dichlorobenzene, ketone and ether; The operating conditions of the rectification tower include: the pressure is 0.0-1.0MPag, the temperature is 40-150℃, and the theoretical plate number is 5-100; Part of the material in the tower bottom of the absorption tower is cooled to 30-80℃ and then returned to the absorption tower; and / or The material in the tower top of the absorption tower 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 tower.

16. The method of claim 15, wherein, The absorbent is selected from gamma-butyrolactone and / or tetrahydrofuran.

17. The method of claim 7, wherein, In the hydrogenation product separation system, the hydrogenation product separation system comprises a light-removing tower and a heavy-removing tower connected in series: The operating conditions of the light-removing tower include: the pressure is 0.5-20KPa, the temperature is 30-150℃, and the theoretical plate number is 10-80; and / or The operating conditions of the heavy-removing tower include: the pressure is 0.5-20KPa, the temperature is 30-150℃, and the theoretical plate number is 10-80.

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