Method for preparing gamma-butyrolactone through selective hydrogenation of succinic anhydride

Abstract

The invention discloses a method for preparing gamma-butyrolactone through selective hydrogenation of succinic anhydride, which comprises the following steps: preparing a raw material succinic anhydride solution by taking gamma-butyrolactone as a solvent, feeding the raw material into a heat exchanger for heat exchange, then mixing with hydrogen, preheating, and feeding into a reactor for catalytic hydrogenation reaction; a high-temperature material flow obtained after the reaction is fed into a heat exchanger to be cooled by the raw materials and partially condensed, then primary gas-liquid separation is performed to obtain a gas-phase material and a liquid-phase material, and the liquid-phase material is reused as a solvent; further cooling the gas-phase material in a cooler to obtain a gas-liquid mixture, carrying out secondary gas-liquid separation to obtain hydrogen and a liquid-phase crude product, feeding the liquid-phase crude product into a product tower, and carrying out normal-pressure or reduced-pressure rectification to obtain a gamma-butyrolactone product at the tower bottom. The product GBL is used as the reaction solvent, introduction of substances outside the system is avoided, the required reaction solvent and unreacted raw materials are directly recycled by reasonably controlling the cooling temperature, the technological process is simple, and the separation energy consumption is greatly reduced.

Description

Technical Field

[0001] The invention belongs to the field of chemical intermediates, and specifically relates to a method for preparing gamma-butyrolactone by selective hydrogenation of succinic anhydride. Background Art

[0002] γ-Butyrolactone (GBL) is an important fine chemical intermediate. Due to its unique physical and chemical properties, it can participate in a variety of chemical reactions. GBL has a very high solubility and is widely used in industrial production as a strong environmentally friendly solvent: in the petrochemical field, GBL can be used as a plasticizer, antioxidant, dispersant, coagulant, absorbent and extractant; in the pharmaceutical field, GBL can be used to produce anesthetics, X-ray contrast agents, sedatives, and ciprofloxacin, interferon, vitamin B1 and other medicines; in the agricultural field, GBL can be used to produce plant growth regulators, herbicides and pesticides; in the textile field, GBL and its downstream products can be used to produce fabric dyes, textile solvents, coagulants and plasticizers; in addition, in the production of lithium batteries, GBL can be used as a special non-aqueous solvent for lithium ions.

[0003] There are many synthetic routes for GBL, including 1,4-butanediol (BDO) dehydrogenation, furfural decarbonylation oxidation, maleic anhydride esterification hydrogenation, and maleic anhydride direct hydrogenation. The BDO dehydrogenation method is to prepare GBL by catalytic dehydrogenation of BDO. It was developed on the basis of the acetylene aldehyde method (acetylene and formaldehyde) to produce BDO. However, due to environmental pollution and high energy consumption, my country has restricted the development of coal-based BDO processes, so the BDO reverse dehydrogenation process for producing GBL is no longer suitable. The furfural decarbonylation oxidation method produces GBL by oxidizing furan generated by catalytic decarbonylation of bio-based furfural. Due to the complex process and high production cost, it is no longer used in industrial production. The maleic anhydride esterification hydrogenation method is to prepare maleic acid diesters by esterification of maleic anhydride with excess monohydric alkanol (commonly methanol or ethanol), and then dehydration and ring closure to obtain GBL. Due to the long process route and the large number of equipment required, it leads to large investment, difficult control, and high production cost.

[0004] Direct hydrogenation of maleic anhydride is the main method of industrial production at present, and its reaction equation is as follows:

[0005] C4H2O3+3H2=C4H6O2+H2OΔH r =-210.02 kJ / mol

[0006] Among them, the gas phase hydrogenation method adopts a low-pressure gas phase one-step hydrogenation process, which simplifies the process flow and saves equipment investment. Currently, many domestic companies have adopted this method for production, but the process equipment is small in scale, the catalyst has a short service life, and the GBL selectivity is low, which affects the economic benefits of the equipment.

[0007] Maleic anhydride liquid phase hydrogenation method usually uses a kettle reactor, and maleic anhydride solution is hydrogenated under the action of a catalyst to obtain GBL. This method has high GBL selectivity, but the reaction pressure is high, the catalyst regeneration is difficult, and liquid maleic anhydride and other organic acids (anhydrides) seriously corrode the equipment, so it has not yet been widely used.

[0008] In addition, there are also reports on the preparation of GBL by coupling maleic anhydride hydrogenation and BDO dehydrogenation. For example, CN1109027C and CN1255214C use maleic anhydride and BDO as raw materials, and couple maleic anhydride hydrogenation and BDO dehydrogenation to prepare GBL; CN103880787A prepares GBL and acetone by coupling maleic anhydride hydrogenation and isopropanol dehydrogenation. However, this method has problems such as complex production process, limited raw material ratio, poor production flexibility, and low economic benefits of co-products, and has not been widely used. Summary of the invention

[0009] The purpose of the present invention is to overcome the deficiencies in the prior art. At present, the highly selective hydrogenation of maleic anhydride to prepare succinic anhydride has been industrialized. The present invention proposes a new process route for preparing GBL by selective hydrogenation of succinic anhydride as a raw material, and the reaction equation is as follows:

[0010] C4H4O3+2H2=C4H6O2+H2OΔH r =-84.22 kJ / mol

[0011] Obviously, the reaction heat of hydrogenation of succinic anhydride to prepare γ-butyrolactone is less than 50% of that of hydrogenation of maleic anhydride to prepare γ-butyrolactone. Therefore, the temperature gradient in the catalyst particles can be reduced, which is convenient for removing the reaction heat, and the reaction process conditions can be independently adjusted to achieve the best reaction effect, which are all conducive to improving the selectivity of γ-butyrolactone.

[0012] On this basis, the present invention provides a method for preparing γ-butyrolactone by selective hydrogenation of succinic anhydride with high yield, low energy consumption and short process. The technical scheme adopted is as follows:

[0013] A method for preparing gamma-butyrolactone by selective hydrogenation of succinic anhydride comprises the following steps:

[0014] (a) Succinic anhydride and a solvent γ-butyrolactone are mixed to obtain a raw material succinic anhydride solution; the raw material is sent to a heat exchanger for heat exchange, then mixed with hydrogen, and after preheating, sent to a reactor for catalytic hydrogenation reaction;

[0015] (b) the high-temperature stream obtained after the reaction is sent to a heat exchanger to be cooled and partially condensed by the raw material, and then subjected to a primary gas-liquid separation to obtain a gas phase material and a liquid phase material, the liquid phase material being reused as a solvent in step (a), wherein the liquid phase material is a required amount of γ-butyrolactone and a small amount of unreacted succinic anhydride for the solvent; the gas phase material is further cooled in a cooler to obtain a gas-liquid mixture;

[0016] (c) The gas-liquid mixture obtained in step (b) is subjected to secondary gas-liquid separation to obtain hydrogen and a crude liquid product. A small portion of the separated hydrogen is released and the rest is recycled to step (a). The crude liquid product is fed into a product tower;

[0017] (d) After the crude liquid product is distilled under normal pressure or vacuum, water generated by the reaction and a small amount of tetrahydrofuran light component produced as a by-product are taken out from the top of the product tower, and a γ-butyrolactone product with a purity of ≥99.5% is obtained at the bottom of the tower.

[0018] The present invention is further configured such that, during the heat exchange process between the high-temperature logistics after the reaction in step (b) and the raw material, the temperature of the reaction logistics after heat exchange cooling is required to be 150-210° C. by controlling the amount of heat exchange material, so as to ensure that the flow rate of γ-butyrolactone in the liquid phase material after gas-liquid separation meets the amount of solvent required for raw material preparation; preferably, the temperature of the reaction logistics after heat exchange cooling is 170-190° C.

[0019] The present invention is further configured that in the catalytic hydrogenation reaction of step (a), the catalyst used is a supported CuNiZnCe / SiO2-Si catalyst, whose weight composition is 15.0-45.0% CuO, 0.5-7.5% NiO, 5.0-15.0% ZnO, 0.5-7.5% CeO2, 30.0-60.0% SiO2 and 5.0-25.0% Si;

[0020] Preferably, the weight composition of the supported CuNiZnCe / SiO2-Si catalyst is 20.0-40.0% CuO, 1.0-5.0% NiO, 7.5-12.5% ​​ZnO, 1.0-5.0% CeO2, 40-50% SiO2 and 5-15% Si;

[0021] The catalyst is a powder catalyst, or a clover or round strip granular catalyst with a diameter of 2.0 to 4.0 mm and a length of 2.0 to 5.0 mm.

[0022] The present invention is further configured such that in the catalytic hydrogenation reaction of step (a), the reactor used is a slurry bed or a fixed bed reactor; the slurry bed reactor is a slurry bed or a suspended bed reactor, and the fixed bed reactor is an adiabatic fixed bed or an isothermal fixed bed reactor.

[0023] The present invention is further configured that, in step (a), when the reactor is a slurry bed, the process conditions for the catalytic hydrogenation reaction are:

[0024] The concentration of the raw material succinic anhydride solution is 10-50wt%, and the feed weight hourly space velocity is 0.20-2.00h -1, reaction temperature 170-250°C, reaction pressure 2.0-5.0MPa, hydrogen anhydride molar ratio 10-100;

[0025] Preferably, the concentration of the raw material succinic anhydride solution is 15-40wt%, and the feed weight hourly space velocity is 0.25-1.50h -1 , reaction temperature 180-240°C, reaction pressure 2.5-4.5MPa, hydrogen anhydride molar ratio 15-75;

[0026] More preferably, the concentration of the raw material succinic anhydride solution is 20-35 wt%, and the feed weight hourly space velocity is 0.5-1.0 h -1 , reaction temperature 190-230°C, reaction pressure 3.0-4.0MPa, hydrogen anhydride molar ratio 20-50.

[0027] The present invention is further configured that, in step (a), when the reactor is a fixed bed reactor, the process conditions for the catalytic hydrogenation reaction are:

[0028] The concentration of the raw material succinic anhydride solution is 10-50wt%, and the feed weight hourly space velocity is 0.1-1.5h -1 , reaction temperature 190-250°C, reaction pressure 1.5-5.0MPa, hydrogen anhydride molar ratio 10-100;

[0029] Preferably, the concentration of the raw material succinic anhydride solution is 20-340wt%, and the feed weight hourly space velocity is 0.20-1.00h -1 , reaction temperature 200-245°C, reaction pressure 2.5-4.5MPa, hydrogen anhydride molar ratio 20-75;

[0030] More preferably, the concentration of the raw material succinic anhydride solution is 20-40 wt%, and the feed weight hourly space velocity is 0.25-1.00 h -1 , reaction temperature 210-240°C, reaction pressure 3.0-4.0MPa, hydrogen anhydride molar ratio 25-50.

[0031] The present invention is further configured such that the cooling temperature of the cooler in step (c) is 5 to 60°C and the pressure is 0.8 to 5.5 MPa to ensure that the molar concentration of the circulating hydrogen after the cooled material is subjected to secondary gas-liquid separation is greater than 99%; preferably, the cooling temperature of the cooler is 10 to 50°C and the pressure is 1.0 to 5.0 MPa.

[0032] The present invention is further configured that the operating conditions of the product in step (d) are: pressure 0.01-0.1 MPa, tower top temperature 35-95°C, tower bottom temperature 125-205°C, reflux ratio 0.1-5, and theoretical plate number 8-50.

[0033] The present invention is further configured that the preparation process of the catalyst is as follows:

[0034] S1. According to the stoichiometric ratio, the precursor compounds of copper, nickel, zinc and cerium are added to the aqueous solution of ethanolamine (the ratio of ethanolamine to the total molar amount of copper, nickel, zinc and cerium is 0.5-2.0:1.0), and then 20-30wt% ammonia water is added, and the mixture is stirred and dissolved at 40-90°C, and the pH value of the solution is adjusted to 9-12 to obtain a mixed solution of the corresponding metal ion ammonia complex;

[0035] S2. According to the stoichiometric ratio, add silica sol and nano silicon powder (particle size 50-150nm) to the above-mentioned mixed solution of amino complex, stir and reflux for aging at 40-90℃ for 5-20h, then dry at 110-150℃ for 5-20h, crush the cake, and then roast at 300-500℃ for 3-8h to obtain a powder catalyst with a particle size of 0.1-2μm; extrude the powder catalyst into strips or sheets, and roast at 300-500℃ for 3-8h to obtain a clover or cylindrical particle catalyst with a diameter of 2.0-4.0mm and a length of 2.0-5.0mm.

[0036] The present invention is further configured that the reduction activation conditions of the catalyst are: reduction temperature 200-450°C, hydrogen pressure 0.1-5.0MPa, hydrogen space velocity 10-100h -1 and reduction time of 2 to 20 hours; preferably reduction temperature of 250 to 400°C, hydrogen pressure of 0.5 to 1.0 MPa, hydrogen space velocity of 20 to 50 h -1 And the reduction time is 5 to 10 hours.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] (1) The present invention uses succinic anhydride as a raw material, adopts a supported metal catalyst and a slurry bed or fixed bed reaction new process, and prepares γ-butyrolactone by one-step high-activity and high-selectivity hydrogenation, thereby shortening the reaction process of maleic anhydride esterification hydrogenation in the prior art or avoiding the problem of low selectivity of maleic anhydride direct hydrogenation in the prior art.

[0039] (2) In the present invention, during the hydrogenation reaction of succinic anhydride, the target product γ-butyrolactone is used as the reaction solvent, thereby avoiding the introduction and separation of substances outside the system. In addition, the solubility of succinic anhydride in γ-butyrolactone is large, which is beneficial to increasing the feed concentration and reducing the use of solvents, thereby simplifying the process and reducing energy consumption.

[0040] (3) The present invention is cleverly designed to achieve the circulation of solvent and unreacted raw materials by simple condensation and gas-liquid separation, greatly reducing the energy consumption for separation of solvent and unreacted raw materials; qualified γ-butyrolactone products can be obtained by using one distillation tower, which greatly simplifies the separation process.

[0041] The above effects are achieved because the boiling point of the solvent γ-butyrolactone is between the light components (water, byproduct tetrahydrofuran) and the raw material succinic anhydride, and has a sufficient boiling point difference with both. In this way, when the hydrogenation reaction stream is partially condensed, the unreacted raw material succinic anhydride can be condensed together with the γ-butyrolactone because the boiling point is higher than that of γ-butyrolactone, and circulated back to the reactor to continue the reaction. At the same time, because the light components and γ-butyrolactone have a sufficient boiling point difference, they will not condense in large quantities, which enables the solvent condensation cycle to be realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a process flow for preparing γ-butyrolactone by selective hydrogenation of succinic anhydride. DETAILED DESCRIPTION

[0043] The technical solution of the present invention is described clearly and in detail by specific embodiments below. It should be understood that the following embodiments are only part of the embodiments of the present invention, and other embodiments obtained by those skilled in the art without creative work are all within the protection scope of the present invention.

[0044] The following examples 1 to 11 are all based on Figure 1 The process flow shown is for selective hydrogenation of succinic anhydride to produce γ-butyrolactone.

[0045] Example 1

[0046] (1) Preparation of 28%CuO-1%NiO-8%ZnO-3%CeO2 / 50%SiO2-10%Si catalyst:

[0047] According to the stoichiometric ratio, the precursor compounds of copper, nickel, zinc and cerium are added to the aqueous solution of ethanolamine (the ratio of ethanolamine to the total molar amount of copper, nickel, zinc and cerium is 1.0:1.0), and then 25wt% ammonia water is added, stirred and dissolved at 50°C, and the pH value of the solution is adjusted to 11 to obtain a mixed solution of ammine complexes of the corresponding metal ions; according to the stoichiometric ratio, silica sol and nano-silicon powder (particle size 80nm) are added to the above-mentioned mixed solution of ammine complexes, stirred and refluxed at 70°C for aging for 10h, and then dried at 120°C for 10h, the cake is crushed, and then calcined at 400°C for 5h to obtain a CuNiZnCe / SiO2-Si powder catalyst with a particle size of 1.0μm.

[0048] (2) Reduction activation of catalyst:

[0049] The catalyst prepared in step (1) was placed in a tubular furnace and hydrogen was introduced for reduction activation. After the reduction was completed, the catalyst was transferred to a reactor for hydrogenation reaction. The reduction conditions were: temperature 400°C, pressure 3.5 MPa, hydrogen volume space velocity 30 h -1 and restoration time 5.0h.

[0050] (3) Slurry bed hydrogenation reaction:

[0051] A 20 wt% succinic anhydride-containing gamma-butyrolactone (GBL) solution was mixed with hydrogen and preheated to the reaction temperature, and then fed into a slurry bed reactor for succinic anhydride hydrogenation reaction. The hydrogenation process conditions and reaction results are shown in Table 2.

[0052] (4) Separation and purification of reaction products:

[0053] The molar flow rate of succinic anhydride in the hydrogenation reaction feed is 1.000 kmol / h, and the molar flow rate of GBL is 4.651 kmol / h. In the high-temperature logistics at the outlet of the slurry bed reactor: the molar flow rate of GBL is 5.621 kmol / h, the molar flow rate of tetrahydrofuran is 0.015 kmol / h, the molar flow rate of n-butanol is 0.007 kmol / h, the molar flow rate of water is 1.013 kmol / h, the molar flow rate of hydrogen is 27.965 mol / h, and the molar flow rate of heavy components (containing succinic anhydride and succinic acid) is 0.008 kmol / h.

[0054] The gas-liquid mixture formed after the high-temperature logistics is cooled by the heat exchanger enters the primary gas-liquid separator for separation. The liquid phase material after separation is directly circulated to the raw material preparation tank as a reaction solvent. The liquid phase material is the required amount of γ-butyrolactone and a small amount of unreacted succinic anhydride for the reaction solvent; the separated gas phase mixture enters the cooler to be further cooled to 10°C, and then enters the secondary gas-liquid separator for gas-liquid separation.

[0055] Except for a small part of the separated hydrogen being released, the rest is circulated back to the reactor to continue the reaction, and the circulating hydrogen concentration is greater than 99.93%; among the separated liquid crude product: the molar flow rate of GBL is 0.970 kmol / h, the molar flow rate of tetrahydrofuran is 0.015 kmol / h, the molar flow rate of n-butanol is 0.007 kmol / h, and the molar flow rate of water is 1.013 kmol / h.

[0056] The crude liquid product obtained by separation enters the product tower, and the water generated by the reaction and a small amount of by-products tetrahydrofuran and n-butanol are taken out from the top of the tower. 0.969 kmol / h of GBL product is obtained at the bottom of the tower. The specific product tower operating conditions, separation and refining effects, and product separation and refining energy consumption are shown in Table 3.

[0057] Embodiments 2 to 5

[0058] Examples 2 to 5 are basically the same as Example 1, and the hydrogenation reactors are all slurry beds. The difference is that the catalyst composition, the specific form of the hydrogenation reactor, the hydrogenation reaction conditions and the product tower operating conditions are different. The specific parameters and condition settings are shown in Tables 1 to 3, and the hydrogenation reaction results, product distillation separation results and product separation and refining energy consumption are shown in Tables 2 to 3.

[0059] Example 6

[0060] (1) Preparation of catalyst: 35% CuO-2% NiO-10% ZnO-5% CeO2 / 40% SiO2-8% Si catalyst powder was prepared according to the same catalyst preparation process as in Example 1, and then extruded into strips and calcined at 450°C for 5.0h to obtain round strip particle catalyst with a diameter of 2.0mm and a length of 3.0-5.00mm.

[0061] (2) Catalyst reduction activation: The granular catalyst was loaded into an isothermal fixed-bed reactor and hydrogen was introduced at a temperature of 400°C, a pressure of 3.5 MPa and a hydrogen volume space velocity of 50 h -1 In situ reduction activation was performed.

[0062] (3) Fixed bed hydrogenation reaction: After the catalyst reduction is completed, the temperature, pressure and hydrogen flow rate are adjusted, the γ-butyrolactone (GBL) solution of succinic anhydride is mixed with hydrogen, preheated to the reaction temperature and then sent into an isothermal fixed bed reactor for hydrogenation of succinic anhydride. The hydrogenation reaction process conditions and reaction results are shown in Table 2.

[0063] (4) Separation and purification of reaction products:

[0064] The high-temperature logistics after the reaction is cooled by the heat exchanger to form a gas-liquid mixture, which enters the primary gas-liquid separator for separation. The separated liquid material is directly circulated to the raw material preparation tank as a reaction solvent. The liquid material is the required amount of γ-butyrolactone and a small amount of unreacted succinic anhydride for the reaction solvent; the separated gas mixture enters the cooler for further cooling, and then enters the secondary gas-liquid separator for gas-liquid separation.

[0065] Except for a small part of the separated hydrogen being released, the rest is recycled back to the reactor to continue the reaction; the separated liquid crude product enters the product tower, the water generated by the reaction and a small amount of by-products tetrahydrofuran and n-butanol are taken out from the top of the tower, and the GBL product is obtained at the bottom of the tower. The specific product tower operating conditions, separation and refining effects, and product separation and refining energy consumption are shown in Table 3.

[0066] Embodiment 7-11

[0067] Examples 7-11 are basically the same as Example 6, and the hydrogenation reactors are all fixed bed reactors. The difference is that the catalyst composition, the specific form of the hydrogenation reactor, the hydrogenation reaction conditions and the product tower operating conditions are different. The specific parameters and condition settings are shown in Tables 1 to 3, and the hydrogenation reaction results, product distillation separation results and product separation and refining energy consumption are shown in Tables 2 to 3.

[0068] Comparative Example 1

[0069] Comparative Example 1 is substantially the same as Example 1, except that, in the separation and purification of the reaction product in step (4), the liquid phase material after the primary gas-liquid separator (i.e., the amount of γ-butyrolactone required for the reaction solvent and a small amount of unreacted succinic anhydride) is not recycled back to the raw material preparation tank, but is mixed with the liquid phase material after the secondary gas-liquid separation and then enters the subsequent separation section together. The light removal tower and the heavy removal tower are sequentially arranged in the separation section. Specifically:

[0070] The liquid material is sent to the light-removing tower and subjected to vacuum distillation. Water and a small amount of by-products, tetrahydrofuran and n-butanol, are removed from the top of the tower. The bottom material is sent to the heavy-removing tower and subjected to vacuum distillation. The product γ-butyrolactone is taken out from the top of the tower. The heavy components containing succinic anhydride and succinic acid at the bottom of the tower are recycled to the raw material preparation tank.

[0071] In the liquid phase material entering the separation section, the molar flow rate of γ-butyrolactone is 5.621 kmol / h, the molar flow rate of tetrahydrofuran is 0.014 kmol / h, the molar flow rate of n-butanol is 0.007 kmol / h, the molar flow rate of water is 1.012 kmol / h, and the molar flow rate of the heavy component is 0.008 kmol / h.

[0072] The water and a small amount of by-products tetrahydrofuran and n-butanol generated by the reaction are taken out from the top of the light tower, and γ-butyrolactone and heavy components are taken out from the bottom of the tower. 5.511 kmol / h of γ-butyrolactone product is taken out from the top of the heavy tower, of which 4.651 kmol / h of γ-butyrolactone is recycled as solvent and the rest is used as product; the heavy components at the bottom of the tower are recycled to the raw material preparation tank. The specific operating conditions, separation and refining effects, and product separation and refining energy consumption of the light tower and heavy tower are shown in Table 3.

[0073] Table 1 CuNiZnCe / SiO2-Si catalyst composition, catalyst morphology and reactor form used in Examples 1 to 11 and Comparative Example 1

[0074]

[0075] Table 2 Hydrogenation reaction process conditions and reaction results of Examples 1 to 11

[0076]

[0077]

[0078] The results in Table 2 show that the preparation of γ-butyrolactone (GBL) by hydrogenation of succinic anhydride (SAA) according to the present invention is carried out by using a CuNiZnCe / SiO2-Si supported catalyst and using the target product GBL as solvent, when the feed succinic anhydride solution concentration is 20-40wt% and the feed liquid hourly space velocity is 0.25-1.00h -1Under the reaction process conditions of reaction temperature of 190-240°C, reaction pressure of 3.0-4.0MPa and hydrogen anhydride molar ratio of 20-50, whether adopting a slurry bed (slurry bed or suspended bed reactor) reaction process or a fixed bed (isothermal or adiabatic fixed bed reactor) reaction process, good reaction results can be obtained, the succinic anhydride conversion rate is 97.58-99.81%, and the GBL selectivity is 97.64-99.61%.

[0079] Table 3 Distillation operating conditions and results used in Examples 1 to 11 and Comparative Example 1

[0080]

[0081] As can be seen from the results in Table 3, the present invention controls the heat exchange temperature between the high-temperature logistics after the hydrogenation reaction and the feed, thereby controlling the amount of partially condensed liquid phase materials (GBL and unconverted succinic anhydride and its trace hydrolysis product succinic acid) to meet the solvent amount for preparing the raw material succinic anhydride solution, and directly recycles this part of the material back to the raw material preparation tank, thereby reducing the amount of material entering the product separation and refining section, and can greatly reduce the separation energy consumption of the solvent and the unreacted raw material. Qualified γ-butyrolactone products can be obtained by using a distillation tower, which greatly simplifies the separation process and greatly reduces the total separation energy consumption. When the product quality reaches the superior product (GBL content ≥99.70%), the total separation energy consumption of Examples 1 to 11 is 25 to 49 kW, which is much lower than the total separation energy consumption of Comparative Example 1, 186 kW.

[0082] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing γ-butyrolactone by selective hydrogenation of succinic anhydride, characterized in that: The following steps are involved: (a) Succinic anhydride and a solvent γ-butyrolactone are mixed to obtain a raw material succinic anhydride solution; the raw material is sent to a heat exchanger for heat exchange, then mixed with hydrogen, and after preheating, sent to a reactor for catalytic hydrogenation reaction; (b) the high-temperature stream obtained after the reaction is sent to a heat exchanger to be cooled and partially condensed by the raw material, and then subjected to a primary gas-liquid separation to obtain a gas phase material and a liquid phase material, and the liquid phase material is reused as a solvent in step (a); the gas phase material enters a cooler for further cooling to obtain a gas-liquid mixture; (c) The gas-liquid mixture obtained in step (b) is subjected to secondary gas-liquid separation to obtain hydrogen and a crude liquid product. The separated hydrogen is recycled to step (a), and the crude liquid product is fed to a product tower; (d) The crude liquid product fed into the product tower is distilled under normal pressure or vacuum distillation, water and by-product tetrahydrofuran are extracted from the top of the tower, and the γ-butyrolactone product is obtained at the bottom of the tower.

2. The method for preparing γ-butyrolactone by selective hydrogenation of succinic anhydride according to claim 1, characterized in that: In step (b), during the heat exchange between the high-temperature logistics after the reaction and the raw materials, the temperature of the reaction logistics after heat exchange cooling is 150-210°C by controlling the amount of heat exchange material; preferably, the temperature of the reaction logistics after heat exchange cooling is 170-190°C.

3. The method for preparing γ-butyrolactone by selective hydrogenation of succinic anhydride according to claim 1, characterized in that: In the catalytic hydrogenation reaction of step (a), the catalyst used is a supported CuNiZnCe / SiO2-Si catalyst, which has a weight composition of 15.0-45.0% CuO, 0.5-7.5% NiO, 5.0-15.0% ZnO, 0.5-7.5% CeO2, 30.0-60.0% SiO2 and 5.0-25.0% Si; Preferably, the weight composition of the supported CuNiZnCe / SiO2-Si catalyst is 20.0-40.0% CuO, 1.0-5.0% NiO, 7.5-12.5% ​​ZnO, 1.0-5.0% CeO2, 40-50% SiO2 and 5-15% Si; The catalyst is a powder catalyst, or a clover or round strip granular catalyst with a diameter of 2.0 to 4.0 mm and a length of 2.0 to 5.0 mm.

4. The method for preparing γ-butyrolactone by selective hydrogenation of succinic anhydride according to claim 1, characterized in that: In step (a), the reactor used for the catalytic hydrogenation reaction is a slurry bed or a fixed bed reactor; the slurry bed is a slurry bed or a suspended bed, and the fixed bed is an adiabatic fixed bed or an isothermal fixed bed.

5. The method for preparing γ-butyrolactone by selective hydrogenation of succinic anhydride according to claim 1, characterized in that: In step (a), when the reactor is a slurry bed, the process conditions for the catalytic hydrogenation reaction are: The concentration of the raw material succinic anhydride solution is 10-50wt%, and the feed weight hourly space velocity is 0.10-2.00h -1 , reaction temperature 170-250°C, reaction pressure 2.0-5.0MPa, hydrogen anhydride molar ratio 5-100; Preferably, the concentration of the raw material succinic anhydride solution is 15-40wt%, and the feed weight hourly space velocity is 0.25-1.50h -1 , reaction temperature 180-240°C, reaction pressure 2.5-4.5MPa, hydrogen anhydride molar ratio 10-75.

6. The method for preparing γ-butyrolactone by selective hydrogenation of succinic anhydride according to claim 1, characterized in that: In step (a), when the reactor is a slurry bed, the process conditions for the catalytic hydrogenation reaction are: The concentration of the raw material succinic anhydride solution is 20-35wt%, and the feed weight hourly space velocity is 0.5-1.0h -1 , reaction temperature 190-230°C, reaction pressure 3.0-4.0MPa, hydrogen anhydride molar ratio 20-50.

7. The method for preparing γ-butyrolactone by selective hydrogenation of succinic anhydride according to claim 1, characterized in that: In step (a), when the reactor is a fixed bed reactor, the process conditions for the catalytic hydrogenation reaction are: The concentration of the raw material succinic anhydride solution is 10-50wt%, and the feed weight hourly space velocity is 0.1-1.5h -1 , reaction temperature 190-250°C, reaction pressure 1.5-5.0MPa, hydrogen anhydride molar ratio 10-100; Preferably, the concentration of the raw material succinic anhydride solution is 20-40wt%, and the feed weight hourly space velocity is 0.20-1.00h -1 , reaction temperature 200-245°C, reaction pressure 2.5-4.5MPa, hydrogen anhydride molar ratio 20-75.

8. The method for preparing γ-butyrolactone by selective hydrogenation of succinic anhydride according to claim 1, characterized in that: In step (a), when the reactor is a fixed bed reactor, the process conditions for the catalytic hydrogenation reaction are: The concentration of the raw material succinic anhydride solution is 20-40wt%, and the feed weight hourly space velocity is 0.25-1.00h -1 , reaction temperature 210-240°C, reaction pressure 3.0-4.0MPa, hydrogen anhydride molar ratio 25-50.

9. The method for preparing γ-butyrolactone by selective hydrogenation of succinic anhydride according to claim 1, characterized in that: In step (c), the cooling temperature of the cooler is 5-60°C and the pressure is 0.8-5.5MPa to ensure that the molar concentration of the circulating hydrogen after the cooled material is separated by secondary gas-liquid separation is greater than 99%; preferably, the cooling temperature of the cooler is 10-50°C and the pressure is 1.0-5.0MPa.

10. The method for preparing γ-butyrolactone by selective hydrogenation of succinic anhydride according to claim 1, characterized in that: In step (d), the operating conditions of the product tower are: pressure 0.01-0.1 MPa, tower top temperature 35-95°C, tower bottom temperature 125-205°C, reflux ratio 0.1-5, and theoretical plate number 8-50.

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