Method for producing succinate by using maleic anhydride airflow

Abstract

The invention provides a method for producing succinate by using maleic anhydride airflow. The method comprises the following two reaction processes: absorbing esterified maleic anhydride airflow by using RR1R2COH alcohol as an absorption solvent to prepare butenedioic acid ester, and hydrogenating the butenedioic acid ester under the action of a metal catalyst to prepare the succinate. According to the technical scheme, the alcohol substances are used as the solvent and the esterifying agent, succinic acid ester can be prepared by carrying out absorption esterification on maleic anhydride gas flow and directly hydrogenating the absorption liquid without separation, raw materials are cheap, the process is short, the system is simple and convenient, investment is saved, material consumption and energy consumption are low, and the production cost is low.

Description

Technical Field

[0001] The present invention relates to the technical field of the production of chemical intermediates, and more specifically, to a method for producing succinate using maleic anhydride gas stream. Background Art

[0002] Succinates (also known as amber acid esters) include monoesters and diesters, and are important synthetic fragrances, food additives, organic solvents, and organic synthesis intermediates. They are widely used in industries such as food, fragrance, daily chemicals, medicine, pesticides, coatings, rubber, plastics, etc. Especially in recent years, due to the enhancement of environmental awareness, green and environmentally friendly products have been favored by people. Environmentally friendly coatings using succinates as solvents, green pigments, medicines, and pesticides prepared using them as intermediates, and biodegradable plastic polybutylene succinate PBSX synthesized using them as monomer raw materials have broad market prospects, which will bring huge market demand for succinates. Developing new preparation methods for succinates is of great significance.

[0003] There are many methods for preparing succinates, including direct esterification of succinic acid with alcohol, addition esterification of succinic acid with olefins, ring-opening esterification of succinic anhydride with alcohol, hydrogenation of maleate (maleic acid ester), and esterification reduction of maleic anhydride with alcohol.

[0004] CN106800510A discloses a method for producing dimethyl succinate. Using succinic acid and methanol as raw materials and potassium bisulfate as a catalyst, an intermittent esterification reaction is carried out in an esterification kettle equipped with a reflux condenser. The product is obtained by recovering methanol at atmospheric pressure, distilling out water under reduced pressure, and vacuum rectification to obtain dimethyl succinate, with a product yield exceeding 97%. CN101323566B discloses a method for preparing diethyl succinate. The material ratio is succinic acid: industrial ethanol: absolute ethanol: catalyst = 1:0.8 - 1.1:0.1:0.01 - 0.02. Succinic acid and ethanol are subjected to intermittent operations such as esterification, filtration, alkali washing, and rectification under the catalytic action of phosphotungstic acid to obtain diethyl succinate with a yield greater than 90%.

[0005] CN1196350A discloses a method for preparing di-tert-butyl succinate, which is prepared by reacting succinic acid or succinic anhydride with isobutene in the presence of a water-containing acid catalyst. CN103012139A provides a method for preparing di-tert-amyl succinate. The reaction is carried out under the conditions that the molar ratio of raw materials succinic acid, succinic anhydride or their mixture to isopentene is 1:2 - 30, the solvent is DMF or 1,4-dioxane, the temperature is 38 - 200°C, the pressure is 0.1 - 0.8 MPa, and in the presence of an acid catalyst. The product is obtained by vacuum distillation at 100°C and a vacuum degree of -0.09 MPa to obtain di-tert-amyl succinate.

[0006] CN104557536B discloses a preparation method of monomethyl succinate. Succinic anhydride and methanol are introduced into a static mixer for monoesterification reaction. The reaction effluent then enters a high-gravity reactor for reaction, and steam is introduced into the high-gravity reactor at the same time. After the reaction, the liquid-phase material is cooled and separated to obtain monomethyl succinate. CN101092358B provides a batch preparation method of diisopropyl succinate. Succinic acid, isopropyl alcohol, a catalyst and a dehydrating agent are added to an esterification reaction kettle equipped with a fractionator to carry out an esterification reaction to prepare diisopropyl succinate. CN110256244B discloses a synthesis method of diisopropyl succinate. Using succinic anhydride and isopropyl alcohol as raw materials, a tubular reactor is used, and an acidic resin and a nano solid superacid are used as catalysts for staged catalytic continuous production of diisopropyl succinate.

[0007] CN102001939B discloses a preparation method of dicarboxylic acid succinate. Hydrogen and maleic dicarboxylate are mixed and passed through a fixed-bed reactor filled with a hydrogenation catalyst to generate part of the dicarboxylic acid succinate as a circulating dilution heat-removing material. The hydrogenation material is subjected to gas-liquid separation, and hydrogen is recycled. The purity of the product dicarboxylic acid succinate exceeds 99.6%. CN101747189B provides a method for hydrogenating maleic dialkyl ester (C1-C5 alkyl ester) to dicarboxylic acid dialkyl ester. A CuZnAl catalyst is loaded into a fixed-bed reactor and reduced with hydrogen at a flow rate of 500 ml / min at 230 °C and normal pressure for 12 hours, and then fed with a raw material containing maleic dialkyl ester for hydrogenation reaction. The liquid product is cooled and separated to obtain the target product.

[0008] In addition, there have been numerous reports on the method for preparing succinate by the esterification and reduction of maleic anhydride. For example, CN102070448B uses maleic anhydride and methanol as raw materials, and synthesizes dimethyl maleate by adopting an acidic cation exchange resin catalyst and a fixed-bed catalytic distillation process. Then, dimethyl succinate is prepared by hydrogenating dimethyl maleate through a Pd catalyst supported on a carrier such as Al2O3, SiO2, TiO2, ZrO2 or activated carbon and a fixed-bed reaction process. The esterification conversion rate of maleic anhydride is 100%, the selectivity of dimethyl maleate is greater than 99%, and both the hydrogenation conversion rate of dimethyl maleate and the selectivity of dimethyl succinate are greater than 99.8%. CN115745772A synthesizes diethyl succinate through two-step reactions of maleic anhydride esterification and hydrogenation of maleic diester. The esterification conversion rate of maleic anhydride is greater than 99.5%, the hydrogenation conversion rate of maleic diester is greater than 99.5%, and the selectivity of diethyl succinate exceeds 99.7%. CN102863335B uses maleic anhydride, alcohol and hydrogen as raw materials, carbon dioxide as a solvent and an acid catalyst, and prepares diethyl succinate by one-step esterification and hydrogenation under the action of a hydrogenation catalyst, with a yield greater than 99%. CN101824627B synthesizes dimethyl maleate through three-step reactions of mono-esterification, di-esterification and re-esterification of maleic anhydride with anhydrous methanol, and then prepares dimethyl succinate by electrochemical reduction. Then, the dimethyl succinate product is obtained by cooling crystallization in water and recrystallization in a methanol or ethanol solvent. Among them, no catalyst is required for mono-esterification, and sulfuric acid or hydrochloric acid catalysts are used for both di-esterification and re-esterification.

[0009] In summary, the existing preparation methods of succinic monoester or diester mainly use succinic acid or succinic anhydride as raw materials, and obtain them through direct esterification or addition esterification reactions with C1-C5 alcohols or C4-C5 isoolefins; or use maleate as raw materials and obtain them by catalytic hydrogenation of double bonds; or use commercial maleic anhydride and C1-C5 alcohols as raw materials and prepare them through two-step reactions of esterification and hydrogenation or hydrogenation esterification or one-step coupling reaction. Among them, the esterification catalysts mainly use liquid acids such as sulfuric acid, potassium bisulfate, heteropolyacid, etc., or solid acids such as acidic ion exchange resins, solid superacids, etc.; the hydrogenation catalysts mainly use supported copper-based catalysts or noble metal catalysts.

[0010] Obviously, the current mainstream production route of succinic acid esters starts with refined maleic anhydride as a product or commodity, through hydrogenation esterification of maleic anhydride, that is, first obtaining succinic anhydride or succinic acid as products, and then esterifying with alcohols for synthesis, or through esterification and hydrogenation of product or commodity maleic anhydride, that is, first obtaining maleic acid esters, and then synthesizing through hydrogenation; moreover, the existing succinic acid ester synthesis technologies are basically all concentrated on single-point work such as changing the synthesis method, improving the preparation efficiency, and optimizing the process conditions to reduce energy consumption or increase the yield, without paying attention to the overall process integration starting from gaseous crude maleic anhydride and reducing the manufacturing cost of the starting material maleic anhydride, resulting in limited reduction in the production cost of succinic acid esters. Currently, the investment and production cost of maleic anhydride industrial plants are mainly consumed in the solvent absorption and desorption of the gas-phase maleic anhydride logistics of the oxidation reaction products, the separation and purification of maleic anhydride, and the purification and recovery of solvents. Summary of the Invention

[0011] In view of this, the present invention provides a method for producing succinic acid esters using a maleic anhydride gas stream to shorten the process flow and thereby significantly reduce the production cost.

[0012] To achieve the above object, the technical solution of the present invention is specifically as follows:

[0013] A method for producing succinic acid esters using a maleic anhydride gas stream, comprising the following steps:

[0014] (1) Using RR 1 R 2 COH alcohol as an absorption solvent, absorbing and esterifying gaseous crude maleic anhydride in the presence or absence of an acid catalyst to prepare maleic acid esters;

[0015] (2) Subjecting the maleic acid esters prepared in step (1) to selective hydrogenation of double bonds under the action of a metal catalyst to prepare succinic acid esters;

[0016] Among them, RR 1 R 2 COH is a single alcohol or a mixed alcohol, and R, R 1 and R 2 are respectively selected from one of the same or different groups of H, halogen, hydroxyl, heterocyclic group, hydroxyalkyl group, alkyl group or halogenated alkyl group, the maleic acid esters include maleic acid monoesters or / and diesters, and the succinic acid esters include succinic acid monoesters or / and diesters.

[0017] In the technical solution of the present invention, the maleic anhydride gas stream is the gaseous crude maleic anhydride obtained by the oxidation reaction of butane or benzene in an oxidation reactor in industrial maleic anhydride production.

[0018] In the above technical solution, in step (1), the reaction formulas for preparing maleic acid monoesters or / and diesters are shown as the following formulas (1) and (2):

[0019]

[0020] In step (2), the double bond of maleic acid monoester or / and diester is selectively hydrogenated and saturated to prepare succinic acid monoester or / and diester. The reaction formulas are shown as the following formulas (3) and (4):

[0021] HOOCCH=CHCOOCRR'R 2 +H2→HOOCCH2CH2COOCRR 1 R 2 (3)

[0022] RR 1 R 2 COOCCH=CHCOOCRR 1 R 2 +H2→RR 1 R 2 COOCCH2CH2COOCRR 1 R 2 (4).

[0023] In the technical solution of the present invention, RR 1 R 2 COH alcohol is used as the absorption solvent for the maleic anhydride gas stream, and is also the solvent for the maleic anhydride esterification reaction, the solvent for the maleic acid ester hydrogenation reaction, and the raw material esterifying agent for the maleic anhydride esterification reaction.

[0024] Furthermore, R, R 1 R 2 of the RR 1 and R 2 COH alcohol are respectively selected from one of the same or different groups of H, Cl, F, or alkyl, alkenyl, alkynyl, aryl, oxygen-containing heterocyclic group, hydroxyalkyl, hydroxyalkenyl, hydroxyalkynyl, hydroxyaryl, alkylaminoalkyl, or haloalkyl with C1-C9;

[0025] Furthermore, the RR 1 R 2The COH alcohol is selected from at least one of n-butanol, isobutanol, tert-butanol, n-pentanol, isopentanol, 3-methylbutanol, neopentanol, n-hexanol, 2-methylpentanol, 3-methylpentanol, 2,2-dimethylbutanol, 3,3-dimethylbutanol, n-heptanol, isoheptanol, n-octanol, isooctanol, 2-ethylhexanol, n-nonanol, isononanol, n-decanol, lauryl alcohol, myristyl alcohol, palmityl alcohol, stearyl alcohol, cyclopentanol, cyclohexanol, methylcyclohexanol, cyclohexylethanol, cyclohexylpropanol, allyl alcohol, butenol, methallyl alcohol, 2-pentenol, isopentenol, 2-cyclohexenol, cinnamyl alcohol, oleyl alcohol, 3-(2-furyl)propenol, propynol, butynol, benzyl alcohol, phenethyl alcohol, α,α-dimethylbenzyl alcohol, hydrocinnamyl alcohol, tetrahydrofurfuryl alcohol, furfuryl alcohol, tetrahydropyranol, ethylene glycol, polyethylene glycol, 1,2-propanediol, polypropylene glycol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 2-methyl-1,3-propanediol, neopentyl glycol, 2-ethyl-2-methyl-1,3-propanediol, 2-isopropyl-2-methyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 2-n-butyl-2-ethyl-1,3-propanediol, cyclohexanediol, cyclohexanedimethanol, 1-phenyl-1,3-propanediol, 2-phenyl-1,3-propanediol, 1-phenyl-1,4-butanediol, benzenedimethanol, 2,5-furandimethanol, glycerol, trimethylolethane, 1,2,6-hexanetriol, trimethylolpropane, erythritol, pentaerythritol, xylitol, sorbitol, mannitol, inositol, butenediol, butynediol, diethylaminoethanol, diethylaminopropanol, or 2,2,2-trifluoroethanol, pentafluoroethanol, heptafluoropropanol, 2,2,2-trichloroethanol, chloropropanol or 1,3-dichloropropanol.

[0026] Furthermore, the RR 1 R 2The CnH2n+1OH is n-octanol, 2-ethylhexanol, n-nonanol, n-decanol, lauryl alcohol, myristyl alcohol, palmityl alcohol, stearyl alcohol, 4-methylcyclohexanol, 2-cyclohexylethanol, 3-cyclohexylpropanol, cinnamyl alcohol, oleyl alcohol, benzyl alcohol, α-phenylethyl alcohol, β-phenylethyl alcohol, α,α-dimethylbenzyl alcohol, hydrocinnamyl alcohol, tetrahydrofurfuryl alcohol, furfuryl alcohol, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol 200-1000, 1,2-propanediol, dipropylene glycol, tripropylene glycol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 2-methyl-1,3-propanediol, 1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 2-phenyl-1,3-propanediol, o-phthalyl alcohol, m-phthalyl alcohol, 2,5-furandimethanol, glycerol, trimethylolpropane, 1,2,6-hexanetriol, butenediol, butynediol, diethylaminoethanol, diethylaminopropanol, or 3-chloropropanol, 1,3-dichloro-2-propanol.

[0027] Further, in step (1), the process flow of preparing maleate by absorption esterification of gaseous crude maleic anhydride includes the following processes: The gaseous crude maleic anhydride is quenched to 55-180 °C and fed into a spray absorption tower from the bottom, and an alcohol absorption solvent containing 0-10.00 wt% of a liquid acid catalyst at 25-85 °C is sprayed from the top, and the maleic anhydride gas stream and the absorbent operate in countercurrent; or, after the gaseous crude maleic anhydride is quenched to 55-180 °C, it is fed into a bubble absorption tower filled with inert packing or solid acid particle catalyst from the bottom, and the alcohol absorption solvent at 25-85 °C is fed into the absorption tower from the bottom or the top, and flows in parallel or countercurrent with the maleic anhydride gas stream; After absorption esterification in the spray absorption tower or the bubble absorption tower, an absorption esterification liquid with a maleate concentration of 10-50 wt% and a temperature of 52-150 °C is obtained.

[0028] Preferably, the gaseous crude maleic anhydride is quenched to 60-150 °C, the temperature of the alcohol absorption solvent is 30-80 °C, the absorption esterification is carried out in 1-3 stages, and the maleate concentration in the absorption esterification liquid is controlled to be 15-45 wt% and the temperature is controlled to be 55-120 °C;

[0029] More preferably, the gaseous crude maleic anhydride is quenched to 65-120 °C, the temperature of the alcohol absorbent is 35-75 °C, the absorption esterification is carried out in 1-2 stages, and the maleate concentration in the absorption esterification liquid is controlled to be 20-40 wt% and the temperature is controlled to be 60-90 °C.

[0030] Further, the gaseous crude maleic anhydride is subjected to 1-3 stages of absorption esterification in a spray absorption tower or a bubble absorption tower to obtain an absorption esterification liquid.

[0031] Furthermore, in step (1), when a spray absorption tower is selected, the concentration of the liquid acid catalyst is 0 to 5.00 wt%, preferably 0 to 2.00 wt%.

[0032] Furthermore, in step (1), when a spray absorption tower is selected and a liquid acid catalyst is added, the concentration of the liquid acid is 1.00 wt% to 2.00 wt%.

[0033] Furthermore, in step (1), 45-85 vol% of the tail gas after esterification and absorption of the maleic anhydride gas flow is recycled back to the oxidation reactor for preparing maleic anhydride, and the remaining tail gas is sent to the incinerator; preferably, the tail gas circulation volume is controlled to 50-80 vol%; further preferably, the tail gas circulation volume is controlled to 55-75 vol%.

[0034] Further, in step (1), the acid catalyst is selected from a liquid acid catalyst and / or a solid acid catalyst, wherein the liquid acid catalyst is selected from one of an alkyl sulfonic acid, an aryl sulfonic acid, a halogenated sulfonic acid, a halogenated carboxylic acid, an amide or an imide of a halogenated sulfonic acid; preferably, the liquid acid catalyst is selected from at least one of methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, β-naphthalenesulfonic acid, fluorosulfonic acid, trifluoromethanesulfonic acid, pentafluoroethanesulfonic acid, trichloroacetic acid, trifluoroacetic acid or pentafluoropropionic acid, or trifluoromethanesulfonamide, bisfluorosulfonimide or bistrifluoromethanesulfonimide; more preferably, the liquid acid catalyst is methanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, fluorosulfonic acid, trifluoromethanesulfonic acid, trifluoroacetic acid, bisfluorosulfonimide or bistrifluoromethanesulfonimide.

[0035] Furthermore, the solid acid catalyst is selected from at least one of hydrogen-type zeolite molecular sieves, acidic oxides, solid superacids or strong acidic cation exchange resins.

[0036] Furthermore, the hydrogen-type zeolite molecules are selected from at least one of HM, Hβ, HZSM-5, HZSM-11, HZSM-22, HZSM-23, HZSM-35, HMCM-22, HMCM-49 or HMCM-56; the acidic oxide is selected from γ-Al2O3, SiO2-Al2O3, Nb2O5, Zr(HPO4)2, H2TiO3, H3PO4, H6TeO6, H3PW 12 O 40 、H3PMo 12 O 40 、H4SiW 12 O 40 、H4SiMo 12 O 40 or Cs 2.5 H 0.5 PW 12 O 40at least one of; the solid superacid is selected from SO4 2- / ZrO2, SO4 2- / TiO2, SO4 2- / Fe2O3, SO4 2- / ZrO2-La2O3, SO4 2- / ZrO2-CeO2, SO4 2- / TiO2-ZrO2, SO4 2- / ZrO2-CeO2-Fe2O3, WO3 / ZrO2 or MoO3 / ZrO2; the strongly acidic macroporous cation exchange resin is selected from at least one of Amberlyst 15, Amberlyst 16, Amberlyst 35, NKC-9, HPK-16, D-61, D-72, D-113, D-732, T-62, SB-DH, CR-11, chlorinated or fluorinated resins.

[0037] Further, the solid acid catalyst is selected from at least one of HM, HZSM-5, HMCM-22, γ-Al2O3, Nb2O5, H3PW 12 O 40 、Cs 2.5 H 0.5 PW 12 O 40 、SO4 2- / ZrO2, WO3 / ZrO2, A-15, A-35, NKC-9, HPK-16, D-72 or Nafinon-H.

[0038] Further, the solid acid catalyst is in the form of spheres with a diameter of 0.4 - 5.0 mm or strips, cylinders or shaped particles with a diameter of 1.0 - 5.0 mm and a length of 2.0 - 8.0 mm; preferably, the solid acid catalyst is in the form of spheres with a diameter of 0.5 - 4.0 mm or strips, cylinders or clover-shaped particles with a diameter of 1.6 - 4.5 mm and a length of 2.0 - 6.0 mm; more preferably, the solid acid catalyst is in the form of spheres with a diameter of 0.6 - 3.0 mm or cylindrical particles with a diameter of 2.0 - 4.0 mm and a length of 2.0 - 4.0 mm.

[0039] Further, the process for preparing succinate by hydrogenating maleate in step (2) includes the following processes:

[0040] Feed the absorbent solution from step (1) into a hydrogenation reactor and operate in co-current or counter-current with hydrogen. In the presence of a supported noble metal catalyst, carry out the double bond hydrogenation of maleate ester to prepare succinate ester at the absorbent solution temperature and concentration. Separate the gas-liquid of the reacted material, and recycle the separated hydrogen to the hydrogenation reactor for reuse; the hydrogenation reactor is selected from a slurry bed reactor or a fixed bed reactor.

[0041] Furthermore, the supported metal catalyst is selected from at least one supported noble metal catalyst of activated carbon, mesoporous carbon, carbon nanotube, graphene, Al2O3, SiO2, Al2O3-SiO2, TiO2, ZrO2, HM, Hβ, HZSM-5, HMCM-22, HMCM-41, HMCM-48 or SBA-15; preferably, the noble metal is selected from one or more of Ru, Pd or Pt.

[0042] Furthermore, the supported metal catalyst is selected from one of activated carbon, Al2O3, SiO2, HZSM-5, HMCM-41 or SBA-15 supporting Ru, Pd, Pt or Pd-Ru catalyst.

[0043] Furthermore, in step (2), when the hydrogenation reactor is a slurry bed reactor, the loading amount of the noble metal in the supported metal catalyst is 1.0-5.0 wt%; preferably, the loading amount of the noble metal is 2.0-4.0 wt%.

[0044] Furthermore, in step (2), when the hydrogenation reactor is a fixed bed reactor, the loading amount of the noble metal in the supported metal catalyst is 0.1-1.0 wt%; preferably, the loading amount of the noble metal is 0.2-0.5 wt%.

[0045] Furthermore, in step (2), when the hydrogenation reactor is a slurry bed reactor, use a supported metal powder catalyst. After gas-liquid separation of the reacted material, the liquid phase material is subjected to solid-liquid separation to recover the catalyst for hydrogenation reaction for reuse, and the separated liquid is sent to the subsequent refining system; the solid-liquid separation method is selected from filtration, pressure filtration, centrifugation or sedimentation separation.

[0046] Furthermore, in step (2), when the hydrogenation reactor is a slurry bed reactor, both the absorbent solution and hydrogen are fed in co-current from the bottom of the hydrogenation reactor or the absorbent solution is fed from the top of the hydrogenation reactor while hydrogen is fed in counter-current from the bottom, and the liquid material after gas-liquid separation is subjected to pressure filtration or centrifugation to recover the hydrogenation catalyst.

[0047] Further, in step (2), the hydrogenation reactor is a slurry bed reactor. After the supported metal powder catalyst and the absorption liquid in step (1) are first mixed and stirred evenly to obtain a slurry, they are then fed into the slurry bed reactor in co-current or counter-current with hydrogen for hydrogenation reaction. Among them, the dosage of the supported metal powder catalyst is 1.0 - 5.0 wt% of the absorption liquid.

[0048] Preferably, in step (2), the hydrogenation reactor is a slurry bed reactor. The absorption liquid is fed in counter-current from the top of the hydrogenation reactor while hydrogen is fed from the bottom. The liquid material after gas-liquid separation is separated by pressure filtration to recover the hydrogenation catalyst.

[0049] Further, in step (2), when the hydrogenation reactor is a fixed bed reactor, the fixed bed reactor is filled with a supported metal particle catalyst. The liquid phase material after the reaction mixture is separated by gas-liquid separation is fed into the subsequent refining system; the fixed bed reactor is a trickle bed reactor or a bubble bed reactor.

[0050] Further, in step (2), when the hydrogenation reactor is a trickle bed reactor, the absorption liquid and hydrogen are both fed in co-current from the top of the reactor, or when a bubble bed reactor is used, the absorption liquid is fed from the top of the reactor while hydrogen is fed from the bottom in counter-current, or the absorption liquid and hydrogen are both fed in co-current from the bottom of the reactor.

[0051] Further, in step (2), the reaction process conditions for the hydrogenation of maleate to succinate are as follows: the concentration of maleate in the feed absorption liquid is 10 - 50 wt%, the temperature is 52 - 150 °C, the weight hourly space velocity is 0.1 - 10.0 h -1 , the hydrogen pressure is 0.2 - 5.0 MPa, and the hydrogen-to-ester molar ratio is 2 - 50;

[0052] Preferably, the concentration of maleate in the feed absorption liquid is 15 - 45 wt%, the temperature is 55 - 120 °C, the weight hourly space velocity is 0.5 - 5.0 h -1 , the hydrogen pressure is 0.5 - 3.0 MPa, and the hydrogen-to-ester molar ratio is 5 - 30;

[0053] More preferably, the concentration of maleate in the feed absorption liquid is 20 - 40 wt%, the temperature is 60 - 90 °C, the weight hourly space velocity is 1.0 - 2.0 h -1 , the hydrogen pressure is 1.0 - 2.0 MPa, and the hydrogen-to-ester molar ratio is 10 - 20.

[0054] In the technical solution of the present invention, the tandem combination process flow of step (1) for preparing maleic acid ester by absorption esterification of maleic anhydride gas stream and step (2) for hydrogenation saturation of maleic acid ester to prepare succinic acid ester has the following several modes: the combination of a spray or bubble absorption esterification tower using a liquid acid catalyst and a slurry bed hydrogenation reactor using a supported metal powder catalyst or a fixed bed hydrogenation reactor using a supported metal particle catalyst, or the combination of a bubble absorption esterification tower using a solid acid particle catalyst and a slurry bed hydrogenation reactor using a supported metal powder catalyst or a fixed bed hydrogenation reactor using a supported metal particle catalyst.

[0055] Compared with the prior art, the present invention has the following beneficial effects:

[0056] 1) The present invention eliminates the cumbersome processes in the prior art, such as the solvent absorption, solvent desorption, solvent purification, and crude maleic anhydride refining of the gas-phase maleic anhydride logistics using high-boiling and low-solubility heavy solvents dibutyl phthalate (DBP) or diisobutyl hexahydrophthalate (DIBE), as well as the re-esterification of the product purified maleic anhydride to prepare maleic acid ester; it also avoids the problems of pipeline and equipment blockage caused by the polymerization of impurity acrylic acid and the crystallization of maleic acid and fumaric acid in the solvent absorption of gas-phase maleic anhydride logistics to prepare the product maleic anhydride, resulting in frequent shutdowns of the device for cleaning, large material losses, high energy consumption, affecting the device production capacity, and generating a large amount of three wastes.

[0057] 2) The present invention uses the gas-phase maleic anhydride logistics (gaseous crude maleic anhydride) as the starting material to prepare maleic acid ester and succinic acid ester, and adopts an overall integrated process of absorption-esterification-hydrogenation. In the prior art, the preparation methods of succinic acid monoester or diester mainly use succinic acid and succinic anhydride as raw materials, and react with C1-C5 alcohols through direct esterification reaction, or use maleic acid ester as the raw material and obtain it by catalytic hydrogenation of double bonds, or use commercial maleic anhydride and C1-C5 alcohols as raw materials and prepare it through two-step reactions of esterification-hydrogenation or hydrogenation-esterification. Obviously, the mainstream production route of succinic acid ester starts with the product or commercial maleic anhydride as the starting material (whether it is succinic anhydride, succinic acid, or maleic acid ester, its source is mainly prepared from maleic anhydride as the raw material), and first prepares the product succinic anhydride or succinic acid through hydrogenation esterification and separation and purification, and then esterifies and refines it with alcohol; or first prepares maleic acid ester through esterification hydrogenation and purification, and then prepares it through hydrogenation and separation and purification. At present, the investment and production cost of maleic anhydride industrial devices are mainly consumed in the solvent absorption and desorption of the oxidation reaction product gas-phase maleic anhydride logistics, the separation and purification of maleic anhydride, and the purification and recovery of the solvent. Therefore, the present invention uses gaseous crude maleic anhydride as the starting material to prepare maleic acid ester and succinic acid ester, which can greatly shorten the process flow, save device investment and energy and material consumption, and thus significantly reduce the production cost.

[0058] Obviously, the prominent advantages of the present invention are as follows: short process, simple system, easy operation, clean production, inexpensive raw materials, savings in investment, low material and energy consumption, low operation and post-treatment costs, and low production costs. Detailed implementation manners

[0059] The following further elaborates the present invention in conjunction with specific embodiments. It should be noted that the embodiments described in this part are only a part of the present invention, rather than all embodiments. In view of this, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present invention.

[0060] Symbol description:

[0061] HTFSI is bis(trifluoromethanesulfonyl)imide, and HPA is cesium heteropolyacid Cs 2.5 H 0.5 PW 12 O 40 。

[0062] Examples 1 to 6

[0063] Maleic anhydride is prepared by gas-phase absorption esterification and catalytic hydrogenation to produce succinic acid monoester without adding an esterification catalyst (acid catalyst). Spray absorption esterification, a slurry bed hydrogenation reactor and a supported metal powder catalyst are used. The specific steps are as follows:

[0064] (1) The gaseous crude maleic anhydride produced by the oxidation of butane in the industrial maleic anhydride plant is quenched to 60 - 150 °C and fed into the spray absorption tower from the bottom. An alcohol absorption solvent at 55 - 85 °C is sprayed from the top of the tower. After 1 - 3 stages of absorption esterification, an absorption liquid with a maleic acid ester concentration of 15 - 40 wt% and a temperature of 58 - 95 °C is obtained;

[0065] (2) The absorption liquid is mixed with the supported metal powder catalyst and stirred evenly to obtain a slurry. The dosage of the supported metal powder catalyst is 1.0 - 2.0 wt% of the absorption liquid dosage. Then, the slurry and hydrogen are fed into the slurry bed hydrogenation reactor in parallel or countercurrent. Under the process conditions of an absorption liquid temperature of 55 - 85 °C, a maleic acid monoester concentration of 15 - 40 wt%, a feed weight hourly space velocity of 0.5 - 5.0 h -1 , a hydrogen pressure of 1.0 - 2.0 MPa, and a hydrogen-to-ester molar ratio of 20 - 30, double-bond hydrogenation is carried out to prepare succinic acid monoester;

[0066] (3) After the material after the hydrogenation reaction is subjected to gas-liquid separation, the hydrogen gas is sent back to the hydrogenation reactor for recycling, the liquid material is filtered to recover the hydrogenation catalyst and recycled, the liquid part is sent to the separation and purification system, the recovered absorbent is recycled, and the remaining material is further refined to obtain the target product succinic acid monoester. The specific operating conditions, corresponding catalysts and results of Examples 1 to 6 are shown in Tables 1 and 2. Table 1 shows the alcohol absorbent solvent and its temperature, the number of absorption stages and the absorption method in step (1) of Examples 1 to 6, the temperature of the maleic anhydride gas stream entering the spray absorption tower, and the temperature of the obtained absorption liquid and the concentration of maleic acid ester, and gives the maleic anhydride absorption rate and the maleic anhydride esterification rate. Table 2 shows the reactor used in the hydrogenation reaction in step (2), the flow mode of the absorption liquid and hydrogen gas, the hydrogenation catalyst used and its dosage, the hydrogenation reaction conditions (including the weight hourly space velocity, the hydrogen to ester molar ratio and the hydrogen pressure), and the double bond conversion rate and the succinic acid ester selectivity.

[0067] As can be seen from Tables 1 and 2, when spray absorption is carried out using 2-ethylhexanol, lauryl alcohol, 3-cyclohexylpropanol, benzyl alcohol, β-phenylethyl alcohol and hydrocinnamyl alcohol as absorbents respectively, under their respective operating conditions, the gas-phase maleic anhydride absorption rate is 92.5-99.5 mol%, and the esterification rate of maleic anhydride reacting with the alcohol absorbent to form maleic acid monoester is 98.5-99.8 mol%. The obtained absorption liquids are respectively subjected to slurry bed hydrogenation reaction under the action of supported powder catalysts Pd / C, Ru / C, Pt / C, Pd-Ru / C, Pd / SiO2 or Pd / HZSM-5, the double bond conversion rate is greater than 99.9 mol%, and the selectivity of the target product succinic acid monoester is greater than 99.7 mol%.

[0068] Examples 7 to 12

[0069] Preparation of succinic acid monoester by absorption esterification and catalytic hydrogenation of maleic anhydride gas stream without adding esterification catalyst, using bubble absorption esterification, fixed bed hydrogenation reactor and supported metal particle catalyst, specifically including the following steps:

[0070] (1) The gaseous crude maleic anhydride, the butane oxidation product gas from the industrial maleic anhydride plant, is quenched to 60-150 °C and fed from the bottom into a bubble absorption tower filled with quartz ball packing with a diameter of 3.2-4.2 mm, while the alcohol absorbent solvent at 55-85 °C is fed from the top of the tower. After 1-2 stages of absorption esterification, an absorption liquid with a maleic acid ester concentration of 25-38 wt% and a temperature of 63-98 °C is obtained;

[0071] (2) The absorption liquid obtained in step (1) and hydrogen gas are fed into a fixed bed hydrogenation reactor filled with supported metal particle catalyst in parallel or countercurrent. At an absorption liquid temperature of 63-98 °C, a maleic acid ester concentration of 25-38 wt% and a feed weight hourly space velocity of 1.5-3.0 h -1, under the operating conditions of hydrogen pressure of 1.0 - 2.0 MPa and a hydrogen to ester molar ratio of 10 - 30, double bond hydrogenation is carried out to prepare succinic acid monoester;

[0072] (3) The material after the reaction in step (2) is subjected to gas-liquid separation. The hydrogen is sent back to the hydrogenation reactor for recycling. The liquid material is filtered to recover the hydrogenation catalyst and recycle it. The filtered liquid is sent into the separation and purification system. The absorbent is recovered and recycled through separation. The remaining material is further refined to obtain the target product succinic acid monoester. The specific operating conditions and the corresponding catalysts and results of Examples 7 - 12 are shown in Tables 1 and 2.

[0073] As can be seen from Tables 1 and 2, when using tetrahydrofurfuryl alcohol, diethylaminoethanol, polyethylene glycol 400, 1,4-butanediol, 1,4-cyclohexanedimethanol, and 1,2,6-hexanetriol as absorbents for bubble absorption respectively, under their respective operating conditions, the absorption rate of maleic anhydride in the gas phase is 93.2 - 99.5 mol%, and the esterification rate of maleic anhydride reacting with the alcohol absorbent to form maleic acid monoester is 99.2 - 100 mol%. The obtained absorption liquids are respectively subjected to trickle bed or bubble bed hydrogenation reactions under the action of supported particulate catalysts Pd / γ-Al2O3, Pd / TiO2, Pd / SiO2, Pd / HMCM-41 or Pd / SBA-15. The double bond conversion rate is 100 mol%, and the selectivity of the target product succinic acid monoester is greater than 99.2 mol%.

[0074] Examples 13 - 16

[0075] Maleic anhydride gas stream is absorbed for esterification and catalytic hydrogenation to prepare succinic acid diester. A liquid acid esterification catalyst is added. Bubble absorption esterification, slurry bed hydrogenation reactor and supported metal powder catalyst are used. The specific steps are as follows:

[0076] (1) The gaseous crude maleic anhydride, the product of butane oxidation in the industrial maleic anhydride plant, is quenched to 65 - 90 °C and fed from the bottom into a bubble absorption tower filled with quartz ball packing with a diameter of 3.2 - 4.2 mm. The alcohol absorption solvent containing 1.00 - 2.00 wt% liquid acid catalyst at 45 - 65 °C is sprayed from the top of the tower. After 1 - 2 stages of absorption esterification, an absorption liquid with a maleic acid ester concentration of 30 - 48 wt% (the proportion of diester is 75.5 - 83.6 mol%) and a temperature of 55 - 75 °C is obtained;

[0077] (2) The absorption liquid obtained in step (1) is mixed with the supported metal powder catalyst and stirred evenly to obtain a slurry. The dosage of the supported metal powder catalyst is 2.0 - 4.0 wt% of the absorption liquid dosage; then the slurry and hydrogen are fed into the slurry bed hydrogenation reactor in parallel or countercurrent. At an absorption liquid temperature of 55 - 75 °C, a maleic acid ester concentration of 30 - 48 wt% and a feed weight hourly space velocity of 0.5 - 1.5 h -1Under the operating conditions of a hydrogen pressure of 2.0 - 3.0 MPa and a hydrogen - to - ester molar ratio of 10, double - bond hydrogenation is carried out to prepare succinic esters.

[0078] (3) The material after the hydrogenation reaction in step (2) is subjected to gas - liquid separation. The hydrogen is sent back to the hydrogenation reactor for recycling. The liquid material is filtered to recover and recycle the hydrogenation catalyst. The filtered liquid is sent into the separation and purification system. The absorbent is recovered and recycled through separation. The remaining material is further refined to obtain the target products, monosuccinate and disuccinate (the selectivity of monosuccinate is 16.5 - 24.4 mol%, and the selectivity of disuccinate is 75.3 - 83.3 mol%). The specific operating conditions, corresponding catalysts, and results of Examples 13 - 16 are shown in Tables 1 and 2.

[0079] As can be seen from Tables 1 and 2, using butanol, 2 - ethylhexanol, 2,4,4 - trimethylpentanol, or 3 - cyclohexylpropanol added with liquid acid catalysts p - toluenesulfonic acid or trifluoromethanesulfonic acid as absorbents for bubble absorption, under their respective operating conditions, the gas - phase maleic anhydride absorption rate is 93.8 - 99.8 mol%, and the esterification rate of maleic anhydride reacting with the alcohol absorbent to form maleic acid ester is 100 mol%. The obtained absorption liquids are respectively subjected to slurry - bed hydrogenation reaction under the action of the supported powder catalyst Pd / C. The double - bond conversion rate is greater than 99.8 mol%, and the selectivity of the target product succinic ester is 100 mol%.

[0080] Examples 17 - 20

[0081] For the preparation of disuccinate by maleic anhydride gas - stream absorption esterification and catalytic hydrogenation, a liquid acid esterification catalyst is added. Bubble - absorption esterification, a fixed - bed hydrogenation reactor, and a supported metal - particle catalyst are used. The specific steps are as follows:

[0082] (1) The gaseous crude maleic anhydride from the industrial maleic anhydride plant obtained by butane oxidation is quenched to 65 - 90 °C and fed from the bottom into a bubble - absorption tower filled with quartz - ball packing with a diameter of 3.2 - 4.2 mm. An alcohol absorption solvent containing 1.00 - 1.50 wt% liquid acid catalyst at 45 - 75 °C is sprayed from the top of the tower. After 1 - 3 - stage absorption esterification, an absorption liquid with a maleic acid ester concentration of 26 - 46 wt% and a temperature of 55 - 82 °C is obtained.

[0083] (2) The absorption liquid obtained in step (1) and hydrogen are fed into a fixed - bed hydrogenation reactor filled with a supported metal - particle catalyst in parallel or counter - current. Under the operating conditions of an absorption - liquid temperature of 55 - 82 °C, a maleic acid ester concentration of 26 - 46 wt% (the proportion of disuccinate is 77.2 - 84.5 mol%), and a feed weight hourly space velocity of 0.5 - 2.0 h -1 Under the operating conditions of a hydrogen pressure of 1.0 - 2.0 MPa and a hydrogen - to - ester molar ratio of 20, double - bond hydrogenation is carried out to prepare succinic esters.

[0084] (3) The logistics after the hydrogenation reaction in step (2) is subjected to gas-liquid separation. The hydrogen gas is sent back to the hydrogenation reactor for recycling use. The liquid material is filtered to recover the hydrogenation catalyst and recycle it. The filtered liquid is sent into the separation and purification system. The liquid is sent into the separation and purification system, the absorbent is recovered by separation and recycled. The remaining material is further refined to obtain the target products of monosuccinate and disuccinate. The selectivity of monosuccinate is 15.5 - 22.6 mol%, and the selectivity of disuccinate is 77.0 - 84.2 mol%.

[0085] The specific operating conditions, corresponding catalysts and results of Examples 17 - 20 are shown in Tables 1 and 2.

[0086] As can be seen from Tables 1 and 2, using benzyl alcohol, β-phenylethyl alcohol, hydrocinnamyl alcohol or furfuryl alcohol added with liquid acid catalysts trifluoromethanesulfonic acid or bis(trifluoromethanesulfonyl)imide (HTFSI) as absorbents for bubble absorption respectively, under their respective operating conditions, the absorption rate of maleic anhydride in the gas phase is 92.5 - 100 mol%, and the esterification rate of maleic anhydride reacting with the alcohol absorbent to form maleate is 100 mol%. The obtained absorption liquids are respectively subjected to trickle bed or bubble bed hydrogenation reaction under the action of the supported particulate catalyst Pd / SiO₂, the double bond conversion rate is greater than 99.9 mol%, and the selectivity of the target product succinate is 100 mol%.

[0087] Examples 21 - 24

[0088] The preparation of disuccinate by maleic anhydride gas absorption esterification and catalytic hydrogenation uses a solid acid esterification catalyst, bubble absorption esterification, a slurry bed hydrogenation reactor and a supported metal powder catalyst, and specifically includes the following steps:

[0089] (1) The gaseous crude maleic anhydride (the butane oxidation product gas from the industrial maleic anhydride plant) is quenched to 75 - 120 °C and fed from the bottom into a bubble absorption tower filled with solid acid particulate catalyst, while the alcohol absorption solvent at 55 - 80 °C is fed from the top. After two-stage absorption esterification, a maleate concentration of 40 - 45 wt% (the disuccinate accounts for 77.8 - 79.8 mol%)

[0090] and an absorption liquid with a temperature of 64 - 98 °C are obtained;

[0091] (2) The absorption liquid obtained in step (1) is mixed with the supported metal powder catalyst and stirred evenly to obtain a slurry. The dosage of the supported metal powder catalyst is 2.0 wt% of the absorption liquid dosage; then the slurry and hydrogen gas are fed into the slurry bed hydrogenation reactor in parallel or countercurrent. Under the operating conditions of an absorption liquid temperature of 64 - 98 °C, a maleate concentration of 40 - 45 wt%, a feed weight hourly space velocity of 1.0 - 2.0 h -1 , a hydrogen pressure of 1.5 - 2.0 MPa and a hydrogen-to-ester molar ratio of 10 - 20, the double bond hydrogenation is carried out to prepare succinate;

[0092] (3) The materials after the hydrogenation reaction are subjected to gas-liquid separation. The hydrogen gas is sent back to the hydrogenation reactor for recycling use. The liquid materials are filtered to recover the hydrogenation catalyst and recycled. The liquid is sent into the separation and purification system, where the absorbent is recovered and recycled through separation. The remaining materials are further refined to obtain the target products of monosuccinate and disuccinate. After detection, the selectivity of monosuccinate is 20.2 - 22.1 mol%, and the selectivity of disuccinate is 77.5 - 79.5 mol%. The specific operating conditions, corresponding catalysts and results of Examples 21 - 24 are shown in Tables 1 and 2.

[0093] As can be seen from Tables 1 and 2, using diethylaminoethanol, ethylene glycol, polyethylene glycol 200 or dipropylene glycol as absorbents respectively, the maleic anhydride gas stream is bubbled and absorbed through the beds of solid acid catalysts Amberlyst 15 (A-15), Amberlyst 35 (A-35), HM or WO3 / ZrO2. Under their respective operating conditions, the gas-phase maleic anhydride absorption rate is 99.2 - 99.8 mol%, and the esterification rate of maleic anhydride reacting with the alcohol absorbent to form maleate is 100 mol%. The obtained absorption liquids are respectively subjected to slurry-phase hydrogenation reaction under the action of supported powder catalysts Pd / γ-Al2O3 or Pd / SiO2. The double bond conversion rate is 100 mol%, and the selectivity of the target product succinate is greater than 99.3 mol%.

[0094] Examples 25 - 28

[0095] The preparation of disuccinate by the absorption esterification and catalytic hydrogenation of maleic anhydride gas stream uses a solid acid esterification catalyst, bubbling absorption esterification, a fixed-bed hydrogenation reactor and a supported metal particle catalyst, and specifically includes the following steps:

[0096] (1) The gaseous crude maleic anhydride, the product of the oxidation of butane in the industrial maleic anhydride plant, is quenched to 90 - 120 °C and fed from the bottom into a bubbling absorption tower filled with solid acid particle catalyst, while the alcohol absorption solvent at 70 - 80 °C is fed from the top. After 1-stage absorption esterification, a maleate concentration of 25 - 30 wt% (the disuccinate accounts for 83.5 - 85.2 mol%)

[0097] and an absorption liquid at a temperature of 76 - 90 °C are obtained;

[0098] (2) The absorption liquid and hydrogen gas are fed into a fixed-bed hydrogenation reactor filled with supported metal particle catalyst in parallel or countercurrent. Under the operating conditions of an absorption liquid temperature of 76 - 90 °C, a maleate concentration of 25 - 30 wt%, a feed weight hourly space velocity of 2.0 h -1 , a hydrogen pressure of 1.5 - 3.0 MPa and a hydrogen-to-ester molar ratio of 20 - 30, double bond hydrogenation is carried out to prepare succinate;

[0099] (3) The material after the hydrogenation reaction is subjected to gas-liquid separation, and the hydrogen is sent back to the hydrogenation reactor for recycling. The liquid material is filtered to recover the hydrogenation catalyst and recycled. The liquid is sent into the separation and purification system, the absorbent is recovered and recycled through separation, and the remaining material is further refined to obtain the target products of monosuccinate and disuccinate. Among them, the selectivity of monosuccinate is 14.5-16.4 mol%, and the selectivity of disuccinate is 83.2-85.0 mol%. The specific operating conditions, corresponding catalysts and results of Examples 25-28 are shown in Tables 1 and 2.

[0100] As can be seen from Tables 1 and 2, using 1,3-propanediol, 1,4-butanediol, 2-methyl-1,3-propanediol or butenediol as absorbents respectively, the maleic anhydride gas stream passes through the solid acid catalysts Nafinon-H, Cs 2.5 H 0.5 PW 12 O 40 (HPA), SO4 2- / ZrO2 or HZSM-5 beds for bubble absorption. Under their respective operating conditions, the gas-phase maleic anhydride absorption rate is 93.5-95.6 mol%, and the esterification rate of maleic anhydride reacting with the alcohol absorbent to form maleate is 100 mol%. The obtained absorption liquid is subjected to trickle-bed or bubble-bed hydrogenation reaction under the action of the supported particulate catalysts Pd / γ-Al2O3 or Pd / SiO2, and the double-bond conversion rate is 100 mol%, and the selectivity of the target product succinate is greater than 99.8 mol%.

[0101] Looking at the absorbents, esterification catalysts and absorption esterification processes for the absorption of maleic anhydride gas stream in Examples 1-28 listed in Tables 1 and 2, the hydrogenation catalysts and hydrogenation processes of the absorption liquid, as well as the absorption esterification and hydrogenation reaction results, it can be seen that: 1) When the temperature of the maleic anhydride gas stream is 60-150 °C, the temperature of the alcohol absorbent is 55-85 °C and no acid catalyst is used, after 1-3 stages of spray or bubble absorption esterification, the obtained absorption liquid has a temperature of 58-98 °C and a maleic acid monoester concentration of 15-40 wt%, the gas-phase maleic anhydride absorption rate is 92.5-99.5 mol%, and the esterification rate of maleic anhydride reacting with the alcohol absorbent to form maleic acid monoester is 98.5-100 mol%; this absorption liquid is under the action of a supported noble metal catalyst, using a slurry bed or fixed bed process, at a feed weight hourly space velocity of 0.5-5.0 h -1, the double bond hydrogenation reaction is carried out under a hydrogen pressure of 1.0 - 2.0 MPa and a hydrogen - to - ester molar ratio of 10 - 30. The conversion rate of the double bond is greater than 99.9 mol%, and the selectivity of the target product monosuccinate is greater than 99.2 mol%. 2) Under the conditions of a maleic anhydride gas flow temperature of 65 - 120 °C, an alcohol absorbent temperature of 45 - 80 °C and using a liquid acid or solid acid catalyst, after 1 - 3 - stage bubbling absorption esterification, the obtained absorption liquid has a temperature of 55 - 98 °C and a maleate concentration of 25 - 48 wt%. The gas - phase maleic anhydride absorption rate is 92.5 - 100 mol%, and the esterification rate of maleic anhydride reacting with the alcohol absorbent to form maleate is 100 mol% (the proportion of diester is 75.5 - 85.2 mol%); under the action of a supported noble metal catalyst, the absorption liquid adopts a slurry bed or fixed - bed process, and the weight hourly space velocity of the feed is 0.5 - 2.0 h -1 , the double bond hydrogenation reaction is carried out under a hydrogen pressure of 1.0 - 3.0 MPa and a hydrogen - to - ester molar ratio of 10 - 30. The conversion rate of the double bond is greater than 99.8 mol%, and the total selectivity of the target product succinate is greater than 99.3 mol%, among which the monoesters selectivity is 14.5 - 24.4 mol% and the diesters selectivity is 75.3 - 85.0 mol%.

[0102] Comparative Example 1

[0103] Using the existing technology, starting from the maleic anhydride gas flow, through maleic anhydride, maleic anhydride esterification and hydrogenation of the esterification product to produce methyl succinate, specifically including the following steps:

[0104] 1) Absorption - desorption of gas - phase maleic anhydride, purification of crude maleic anhydride and recycling of the solvent

[0105] The butane oxidation product gas (gaseous crude maleic anhydride) of the industrial maleic anhydride unit is quenched to ~120°C and fed into the spray absorption tower from the bottom. The 55°C dibutyl phthalate (DBP) absorbent is sprayed from the top of the tower. After two-stage absorption, an absorption liquid with a maleic anhydride concentration of ~18 wt% and a temperature of 65°C is obtained. The absorption liquid is directly fed from the solvent absorption tower into the solvent desorption tower, and the crude maleic anhydride containing light components is separated from the solvent containing heavy components through negative pressure flashing. The crude maleic anhydride is fed into the product refining system. By-products such as acetic acid and acrylic acid are removed under negative pressure in the light component removal tower, and maleic anhydride product is obtained through distillation in the product tower. The solvent containing heavy components enters the demineralized water washing tower. After washing and extracting the acidic components, the aqueous phase and the solvent phase are separated. The solvent, dibutyl orthophthalate, is sent back to the solvent absorption tower for recycling, and the aqueous phase is fed into the wastewater treatment system. Operating conditions of the maleic anhydride product refining system: the top pressure of the light component removal tower is 10 kPa, the top temperature is 130°C, and the bottom temperature is 170°C; the product tower is at 5 kPa, the top temperature is 130°C, and the bottom temperature is 140°C. The gas-phase maleic anhydride absorption rate is 99.50 mol%, the solvent recovery rate is 99.55 mol%, the total yield of maleic anhydride absorption and refining is 97.0 mol% (maleic anhydride entering the tail gas is ~0.50 mol%, and maleic anhydride lost in the formation of maleic acid and fumaric acid and entering the solvent system is ~2.20 mol%), and the purity of the product maleic anhydride is 99.68 wt%.

[0106] 2) Preparation of monomethyl succinate by esterification - hydrogenation and separation and purification of maleic anhydride and methanol

[0107] The product maleic anhydride and methanol are mixed according to the mass ratio of maleic anhydride: methanol = 1.00:1.50 and fed into the esterification reactor. The esterification reaction is carried out at a temperature of 65°C and a feed volume (relative to the reactor volume) space velocity of 0.5 h -1 to obtain an esterification liquid containing monomethyl maleate. The esterification liquid and hydrogen are fed into the slurry bed hydrogenation reactor in parallel. At a 5.0 wt% Pd / C catalyst dosage of 2.00 wt% of the esterification liquid, a temperature of 65°C, a feed weight space velocity of 0.5 h -1 (relative to the catalyst weight), a hydrogen pressure of 1.0 MPa, and a hydrogen - ester molar ratio of 20, the double - bond hydrogenation is carried out to prepare monomethyl succinate. The post - reaction logistics is subjected to gas - liquid separation, the hydrogen is sent back to the hydrogenation reactor for recycling, the liquid material is filtered to recover the Pd / C catalyst and recycled, and the liquid is fed into the separation and purification system. The maleic anhydride esterification rate is 99.8 mol%, the double - bond hydrogenation conversion rate is 100 mol%, and the monomethyl succinate selectivity is 98.8 mol%.

[0108] 3) Preparation of dimethyl succinate by esterification - hydrogenation and separation and purification of maleic anhydride and methanol

[0109] Maleic anhydride, methanol, and p-toluenesulfonic acid were mixed in a mass ratio of 1.00:2.50:0.07, and the resulting maleic anhydride product and methanol were fed into a reaction kettle. The esterification reaction was carried out at a temperature of 65 °C and a feed volume (relative to the reactor volume) space velocity of 0.2 h -1 to obtain an esterification solution containing methyl maleate (with a dimethyl ester content of 78.5%). The esterification solution and hydrogen were fed into a slurry bed hydrogenation reactor in parallel. At a 5.0 wt% Pd / C catalyst dosage of 2.0 wt% of the esterification solution, a temperature of 65 °C, a feed weight space velocity of 0.5 h -1 (relative to the catalyst weight), a hydrogen pressure of 1.0 MPa, and a hydrogen / ester molar ratio of 20, the double bond was hydrogenated to prepare methyl succinate. The post-reaction logistics were subjected to gas-liquid separation, and the hydrogen was sent back to the hydrogenation reactor for recycling. The liquid material was filtered to recover the Pd / C catalyst for recycling, and the liquid was fed into a separation and purification system. The maleic anhydride esterification rate was 100 mol%, the double bond hydrogenation conversion rate was 100 mol%, and the total selectivity of methyl succinate was 99.2 mol%.

[0110] Table 1 Alcohol absorbents, esterification catalysts, absorption and esterification conditions, and results used in the examples and comparative examples

[0111]

[0112]

[0113] Table 2 Catalysts, reaction conditions, and results used for hydrogenation of the absorption and esterification solution in the examples and comparative examples

[0114]

[0115]

[0116] By comparing Examples 1 to 28 with Comparative Example 1, it can be concluded that the present invention adopts an overall integrated process of absorption-esterification-hydrogenation, and uses industrial gaseous crude maleic anhydride as the starting material to prepare maleate and succinate. An alcohol is used as the absorbent for the gaseous maleic anhydride stream at the outlet of the maleic anhydride oxidation device. In the presence or absence of an acid catalyst, an esterification reaction occurs while absorbing gaseous maleic anhydride to form monoester or diester of maleic acid, and then the absorbent liquid is directly subjected to double bond hydrogenation to form monoester or diester of succinic acid. This avoids the cumbersome processes of solvent absorption, solvent desorption, solvent purification, and crude maleic anhydride refining in the existing maleic anhydride production technology using dibutyl phthalate (DBP) as the absorbent, as well as the problems of pipeline and equipment blockage caused by polymerization of impurity acrylic acid and crystallization of maleic acid and fumaric acid. It also eliminates the process of separately preparing maleate by esterifying maleic anhydride and the loss of maleic anhydride due to hydrolysis to form maleic acid and fumaric acid during the DBP absorption of gaseous maleic anhydride, thereby reducing the yield of maleic anhydride. Therefore, the method for producing succinate of the present invention has a short process flow, high efficiency; inexpensive raw materials, material savings; low device investment, large production capacity, low operating energy consumption, and few three wastes, and can greatly reduce production costs.

[0117] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for producing succinates using a maleic anhydride gas stream, characterized in that: The steps include: (1) Using RR 1 R 2 COH alcohol is used as an absorption solvent to absorb and esterify gaseous crude maleic anhydride in the presence or absence of an acid catalyst to prepare maleic acid esters; (2) subjecting the succinate obtained in step (1) to a double bond selective hydrogenation reaction in the presence of a metal catalyst to prepare a succinate; Among them, RR 1 R 2 COH is a single alcohol or a mixed alcohol, R, R 1 and R 2 They are respectively selected from one of the same or different groups selected from H, halogen, hydroxyl, heterocyclic group, hydroxyalkyl, alkyl or halogenated alkyl, the butenedioic acid ester includes butenedioic acid monoester or / and diester, and the succinic acid ester includes succinic acid monoester or / and diester.

2. The method according to claim 1, characterized in that The RR 1 R 2 COH alcohol R, R 1 and R 2 Each of the following groups is selected from H, Cl, F or a C1-C9 alkyl, alkenyl, alkynyl, aryl, oxygen-containing heterocyclic group, hydroxyalkyl, hydroxyalkenyl, hydroxyalkynyl, hydroxyaryl, alkylamine or halogenated alkyl, which may be the same or different; Preferably, the RR 1 R 2 The COH alcohol is selected from the group consisting of n-butanol, isobutanol, tert-butanol, n-pentanol, isopentanol, 3-methylbutanol, neopentyl alcohol, n-hexanol, 2-methylpentanol, 3-methylpentanol, 2,2-dimethylbutanol, 3,3-dimethylbutanol, n-heptanol, isoheptanol, n-octanol, isooctyl alcohol, 2-ethylhexanol, n-nonanol, isononanol, n-decanol, lauryl alcohol, myristyl alcohol, palmityl alcohol, stearyl alcohol, cyclopentanol, cyclohexanol, methylcyclohexanol, cyclohexylethanol, cyclohexylpropanol, allyl alcohol, butanol 1,2-Butanediol, 1,3-Butanediol, 1,4-Butanediol, 1,5-Pentanediol, 1,6-Hexanediol, 1,6-Hexanediol, 1,2-Butanediol, 1,3-Butanediol, 1,4-Butanediol, 1,5-Pentanediol, 1,6-Hex ...2-Pentanediol, 2-Pentanediol, 2-Pentanediol, 2-Pentanediol, 2-Pentanediol, 2-Pentanediol, 2-Pentanediol, 2-Pentanediol, 2-Pentanediol, 2-Pentanediol, 2-Pentanediol diol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 2-methyl-1,3-propanediol, neopentyl glycol, 2-ethyl-2-methyl-1,3-propanediol, 2-isopropyl-2-methyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 2-n-butyl-2-ethyl-1,3-propanediol, cyclohexanediol, cyclohexanedimethanol, 1-phenyl-1,3-propanediol, 2-phenyl-1,3- Propylene glycol, 1-phenyl-1,4-butanediol, benzyl alcohol, 2,5-furan dimethanol, glycerol, trimethylolethane, 1,2,6-hexanetriol, trimethylolpropane, erythritol, pentaerythritol, xylitol, sorbitol, mannitol, inositol, butene glycol, butynediol, diethylaminoethanol, diethylaminopropanol, or at least one of 2,2,2-trifluoroethanol, pentafluoroethanol, heptafluoropropanol, 2,2,2-trichloroethanol, chloropropanol or 1,3-dichloropropanol.

3. The method according to claim 1, characterized in that: In step (1), the process flow of preparing maleic acid ester by absorption esterification of gaseous crude maleic anhydride comprises the following process: cooling the gaseous crude maleic anhydride to 55-180° C. and feeding it into a spray absorption tower from the bottom, spraying an alcohol absorption solvent containing 0-10.0 wt% of a liquid acid catalyst at 25-85° C. from the top of the tower, and operating the maleic anhydride gas flow in countercurrent with the absorbent; or cooling the gaseous crude maleic anhydride to 55-180° C. and feeding it into a bubbling absorption tower filled with an inert filler or a solid acid particle catalyst from the bottom, and feeding an alcohol absorption solvent at 25-85° C. from the bottom or the top of the absorption tower, and operating in parallel or countercurrent with the maleic anhydride gas flow; after absorption esterification in the spray absorption tower or the bubbling absorption tower, an absorption esterification liquid with a maleic acid ester concentration of 10-50 wt% and a temperature of 52-150° C. is obtained; Preferably, the gaseous crude maleic anhydride is quenched to 60-150°C, the alcohol absorption solvent temperature is 30-80°C, the absorption esterification adopts 1-3 stages, the concentration of maleic acid ester in the absorption esterification liquid is controlled to be 15-45wt%, and the temperature is controlled to be 55-120°C; More preferably, the gaseous crude maleic anhydride is quenched to 65-120°C, the alcohol absorbent temperature is 35-75°C, the absorption esterification adopts 1-2 stages, the concentration of maleic acid ester in the absorption esterification liquid is controlled to be 20-40wt%, and the temperature is controlled to be 60-90°C.

4. The method according to claim 3, characterized in that In step (1), when a spray absorption tower is selected, the concentration of the liquid acid catalyst is 0 to 5.0 wt%, preferably 0 to 2.0 wt%.

5. The method according to claim 1, characterized in that: In step (1), the acid catalyst is selected from a liquid acid catalyst and / or a solid acid catalyst, wherein: The liquid acid catalyst is selected from one of alkyl sulfonic acid, aryl sulfonic acid, halogenated sulfonic acid, halogenated carboxylic acid, amide or imide of halogenated sulfonic acid; preferably, the liquid acid catalyst is selected from at least one of methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, β-naphthalenesulfonic acid, fluorosulfonic acid, trifluoromethanesulfonic acid, pentafluoroethanesulfonic acid, trichloroacetic acid, trifluoroacetic acid or pentafluoropropionic acid, or trifluoromethanesulfonamide, bisfluorosulfonimide or bistrifluoromethanesulfonimide; The solid acid catalyst is selected from at least one of hydrogen-type zeolite molecular sieve, acidic oxide, solid superacid or strong acidic cation exchange resin; The solid acid catalyst is selected from spherical particles with a diameter of 0.4 to 5.0 mm or strips, cylinders or irregular particles with a diameter of 1.0 to 5.0 mm and a length of 2.0 to 8.0 mm; preferably, the solid acid catalyst is selected from spherical particles with a diameter of 0.5 to 4.0 mm or strips, cylinders or cloverleaf particles with a diameter of 1.6 to 4.5 mm and a length of 2.0 to 6.0 mm; more preferably, the solid acid catalyst is selected from spherical particles with a diameter of 0.6 to 3.0 mm or cylindrical particles with a diameter of 2.0 to 4.0 mm and a length of 2.0 to 4.0 mm.

6. The method according to claim 5, characterized in that The hydrogen-type zeolite molecule is selected from at least one of HM, Hβ, HZSM-5, HZSM-11, HZSM-22, HZSM-23, HZSM-35, HMCM-22, HMCM-49 or HMCM-56; the acidic oxide is selected from γ-Al2O3, SiO2-Al2O3, Nb2O5, Zr(HPO4)2, H2TiO3, H3PO4, H6TeO6, H3PW 12 O 40 、H3PMo 12 O 40 、H4SiW 12 O 40 、H4SiMo 12 O 40 or Cs 2.5 H 0.5 PW 12 O 40 At least one of; the solid superacid is selected from SO4 2- / ZrO2、SO4 2- / TiO2、SO4 2- / Fe2O3、SO4 2- / ZrO2-La2O3, SO4 2- / ZrO2-CeO2, SO4 2- / TiO2-ZrO2, SO4 2- / ZrO2-CeO2-Fe2O3, WO3 / ZrO2 or MoO3 / ZrO2; the strongly acidic macroporous cation exchange resin is selected from at least one of Amberlyst 15, Amberlyst 16, Amberlyst 35, NKC-9, HPK-16, D-61, D-72, D-113, D-732, T-62, SB-DH, CR-11, chlorinated or fluorinated resin.

7. The method according to claim 1, characterized in that In step (2), the process flow of preparing succinate by hydrogenating succinate ester includes the following process: The absorption liquid in step (1) is fed into a hydrogenation reactor, and operated in parallel or countercurrent with hydrogen, and double bonds of succinate are hydrogenated to prepare succinate in the presence of a supported metal catalyst at the temperature and concentration of the absorption liquid, and the materials after the reaction are subjected to gas-liquid separation, and the separated hydrogen is circulated to the hydrogenation reactor for recycling; the hydrogenation reactor is selected from a slurry bed reactor or a fixed bed reactor; The supported metal catalyst is selected from at least one supported precious metal catalyst selected from activated carbon, mesoporous carbon, carbon nanotubes, graphene, Al2O3, SiO2, Al2O3-SiO2, TiO2, ZrO2, HM, Hβ, HZSM-5, HMCM-22, HMCM-41, HMCM-48 or SBA-15; preferably, the precious metal is selected from one or more of Ru, Pd or Pt.

8. The method according to claim 7, characterized in that In step (2), when the hydrogenation reactor is a slurry bed reactor, a supported precious metal powder catalyst is used, the liquid phase material after gas-liquid separation of the reacted material is subjected to solid-liquid separation, the catalyst of the hydrogenation reaction is recovered and recycled, and the separated liquid is sent to a subsequent refining system; or, When the hydrogenation reactor is a fixed bed reactor, the fixed bed reactor is filled with a supported metal particle catalyst, and the liquid phase material after the reaction is separated by gas and liquid is sent to the subsequent refining system; the fixed bed reactor is a trickle bed or a bubbling bed reactor.

9. The method according to claim 8, characterized in that In step (2), when a slurry bed reactor is used, the supported metal powder catalyst and the absorption liquid of step (1) are first mixed and stirred to obtain a slurry, and then fed into the slurry bed reactor in parallel or countercurrent with hydrogen for hydrogenation reaction, wherein the amount of the supported metal powder catalyst is 1.0 to 5.0 wt % of the absorption liquid.

10. The method according to claim 1, characterized in that In step (2), the reaction process conditions for preparing succinate by hydrogenation of succinate ester are: The feed absorption liquid has a butyrate concentration of 10-50 wt%, a temperature of 52-150°C, and a weight hourly space velocity of 0.1-10.0 h -1 , hydrogen pressure is 0.2-5.0 MPa and hydrogen-ester molar ratio is 2-50; Preferably, the concentration of butenedioic acid ester in the feed absorption liquid is 15-45wt%, the temperature is 55-120°C, and the weight hourly space velocity is 0.5-5.0h -1 , hydrogen pressure is 0.5-3.0MPa and hydrogen-ester molar ratio is 5-30; More preferably, the concentration of butenedioic acid ester in the feed absorption liquid is 20-40 wt%, the temperature is 60-90°C, and the weight hourly space velocity is 1.0-2.0 h -1 , the hydrogen pressure is 1.0-2.0 MPa and the hydrogen-ester molar ratio is 10-20.

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