System and method for preparing succinic anhydride

Abstract

The present invention provides a method and system for preparing succinic anhydride, which comprises: (1) maleic anhydride solution is divided into two streams, one stream is mixed with a liquid phase material of a part of a second-stage hydrogenation reaction that has been cooled or not cooled, and then enters a first-stage hydrogenation reactor from a bottom liquid phase feed port and / or a lower liquid phase feed port of the first-stage hydrogenation reactor to contact with hydrogen for hydrogenation, and hydrogen enters the first-stage hydrogenation reactor from a bottom gas phase inlet and / or a lower gas phase inlet of the first-stage hydrogenation reactor; (2) the first-stage hydrogenation product is cooled and cooled in sequence, and the gas and liquid are separated, and the gas phase enters the second-stage hydrogenation reactor from the bottom and / or the lower gas phase inlet of the second-stage hydrogenation reactor, and the liquid phase separated by gas and liquid is mixed with another stream of maleic anhydride solution, and then enters the second-stage hydrogenation reactor from the bottom and / or the lower liquid phase feed port of the second-stage reactor. The method of the present invention can effectively remove the heat released by the reaction, the gas-liquid-solid contact is good, the effective utilization rate of the catalyst is high, and the investment is low.

Description

Technical Field

[0001] The present invention relates to a liquid phase hydrogenation reaction process of maleic anhydride, and more particularly to a system and method for preparing succinic anhydride by hydrogenation using maleic anhydride as raw material. Background Art

[0002] Succinic anhydride has the molecular formula of C4H4O3. It is an important intermediate in organic synthesis. It is soluble in ethanol, chloroform and carbon tetrachloride, slightly soluble in water and ether, and can be hydrolyzed into succinic acid with hot water. Succinic anhydride is widely used in the synthesis of medicines, pesticides, esters and resins. It can also be used in the synthesis of succinic acid and analytical reagents. It is used in the synthetic resin industry to manufacture alkyd resins and ion exchange resins, in the plastics industry to manufacture glass fiber reinforced plastics, and in the pesticide industry to create plant growth regulators. Succinic anhydride is an important intermediate in the synthesis of other organic substances. It is mainly obtained through chemical synthesis, with many synthesis routes. The current industrial production methods are mainly maleic anhydride method and succinic acid dehydration method.

[0003] The succinic acid dehydration method is to produce succinic anhydride by dehydrating succinic acid raw materials under certain conditions. The yield of succinic anhydride prepared by this method is low, the product quality is unstable, and the succinic anhydride content is generally 85%-94%. Succinic acid is easily carbonized during the production process, the operation process is difficult to control, the process flow is long, and the production cost is relatively high. Therefore, this method has no development prospects.

[0004] The direct hydrogenation of maleic anhydride is the method with the highest conversion rate and product purity for producing succinic anhydride. This method has no obvious side reactions and the product purity is good. However, since the hydrogenation of maleic anhydride to produce succinic anhydride is a highly exothermic reaction, how to take effective measures to reduce the heat release of the reaction is the key and difficulty of the maleic anhydride hydrogenation process.

[0005] US2245404 (A) discloses a method for controlling the temperature rise of the catalyst bed by removing the heat of maleic anhydride hydrogenation reaction using an internal heat transfer tube. The heat transfer tube in this method cannot remove the reaction heat uniformly, and also affects the distribution of the reaction liquid in the reactor, thereby affecting the catalyst reaction performance. Therefore, this method is not suitable for removing the reaction heat of large-scale reaction equipment.

[0006] CN105801536A discloses a method for preparing succinic anhydride by liquid phase selective hydrogenation of maleic anhydride, wherein two reactors are connected in series, hydrogen is used for heat removal, hydrogen is introduced into the first reactor and the second reactor, the reaction heat is reduced, and then separated by a gas-liquid separator and recycled, and the molar ratio of the circulating hydrogen to maleic anhydride is 30 to 200: 1. This method can achieve a certain heat removal effect, but due to the large amount of circulating hydrogen, the energy consumption of the circulating hydrogen compressor is relatively large, and the amount of hydrogen entering the reactor is large, and the corresponding reactor volume needs to be increased, resulting in increased investment and increased energy consumption.

[0007] Therefore, it is urgent to develop a maleic anhydride hydrogenation reaction process to effectively remove the heat released by the reaction and solve the problems of large investment and high energy consumption. Summary of the invention

[0008] The purpose of the present invention is to solve the problems in the prior art that the reaction of hydrogenating maleic anhydride to produce succinic anhydride has large heat release, is difficult to remove heat, has large production process investment, and has high energy consumption. A new maleic anhydride liquid phase hydrogenation reaction process and method are proposed, which has the characteristics of easy removal of reaction heat, low investment, and low energy consumption.

[0009] The present invention provides a method for preparing succinic anhydride, which comprises performing a two-stage hydrogenation reaction.

[0010] (1) The maleic anhydride solution is divided into two streams, wherein one stream is mixed with a portion of the liquid phase material of the second-stage hydrogenation reaction that has been cooled or not cooled, and then enters 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 for hydrogenation, and the hydrogen enters the first-stage hydrogenation reactor from the bottom gas phase inlet and / or the lower gas phase inlet of the first-stage hydrogenation reactor;

[0011] (2) the first stage hydrogenation product is sequentially cooled and gas-liquid separated, the gas phase of the gas-liquid separation is all fed 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 another stream of maleic anhydride solution and then fed into the second stage hydrogenation reactor from the bottom liquid phase feed port and / or the lower liquid phase feed port of the second stage hydrogenation reactor;

[0012] (3) The second-stage hydrogenation product is subjected to gas-liquid separation to obtain a gas phase and a liquid phase material of the second-stage hydrogenation reaction, and part or all of the gas phase can be optionally used as circulating hydrogen.

[0013] Preferably, the hydrogen feedstock of step (1) is a mixed hydrogen feedstock of circulating hydrogen and supplementary hydrogen.

[0014] Preferably, the liquid phase material of the second-stage hydrogenation reaction in step (1) is a cooled material.

[0015] Preferably, the liquid phase material of the second-stage hydrogenation reaction in step (1) is cooled to 30-80°C, preferably cooled to 40-60°C.

[0016] Preferably, the method further comprises:

[0017] The gas phase obtained by gas-liquid separation of the second-stage hydrogenation product is cooled and then subjected to a third gas-liquid separation. Part or all of the obtained gas phase is used as the circulating hydrogen and mixed with supplementary hydrogen as the hydrogen feedstock of the first-stage hydrogenation reactor; optionally, the obtained liquid phase is returned to the second-stage gas-liquid separator for gas-liquid separation.

[0018] Preferably, the temperature at which the gas phase obtained by gas-liquid separation of the second-stage hydrogenation product is cooled is 30-80°C.

[0019] Preferably, 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, γ-butyrolactone, dioxane, tetrahydrofuran, aromatic hydrocarbons, ethyl acetate, tetracarbon dibasic esters, ethanol, isopropanol, hexane, cyclohexane, propylene oxide, ketones and ethers.

[0020] Preferably, the maleic anhydride concentration of the maleic anhydride solution is 1 to 90% by weight, preferably 10 to 40% by weight.

[0021] Preferably, one strand accounts for 5 to 95 weight % each and the other strand accounts for 20 to 50 weight % and the other strand accounts for 50 to 80 weight %.

[0022] Preferably, the molar ratio of the total amount of hydrogen to the total amount of maleic anhydride in the maleic anhydride solution is 5-100, preferably 10-40.

[0023] 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, etc., and so on, and each reaction temperature is applicable to the present invention; and / or a reaction pressure of 0.1-10MPa, preferably 0.5-5MPa; and / or a space velocity of 0.5-5h -1 .

[0024] Preferably, in step (2), 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, etc., and so on, and each reaction temperature is applicable to the present invention; and / or a pressure of 0.1-10MPa, preferably 0.5-5MPa; and / or a space velocity of 0.5-5h -1 .

[0025] Preferably, 20-90% by weight of the liquid phase material of the second-stage hydrogenation reaction is returned to step (1) for use as a raw material, and the rest is sent to a subsequent separation system as a liquid phase product.

[0026] Preferably, 0.5-2 volume % of the gaseous material in the second-stage hydrogenation reaction is extracted as fuel gas, and the rest is used as the circulating hydrogen.

[0027] In a second aspect, the present invention provides a system for preparing succinic anhydride, the system comprising:

[0028] A first stage hydrogenation reactor, the first stage hydrogenation reactor comprising a lower gas phase inlet and / or a bottom gas phase inlet, a lower liquid phase feed port and / or a bottom liquid phase feed port, a top discharge port and / or an upper discharge port; and a first stage reaction product cooler and a first stage gas-liquid separator sequentially connected in series to the discharge port end of the first stage hydrogenation reactor;

[0029] A two-stage hydrogenation reactor, the two-stage hydrogenation reactor is connected in series with the one-stage gas-liquid separator, and the two-stage hydrogenation reactor comprises a lower gas phase inlet and / or a bottom gas phase inlet, a lower liquid phase feed port and / or a bottom liquid phase feed port, and a top discharge port and / or an upper discharge port;

[0030] A second-stage gas-liquid separator, the second-stage gas-liquid separator is connected in series with the discharge port of the second-stage hydrogenation reactor;

[0031] The liquid-phase raw material supply pipeline is connected to both the liquid-phase feed port of the first-stage hydrogenation reactor and the liquid-phase feed port of the second-stage hydrogenation reactor.

[0032] Preferably, the top gas phase outlet of the first-stage gas-liquid separator is connected to the lower gas phase inlet and / or the bottom gas phase inlet of the second-stage hydrogenation reactor through a pipeline.

[0033] Preferably, the bottom liquid phase outlet of the first-stage gas-liquid separator is connected to the lower liquid phase feed inlet and / or the bottom liquid phase feed inlet of the second-stage hydrogenation reactor through a pipeline.

[0034] Preferably, the top gas phase outlet of the second-stage gas-liquid separator is connected to the lower gas phase inlet and / or the bottom gas phase inlet of the first-stage hydrogenation reactor through a pipeline.

[0035] Preferably, the bottom liquid phase outlet of the second-stage gas-liquid separator is connected to the lower liquid phase feed inlet and / or the bottom liquid phase feed inlet of the first-stage hydrogenation reactor through a pipeline.

[0036] Preferably, a circulating material cooler is provided on the connecting pipeline between the bottom liquid phase outlet of the second-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.

[0037] Preferably, a second-stage cooler is arranged at the top gas phase outlet end of the second-stage gas-liquid separator, or a second-stage cooler and a third gas-liquid separator are arranged in series in sequence, and the gas phase outlet of the third gas-liquid separator is connected to 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 connected to the liquid phase feed port of the second-stage gas-liquid separator.

[0038] Preferably, the system further comprises: a distributor for distributing the liquid-phase feedstock into two streams to supply the first-stage hydrogenation reactor and the second-stage hydrogenation reactor as required.

[0039] In summary, the process and method for producing succinic anhydride by hydrogenation of the present invention is that the maleic anhydride solution is divided into two streams of materials, one of which is mixed with part of the liquid phase material of the second stage reaction and enters the first stage hydrogenation reactor from the lower part of the reactor, and the other maleic anhydride solution is mixed with the liquid phase material of the first stage reaction and enters the second stage hydrogenation reactor from the lower part of the reactor. After two stages of hydrogenation reaction, maleic anhydride is completely converted into succinic anhydride. The present invention divides the maleic anhydride solution into two streams, which are mixed with different materials and enter two hydrogenation reactors. The above scheme of the present invention can achieve the following technical advantages:

[0040] (1) The method of the present invention can effectively remove the heat released by the reaction, and the operation is flexible and easy to control;

[0041] (2) By adopting the method of the present invention, the maleic anhydride concentration in the incoming maleic anhydride solution does not need to be too low, thereby reducing the amount of solvent used and reducing the energy consumption of subsequent solvent recovery.

[0042] (3) The method of the present invention has good gas-liquid-solid contact, high catalyst utilization rate and low investment.

[0043] (4) The reaction operating conditions of the present invention are mild and the temperature rise of the reaction bed is low, which is beneficial to improving the catalyst selectivity and extending the catalyst life. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 The present invention is a schematic diagram of a process for preparing succinic anhydride by hydrogenating maleic anhydride according to an embodiment of the present invention.

[0045] Figure 2 The present invention is a schematic diagram of a process for preparing succinic anhydride by hydrogenating maleic anhydride according to an embodiment of the present invention.

[0046] Description of reference numerals:

[0047] 1 distributor; 2 first stage hydrogenation reactor; 3 first stage reaction product cooler; 4 first stage gas-liquid separator; 5 second stage hydrogenation reactor; 6 second stage gas-liquid separator; 7 circulating material cooler; 8 second stage cooler; 9 third gas-liquid separator; 11 maleic anhydride solution; 12 reaction product; 13 supplemental hydrogen DETAILED DESCRIPTION

[0048] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0049] Below is a detailed diagram of the Figure 1 and Figure 2 The present invention is specifically described with reference to the following embodiments. It is necessary to point out that the following embodiments are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made to the present invention by those skilled in the art based on the content of the present invention still fall within the scope of protection of the present invention.

[0050] The present invention provides a method for preparing succinic anhydride, which comprises performing a two-stage hydrogenation reaction.

[0051] (1) The maleic anhydride solution is divided into two streams, wherein one stream is mixed with a portion of the liquid phase material of the second-stage hydrogenation reaction that has been cooled or not cooled, and then enters 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 for hydrogenation, and the hydrogen enters the first-stage hydrogenation reactor from the bottom gas phase inlet and / or the lower gas phase inlet of the first-stage hydrogenation reactor;

[0052] (2) the first stage hydrogenation product is sequentially cooled and gas-liquid separated, the gas phase of the gas-liquid separation is all fed 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 another stream of maleic anhydride solution and then fed into the second stage hydrogenation reactor from the bottom liquid phase feed port and / or the lower liquid phase feed port of the second stage hydrogenation reactor;

[0053] (3) The second-stage hydrogenation product is subjected to gas-liquid separation to obtain a gas phase and a liquid phase material of the second-stage hydrogenation reaction, and part or all of the gas phase can be optionally used as circulating hydrogen.

[0054] The method of the present invention can effectively remove the heat released by the reaction, and the operation is flexible and easy to control; the maleic anhydride concentration in the incoming maleic anhydride solution does not need to be too low, which reduces the amount of solvent used and reduces the energy consumption of subsequent solvent recovery; the gas-liquid-solid contact is good, the effective utilization rate of the catalyst is high, and the investment is low; the reaction operating conditions of the present invention are mild, the temperature rise of the reaction bed is low, which is conducive to improving the catalyst selectivity and extending the catalyst life.

[0055] According to a preferred embodiment of the present invention, the hydrogen feedstock of step (1) is a mixed hydrogen feedstock of circulating hydrogen and supplementary hydrogen.

[0056] According to a preferred embodiment of the present invention, preferably, the liquid phase material of the second-stage hydrogenation reaction in step (1) is a cooled material, thereby effectively removing heat and improving the effective utilization rate of the catalyst, thereby extending the catalyst life.

[0057] According to a preferred embodiment of the present invention, preferably, the liquid phase material of the second-stage hydrogenation reaction in step (1) is cooled to 30-80° C., preferably to 40-60° C. This can effectively remove heat, improve the effective utilization rate of the catalyst, and extend the catalyst life.

[0058] According to a preferred embodiment of the present invention, preferably, the method further comprises:

[0059] The gas phase obtained by gas-liquid separation of the second-stage hydrogenation product is cooled and then subjected to the third gas-liquid separation. Part or all of the obtained gas phase is used as the circulating hydrogen and mixed with the supplementary hydrogen as the hydrogen raw material of the first-stage hydrogenation reactor; optionally, the obtained liquid phase is returned to the second-stage gas-liquid separator for gas-liquid separation. In this way, heat can be effectively removed, the effective utilization rate of the catalyst can be improved, and the catalyst life can be extended.

[0060] According to a preferred embodiment of the present invention, preferably, the temperature at which the gas phase obtained by gas-liquid separation of the second-stage hydrogenation product is cooled is 30-80° C. This can effectively remove heat, improve the effective utilization rate of the catalyst, and extend the catalyst life.

[0061] According to a preferred embodiment of the present invention, preferably, in step (1), the maleic anhydride solution has no special requirements and can be a commonly used maleic anhydride raw material. For the present invention, it is preferably a mixture of maleic anhydride and a solvent. There is no special requirement for the type of the solvent. For the present invention, it is preferably one or more of acetic anhydride, γ-butyrolactone, dioxane, tetrahydrofuran, aromatic hydrocarbons, ethyl acetate, tetracarbon dibasic esters, ethanol, isopropanol, hexane, cyclohexane, propylene oxide, ketone and ether.

[0062] By adopting the method of the present invention, the maleic anhydride concentration in the incoming maleic anhydride solution does not need to be too low, which reduces the amount of solvent used and reduces the energy consumption of subsequent solvent recovery. According to a preferred embodiment of the present invention, preferably, the maleic anhydride concentration of the maleic anhydride solution is 1 to 90% by weight, preferably 10 to 40% by weight.

[0063] According to a preferred embodiment of the present invention, preferably, one strand accounts for 5 to 95 weight percent each, preferably one strand accounts for 20 to 50 weight percent, and the other strand accounts for 50 to 80 weight percent. This can effectively remove heat, improve the effective utilization rate of the catalyst, and extend the life of the catalyst.

[0064] According to a preferred embodiment of the present invention, preferably, the molar ratio of the total amount of hydrogen to the total amount of maleic anhydride in the maleic anhydride solution is 5-100, preferably 10-40.

[0065] According to a preferred embodiment of the present invention, 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, etc., and so on, each reaction temperature is applicable to the present invention; and / or a reaction pressure of 0.1-10MPa, preferably 0.5-5MPa; and / or a space velocity of 0.5-5h -1 This can effectively remove heat and improve the effective utilization rate of the catalyst, thereby extending the life of the catalyst.

[0066] According to a preferred embodiment of the present invention, preferably, in step (2), 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, etc., and so on, and each reaction temperature is applicable to the present invention; and / or a pressure of 0.1-10MPa, preferably 0.5-5MPa; and / or a space velocity of 0.5-5h -1 This can effectively remove heat and improve the effective utilization rate of the catalyst, thereby extending the life of the catalyst.

[0067] According to a preferred embodiment of the present invention, preferably, 20-90% by weight of the liquid phase material of the second stage hydrogenation reaction is returned to step (1) for use as a raw material, and the rest is sent to a subsequent separation system as a liquid phase product. This can effectively remove heat, improve the effective utilization rate of the catalyst, and extend the catalyst life.

[0068] According to a preferred embodiment of the present invention, preferably, 0.5-2% by volume of the gas phase material of the second stage hydrogenation reaction is extracted as fuel gas, and the rest is used as the circulating hydrogen, thereby effectively removing heat, improving the effective utilization rate of the catalyst, and extending the catalyst life.

[0069] According to the present invention, the present invention specifically includes

[0070] (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 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;

[0071] (2) After the circulating hydrogen is mixed with the supplemented fresh hydrogen, it enters a hydrogenation reactor from the bottom of the reactor to react with maleic anhydride to convert all / part of the maleic anhydride into succinic anhydride;

[0072] (3) The first stage hydrogenation product is first cooled in a cooler and then separated into gas and liquid phases in a gas-liquid separator. The gas phase enters the second stage hydrogenation reactor from the bottom of the reactor. The liquid phase is mixed with part of the maleic anhydride solution and then enters the second stage hydrogenation reactor from the bottom / lower part of the reactor to react with hydrogen to convert all maleic anhydride into succinic anhydride.

[0073] (4) After the gas-liquid separation of the second-stage hydrogenation reaction product, the gas phase is cooled to the reaction temperature and then circulated to step (2), and the liquid phase is partially extracted and sent to the subsequent distillation system, and the liquid phase is partially cooled, mixed with the maleic anhydride solution, and enters the first-stage hydrogenation reactor.

[0074] According to the present invention, in the aforementioned step (3), after the first-stage hydrogenation product is separated into gas and liquid, the gas phase enters 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 enters the second-stage hydrogenation reactor from the bottom / lower part of the reactor. After two-stage hydrogenation reactions, maleic anhydride is completely converted into succinic anhydride.

[0075] According to the present invention, optionally, in the aforementioned step (4), after the second-stage hydrogenation reaction product is subjected to gas-liquid separation, the gas phase material can be cooled by a heat exchanger, and the cooling temperature is preferably 30 to 80° C. The cooled material is further subjected to gas-liquid separation, and the gas phase is circulated to step (2), and the liquid phase is returned to the previous gas-liquid separator.

[0076] According to the present invention, optionally, in the aforementioned step (4), after the second-stage hydrogenation product is subjected to gas-liquid separation, preferably about 0.5% to 2% of the material is extracted from the gas phase to remove the fuel gas, and the rest is circulated to the first-stage hydrogenation reactor, mixed with the supplementary fresh hydrogen, and then enters the first-stage hydrogenation reactor.

[0077] According to the present invention, optionally, in the aforementioned step (4), after the second-stage hydrogenation product is subjected to gas-liquid separation, the liquid phase, preferably 10% to 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 to 80° C. in a cooler, and then mixed with the maleic anhydride solution, and then enters the first-stage hydrogenation reactor from the bottom / lower part of the reactor.

[0078] In the present invention, the catalyst loaded in the first-stage hydrogenation reactor and the second-stage hydrogenation reactor is not limited, and any maleic anhydride hydrogenation catalyst can be used, such as the catalyst described in Chinese Patent CN202011118431.X and Chinese Patent CN202011120495.3.

[0079] In the present invention, optionally, in the steps (1) to (3), when the gas phase and the liquid phase enter the first-stage reactor and the second-stage reactor, they pass through the distributor and then contact the catalyst.

[0080] The maleic anhydride hydrogenation reaction process and method of the present invention have the following characteristics:

[0081] (1) The present invention divides the maleic anhydride solution into two streams, which are mixed with different materials and then enter two hydrogenation reactors, so that the maleic anhydride content entering the reactor is reduced, and the heat released by the reaction can be effectively withdrawn, and the operation is flexible and easy to control.

[0082] (2) By adopting the method of the present invention, the maleic anhydride concentration in the incoming maleic anhydride solution does not need to be too low, thereby reducing the amount of solvent used and reducing the energy consumption of subsequent solvent recovery.

[0083] (3) In the present invention, after the first-stage reaction, the gas phase enters the second-stage reactor after cooling and gas-liquid separation, which is conducive to effectively removing the reaction heat generated by the second-stage reaction.

[0084] (4) In the present invention, the reaction materials all enter the reactor from the bottom, and after one stage of the reactor, a gas-liquid separation is provided, and the gas phase and the liquid phase enter the reactor separately, so that the materials entering the reactor are in more complete contact, the gas-liquid-solid contact is good, the catalyst is effectively utilized at a high rate, and the investment is saved.

[0085] (5) The reaction operating conditions of the present invention are mild, the reaction temperature is between 40 and 50°C, the reaction temperature is greatly reduced, and the temperature rise of the reaction bed is low, which is beneficial to improving the catalyst selectivity and extending the catalyst life.

[0086] The present invention provides a system for preparing succinic anhydride, the system comprising:

[0087] A first stage hydrogenation reactor, the first stage hydrogenation reactor comprising a lower gas phase inlet and / or a bottom gas phase inlet, a lower liquid phase feed port and / or a bottom liquid phase feed port, a top discharge port and / or an upper discharge port; and a first stage reaction product cooler and a first stage gas-liquid separator sequentially connected in series to the discharge port end of the first stage hydrogenation reactor;

[0088] A two-stage hydrogenation reactor, the two-stage hydrogenation reactor is connected in series with the one-stage gas-liquid separator, and the two-stage hydrogenation reactor comprises a lower gas phase inlet and / or a bottom gas phase inlet, a lower liquid phase feed port and / or a bottom liquid phase feed port, and a top discharge port and / or an upper discharge port;

[0089] A second-stage gas-liquid separator, the second-stage gas-liquid separator is connected in series with the discharge port of the second-stage hydrogenation reactor;

[0090] The liquid-phase raw material supply pipeline is connected to both the liquid-phase feed port of the first-stage hydrogenation reactor and the liquid-phase feed port of the second-stage hydrogenation reactor.

[0091] According to a preferred embodiment of the present invention, preferably, the top gas phase outlet of the first-stage gas-liquid separator is connected to the lower gas phase inlet and / or the bottom gas phase inlet of the second-stage hydrogenation reactor through a pipeline.

[0092] According to a preferred embodiment of the present invention, preferably, the bottom liquid phase outlet of the first-stage gas-liquid separator is connected to the lower liquid phase feed port and / or the bottom liquid phase feed port of the second-stage hydrogenation reactor through a pipeline.

[0093] According to a preferred embodiment of the present invention, preferably, the top gas phase outlet of the second-stage gas-liquid separator is connected to the lower gas phase inlet and / or the bottom gas phase inlet of the first-stage hydrogenation reactor through a pipeline.

[0094] According to a preferred embodiment of the present invention, preferably, the bottom liquid phase outlet of the second-stage gas-liquid separator is connected to the lower liquid phase feed inlet and / or the bottom liquid phase feed inlet of the first-stage hydrogenation reactor through a pipeline.

[0095] According to a preferred embodiment of the present invention, preferably, a circulating material cooler is provided on the connecting pipeline between the bottom liquid phase outlet of the second-stage gas-liquid separator and the lower liquid phase feed port and / or the bottom liquid phase feed port of the first-stage hydrogenation reactor.

[0096] According to a preferred embodiment of the present invention, preferably, a second-stage cooler is arranged at the top gas phase outlet end of the second-stage gas-liquid separator, or a second-stage cooler and a third gas-liquid separator are arranged in series in sequence, and the gas phase outlet of the third gas-liquid separator is connected to 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 connected to the liquid phase feed port of the second-stage gas-liquid separator.

[0097] According to a preferred embodiment of the present invention, preferably, the system further comprises: a distributor for distributing the liquid-phase feedstock into two streams to supply the first-stage hydrogenation reactor and the second-stage hydrogenation reactor as required.

[0098] According to a preferred embodiment of the present invention, the following examples adopt Figure 1 or Figure 2 The process shown in the figure is as follows: 1 distributor; 2 first stage hydrogenation reactor; 3 first stage reaction product cooler; 4 first stage gas-liquid separator; 5 second stage hydrogenation reactor; 6 second stage gas-liquid separator; 7 circulating material cooler; 8 second stage cooler; 9 third gas-liquid separator; 11 maleic anhydride solution; 12 reaction product; 13 supplemental hydrogen. The method of the present invention comprises:

[0099] (1) Maleic anhydride solution 11 is divided into two streams through a raw material distributor 1, wherein one stream is mixed with a portion of the liquid phase material of the second-stage hydrogenation reaction that has been cooled or not cooled (cooling is performed in a circulating material cooler 7), and then enters the first-stage hydrogenation reactor 2 from the bottom liquid phase feed port and / or the lower liquid phase feed port of the first-stage hydrogenation reactor 2 to contact with hydrogen (including supplementary hydrogen 13 and circulating hydrogen) for hydrogenation, and the hydrogen enters the first-stage hydrogenation reactor from the bottom gas phase inlet and / or the lower gas phase inlet of the first-stage hydrogenation reactor;

[0100] (2) The first stage hydrogenation product enters the first stage reaction product cooler 3 in sequence for cooling, and the first stage gas-liquid separator 4 performs gas-liquid separation, and the gas phase of the gas-liquid separation enters the second stage hydrogenation reactor 5 from the bottom gas phase inlet and / or the lower gas phase inlet of the second stage hydrogenation reactor 5, and the liquid phase of the gas-liquid separation is mixed with another stream of maleic anhydride solution and enters the second stage hydrogenation reactor 5 from the bottom liquid phase feed port and / or the lower liquid phase feed port of the second stage reactor;

[0101] (3) The second-stage hydrogenation product enters the 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 described in step (1) (the other part is used as the reaction product 12), and part or all of the gas phase can be used as circulating hydrogen.

[0102] Alternatively, the second-stage hydrogenation product enters the second-stage cooler 8 for cooling and then enters the third gas-liquid separator 9 for gas-liquid separation, and part or all of the obtained gas phase is used as the circulating hydrogen and mixed with the supplementary hydrogen 13 as the hydrogen raw material of the first-stage hydrogenation reactor; optionally, the obtained liquid phase is returned to the second-stage gas-liquid separator 6 for gas-liquid separation; preferably, the gas phase obtained by gas-liquid separation of the second-stage hydrogenation product is cooled in the second-stage cooler 8 at a temperature of 30 to 80° C., thereby effectively removing heat and improving catalytic efficiency.

[0103] The following examples use the following catalyst:

[0104] Chinese Patent Application CN202011118431.X-Example 1

[0105] (1) 50.00 g of basic nickel carbonate (nickel content 45 wt %), 9.16 g of Cu(NO 3 ) 2 · 3H 2 O, 49.91 g of ethylenediaminetetraacetic acid, 500 g of deionized water and 100 g of 25 wt % ammonia water were weighed and mixed, and ammonia gas was introduced to adjust the pH value of the solution to 10.5, and the mixture was stirred at 45° C. until all solids were dissolved to obtain a nickel-copper ammine complex solution;

[0106] (2) weighing 458.31 g of silica sol and mixing it with the nickel-copper ammine complex solution obtained in step (1) to obtain a mixed solution;

[0107] (3) Under stirring, aging the mixed solution at 60° C. for 14 h, and then drying at 120° C. for 12 h to obtain a catalyst precursor;

[0108] (4) saturating the catalyst precursor with a cerium nitrate solution containing 11.41 g of Ce(NO3)3·6H2O to obtain a base catalyst;

[0109] (5) The base catalyst was dried at 115° C. for 12 h, and then calcined at 400° C. for 4 h to obtain catalyst S1.

[0110] Based on the total weight of the catalyst S1, the catalyst S1 contains: 19 wt% NiO, 2 wt% CuO, 3 wt% CeO2 and 76 wt% SiO2.

[0111] Chinese Patent Application CN202011120495.3-Example 1

[0112] (1) 10.90 g of Ni(NO3)3·6H2O and 5.04 g of Ce(NO3)3·6H2O were weighed, dissolved in water and fixed to 50.0 ml, and then 50 g of carrier SiO2 (specific surface area 300 m2 / g, water absorption rate 1.0 mL / g) was immersed in the nickel nitrate-cerium nitrate mixed solution, stirred evenly, and allowed to stand for aging for 4 hours, then dried at 120°C for 12 hours, and finally calcined in air at 450°C for 4 hours to obtain a composite oxide carrier E;

[0113] (2) The composite oxide carrier E was added to 100 ml of a ruthenium metal solution having an exothermic Ru content of 0.02 g / L. Under stirring conditions, 25% ammonia water was added dropwise. The pH value of the solution was adjusted and maintained at 9.55°C. After reacting 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.

[0114] The catalyst S1 contains: based on the mass of the catalyst carrier SiO2, the mass fraction of Ni in the catalyst is 7% of the mass of the carrier, the mass fraction of CeO2 is 4% of the mass of the carrier, and the mass fraction of Ru is 0.4% of the mass of the carrier.

[0115] Example 1

[0116] use Figure 1 The maleic anhydride hydrogenation reaction method shown in the figure uses γ-butyrolactone as the solvent, the maleic anhydride content in the maleic anhydride solution is 10% by weight, and the maleic anhydride solution is divided into two streams at a ratio of 50% by weight and 50% by weight, one of which 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 molar ratio of the total amount of hydrogen of the recycled hydrogen and the supplemented fresh hydrogen to the total amount of maleic anhydride in the incoming maleic anhydride solution is 10.

[0117] In the first stage hydrogenation reactor, the space velocity of the first stage hydrogenation reactor is 2.5h -1, reaction temperature 40℃, reaction pressure 1.5MPa. The first stage hydrogenation reaction product is cooled to 40℃, and after gas-liquid separation, the gas phase enters 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 enters the second stage hydrogenation reactor from the bottom of the reactor. The space velocity of the second stage hydrogenation reactor is 1h -1 , reaction temperature 42°C, reaction pressure 1.3MPa. After the second stage hydrogenation reaction product passes through the gas-liquid separator, 1 volume % of the gas phase is extracted and discharged, and the remaining gas phase is cooled to 40°C and enters the first stage hydrogenation reactor from the bottom of the reactor together with the fresh hydrogen added. After the second stage hydrogenation reaction product is separated by gas and liquid, 65 weight % of the liquid phase is sent to the subsequent separation system, and 35 weight % of the liquid phase is mixed with the maleic anhydride solution, and then heat exchanged to 40°C and enters the first stage hydrogenation reactor.

[0118] The catalysts loaded in the first and second stage hydrogenation reactors are both Ni active component catalysts, and the specific composition can be found in Chinese patent CN202011118431.X-Example 1.

[0119] After two-stage reaction, the total conversion rate of maleic anhydride was 99.0%, and the total selectivity of succinic anhydride was 99.42%.

[0120] Example 2

[0121] use Figure 2 The maleic anhydride hydrogenation reaction method shown in the figure uses hexane as a solvent, the maleic anhydride content in the maleic anhydride solution is 25% by weight, and the maleic anhydride solution is divided into two streams according to the ratio of 40% by weight and 60% by weight, wherein the 40% maleic anhydride solution is mixed with the second-stage hydrogenation reaction product and then enters the first-stage hydrogenation reactor from the bottom of the reactor, and the 60% maleic anhydride solution is mixed with the first-stage hydrogenation reaction product and then enters the second-stage hydrogenation reactor from the bottom of the reactor. The molar ratio of the total amount of hydrogen of the circulating hydrogen and the supplemented fresh hydrogen to the total amount of maleic anhydride in the incoming maleic anhydride solution is 40.

[0122] In the first stage hydrogenation reactor, the space velocity of the first stage hydrogenation reactor is 3h -1 , reaction temperature 40℃, reaction pressure 1.7MPa. The first stage hydrogenation reaction product is cooled to 42℃, and after gas-liquid separation, the gas phase enters the second stage hydrogenation reactor from the bottom of the reactor, and the liquid phase is mixed with another part of the maleic anhydride solution and enters the second stage hydrogenation reactor from the bottom of the reactor. The space velocity of the second stage hydrogenation reactor is 0.8h -1 , reaction temperature 45°C, reaction pressure 1.5MPa. After the second stage hydrogenation reaction product passes through the gas-liquid separator, the gas phase is cooled to 40°C again, and then after passing through the gas-liquid separator, the gas phase and the supplemented fresh hydrogen are sent to the first stage hydrogenation reactor. 50% by weight of the liquid phase of the gas-liquid separator B is sent to the light removal tower, and 50% by weight of the liquid phase is returned to the first stage hydrogenation reactor, mixed with part of the maleic anhydride solution, and then heat exchanged to 40°C and entered the first stage hydrogenation reactor.

[0123] The catalysts loaded in the first and second stage hydrogenation reactors are both Ni active component catalysts, and the specific composition can be found in Chinese patent CN202011120495.3-Example 1.

[0124] After two-stage reaction, the total conversion rate of maleic anhydride was 99.58%, and the total selectivity of succinic anhydride was 99.27%.

[0125] Example 3

[0126] use Figure 1 The maleic anhydride hydrogenation reaction method shown in the figure uses dioxane as solvent, the maleic anhydride content in the maleic anhydride solution is 18% by weight, and the maleic anhydride solution is divided into two streams according to the ratio of 20% by weight and 80% by weight, wherein the maleic anhydride solution of 20% by weight 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, and the maleic anhydride solution of 80% by weight 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 hydrogen of the circulating hydrogen and the supplemented fresh hydrogen to the total amount of maleic anhydride in the incoming maleic anhydride solution is 30.

[0127] In the first stage hydrogenation reactor, the space velocity of the first stage hydrogenation reactor is 1.8h -1 , reaction temperature 40℃, reaction pressure 1.2MPa. The first stage hydrogenation reaction product is cooled to 45℃, and after gas-liquid separation, the gas phase enters the second stage hydrogenation reactor from the bottom of the reactor, and the liquid phase is mixed with another part of the maleic anhydride solution and enters the second stage hydrogenation reactor from the bottom of the reactor. The space velocity of the second stage hydrogenation reactor is 1.2h -1 , reaction temperature 48°C, reaction pressure 1.2MPa. After the second stage hydrogenation reaction product passes through the gas-liquid separator, 1 volume % of the gas phase is extracted and vented, and the remaining gas phase is sent to the first stage hydrogenation reactor together with the supplemented fresh hydrogen. 60 weight % of the liquid phase is sent to the subsequent separation system, and 40 weight % of the liquid phase is returned to the first stage hydrogenation reactor, mixed with the maleic anhydride solution, and then heat exchanged to the reaction temperature and entered the first stage hydrogenation reactor.

[0128] The catalysts loaded in the first and second stage hydrogenation reactors are both Ni active component catalysts, and the specific composition can be found in Chinese patent CN202011118431.X-Example 1.

[0129] After two-stage reaction, the total conversion rate of maleic anhydride is 99.4%, and the total selectivity of succinic anhydride is 99.38%.

[0130] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for preparing succinic anhydride, characterized in that: The method comprises carrying out a two-stage hydrogenation reaction, (1) The maleic anhydride solution is divided into two streams, wherein one stream accounts for 20 to 50% by weight and the other stream accounts for 50 to 80% by weight; One stream is mixed with a portion of the liquid phase material of the second stage hydrogenation reaction cooled to 30-80° C., and then enters the first stage hydrogenation reactor from the bottom liquid phase feed port and / or the lower liquid phase feed port of the first stage hydrogenation reactor to contact with hydrogen for hydrogenation, and the hydrogen enters the first stage hydrogenation reactor from the bottom gas phase inlet and / or the lower gas phase inlet of the first stage hydrogenation reactor; (2) the first stage hydrogenation product is sequentially cooled and gas-liquid separated, the gas phase of the gas-liquid separation is all fed 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 another stream of maleic anhydride solution and then fed into the second stage hydrogenation reactor from the bottom liquid phase feed port and / or the lower liquid phase feed port of the second stage hydrogenation reactor; (3) The second-stage hydrogenation product is subjected to gas-liquid separation to obtain a gas phase and a liquid phase material of the second-stage hydrogenation reaction, and the gas phase obtained by the gas-liquid separation of the second-stage hydrogenation product is cooled at a cooling temperature of 30 to 80° C.; and part or all of the gas phase is used as circulating hydrogen.

2. The method according to claim 1, wherein: The hydrogen feedstock of step (1) is a mixed hydrogen feedstock of circulating hydrogen and supplementary hydrogen; and / or The liquid phase material of the second-stage hydrogenation reaction in step (1) is a material cooled to 40-60°C.

3. The method according to claim 1 or 2, wherein: The method further includes: The gas phase obtained by gas-liquid separation of the second-stage hydrogenation product is cooled and then subjected to a third gas-liquid separation. Part or all of the obtained gas phase is used as the circulating hydrogen and mixed with supplementary hydrogen as the hydrogen feedstock of the first-stage hydrogenation reactor; optionally, the obtained liquid phase is returned to the second-stage gas-liquid separator for gas-liquid separation.

4. The method according to claim 1 or 2, wherein: In step (1), The maleic anhydride solution is a mixture of maleic anhydride and a solvent, wherein the solvent is one or more of acetic anhydride, γ-butyrolactone, dioxane, tetrahydrofuran, aromatic hydrocarbons, ethyl acetate, tetracarbon dibasic esters, ethanol, isopropanol, hexane, cyclohexane, propylene oxide, ketones and ethers; and / or The maleic anhydride concentration of the maleic anhydride solution is 1 to 90 weight %; and / or The molar ratio of the total amount of hydrogen to the total amount of maleic anhydride in the maleic anhydride solution is 5 to 100; and / or The operating conditions of the first stage hydrogenation reactor include: a temperature of 30-100°C; and / or The reaction pressure is 0.1 to 10 MPa; and / or Airspeed: 0.5-5h -1 .

5. The method according to claim 1 or 2, wherein: In step (1), The maleic anhydride concentration of the maleic anhydride solution is 10 to 40% by weight; and / or The molar ratio of the total amount of hydrogen to the total amount of maleic anhydride in the maleic anhydride solution is 10 to 40; and / or The operating conditions of the first stage hydrogenation reactor include: a temperature of 40-80°C; and / or The reaction pressure is 0.5-5 MPa; and / or Airspeed is 1.5-3h -1 .

6. The method according to claim 1 or 2, wherein: In step (2), the operating conditions of the second-stage hydrogenation reactor include: Temperature of 30-100°C; and / or The pressure is 0.1 to 10 MPa; and / or Airspeed: 0.5-5h -1 .

7. The method according to claim 1 or 2, wherein: In step (2), the operating conditions of the second-stage hydrogenation reactor include: The temperature is 40-80°C; and / or The pressure is 0.5-5MPa.

8. The method according to claim 1 or 2, wherein: 20-90% by weight of the liquid phase material from the second-stage hydrogenation reaction is returned to step (1) for use as a raw material, and the rest is sent to a subsequent separation system as a liquid phase product; 0.5-2 volume % of the gas phase material in the second stage hydrogenation reaction is extracted as fuel gas, and the rest is used as the circulating hydrogen.

9. A system for preparing succinic anhydride, characterized in that: The system includes: A first stage hydrogenation reactor, the first stage hydrogenation reactor comprising a lower gas phase inlet and / or a bottom gas phase inlet, a lower liquid phase feed port and / or a bottom liquid phase feed port, a top discharge port and / or an upper discharge port; and a first stage reaction product cooler and a first stage gas-liquid separator sequentially connected in series to the discharge port end of the first stage hydrogenation reactor; A two-stage hydrogenation reactor, the two-stage hydrogenation reactor is connected in series with the one-stage gas-liquid separator, and the two-stage hydrogenation reactor comprises a lower gas phase inlet and / or a bottom gas phase inlet, a lower liquid phase feed port and / or a bottom liquid phase feed port, and a top discharge port and / or an upper discharge port; A second-stage gas-liquid separator, the second-stage gas-liquid separator is connected in series with the discharge port of the second-stage hydrogenation reactor; a second-stage cooler is arranged at the top gas phase outlet of the second-stage gas-liquid separator; The liquid-phase raw material supply pipeline is connected to both the liquid-phase feed port of the first-stage hydrogenation reactor and the liquid-phase feed port of the second-stage hydrogenation reactor.

10. The system according to claim 9, The top gas phase outlet of the first stage gas-liquid separator is connected to the lower gas phase inlet and / or the bottom gas phase inlet of the second stage hydrogenation reactor through a pipeline; and / or The bottom liquid phase outlet of the first-stage gas-liquid separator is connected to the lower liquid phase feed port and / or the bottom liquid phase feed port of the second-stage hydrogenation reactor through a pipeline; and / or The top gas phase outlet of the second-stage gas-liquid separator is connected to the lower gas phase inlet and / or the bottom gas phase inlet of the first-stage hydrogenation reactor through a pipeline; and / or The bottom liquid phase outlet of the second-stage gas-liquid separator is connected to the lower liquid phase feed inlet and / or the bottom liquid phase feed inlet of the first-stage hydrogenation reactor through a pipeline.

11. The system according to claim 9, wherein: A circulating material cooler is arranged on the connecting pipeline between the bottom liquid phase outlet of the second-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.

12. The system according to claim 9, wherein: A second-stage cooler and a third gas-liquid separator are sequentially arranged in series on the top of the second-stage gas-liquid separator, and the gas phase outlet of the third gas-liquid separator is connected to 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 connected to the liquid phase feed port of the second-stage gas-liquid separator.

13. The system according to any one of claims 9 to 12, further comprising: The distributor is used to distribute the liquid raw material into two streams according to needs to supply the first stage hydrogenation reactor and the second stage hydrogenation reactor.

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