CN115322092A - Method for preparing dimethyl maleate by using maleic anhydride tail gas - Google Patents
Method for preparing dimethyl maleate by using maleic anhydride tail gas Download PDFInfo
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- CN115322092A CN115322092A CN202211112422.9A CN202211112422A CN115322092A CN 115322092 A CN115322092 A CN 115322092A CN 202211112422 A CN202211112422 A CN 202211112422A CN 115322092 A CN115322092 A CN 115322092A
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- maleic anhydride
- methanol
- sulfonic acid
- heat exchange
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- FPYJFEHAWHCUMM-UHFFFAOYSA-N maleic anhydride Chemical compound O=C1OC(=O)C=C1 FPYJFEHAWHCUMM-UHFFFAOYSA-N 0.000 title claims abstract description 220
- LDCRTTXIJACKKU-ARJAWSKDSA-N dimethyl maleate Chemical compound COC(=O)\C=C/C(=O)OC LDCRTTXIJACKKU-ARJAWSKDSA-N 0.000 title claims abstract description 70
- 238000000034 method Methods 0.000 title claims abstract description 44
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims abstract description 321
- 238000010521 absorption reaction Methods 0.000 claims abstract description 130
- 239000007788 liquid Substances 0.000 claims abstract description 126
- 238000005886 esterification reaction Methods 0.000 claims abstract description 72
- 239000012452 mother liquor Substances 0.000 claims abstract description 21
- 239000002994 raw material Substances 0.000 claims abstract description 21
- LSNNMFCWUKXFEE-UHFFFAOYSA-M Bisulfite Chemical compound OS([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-M 0.000 claims abstract description 20
- 238000000926 separation method Methods 0.000 claims abstract description 19
- 239000003377 acid catalyst Substances 0.000 claims abstract description 18
- IJDNQMDRQITEOD-UHFFFAOYSA-N n-butane Chemical compound CCCC IJDNQMDRQITEOD-UHFFFAOYSA-N 0.000 claims abstract description 15
- 238000002156 mixing Methods 0.000 claims abstract description 13
- 230000001590 oxidative effect Effects 0.000 claims abstract description 7
- 230000032050 esterification Effects 0.000 claims description 24
- 238000006243 chemical reaction Methods 0.000 claims description 22
- 239000011259 mixed solution Substances 0.000 claims description 20
- JOXIMZWYDAKGHI-UHFFFAOYSA-N toluene-4-sulfonic acid Chemical compound CC1=CC=C(S(O)(=O)=O)C=C1 JOXIMZWYDAKGHI-UHFFFAOYSA-N 0.000 claims description 12
- 229940092714 benzenesulfonic acid Drugs 0.000 claims description 10
- 239000002253 acid Substances 0.000 claims description 9
- -1 alkyl sulfonic acid Chemical compound 0.000 claims description 9
- SRSXLGNVWSONIS-UHFFFAOYSA-N benzenesulfonic acid Chemical compound OS(=O)(=O)C1=CC=CC=C1 SRSXLGNVWSONIS-UHFFFAOYSA-N 0.000 claims description 9
- AFVFQIVMOAPDHO-UHFFFAOYSA-N Methanesulfonic acid Chemical compound CS(O)(=O)=O AFVFQIVMOAPDHO-UHFFFAOYSA-N 0.000 claims description 8
- CTIFKKWVNGEOBU-UHFFFAOYSA-N 2-hexadecylbenzenesulfonic acid Chemical compound CCCCCCCCCCCCCCCCC1=CC=CC=C1S(O)(=O)=O CTIFKKWVNGEOBU-UHFFFAOYSA-N 0.000 claims description 6
- 150000004996 alkyl benzenes Chemical class 0.000 claims description 6
- KCXFHTAICRTXLI-UHFFFAOYSA-N propane-1-sulfonic acid Chemical compound CCCS(O)(=O)=O KCXFHTAICRTXLI-UHFFFAOYSA-N 0.000 claims description 5
- WBIQQQGBSDOWNP-UHFFFAOYSA-N 2-dodecylbenzenesulfonic acid Chemical compound CCCCCCCCCCCCC1=CC=CC=C1S(O)(=O)=O WBIQQQGBSDOWNP-UHFFFAOYSA-N 0.000 claims description 4
- 229940060296 dodecylbenzenesulfonic acid Drugs 0.000 claims description 4
- 229940098779 methanesulfonic acid Drugs 0.000 claims description 4
- UDTHXSLCACXSKA-UHFFFAOYSA-N 3-tetradecylbenzenesulfonic acid Chemical compound CCCCCCCCCCCCCCC1=CC=CC(S(O)(=O)=O)=C1 UDTHXSLCACXSKA-UHFFFAOYSA-N 0.000 claims description 3
- QJRVOJKLQNSNDB-UHFFFAOYSA-N 4-dodecan-3-ylbenzenesulfonic acid Chemical compound CCCCCCCCCC(CC)C1=CC=C(S(O)(=O)=O)C=C1 QJRVOJKLQNSNDB-UHFFFAOYSA-N 0.000 claims description 3
- 150000008107 benzenesulfonic acids Chemical class 0.000 claims description 3
- CCIVGXIOQKPBKL-UHFFFAOYSA-M ethanesulfonate Chemical compound CCS([O-])(=O)=O CCIVGXIOQKPBKL-UHFFFAOYSA-M 0.000 claims description 3
- 238000002360 preparation method Methods 0.000 claims description 3
- ITMCEJHCFYSIIV-UHFFFAOYSA-N triflic acid Chemical compound OS(=O)(=O)C(F)(F)F ITMCEJHCFYSIIV-UHFFFAOYSA-N 0.000 claims description 3
- 238000010438 heat treatment Methods 0.000 claims 1
- 238000004519 manufacturing process Methods 0.000 claims 1
- 238000005265 energy consumption Methods 0.000 abstract description 5
- 238000009776 industrial production Methods 0.000 abstract description 5
- 238000003786 synthesis reaction Methods 0.000 abstract description 2
- NIQCNGHVCWTJSM-UHFFFAOYSA-N Dimethyl phthalate Chemical compound COC(=O)C1=CC=CC=C1C(=O)OC NIQCNGHVCWTJSM-UHFFFAOYSA-N 0.000 description 38
- FBSAITBEAPNWJG-UHFFFAOYSA-N dimethyl phthalate Natural products CC(=O)OC1=CC=CC=C1OC(C)=O FBSAITBEAPNWJG-UHFFFAOYSA-N 0.000 description 19
- 229960001826 dimethylphthalate Drugs 0.000 description 19
- NKHAVTQWNUWKEO-UHFFFAOYSA-N fumaric acid monomethyl ester Natural products COC(=O)C=CC(O)=O NKHAVTQWNUWKEO-UHFFFAOYSA-N 0.000 description 19
- NKHAVTQWNUWKEO-IHWYPQMZSA-N methyl hydrogen fumarate Chemical compound COC(=O)\C=C/C(O)=O NKHAVTQWNUWKEO-IHWYPQMZSA-N 0.000 description 19
- 238000007254 oxidation reaction Methods 0.000 description 11
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 10
- 238000001816 cooling Methods 0.000 description 9
- 239000003960 organic solvent Substances 0.000 description 7
- 238000011084 recovery Methods 0.000 description 5
- 239000000945 filler Substances 0.000 description 4
- 230000003647 oxidation Effects 0.000 description 4
- 239000000243 solution Substances 0.000 description 4
- IXSGUIFSMPTAGW-UHFFFAOYSA-N 2-(trifluoromethyl)benzenesulfonic acid Chemical compound OS(=O)(=O)C1=CC=CC=C1C(F)(F)F IXSGUIFSMPTAGW-UHFFFAOYSA-N 0.000 description 3
- 239000002351 wastewater Substances 0.000 description 3
- VZCYOOQTPOCHFL-OWOJBTEDSA-N Fumaric acid Chemical compound OC(=O)\C=C\C(O)=O VZCYOOQTPOCHFL-OWOJBTEDSA-N 0.000 description 2
- 230000002745 absorbent Effects 0.000 description 2
- 239000002250 absorbent Substances 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- DOIRQSBPFJWKBE-UHFFFAOYSA-N dibutyl phthalate Chemical compound CCCCOC(=O)C1=CC=CC=C1C(=O)OCCCC DOIRQSBPFJWKBE-UHFFFAOYSA-N 0.000 description 2
- 238000004821 distillation Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- VZCYOOQTPOCHFL-UHFFFAOYSA-N trans-butenedioic acid Natural products OC(=O)C=CC(O)=O VZCYOOQTPOCHFL-UHFFFAOYSA-N 0.000 description 2
- XMTOUDRCWLYEHL-UHFFFAOYSA-N (2-bromo-3-ethoxy-6-fluorophenyl)boronic acid Chemical compound CCOC1=CC=C(F)C(B(O)O)=C1Br XMTOUDRCWLYEHL-UHFFFAOYSA-N 0.000 description 1
- OFOBLEOULBTSOW-UHFFFAOYSA-N Propanedioic acid Natural products OC(=O)CC(O)=O OFOBLEOULBTSOW-UHFFFAOYSA-N 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- ANSWCYTXKAIJOK-UHFFFAOYSA-N dibutyl cyclohexane-1,2-dicarboxylate Chemical compound CCCCOC(=O)C1CCCCC1C(=O)OCCCC ANSWCYTXKAIJOK-UHFFFAOYSA-N 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000001530 fumaric acid Substances 0.000 description 1
- VZCYOOQTPOCHFL-UPHRSURJSA-N maleic acid Chemical compound OC(=O)\C=C/C(O)=O VZCYOOQTPOCHFL-UPHRSURJSA-N 0.000 description 1
- 239000011976 maleic acid Substances 0.000 description 1
- 239000010413 mother solution Substances 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C67/00—Preparation of carboxylic acid esters
- C07C67/08—Preparation of carboxylic acid esters by reacting carboxylic acids or symmetrical anhydrides with the hydroxy or O-metal group of organic compounds
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D307/00—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom
- C07D307/02—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings
- C07D307/34—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings having two or three double bonds between ring members or between ring members and non-ring members
- C07D307/56—Heterocyclic compounds containing five-membered rings having one oxygen atom as the only ring hetero atom not condensed with other rings having two or three double bonds between ring members or between ring members and non-ring members with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
- C07D307/60—Two oxygen atoms, e.g. succinic anhydride
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention belongs to the technical field of organic synthesis, and particularly relates to a method for preparing dimethyl maleate by using maleic anhydride tail gas. The invention provides a method for preparing dimethyl maleate by using maleic anhydride tail gas, which comprises the following steps: carrying out heat exchange on the mixed gas containing maleic anhydride and methanol to obtain the mixed gas containing maleic anhydride after heat exchange and the methanol after heat exchange; mixing the mixed gas containing maleic anhydride after heat exchange with the absorption liquid for countercurrent absorption to obtain mixed liquid containing maleic anhydride; mixing the mixed liquid containing maleic anhydride and methanol obtained after heat exchange for esterification reaction, and separating the obtained esterified liquid to obtain the dimethyl maleate and a separation mother liquid; the separation mother liquor is reused as absorption liquid; the absorption liquid comprises dimethyl maleate and an organic sulfonic acid catalyst; the mixed gas containing maleic anhydride is obtained by oxidizing n-butane serving as a raw material. The method provided by the invention has the advantages that the cost of raw materials is low; and the energy consumption is low, and the method is suitable for industrial production.
Description
Technical Field
The invention belongs to the technical field of organic synthesis, and particularly relates to a method for preparing dimethyl maleate by using maleic anhydride tail gas.
Background
The method is characterized in that n-butane is used as a raw material to obtain high-temperature mixed gas containing maleic anhydride through oxidation, and at present, two methods are mainly adopted to recover the maleic anhydride, including a water recovery process and an organic solvent recovery process.
The water recovery process has the advantages that water which is cheap and easy to obtain is used as an absorbent, and the chemical absorption rate is high. However, maleic acid and fumaric acid generated by the reaction of maleic anhydride and water easily corrode equipment to block pipelines, so that the yield of maleic anhydride is low, and a large amount of wastewater is easily generated.
The organic solvent absorption process is to absorb maleic anhydride by using an organic solvent as an absorbent, and the currently commonly used organic solvents comprise dibutyl phthalate, dibutyl hexahydrophthalate and diisobutyl hexahydrophthalate. The organic solvent absorption process effectively overcomes the defects of easy corrosion of equipment, low yield of maleic anhydride and large amount of wastewater existing in the water absorption process, and gradually replaces the water recovery process to become the main recovery method of maleic anhydride. However, the cost of the organic solvent is high, and the maleic anhydride product can be obtained only by rectification separation after maleic anhydride is absorbed, so that the energy consumption is high, and the method is not suitable for industrial production.
Disclosure of Invention
The invention aims to provide a method for preparing dimethyl maleate by using maleic anhydride tail gas, which has the advantages of low cost of raw materials, low energy consumption and suitability for industrial production.
In order to achieve the above purpose, the invention provides the following technical scheme:
the invention provides a method for preparing dimethyl maleate by using maleic anhydride tail gas, which comprises the following steps:
carrying out heat exchange on the mixed gas containing maleic anhydride and methanol to obtain the mixed gas containing maleic anhydride after heat exchange and the methanol after heat exchange;
mixing the mixed gas containing maleic anhydride after heat exchange with absorption liquid for countercurrent absorption to obtain mixed liquid containing maleic anhydride;
mixing the mixed liquid containing maleic anhydride and methanol obtained after heat exchange for esterification reaction, and separating the obtained esterified liquid to obtain the dimethyl maleate and a separated mother liquid;
the separation mother liquor is reused as absorption liquid;
the absorption liquid comprises dimethyl maleate and an organic sulfonic acid catalyst;
the mixed gas containing maleic anhydride is obtained by oxidizing n-butane serving as a raw material.
Preferably, the temperature of the mixed gas containing maleic anhydride is 120-250 ℃;
the mass ratio of the maleic anhydride in the absorption liquid to the maleic anhydride in the maleic anhydride-containing mixed gas is (0.01-0.1): 1.0.
preferably, the molar ratio of the heat-exchanged methanol to the maleic anhydride in the mixed liquid containing maleic anhydride after heat exchange is 2.0 to 8.0:1.
preferably, the methanol from the heat exchange is in the form of methanol vapor;
the temperature of the methanol steam is 80-160 ℃.
Preferably, the esterification reaction is carried out in an esterification reactor;
the esterification reactor is one or more of a packed tower, a bubble column, a plate tower, a tubular reactor, a loop reactor, a reaction kettle and a heat exchanger which are connected in series for use.
Preferably, the temperature of the esterification reaction is 80-150 ℃ and the time is 30-720 min.
Preferably, the organic sulfonic acid catalyst in the absorption liquid comprises one or more of alkyl sulfonic acid, halogenated alkyl sulfonic acid, benzene sulfonic acid and substituted benzene sulfonic acid.
Preferably, the alkyl sulfonic acid comprises one or more of methane sulfonic acid, ethane sulfonic acid and propane sulfonic acid;
the haloalkylsulfonic acid is preferably trifluoromethanesulfonic acid;
the substituted benzene sulphonic acid preferably comprises a linear alkyl benzene sulphonic acid and/or a branched alkyl benzene sulphonic acid;
the linear alkyl benzene sulfonic acid comprises one or more of p-toluenesulfonic acid, dodecyl benzene sulfonic acid, tetradecyl benzene sulfonic acid and hexadecyl benzene sulfonic acid.
Preferably, the mixed solution containing maleic anhydride includes maleic anhydride, dimethyl maleate and an organic sulfonic acid catalyst;
the mass of the organic sulfonic acid catalyst is 0.1-0.5% of that of maleic anhydride.
The invention provides a method for preparing dimethyl maleate by using maleic anhydride tail gas, which comprises the following steps: carrying out heat exchange on the mixed gas containing maleic anhydride and methanol to obtain the mixed gas containing maleic anhydride after heat exchange and the methanol after heat exchange; mixing the mixed gas containing maleic anhydride after heat exchange with absorption liquid for countercurrent absorption to obtain mixed liquid containing maleic anhydride; mixing the mixed liquid containing maleic anhydride and methanol obtained after heat exchange for esterification reaction, and separating the obtained esterified liquid to obtain the dimethyl maleate and a separation mother liquid; the separation mother liquor is reused as absorption liquid; the absorption liquid comprises dimethyl maleate and an organic sulfonic acid catalyst; the mixed gas containing maleic anhydride is obtained by oxidizing n-butane serving as a raw material. The maleic anhydride in the mixed gas containing maleic anhydride tail is absorbed by the dimethyl maleate absorption liquid containing the organic sulfonic acid catalyst, and then the maleic anhydride is directly subjected to esterification reaction with methanol, so that the maleic anhydride is not required to be recovered by using an organic solvent, and the cost of the raw material is low; and rectification is not needed, the energy consumption is low, and the method is suitable for industrial production.
Detailed Description
The invention provides a method for preparing dimethyl maleate by using maleic anhydride tail gas, which comprises the following steps:
carrying out heat exchange on the mixed gas containing maleic anhydride and methanol to obtain the mixed gas containing maleic anhydride after heat exchange and the methanol after heat exchange;
mixing the mixed gas containing maleic anhydride after heat exchange with absorption liquid for countercurrent absorption to obtain mixed liquid containing maleic anhydride;
mixing the mixed liquid containing maleic anhydride and methanol obtained after heat exchange for esterification reaction, and separating the obtained esterified liquid to obtain the dimethyl maleate and a separation mother liquid;
the separation mother liquor is reused as absorption liquid;
the absorption liquid comprises dimethyl maleate and an organic sulfonic acid catalyst;
the mixed gas containing maleic anhydride is obtained by oxidizing n-butane serving as a raw material.
In the present invention, all the starting materials for the preparation are commercially available products known to those skilled in the art unless otherwise specified.
The mixed gas containing maleic anhydride and methanol are subjected to heat exchange to obtain the mixed gas containing maleic anhydride and the methanol after the heat exchange.
In the invention, the mixed gas containing maleic anhydride is obtained by oxidizing n-butane serving as a raw material; the oxidation preferably comprises the steps of:
and (2) sequentially oxidizing and cooling by using n-butane as a raw material to obtain the mixed gas containing the maleic anhydride.
In the present invention, the temperature of the oxidation is preferably 450 ℃. The oxidation and cooling processes are not particularly limited in the present invention and may be performed by processes well known to those skilled in the art.
The heat exchange process is not particularly limited in the present invention, and may be performed by a process known to those skilled in the art. In a specific embodiment of the present invention, the heat exchange process is preferably as follows: and (3) carrying out heat exchange on the mixed gas containing the maleic anhydride sequentially through a methanol superheater and a methanol reboiler to obtain the mixed gas containing the maleic anhydride after heat exchange and the methanol after heat exchange.
In the present invention, the temperature of the mixed gas containing maleic anhydride after the heat exchange is preferably 120 to 250 ℃, more preferably 130 to 240 ℃, and still more preferably 140 to 230. In the present invention, the temperature of the methanol after the heat exchange is preferably 80 to 160 ℃, more preferably 90 to 150 ℃, and still more preferably 100 to 140 ℃. In the present invention, the heat-exchanged methanol is preferably present in the form of a gas. In the present invention, the heat-exchanged methanol is preferably used as a raw material for the second-stage mixing to perform the esterification reaction.
In the present invention, the molar percentage of maleic anhydride in the mixed gas containing maleic anhydride after the heat exchange is preferably 1.0 to 5.0mol%.
After the mixed gas containing maleic anhydride and the methanol are obtained after heat exchange, the mixed gas containing maleic anhydride and the absorption liquid are mixed for countercurrent absorption to obtain mixed liquid containing maleic anhydride.
In the invention, the absorption liquid comprises dimethyl maleate and an organic sulfonic acid catalyst. The absorption liquid preferably comprises 80.0-96.0 wt% of dimethyl maleate and 0.1-5.0 wt% of organic sulfonic acid catalyst by mass percentage. In the present invention, the absorption liquid preferably further comprises 1.0 to 5.0wt% of monomethyl maleate and 2 to 10wt% of dimethyl phthalate.
In the invention, the organic sulfonic acid catalyst preferably comprises one or more of alkyl sulfonic acid, halogenated alkyl sulfonic acid, benzene sulfonic acid and substituted benzene sulfonic acid; the alkyl sulfonic acid preferably comprises one or more of methane sulfonic acid, ethane sulfonic acid and propane sulfonic acid; the haloalkylsulfonic acid is preferably trifluoromethanesulfonic acid; the substituted benzene sulphonic acid preferably comprises a linear alkyl benzene sulphonic acid and/or a branched alkyl benzene sulphonic acid; the linear alkyl benzene sulfonic acid further preferably comprises one or more of p-toluene sulfonic acid, deca-alkyl benzene sulfonic acid, dodecyl benzene sulfonic acid, tetradecyl benzene sulfonic acid and hexadecyl benzene sulfonic acid. In the present invention, when the organic sulfonic acid catalyst is two or more selected from the above-mentioned groups, the ratio of the specific substance in the present invention is not particularly limited, and the organic sulfonic acid catalyst may be mixed in any ratio. In the invention, the organic sulfonic acid catalyst is easy to separate from the product, has small corrosion effect on equipment, and does not generate acidic wastewater; and the cost is low, and the method is suitable for industrial application.
In the present invention, the mass ratio of the dimethyl maleate in the absorbing liquid to the maleic anhydride in the mixed gas containing maleic anhydride after heat exchange is preferably 0.01 to 0.1:1.0, more preferably 0.03 to 0.08:1.0, more preferably 0.05 to 0.06:1.0.
in the present invention, the mixed solution containing maleic anhydride preferably contains maleic anhydride in an amount of 60% by mass.
The process of mixing is not particularly limited in the present invention, and may be performed by a process known to those skilled in the art.
In a particular embodiment of the invention, the countercurrent absorption is preferably carried out in an absorption column; the process of countercurrent absorption preferably comprises the steps of:
injecting the mixed gas containing maleic anhydride after heat exchange from the bottom of an absorption tower, injecting the absorption liquid from the top of the absorption tower, carrying out countercurrent contact on the mixed gas containing maleic anhydride after heat exchange and the absorption liquid, and absorbing maleic anhydride by using the absorption liquid to obtain the mixed liquid containing maleic anhydride.
In the present invention, the temperature of the absorbing solution is preferably 20 to 60 ℃. In the invention, the mixed gas containing maleic anhydride and the absorption liquid after heat exchange are subjected to countercurrent absorption to generate heat exchange; the temperature of the mixed solution containing maleic anhydride is preferably 60 to 100 ℃, and more preferably 70 to 90 ℃.
In a specific embodiment of the present invention, the temperature of the bottom of the absorption column is preferably 60 ℃ and the gauge pressure is 40KPa; the temperature at the top of the absorption column is preferably 50 ℃ and the gauge pressure is normal pressure.
In a particular embodiment of the invention, the absorption column also preferably comprises a circulation pump. In the invention, after the absorption liquid and the mixed gas containing maleic anhydride after heat exchange are in countercurrent contact, the obtained mixed liquid preferably returns to the top of the absorption tower through a circulating pump, and is used as a raw material to continuously carry out circulating absorption on the maleic anhydride in the maleic anhydride tail gas until the mass concentration of the maleic anhydride in the mixed liquid reaches 60%. In the invention, the absorption rate of the absorption liquid to the maleic anhydride in the maleic anhydride tail gas is preferably more than 98%.
After the mixed liquid containing maleic anhydride is obtained, the mixed liquid containing maleic anhydride and methanol from heat exchange are mixed for esterification reaction, and the obtained esterified liquid is separated to obtain the dimethyl maleate and a separated mother solution.
In the present invention, the methanol resulting from the heat exchange is preferably mixed with a mixed liquid containing maleic anhydride in the form of methanol vapor.
In the present invention, the molar ratio of maleic anhydride in the heat-exchanged methanol and the mixed liquid containing maleic anhydride is preferably 2.0 to 8.0:1.0, more preferably 3.0 to 7.0:1.0, more preferably 4.0 to 6.0:1.0.
the mixing process is not particularly limited in the present invention, and may be performed by a process known to those skilled in the art.
In the present invention, the temperature of the esterification reaction is preferably 80 to 150 ℃, more preferably 90 to 140 ℃, and even more preferably 100 to 130 ℃; the time is preferably 30 to 720min, more preferably 50 to 700min, and still more preferably 100 to 650min.
In the present invention, the separation method is preferably distillation under reduced pressure. The process of the reduced pressure distillation is not particularly limited in the present invention, and may be performed by a process known to those skilled in the art. In the present invention, the selectivity of the dimethyl maleate is preferably > 98wt%. In the present invention, the purity of the dimethyl maleate is preferably not less than 99.0wt%. In the present invention, the separation mother liquor is reused as an absorption liquid.
In a particular embodiment of the invention, the esterification reaction preferably comprises the steps of: injecting the mixed liquid containing maleic anhydride from the top of the esterification reactor, and injecting the methanol from the heat exchange from the bottom of the esterification reactor; the mixed liquid containing maleic anhydride and the methanol after heat exchange are in countercurrent contact in an esterification reactor to generate esterification reaction.
In a particular embodiment of the present invention, after completion of the esterification reaction, unreacted methanol is preferably withdrawn from the top of the esterification reactor in the form of methanol vapor. After the methanol vapor is discharged, the invention also preferably comprises the step of rectifying the methanol vapor to obtain anhydrous methanol, and the obtained anhydrous methanol is used as a raw material to exchange heat with the mixed gas containing the maleic anhydride. The rectification process is not particularly limited in the present invention, and may be performed by a process known to those skilled in the art.
In the present invention, the esterification reactor preferably comprises one or more esterification reactors selected from a packed column, a bubble column, a plate column, a tubular reactor, a loop reactor, a reaction kettle and a heat exchanger, which are used in series.
In a particular embodiment of the invention, when the esterification reactors are preferably two of the reactors defined above in series, the esterification reaction preferably comprises a first esterification reaction and a second esterification reaction carried out in sequence; the first-stage esterification reaction is carried out in a first-stage esterification reactor, and the second-stage esterification reaction is carried out in a second-stage esterification reactor. Specifically, the mixed solution containing maleic anhydride is injected from the top of a primary esterification reactor, methanol is injected from the bottom of the primary esterification reactor, and a primary esterification reaction is carried out in the primary esterification reactor to obtain a mono-esterification product; the mono-esterification product is injected from the top of the secondary esterification reactor, the methanol from the heat exchange is injected from the bottom of the secondary esterification reactor, and the mono-esterification product and the methanol from the heat exchange are subjected to secondary esterification reaction in the secondary esterification reactor.
In a specific embodiment of the present invention, in the first-stage esterification reaction, the molar ratio of maleic anhydride to methanol in the mixed solution containing maleic anhydride is preferably 1:2 to 10. In the embodiment of the present invention, the temperature of the first-stage esterification reaction is preferably 100 to 150 ℃, and the time is preferably 20 to 60min. In a particular embodiment of the invention, in the secondary esterification reaction, the mass ratio of the mono-esterification product to the methanol coming from the heat exchange is preferably from 7 to 10:3, more preferably 8 to 9:3. in the embodiment of the present invention, the temperature of the secondary esterification reaction is preferably 100 to 150 ℃, and the time is preferably 0.5 to 10.0 hours.
In the invention, the absorption liquid and the methanol exchange heat with the maleic anhydride tail gas, so no additional heat source is provided in the esterification reaction process, the esterification reaction can be directly carried out, the energy consumption is low, and the method is suitable for industrial production.
To further illustrate the present invention, the following examples are provided to describe the method for preparing dimethyl maleate from maleic anhydride tail gas in detail, but they should not be construed as limiting the scope of the present invention.
Example 1
Carrying out oxidation reaction on n-butane serving as a raw material at the temperature of 450 ℃, and cooling a product to obtain mixed gas containing maleic anhydride; the mixed gas containing the maleic anhydride is subjected to heat exchange with methanol sequentially through a methanol superheater and a methanol reboiler to obtain mixed gas containing the maleic anhydride (wherein the molar percentage of the maleic anhydride is 3.3 mol%) (the temperature is 125 ℃) after heat exchange and the methanol (the temperature is 130 ℃) after heat exchange;
injecting the mixed gas containing maleic anhydride after heat exchange from the bottom of an absorption tower, injecting an absorption liquid (comprising 86.0wt% of dimethyl maleate, 1.0wt% of monomethyl maleate, 3.0wt% of hexadecylbenzene sulfonic acid and 10wt% of dimethyl phthalate; the temperature is 35 ℃) from the top of the absorption tower, carrying out countercurrent contact, absorbing the maleic anhydride by using the absorption liquid, returning the obtained mixed liquid to the top of the absorption tower through a circulating pump to continuously carry out circulating absorption on the maleic anhydride until the mass concentration of the maleic anhydride in the mixed liquid reaches 60%, and obtaining the mixed liquid containing the maleic anhydride (the absorption rate of the maleic anhydride is 99.1%); wherein the mass ratio of the dimethyl maleate to the maleic anhydride tail gas in the absorption liquid is 0.05:1.0; the temperature at the bottom of the absorption tower is 60 ℃, the gauge pressure is 40KPa, the temperature at the top of the absorption tower is 50 ℃, and the gauge pressure is normal pressure;
injecting the obtained mixed liquid containing the maleic anhydride from the top of a packed tower (the temperature of the packed tower is 125 ℃, and the packed filler is 316L pall ring), injecting the methanol after heat exchange from the bottom of the packed tower (in the reaction process, the molar ratio of the methanol after heat exchange to the maleic anhydride in the mixed liquid containing the maleic anhydride is 3.0; the mixed solution containing maleic anhydride is in countercurrent contact with methanol in a packed tower, and esterification reaction is carried out for 4 hours to obtain esterification liquid (comprising 92.17wt% of dimethyl maleate, 1.18 wt% of monomethyl maleate, 4.2wt% of methanol, 1.7wt% of dimethyl phthalate, 0.3wt% of water and 0.45wt% of hexadecyl benzene sulfonic acid); distilling the obtained esterified liquid under reduced pressure to obtain dimethyl maleate (the conversion rate of maleic anhydride is 100%, the selectivity of dimethyl maleate is 99.2%, and the purity is 99.5%) and separating mother liquor (which comprises 86wt% of dimethyl maleate, 5.0wt% of monomethyl maleate, 1.9wt% of hexadecyl benzene sulfonic acid and 7.1wt% of dimethyl phthalate);
the obtained separation mother liquor is reused as an absorption liquid.
Example 2
Performing oxidation reaction on n-butane serving as a raw material at the temperature of 450 ℃, cooling a product to obtain mixed gas containing maleic anhydride, and performing heat exchange on the mixed gas containing the maleic anhydride and methanol sequentially through a methanol superheater and a methanol reboiler to obtain heat-exchanged mixed gas containing the maleic anhydride (wherein the molar percentage content of the maleic anhydride is 3.3 mol%) (the temperature is 145 ℃) and heat-exchanged methanol (the temperature is 135 ℃);
injecting mixed gas containing maleic anhydride after heat exchange from the bottom of an absorption tower, injecting absorption liquid (comprising 86wtwt% of dimethyl maleate, 5.0wt% of monomethyl maleate, 2.5wt% of decaalkylbenzene sulfonic acid and 6.5wt% of dimethyl phthalate; the temperature is 35 ℃) from the top of the absorption tower, carrying out countercurrent contact, absorbing the maleic anhydride by using the absorption liquid, returning the obtained mixed liquid to the top of the absorption tower through a circulating pump to continuously carry out circulating absorption on the maleic anhydride until the mass concentration of the maleic anhydride in the mixed liquid reaches 60%, and obtaining mixed liquid containing the maleic anhydride (the absorption rate of the maleic anhydride is 98.5%); wherein the mass ratio of the maleic acid dimethyl ester to the maleic anhydride tail gas in the absorption liquid is 0.06:1.0; the temperature at the bottom of the absorption tower is 65 ℃, the gauge pressure is 40KPa, the temperature at the top of the absorption tower is 50 ℃, and the gauge pressure is normal pressure;
injecting the obtained mixed liquid containing the maleic anhydride from the top of a packed tower (the temperature of the packed tower is 130 ℃, the packed filler is 316L pall ring), injecting the methanol after heat exchange from the bottom of the packed tower (in the reaction process, the molar ratio of the methanol after heat exchange to the maleic anhydride in the mixed liquid containing the maleic anhydride is 2.5; the mixed solution containing maleic anhydride is in countercurrent contact with methanol in a packed tower to carry out esterification reaction for 6 hours, so as to obtain esterified liquid (comprising 92.29wt% of dimethyl maleate, 0.61wt% of monomethyl maleate, 3.96wt% of methanol, 2.1wt% of dimethyl phthalate, 0.4wt% of water and 0.64wt% of dodecyl benzene sulfonic acid); distilling the obtained esterified liquid under reduced pressure to obtain dimethyl maleate (the conversion rate of maleic anhydride is 100%, the selectivity of dimethyl maleate is 99.0%, and the purity is 99.5%) and separating mother liquor (which comprises 89wt% of dimethyl maleate, 2.0wt% of monomethyl maleate, 2.1wt% of decaalkylbenzene sulfonic acid and 6.9wt% of dimethyl phthalate);
the obtained separation mother liquor is reused as an absorption liquid.
Example 3
Carrying out oxidation reaction on n-butane serving as a raw material at the temperature of 450 ℃, and cooling a product to obtain mixed gas containing maleic anhydride; the mixed gas containing the maleic anhydride is subjected to heat exchange with methanol sequentially through a methanol superheater and a methanol reboiler to obtain mixed gas containing the maleic anhydride (wherein the molar percentage of the maleic anhydride is 3.3 mol%) (the temperature is 120 ℃) after heat exchange and the methanol (the temperature is 125 ℃) after heat exchange;
feeding the mixed gas containing maleic anhydride after heat exchange from the bottom of an absorption tower, injecting an absorption liquid (comprising 87wt% of dimethyl maleate, 1.5wt% of monomethyl maleate, 2wt% of p-toluenesulfonic acid and 9.5wt% of dimethyl phthalate; the temperature is 30 ℃) from the top of the absorption tower, carrying out countercurrent contact, absorbing the maleic anhydride by using the absorption liquid, returning the obtained mixed liquid to the top of the absorption tower through a circulating pump to continuously carry out circulating absorption on the maleic anhydride until the mass concentration of the maleic anhydride in the mixed liquid reaches 60%, and obtaining the mixed liquid containing the maleic anhydride (the absorption rate of the maleic anhydride is 98.9%); wherein the mass ratio of the maleic acid dimethyl ester to the maleic anhydride tail gas in the absorption liquid is 0.07:1.0; the temperature at the bottom of the absorption tower is 55 ℃, the gauge pressure is 40KPa, the temperature at the top of the absorption tower is 40 ℃, and the gauge pressure is normal pressure;
injecting the obtained mixed solution containing the maleic anhydride from the top of a loop reactor (the temperature of the loop reactor is 125 ℃), injecting methanol from the bottom of the loop reactor (the molar ratio of the methanol to the maleic anhydride in the mixed solution containing the maleic anhydride is 2.5:1 in the reaction process), and carrying out primary esterification reaction for 1h to obtain a mono-esterification product; the obtained monoesterification product was injected from the top in a bubble column (temperature of the bubble column was 125 ℃), and heat-exchanged methanol was injected from the bottom of the bubble column (mass ratio of monoesterification product to methanol from heat exchange during the reaction was 8; distilling the obtained esterified liquid under reduced pressure to obtain dimethyl maleate (the conversion rate of maleic anhydride is 100%, the selectivity of dimethyl maleate is 99.3%, and the purity is 99.5%) and separating mother liquor (which comprises 90.5wt% of dimethyl maleate, 1.5wt% of monomethyl maleate, 2.3 wt% of p-toluenesulfonic acid and 5.7wt% of dimethyl phthalate);
the resulting separation mother liquor is reused as an absorption liquid.
Example 4
Carrying out oxidation reaction on n-butane serving as a raw material at the temperature of 450 ℃, and cooling a product to obtain mixed gas containing maleic anhydride; the mixed gas containing the maleic anhydride is subjected to heat exchange with methanol sequentially through a methanol superheater and a methanol reboiler to obtain mixed gas containing the maleic anhydride (wherein the molar percentage of the maleic anhydride is 3.3 mol%) (the temperature is 120 ℃) after heat exchange and the methanol (the temperature is 125 ℃) after heat exchange;
injecting heat-exchanged maleic anhydride tail gas from the bottom of an absorption tower, injecting absorption liquid (comprising 87wt% of dimethyl maleate, 1.5wt% of monomethyl maleate, 2wt% of p-toluenesulfonic acid and 9.5wt% of dimethyl phthalate; the temperature is 30 ℃) from the top of the absorption tower, carrying out countercurrent contact, absorbing maleic anhydride by using the absorption liquid, returning the obtained mixed solution to the top of the absorption tower through a circulating pump to continuously carry out circulating absorption on the maleic anhydride until the mass concentration of the maleic anhydride in the mixed solution reaches 60%, and obtaining mixed solution containing the maleic anhydride (the absorption rate of the maleic anhydride is 98.9%); wherein the mass ratio of the maleic acid dimethyl ester to the maleic anhydride tail gas in the absorption liquid is 0.07:1.0; the temperature at the bottom of the absorption tower is 55 ℃, the gauge pressure is 40KPa, the temperature at the top of the absorption tower is 40 ℃, and the gauge pressure is normal pressure;
injecting the obtained mixed solution containing maleic anhydride from the top of a tubular reactor (the temperature of the tubular reactor is 135 ℃), injecting methanol from the bottom of the tubular reactor (the molar ratio of the methanol to the maleic anhydride in the mixed solution containing the maleic anhydride is 2.5 in the reaction process is 1), and carrying out primary esterification reaction for 1h to obtain a mono-esterification product; injecting the obtained mono-esterification product from the top of a bubble column (the temperature of the bubble column is 135 ℃), injecting heat-exchanged methanol from the bottom of the bubble column (the mass ratio of the mono-esterification product to the methanol from the heat exchange is 10; distilling the obtained esterification solution under reduced pressure to obtain dimethyl maleate (the conversion rate of maleic anhydride is 100%, the selectivity of dimethyl maleate is 98.5%, and the purity is 99%) and separating mother liquor (which comprises 87.0wt% of dimethyl maleate, 1.0wt% of monomethyl maleate, 1.7wt% of methane sulfonic acid and 10.3wt% of dimethyl phthalate);
the resulting separation mother liquor is reused as an absorption liquid.
Example 5
Carrying out oxidation reaction on n-butane serving as a raw material at the temperature of 450 ℃, and cooling a product to obtain mixed gas containing maleic anhydride; the mixed gas containing the maleic anhydride is subjected to heat exchange with methanol sequentially through a methanol superheater and a methanol reboiler to obtain mixed gas containing the maleic anhydride (wherein the molar percentage of the maleic anhydride is 3.3 mol%) (the temperature is 120 ℃) after heat exchange and the methanol (the temperature is 125 ℃) after heat exchange;
feeding the mixed gas containing maleic anhydride after heat exchange from the bottom of an absorption tower, injecting absorption liquid (comprising 87wt% of dimethyl maleate, 1.0wt% of monomethyl maleate, 1.7wt% of propanesulfonic acid and 10.3wt% of dimethyl phthalate; the temperature is 30 ℃) from the top of the absorption tower for countercurrent contact, absorbing the maleic anhydride by using the absorption liquid, returning the obtained mixed liquid to the top of the absorption tower through a circulating pump to continuously carry out circulating absorption on the maleic anhydride until the mass concentration of the maleic anhydride in the mixed liquid reaches 60%, and obtaining the mixed liquid containing the maleic anhydride (the absorption rate of the maleic anhydride is 98.9%); wherein the mass ratio of the maleic acid dimethyl ester to the maleic anhydride tail gas in the absorption liquid is 0.07:1.0; the temperature at the bottom of the absorption tower is 55 ℃, the gauge pressure is 40KPa, the temperature at the top of the absorption tower is 40 ℃, and the gauge pressure is normal pressure;
injecting the obtained mixed solution containing maleic anhydride from the top of a reaction kettle (the temperature of the reaction kettle is 130 ℃), injecting methanol from the bottom of the reaction kettle (in the reaction process, the molar ratio of the methanol to the maleic anhydride in the mixed solution containing the maleic anhydride is 2.0: 1), and carrying out primary esterification reaction for 1h to obtain a mono-esterification product; injecting the obtained mono-esterification product from the top of a bubble column (the temperature of the bubble column is 130 ℃), injecting heat-exchanged methanol from the bottom of the bubble column (the mass ratio of the mono-esterification product to the methanol after heat exchange is 7; distilling the obtained esterification solution under reduced pressure to obtain dimethyl maleate (the conversion rate of maleic anhydride is 100%, the selectivity of dimethyl maleate is 98.5%, and the purity is 99.0%) and separating mother liquor (which comprises 86.8wt% of dimethyl maleate, 0.6wt% of monomethyl maleate, 2.5wt% of propane sulfonic acid and 10.1wt% of dimethyl phthalate);
the resulting separation mother liquor is reused as an absorption liquid.
Example 6
Carrying out oxidation reaction on n-butane serving as a raw material at the temperature of 450 ℃, and cooling a product to obtain mixed gas containing maleic anhydride; the mixed gas containing the maleic anhydride is subjected to heat exchange with methanol sequentially through a methanol superheater and a methanol reboiler to obtain heat-exchanged mixed gas containing the maleic anhydride (wherein the molar percentage content of the maleic anhydride is 3.3 mol%) (the temperature is 120 ℃) and heat-exchanged methanol (the temperature is 125 ℃);
injecting mixed gas containing maleic anhydride after heat exchange from the bottom of an absorption tower, injecting absorption liquid (comprising 86.8wt% of dimethyl maleate, 0.6wt% of monomethyl maleate, 2.5wt% of trifluoromethylbenzenesulfonic acid and 10.1wt% of dimethyl phthalate; the temperature is 30 ℃) from the top of the absorption tower, carrying out countercurrent contact, absorbing the maleic anhydride by using the absorption liquid, returning the obtained mixed liquid to the top of the absorption tower through a circulating pump to continuously carry out circulating absorption on the maleic anhydride until the mass concentration of the maleic anhydride in the mixed liquid reaches 60%, and obtaining mixed liquid containing the maleic anhydride (the absorption rate of the maleic anhydride is 98.9%); wherein the mass ratio of the maleic acid dimethyl ester to the maleic anhydride tail gas in the absorption liquid is 0.07:1.0; the temperature at the bottom of the absorption tower is 55 ℃, the gauge pressure is 40KPa, the temperature at the top of the absorption tower is 40 ℃, and the gauge pressure is normal pressure;
the obtained mixed liquid containing maleic anhydride was injected from the top of a bubble column (the temperature of the bubble column was 135 ℃), and methanol after heat exchange was injected from the bottom of the bubble column (during the reaction, the molar ratio of maleic anhydride in the mixed liquid containing maleic anhydride to methanol after heat exchange was 2.5; the mixed solution containing maleic anhydride and methanol are in countercurrent contact in a bubble column, and esterification reaction is carried out for 6h to obtain esterified liquid (comprising 92.08wt% of dimethyl maleate, 0.14wt% of monomethyl maleate, 5.8wt% of methanol, 1.28wt% of dimethyl phthalate, 0.3wt% of water and 0.4wt% of trifluoromethylbenzene sulfonic acid); distilling the esterification solution under reduced pressure to obtain dimethyl maleate (the conversion rate of maleic anhydride is 100%, the selectivity of dimethyl maleate is 98.5%, and the purity is 99%) and separating mother liquor (which comprises 88.2wt% of dimethyl maleate, 0.9wt% of monomethyl maleate, 2.6wt% of trifluoromethylbenzenesulfonic acid and 8.3wt% of dimethyl phthalate);
the obtained separation mother liquor is reused as an absorption liquid.
Example 7
Carrying out oxidation reaction on n-butane serving as a raw material at the temperature of 450 ℃, and cooling a product to obtain mixed gas containing maleic anhydride; the mixed gas containing the maleic anhydride is subjected to heat exchange with methanol sequentially through a methanol superheater and a methanol reboiler to obtain heat-exchanged mixed gas containing the maleic anhydride (wherein the molar percentage content of the maleic anhydride is 3.3 mol%) (the temperature is 120 ℃) and heat-exchanged methanol (the temperature is 125 ℃);
injecting mixed gas containing maleic anhydride after heat exchange from the bottom of an absorption tower, injecting absorption liquid (comprising 88.2wt% of dimethyl maleate, 0.9wt% of monomethyl maleate, 2.6wt% of benzenesulfonic acid and 8.3wt% of dimethyl phthalate; the temperature is 30 ℃) from the top of the absorption tower, carrying out countercurrent contact, absorbing the maleic anhydride by using the absorption liquid, returning the obtained mixed liquid to the top of the absorption tower through a circulating pump to continuously carry out circulating absorption on the maleic anhydride until the mass concentration of the maleic anhydride in the mixed liquid reaches 60%, and obtaining mixed liquid containing the maleic anhydride (the absorption rate of the maleic anhydride is 98.9%); wherein the mass ratio of the maleic acid dimethyl ester to the maleic anhydride tail gas in the absorption liquid is 0.07:1.0; the temperature at the bottom of the absorption tower is 55 ℃, the gauge pressure is 40KPa, the temperature at the top of the absorption tower is 40 ℃, and the gauge pressure is normal pressure;
injecting the obtained mixed liquid containing maleic anhydride from the top of a packed tower (the temperature of the packed tower is 125 ℃, and the packed filler is triangular spiral filler), injecting the methanol after heat exchange from the bottom of the packed tower (in the reaction process, the molar ratio of the methanol after heat exchange to the maleic anhydride in the mixed liquid containing maleic anhydride is 4.0; the mixed solution containing maleic anhydride is in countercurrent contact with methanol in a packed tower, and esterification reaction is carried out for 8 hours to obtain esterification liquid (comprising 91.9wt% of dimethyl maleate, 0.33wt% of monomethyl maleate, 5.67wt% of methanol, 1.5wt% of dimethyl phthalate, 0.3wt% of water and 0.3wt% of benzene sulfonic acid); distilling the obtained esterified liquid under reduced pressure to obtain dimethyl maleate (the conversion rate of maleic anhydride is 100%, the selectivity of dimethyl maleate is 98.4%, and the purity is 99%) and separating mother liquor (the mother liquor comprises 87.2wt% of dimethyl maleate, 2.0wt% of monomethyl maleate, 1.8% of benzenesulfonic acid and 9.0wt% of dimethyl phthalate);
the obtained separation mother liquor is reused as an absorption liquid.
Although the present invention has been described in detail with reference to the above embodiments, it is only a part of the embodiments of the present invention, not all of the embodiments, and other embodiments can be obtained without inventive step according to the embodiments, and all of the embodiments belong to the protection scope of the present invention.
Claims (10)
1. A method for preparing dimethyl maleate by using maleic anhydride tail gas is characterized by comprising the following steps:
carrying out heat exchange on the mixed gas containing maleic anhydride and methanol to obtain the mixed gas containing maleic anhydride after heat exchange and the methanol after heat exchange;
mixing the mixed gas containing maleic anhydride after heat exchange with the absorption liquid for countercurrent absorption to obtain mixed liquid containing maleic anhydride;
mixing the mixed liquid containing maleic anhydride and methanol obtained after heat exchange for esterification reaction, and separating the obtained esterified liquid to obtain the dimethyl maleate and a separation mother liquid;
the separation mother liquor is reused as absorption liquid;
the absorption liquid comprises dimethyl maleate and an organic sulfonic acid catalyst;
the mixed gas containing maleic anhydride is obtained by using n-butane as a raw material and oxidizing.
2. The method of claim 1, wherein the esterification reaction does not require additional heating.
3. The method according to claim 1, wherein the temperature of the mixed gas containing maleic anhydride is 120 to 250 ℃;
the mass ratio of the dimethyl maleate in the absorption liquid to the maleic anhydride in the mixed gas containing the maleic anhydride after heat exchange is 0.01-0.1: 1.0.
4. the process according to claim 1, wherein the molar ratio of maleic anhydride in the mixed solution containing maleic anhydride to methanol after heat exchange is 2.0 to 8.0:1.
5. the process according to claim 1, wherein the methanol from the heat exchange is present in the form of methanol vapor;
the temperature of the methanol steam is 80-160 ℃.
6. The production method according to claim 1, wherein the esterification reaction is carried out in an esterification reactor;
the esterification reactor is one or more of a packed tower, a bubble column, a plate tower, a tubular reactor, a loop reactor, a reaction kettle and a heat exchanger which are used in series.
7. The method according to claim 6, wherein the esterification reaction is carried out at a temperature of 80 to 150 ℃ for 30 to 720min.
8. The preparation method according to claim 1, wherein the organic sulfonic acid catalyst comprises one or more of alkyl sulfonic acid, halogenated alkyl sulfonic acid, benzene sulfonic acid and substituted benzene sulfonic acid.
9. The preparation method according to claim 8, wherein the alkyl sulfonic acid comprises one or more of methane sulfonic acid, ethane sulfonic acid and propane sulfonic acid;
the haloalkylsulfonic acid is preferably trifluoromethanesulfonic acid;
the substituted benzene sulphonic acid preferably comprises a linear alkyl benzene sulphonic acid and/or a branched alkyl benzene sulphonic acid;
the linear alkyl benzene sulfonic acid comprises one or more of p-toluenesulfonic acid, dodecyl benzene sulfonic acid, tetradecyl benzene sulfonic acid and hexadecyl benzene sulfonic acid.
10. The method according to claim 8 or 9, wherein the mixed solution containing maleic anhydride comprises maleic anhydride, dimethyl maleate, and an organic sulfonic acid catalyst;
the mass of the organic sulfonic acid catalyst is 0.1-0.5% of that of maleic anhydride.
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| CN112961058A (en) * | 2021-02-08 | 2021-06-15 | 宁波窦氏化学科技有限公司 | Process method for preparing glycol maleate |
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| CN112961058A (en) * | 2021-02-08 | 2021-06-15 | 宁波窦氏化学科技有限公司 | Process method for preparing glycol maleate |
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