A method and system for preparing succinic anhydride

Abstract

The present invention provides a method for preparing succinic anhydride and a system for preparing succinic anhydride. The method of the present invention preferably comprises: (1) maleic anhydride solution is heated to the reaction temperature through a raw material heat exchanger, enters a first-stage hydrogenation reactor from the upper part of the reactor, and the circulating hydrogen and the supplemented fresh hydrogen are mixed and enter from the top of the first-stage reactor; (2) the first-stage hydrogenation product is first cooled to the reaction temperature through a heat exchanger, and then separated from gas and liquid, the gas phase enters the reactor from the top of the second-stage reactor, and the liquid phase enters the second-stage reactor from the upper part of the reactor; (3) after the second-stage hydrogenation reaction product is separated from gas and liquid, the gas phase is circulated to the first-stage reactor for recycling, and the liquid phase is partially sent to the subsequent distillation system, partially circulated, mixed with maleic anhydride solution, and then enters the first-stage hydrogenation reactor from the upper part of the reactor. The method of the present invention has mild reaction operating conditions and low temperature rise of the reaction bed, which is conducive to improving catalyst selectivity and extending catalyst life.

Description

Technical Field

[0001] The invention relates to a method for preparing succinic anhydride and a system for preparing succinic anhydride. Background Art

[0002] Succinic anhydride molecular formula: C4H4O3, can undergo hydrolysis, alcoholysis, esterification, halogenation, acylation and other reactions. It is an important organic synthesis intermediate and is widely used in medicine, food flavoring, pesticides, fine chemicals, alkyd resins and other fields.

[0003] At present, the industrial production of succinic anhydride can be divided into two methods: succinic acid dehydration method and maleic anhydride hydrogenation method. Most succinic anhydride production in the world adopts maleic anhydride hydrogenation method, which is divided into electrochemical reduction method and maleic anhydride direct hydrogenation method. The electrochemical reduction method has the disadvantages of high energy consumption, easy damage of ion membrane, and complicated process operation conditions.

[0004] The direct hydrogenation of maleic anhydride is the method with the highest conversion rate and purity of succinic anhydride. It improves many problems of biological fermentation and succinic acid dehydration in process flow, operating conditions and production cost. However, the hydrogenation of maleic anhydride to generate succinic anhydride is a strong exothermic reaction (AH = -128KJ / mol), and the adiabatic temperature rise of the reaction is large, which easily causes organic matter to polymerize and coke on the catalyst surface, reducing the activity of the catalyst. At the same time, it is easy to cause the catalyst bed temperature to rise sharply, resulting in a temperature runaway phenomenon. Therefore, it is urgent to develop a maleic anhydride hydrogenation reaction process to effectively remove the heat released by the reaction.

[0005] CN101891718A discloses a continuous production process for preparing succinic anhydride by hydrogenating maleic anhydride, wherein maleic anhydride and a solvent are dissolved and reacted in a trickle bed reactor, and the finished succinic anhydride is obtained after gas-liquid separation and the separation solvent is recovered. This method has great advantages over the intermittent stirred tank process and can effectively improve production efficiency, but the reaction pressure of the production process is high (reaction pressure 2.0-8.0MPa), the reaction energy consumption is relatively high, and only a single trickle bed reactor is used, and the heat removal effect is not good, and the strong exothermic effect of the reaction of preparing succinic anhydride by hydrogenating maleic anhydride cannot be effectively solved. Summary of the invention

[0006] In order to solve the problems in the prior art of preparing succinic anhydride by hydrogenation of maleic anhydride as a raw material, the reaction has large exothermicity, is difficult to remove heat, has large production process investment, and high energy consumption, a new method and system for preparing succinic anhydride is proposed. The process and method have the characteristics of easy removal of reaction heat, low investment, and low energy consumption.

[0007] According to a first aspect of the present invention, the present invention provides a method for preparing succinic anhydride, the method comprising performing a two-stage hydrogenation reaction,

[0008] (1) The maleic anhydride solution is heated to the reaction temperature through a raw material heat exchanger and enters a first-stage hydrogenation reactor from a liquid phase feed port at the top of the first-stage hydrogenation reactor to contact with hydrogen for hydrogenation, and the hydrogen enters the first-stage hydrogenation reactor from a gas phase inlet at the top of the first-stage hydrogenation reactor;

[0009] (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 gas phase feed port at the top of the second stage hydrogenation reactor, the liquid phase of the gas-liquid separation is fed into the second stage hydrogenation reactor from the liquid phase feed port at the top of the second stage reactor, reacts with hydrogen to obtain the second stage hydrogenation product, and the gas-liquid separation is performed to obtain gas phase and liquid phase materials;

[0010] (3) Part or all of the gas phase separated from the second-stage hydrogenation product is recycled to the first-stage hydrogenation reactor for use as circulating hydrogen. Optionally, part of the liquid phase material separated from the second-stage hydrogenation product is recycled to the first-stage hydrogenation reactor for use as a raw material.

[0011] According to a second aspect of the present invention, the present invention provides a system for preparing succinic anhydride, the system comprising:

[0012] A raw material heat exchanger, a first stage hydrogenation reactor, a second stage hydrogenation reactor, a second stage gas-liquid separator are sequentially connected in series along the material flow direction, and a first stage reaction product cooler and a first stage gas-liquid separator are sequentially connected in series at the bottom discharge port of the first stage hydrogenation reactor;

[0013] The one-stage hydrogenation reactor comprises a top gas phase feed inlet, an upper liquid phase feed inlet and a bottom discharge port;

[0014] The second-stage hydrogenation reactor is connected in series with the first-stage gas-liquid separator, and the second-stage hydrogenation reactor includes a top gas phase feed port, an upper liquid phase feed port, and a bottom discharge port. The top gas phase feed port is connected to the top gas phase outlet of the first-stage gas-liquid separator through a pipeline, and the upper liquid phase feed port is connected to the bottom liquid phase outlet of the first-stage gas-liquid separator through a pipeline.

[0015] The second-stage gas-liquid separator is connected in series with the bottom discharge port of the second-stage hydrogenation reactor.

[0016] In the method of the present invention, the raw materials are preheated to the reaction temperature, and after the first stage reaction, the gas phase enters the second stage reactor after cooling and gas-liquid separation, which can effectively remove the reaction heat generated by the second stage reaction. The process and method of the present invention have the characteristics of simple flow, low investment, strong applicability, easy control, etc.

[0017] According to a preferred embodiment of the present invention, the method of the present invention comprises:

[0018] (1) The maleic anhydride solution is heated to the reaction temperature through the raw material heat exchanger and enters the first-stage hydrogenation reactor from the upper part of the reactor. The circulating hydrogen and the supplemented fresh hydrogen are mixed and enter from the top of the first-stage reactor;

[0019] (2) The first stage hydrogenation product is first cooled to the reaction temperature by a heat exchanger, and then separated into gas and liquid. The gas phase enters the reactor from the top of the second stage reactor, and the liquid phase enters the second stage reactor from the upper part of the reactor;

[0020] (3) After the gas-liquid separation of the second-stage hydrogenation reaction products, the gas phase is circulated to the first-stage reactor for recycling, and the liquid phase is sent to the subsequent distillation system and partially circulated, mixed with the maleic anhydride solution, and then enters the first-stage hydrogenation reactor from the upper part of the reactor.

[0021] In summary, the method of the present invention has the following characteristics: the present invention adopts a two-stage hydrogenation reactor, the raw material is preheated to the reaction temperature, and part of the material at the outlet of the second-stage reactor is taken out and circulated to the first-stage reactor. After the first-stage reaction, the gas phase and the liquid phase enter the reactor respectively after cooling and gas-liquid separation, so that the method of the present invention can effectively remove the reaction heat generated by the second-stage reaction, the catalyst has a high effective utilization rate, and the investment is low. The method of the present invention has mild reaction operating conditions and low temperature rise of the reaction bed, which is conducive to improving the catalyst selectivity and extending the catalyst life. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of a flow chart according to a preferred embodiment of the present invention.

[0023] Figure 2 It is a schematic diagram of a flow chart according to another preferred embodiment of the present invention.

[0024] Description of Reference Numerals

[0025] 1 raw material heat exchanger; 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 second stage cooler; 8 third gas-liquid separator; 11 maleic anhydride solution; 12 reaction product; 13 supplemental hydrogen. DETAILED DESCRIPTION

[0026] 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.

[0027] The present invention is described in detail below in conjunction with specific drawings and 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.

[0028] The present invention provides a method for preparing succinic anhydride, which comprises performing a two-stage hydrogenation reaction.

[0029] (1) The maleic anhydride solution 11 is heated to the reaction temperature through the raw material heat exchanger 1 and enters the first-stage hydrogenation reactor 2 from the upper liquid phase feed port of the first-stage hydrogenation reactor 2 to contact with hydrogen for hydrogenation, and the hydrogen (including supplementary hydrogen (or fresh hydrogen) 13, or a mixture of supplementary hydrogen and recycled hydrogen) enters the first-stage hydrogenation reactor 2 from the top gas phase inlet of the first-stage hydrogenation reactor 2;

[0030] (2) The first stage hydrogenation product is sequentially cooled and gas-liquid separated, the gas phase of the gas-liquid separation enters the second stage hydrogenation reactor 5 from the gas phase feed port at the top of the second stage hydrogenation reactor 5, and the liquid phase of the gas-liquid separation enters the second stage hydrogenation reactor from the liquid phase feed port at the upper part of the second stage reactor to react with hydrogen to obtain the second stage hydrogenation product, and the gas-liquid separation obtains gas phase and liquid phase materials;

[0031] (3) Part or all of the gas phase obtained by separating the second-stage hydrogenation product is circulated to the first-stage hydrogenation reactor for use as circulating hydrogen. Optionally, part of the liquid phase material obtained by separating the second-stage hydrogenation product is circulated to the first-stage hydrogenation reactor for use as raw material, and the rest enters the subsequent separation system as reaction product 12. The present invention adopts a two-stage hydrogenation reactor, the raw material is preheated to the reaction temperature, and part of the material at the outlet of the second-stage reactor is taken out and circulated to the first-stage reactor. After the first-stage reaction, after cooling and gas-liquid separation, the gas phase and liquid phase enter the reactor respectively, so that the method of the present invention has the advantages of being able to effectively remove the reaction heat generated by the second-stage reaction, high catalyst effective utilization rate, and low investment. The method of the present invention has mild reaction operating conditions and low temperature rise of the reaction bed, which is conducive to improving catalyst selectivity and extending catalyst life.

[0032] According to a preferred embodiment of the present invention, in step (2), the gas phase after gas-liquid separation enters the two-stage hydrogenation reactor from the top, and the liquid phase enters the hydrogenation reactor from the upper part of the two-stage reactor. After the two-stage hydrogenation reaction, maleic anhydride is completely converted into succinic anhydride.

[0033] According to a preferred embodiment of the present invention, in step (2), after the gas-liquid separation of the second-stage hydrogenation reaction product, the gas phase material is first cooled by a heat exchanger, and the cooling temperature is preferably 30-80°C. The cooled material is then subjected to gas-liquid separation, and the gas phase is circulated to the first reactor for recycling, and the liquid phase is returned to the previous gas-liquid separator.

[0034] According to a preferred embodiment of the present invention, in step (2), after the second-stage hydrogenation product is separated into gas and liquid, preferably about 0.5% to 2% by volume 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.

[0035] According to a preferred embodiment of the present invention, in step (2), the liquid phase after gas-liquid separation, preferably 10% to 80% by volume, preferably 30-70% by volume of the liquid reaction product, is sent to a subsequent separation system, and the remaining liquid reaction product is returned to the first hydrogenation reactor for recycling.

[0036] According to a preferred embodiment of the present invention, optionally, in step (1) and step (2), 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.

[0037] According to a preferred embodiment of the present invention, 10-80% by weight of the liquid phase material of the second stage hydrogenation reaction is sent to the subsequent separation system as the reaction product (or liquid phase product), and the rest is returned to step (1) for use as a raw material. This can effectively remove the reaction heat generated by the second stage reaction and improve the effective utilization rate of the catalyst.

[0038] According to a preferred embodiment of the present invention, 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 the reaction heat generated by the second stage reaction and improving the effective utilization rate of the catalyst.

[0039] According to a preferred embodiment of the present invention, in step (2), the operating conditions of the second-stage hydrogenation reactor include: a temperature of 30-120°C, preferably 40-100°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 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 of the catalyst.

[0040] According to a preferred embodiment of the present invention, in step (1), the molar ratio of hydrogen to maleic anhydride is 5 to 100, preferably 10 to 40. In the present invention, the hydrogen in step (1) is fresh hydrogen, or a mixture of fresh hydrogen and recycled hydrogen. The aforementioned hydrogen formula is a formula based on the total amount of hydrogen, and the aforementioned maleic anhydride formula is a formula based on the total amount of maleic anhydride.

[0041] According to a preferred embodiment of the present invention, in step (1), there is no special requirement for the formula of maleic anhydride solution, which is generally a mixture of maleic anhydride and a solvent. There is no special requirement for the type of solvent. According to a preferred embodiment of the present invention, 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, ketone and ether.

[0042] 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, in step (1), the maleic anhydride concentration of the maleic anhydride solution is 1 to 90% by weight, preferably 10 to 40% by weight.

[0043] According to a preferred embodiment of the present invention, in step (1), 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 This can effectively improve the catalyst utilization rate and effectively remove the reaction heat.

[0044] According to a preferred embodiment of the present invention, after the operation of the first stage hydrogenation reactor is completed, the maleic anhydride conversion rate is preferably 30-90%, thereby maximizing the overall conversion rate and selectivity, and the whole hydrogenation reaction can effectively remove heat.

[0045] According to a preferred embodiment of the present invention, the method further comprises:

[0046] 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, and part or all of the obtained gas phase is returned to the first-stage hydrogenation reactor as circulating hydrogen; optionally, the liquid phase obtained by the third gas-liquid separation is returned to the second-stage gas-liquid separator for gas-liquid separation. This can effectively improve the catalyst utilization rate and effectively remove the reaction heat.

[0047] According to a preferred embodiment of the present invention, 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 improve the catalyst utilization rate and effectively remove the reaction heat.

[0048] The present invention mainly focuses on process design. For hydrogenation catalysts such as a first-stage hydrogenation reactor and a second-stage hydrogenation reactor, the catalyst loaded therein is not limited, and any hydrogenation catalyst can be used, such as the catalysts described in Chinese patent applications 202011118431.X and CN202011120495.3.

[0049] The method of the invention has mild reaction operating conditions and low temperature rise of the reaction bed, which is beneficial to improving catalyst selectivity and extending catalyst life.

[0050] According to the present invention, a system for preparing succinic anhydride is provided, the system comprising:

[0051] Along the material flow direction, a raw material heat exchanger 1, a first stage hydrogenation reactor 2, a second stage hydrogenation reactor 5, a second stage gas-liquid separator 6 are sequentially connected in series, and a first stage reaction product cooler 3 and a first stage gas-liquid separator 4 are sequentially connected in series at the bottom discharge port end of the first stage hydrogenation reactor 2;

[0052] The one-stage hydrogenation reactor 2 comprises a top gas phase feed port, an upper liquid phase feed port and a bottom discharge port;

[0053] The second-stage hydrogenation reactor 5 is connected in series with the first-stage gas-liquid separator 4. The second-stage hydrogenation reactor 5 includes a top gas phase feed port, an upper liquid phase feed port, and a bottom discharge port. The top gas phase feed port is connected to the top gas phase outlet of the first-stage gas-liquid separator 4 through a pipeline, and the upper liquid phase feed port is connected to the bottom liquid phase outlet of the first-stage gas-liquid separator 4 through a pipeline.

[0054] The second-stage gas-liquid separator 6 is connected in series with the bottom discharge port of the second-stage hydrogenation reactor 5 .

[0055] According to a preferred embodiment of the present invention, the top gas phase outlet of the second-stage gas-liquid separator 6 is connected to the top gas phase feed inlet of the first-stage hydrogenation reactor 2 through a pipeline.

[0056] According to a preferred embodiment of the present invention, the bottom liquid phase outlet of the second-stage gas-liquid separator 6 is connected to the upper liquid phase feed port of the first-stage hydrogenation reactor 2 through a pipeline.

[0057] According to a preferred embodiment of the present invention, a second-stage cooler 7 and a third gas-liquid separator 8 are sequentially arranged in series at the top gas phase outlet end of the second-stage gas-liquid separator 6, and the gas phase outlet of the third gas-liquid separator 8 is connected to the top gas phase feed port of the first-stage hydrogenation reactor 2 through a pipeline; the bottom liquid phase outlet of the third gas-liquid separator 8 is connected to the liquid phase feed port of the second-stage gas-liquid separator 6.

[0058] According to a preferred embodiment of the present invention, a raw material distributor is arranged in the upper part of the reactor of the first-stage hydrogenation reactor 2 and the second-stage hydrogenation reactor 5 so that the gas-liquid two-phase is mixed more evenly before contacting with the catalyst. The shape and structure of the raw material distributor have special requirements. Existing components that can enhance gas-liquid mixing can be used in the present invention, and the present invention is not described in detail herein.

[0059] The system of the present invention, in addition to the equipment listed in the drawings, may also include pumps, heat exchangers, tanks, compressors and other equipment, which can be configured by those skilled in the art according to needs and professional common sense.

[0060] According to a preferred embodiment of the present invention, the following examples adopt Figure 1 or Figure 2 The process shown is carried out.

[0061] Figure 1 and Figure 2 In the figure, 1 is a raw material heat exchanger; 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 second-stage cooler; 8 is a third gas-liquid separator; 11 is maleic anhydride solution; 12 is a reaction product; and 13 is supplemented with hydrogen.

[0062] The method of the present invention comprises:

[0063] (1) The maleic anhydride solution 11 is heated to the reaction temperature through the raw material heat exchanger 1 and enters the first-stage hydrogenation reactor 2 from the upper liquid phase feed port of the first-stage hydrogenation reactor 2 to contact with hydrogen for hydrogenation, and the hydrogen (including supplementary hydrogen (or fresh hydrogen) 13, or a mixture of supplementary hydrogen and recycled hydrogen) enters the first-stage hydrogenation reactor 2 from the top gas phase inlet of the first-stage hydrogenation reactor 2;

[0064] (2) The first stage hydrogenation product is sequentially cooled in the first stage reaction product cooler 3, and separated into gas and liquid in the first stage gas-liquid separator 4. The gas phase of the gas-liquid separation enters the second stage hydrogenation reactor 5 from the gas phase feed port at the top of the second stage hydrogenation reactor 5, and the liquid phase of the gas-liquid separation enters the second stage hydrogenation reactor from the liquid phase feed port at the upper part of the second stage reactor to react to obtain the second stage hydrogenation product. The gas-liquid separation is carried out in the second stage gas-liquid separator 6 to obtain gas phase and liquid phase materials;

[0065] (3) Optionally, part or all of the gas phase obtained by separating the second-stage hydrogenation product is recycled to the first-stage hydrogenation reactor for use as circulating hydrogen, and part of the liquid phase material obtained by separating the second-stage hydrogenation product is recycled to the first-stage hydrogenation reactor for use as a raw material, and the rest is used as a reaction product 12 to enter the subsequent separation system.

[0066] Or Figure 2As shown, in step (2), after the second-stage hydrogenation reaction product is separated into gas and liquid by the second-stage gas-liquid separator 6, the gas phase material is first cooled by the second-stage cooler 7, and the cooling temperature is preferably 30-80°C. The cooled material then enters the third gas-liquid separator 8 for gas-liquid separation, and the gas phase is circulated to the first-stage hydrogenation reactor for recycling, and the liquid phase returns to the previous gas-liquid separator.

[0067] The maleic anhydride hydrogenation reaction process and method of the present invention have the following characteristics:

[0068] (1) The present invention adopts a two-stage hydrogenation reactor, and extracts part of the material at the outlet of the second-stage reactor and recycles it to the first-stage reactor. Since the material does not contain maleic anhydride, it can effectively dilute the maleic anhydride content in the feed of the first-stage reaction and take away the reaction heat generated by the first-stage reaction.

[0069] (2) In the present invention, after the first-stage reaction, the gas phase is cooled and separated from the liquid phase, and then the gas phase enters the second-stage reactor, thereby effectively removing the reaction heat generated by the second-stage reaction.

[0070] (3) The present invention sets a gas-liquid separation after a first stage reactor, and the gas phase and liquid phase enter the reactor separately, and optionally pass through a gas-liquid phase distribution device, so that the materials entering the reactor are more fully contacted, the gas-liquid-solid contact is good, the catalyst is effectively utilized, and the investment is saved.

[0071] (4) The reaction operating conditions of the present invention are mild, and the reaction can be carried out at about 40°C, which greatly reduces the reaction temperature and reduces the temperature rise of the reaction bed, which is beneficial to improving the catalyst selectivity and extending the catalyst life.

[0072] The following examples use the following catalyst:

[0073] Chinese Patent Application CN202011118431.X-Example 1

[0074] (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;

[0075] (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;

[0076] (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;

[0077] (4) saturating the catalyst precursor with a cerium nitrate solution containing 11.41 g of Ce(NO3)3·6H2O to obtain a base catalyst;

[0078] (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.

[0079] 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.

[0080] Chinese Patent Application CN202011120495.3-Example 1

[0081] (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;

[0082] (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.

[0083] 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.

[0084] Example 1

[0085] 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 continuously introduced into a first-stage hydrogenation reactor, the molar ratio of hydrogen to maleic anhydride is 12, and 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 and liquid phase enter the second stage hydrogenation reactor respectively. The space velocity of the second stage hydrogenation reactor is 1h -1, reaction temperature 45 ° C, reaction pressure 1.3MPa. After the second-stage hydrogenation reaction product passes through the gas-liquid separator, 1% by 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, and 65% by volume of the liquid phase is sent to the subsequent separation system, and 35% by volume of the liquid phase returns to the first-stage hydrogenation reactor, mixed with the maleic anhydride solution, and then heat exchanged to 40 ° C to enter the first-stage hydrogenation reactor. The catalysts loaded in the first and second-stage hydrogenation reactors are Ni active component catalysts, and the specific composition is shown in Chinese patent CN202011118431.X-Example 1.

[0086] The maleic anhydride conversion rate in the first stage hydrogenation reactor is 45%. After two stages of reaction, the total maleic anhydride conversion rate is 99.5%, and the total selectivity of succinic anhydride is 98.9%.

[0087] Example 2

[0088] use Figure 2 The maleic anhydride hydrogenation reaction method shown in the figure uses dioxane as the solvent, the maleic anhydride content in the maleic anhydride solution is 18% by weight, and the maleic anhydride solution is continuously introduced into a first-stage hydrogenation reactor, the molar ratio of hydrogen to maleic anhydride is 30, and the space velocity of the first-stage hydrogenation reactor is 1.8h -1 , reaction temperature 40℃, reaction pressure 1.3MPa. The first stage hydrogenation reaction product is cooled to 45℃, and after gas-liquid separation, the gas phase and liquid phase enter the second stage hydrogenation reactor respectively. The space velocity of the second stage hydrogenation reactor is 0.6h -1 , reaction temperature 48℃, reaction pressure 1.2MPa. After the second stage hydrogenation reaction product passes through the gas-liquid separator, the gas phase is cooled to 40℃ 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, and 50% of the liquid phase is sent to the subsequent separation system, and 50% of the liquid phase returns to the first stage hydrogenation reactor, mixed with the maleic anhydride solution, and then heat exchanged to 40℃ and entered the first stage hydrogenation reactor.

[0089] 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.

[0090] The maleic anhydride conversion rate in the first stage hydrogenation reactor is 40%. After two stages of reaction, the total maleic anhydride conversion rate is 99.8%, and the total selectivity of succinic anhydride is 99.6%.

[0091] 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 heated to the reaction temperature through a raw material heat exchanger and enters a first-stage hydrogenation reactor from a liquid phase feed port at the top of the first-stage hydrogenation reactor to contact with hydrogen for hydrogenation. The hydrogen enters the first-stage hydrogenation reactor from a gas phase inlet at the top of the first-stage hydrogenation reactor; (2) The first stage hydrogenation product is cooled and cooled in sequence, and the gas-liquid separation is performed. The gas phase of the gas-liquid separation enters the second stage hydrogenation reactor from the gas phase feed port at the top of the second stage hydrogenation reactor, and the liquid phase of the gas-liquid separation enters the second stage hydrogenation reactor from the liquid phase feed port at the top of the second stage reactor, reacts with hydrogen to obtain the second stage hydrogenation product, and the gas-liquid separation obtains gas phase and liquid phase materials; (3) Part of the gas phase obtained by separation of the second-stage hydrogenation product is recycled to the first-stage hydrogenation reactor for use as circulating hydrogen, 0.5-2 volume % of the gas phase obtained by separation of the second-stage hydrogenation product is extracted as fuel gas, and the rest is used as the circulating hydrogen; part of the liquid phase material obtained by separation of the second-stage hydrogenation product is recycled to the first-stage hydrogenation reactor for use as raw material, 10-80 volume % of the liquid phase material of the second-stage hydrogenation reaction is sent to the subsequent separation system as liquid phase product, and the rest is returned to step (1) for use as raw material.

2. The preparation method according to claim 1, wherein 30-70 volume % of the liquid phase material in the second-stage hydrogenation reaction is sent to the subsequent separation system as a liquid phase product, and the rest is returned to step (1) for use as a raw material.

3. The preparation method according to claim 1, wherein In step (2), the operating conditions of the second-stage hydrogenation reactor include: The temperature is 30-120°C, and / or the pressure is 0.1-10MPa, and / or the air velocity is 0.5-5h -1 .

4. The preparation method according to claim 3, wherein In step (2), the operating conditions of the second-stage hydrogenation reactor include: The temperature is 40-100°C; and / or the pressure is 0.5-5MPa.

5. The preparation method according to claim 1, wherein In step (1), The molar ratio of hydrogen to maleic anhydride is 5-100; and / or 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 1-90% by weight.

6. The preparation method according to claim 5, wherein: In step (1), The molar ratio of hydrogen to maleic anhydride is 10-40; and / or The maleic anhydride concentration of the maleic anhydride solution is 10-40% by weight.

7. The preparation method according to claim 1, wherein In step (1), The operating conditions of the first stage hydrogenation reactor include: temperature of 30-100°C; and / or reaction pressure of 0.1-10 MPa; and / or space velocity of 0.5-5 h -1 .

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

9. The preparation method according to any one of claims 1 to 8, 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, and part or all of the obtained gas phase is returned to the first-stage hydrogenation reactor as circulating hydrogen; optionally, the liquid phase obtained by the third gas-liquid separation is returned to the second-stage gas-liquid separator for gas-liquid separation.

10. The preparation method according to claim 9, wherein: The temperature at which the gas phase obtained by gas-liquid separation of the second-stage hydrogenation product is cooled is 30~80℃.

11. A system for preparing succinic anhydride, characterized in that: The system includes: A raw material heat exchanger (1), a first stage hydrogenation reactor (2), a second stage hydrogenation reactor (5), a second stage gas-liquid separator (6) are sequentially connected in series along the material flow direction, and a first stage reaction product cooler (3) and a first stage gas-liquid separator (4) are sequentially connected in series at the bottom discharge port of the first stage hydrogenation reactor (2); The first stage hydrogenation reactor (2) comprises a top gas phase feed inlet, an upper liquid phase feed inlet and a bottom discharge port; The second-stage hydrogenation reactor (5) is connected in series with the first-stage gas-liquid separator (4), and the second-stage hydrogenation reactor (5) comprises a top gas phase feed port, an upper liquid phase feed port and a bottom discharge port, the top gas phase feed port is connected to the top gas phase outlet of the first-stage gas-liquid separator (4) through a pipeline, and the upper liquid phase feed port is connected to the bottom liquid phase outlet of the first-stage gas-liquid separator (4) through a pipeline; The second-stage gas-liquid separator (6) is connected in series with the bottom discharge port of the second-stage hydrogenation reactor (5).

12. The system according to claim 11, The top gas phase outlet of the second-stage gas-liquid separator (6) is connected to the top gas phase feed inlet of the first-stage hydrogenation reactor (2) through a pipeline; and / or The bottom liquid phase outlet of the second-stage gas-liquid separator (6) is connected to the upper liquid phase feed inlet of the first-stage hydrogenation reactor (2) through a pipeline.

13. The system according to claim 11, wherein: A second-stage cooler (7) and a third gas-liquid separator (8) are sequentially arranged in series at the top gas phase outlet of the second-stage gas-liquid separator (6); the gas phase outlet of the third gas-liquid separator (8) is connected to the top gas phase feed port of the first-stage hydrogenation reactor (2) through a pipeline; and the bottom liquid phase outlet of the third gas-liquid separator (8) is connected to the liquid phase feed port of the second-stage gas-liquid separator (6).

Images