CN115322092B - 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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- CN115322092B CN115322092B CN202211112422.9A CN202211112422A CN115322092B CN 115322092 B CN115322092 B CN 115322092B CN 202211112422 A CN202211112422 A CN 202211112422A CN 115322092 B CN115322092 B CN 115322092B
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- maleic anhydride
- methanol
- sulfonic acid
- heat exchange
- dimethyl maleate
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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 214
- LDCRTTXIJACKKU-ARJAWSKDSA-N dimethyl maleate Chemical compound COC(=O)\C=C/C(=O)OC LDCRTTXIJACKKU-ARJAWSKDSA-N 0.000 title claims abstract description 73
- 238000000034 method Methods 0.000 title claims abstract description 43
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims abstract description 330
- 238000010521 absorption reaction Methods 0.000 claims abstract description 123
- 239000007788 liquid Substances 0.000 claims abstract description 96
- 238000005886 esterification reaction Methods 0.000 claims abstract description 64
- 239000011259 mixed solution Substances 0.000 claims abstract description 36
- LSNNMFCWUKXFEE-UHFFFAOYSA-M Bisulfite Chemical compound OS([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-M 0.000 claims abstract description 21
- 239000012452 mother liquor Substances 0.000 claims abstract description 21
- IJDNQMDRQITEOD-UHFFFAOYSA-N n-butane Chemical compound CCCC IJDNQMDRQITEOD-UHFFFAOYSA-N 0.000 claims abstract description 21
- 239000002994 raw material Substances 0.000 claims abstract description 21
- 239000003377 acid catalyst Substances 0.000 claims abstract description 16
- 238000000926 separation method Methods 0.000 claims abstract description 16
- 239000000243 solution Substances 0.000 claims abstract description 14
- 238000002156 mixing Methods 0.000 claims abstract description 12
- 230000001590 oxidative effect Effects 0.000 claims abstract description 8
- 239000010413 mother solution Substances 0.000 claims abstract description 5
- 230000032050 esterification Effects 0.000 claims description 27
- 238000006243 chemical reaction Methods 0.000 claims description 24
- 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 14
- 229940092714 benzenesulfonic acid Drugs 0.000 claims description 12
- AFVFQIVMOAPDHO-UHFFFAOYSA-N Methanesulfonic acid Chemical compound CS(O)(=O)=O AFVFQIVMOAPDHO-UHFFFAOYSA-N 0.000 claims description 10
- 239000002253 acid Substances 0.000 claims description 8
- -1 alkyl sulfonic acid Chemical compound 0.000 claims description 7
- CTIFKKWVNGEOBU-UHFFFAOYSA-N 2-hexadecylbenzenesulfonic acid Chemical compound CCCCCCCCCCCCCCCCC1=CC=CC=C1S(O)(=O)=O CTIFKKWVNGEOBU-UHFFFAOYSA-N 0.000 claims description 6
- SRSXLGNVWSONIS-UHFFFAOYSA-N benzenesulfonic acid Chemical compound OS(=O)(=O)C1=CC=CC=C1 SRSXLGNVWSONIS-UHFFFAOYSA-N 0.000 claims description 6
- 150000008107 benzenesulfonic acids 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 6
- 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 5
- 229940098779 methanesulfonic acid Drugs 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
- 239000000203 mixture Substances 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
- CCIVGXIOQKPBKL-UHFFFAOYSA-M ethanesulfonate Chemical compound CCS([O-])(=O)=O CCIVGXIOQKPBKL-UHFFFAOYSA-M 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
- 150000004996 alkyl benzenes Chemical class 0.000 claims 2
- 238000010438 heat treatment 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 42
- NKHAVTQWNUWKEO-UHFFFAOYSA-N fumaric acid monomethyl ester Natural products COC(=O)C=CC(O)=O NKHAVTQWNUWKEO-UHFFFAOYSA-N 0.000 description 22
- NKHAVTQWNUWKEO-IHWYPQMZSA-N methyl hydrogen fumarate Chemical compound COC(=O)\C=C/C(O)=O NKHAVTQWNUWKEO-IHWYPQMZSA-N 0.000 description 22
- FBSAITBEAPNWJG-UHFFFAOYSA-N dimethyl phthalate Natural products CC(=O)OC1=CC=CC=C1OC(C)=O FBSAITBEAPNWJG-UHFFFAOYSA-N 0.000 description 21
- 229960001826 dimethylphthalate Drugs 0.000 description 21
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 13
- 238000007254 oxidation reaction Methods 0.000 description 10
- 239000003960 organic solvent Substances 0.000 description 8
- 238000011084 recovery Methods 0.000 description 5
- 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
- 238000001816 cooling Methods 0.000 description 3
- 230000003647 oxidation Effects 0.000 description 3
- 238000012856 packing Methods 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
- 239000003054 catalyst Substances 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
- 239000000945 filler Substances 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
- 239000000463 material Substances 0.000 description 1
- 238000002360 preparation method Methods 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 heat-exchanged mixed gas containing maleic anhydride with the absorption liquid for countercurrent absorption to obtain a mixed liquid containing maleic anhydride; mixing the mixed solution containing maleic anhydride with methanol from heat exchange to perform esterification reaction, and separating the obtained esterified solution to obtain the dimethyl maleate and a separation mother solution; the separated mother liquor is used as absorption liquor for reutilization; the absorption liquid comprises dimethyl maleate and an organic sulfonic acid catalyst; the mixed gas containing maleic anhydride is obtained by oxidizing n-butane 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 lower, 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 high-temperature mixed gas containing maleic anhydride is obtained by oxidizing n-butane as a raw material, and at present, two methods are mainly adopted for recovering the maleic anhydride, including a water recovery process and an organic solvent recovery process.
The water recovery process has the advantages of using cheap and easily available water as the absorbent and having the characteristic of high chemical absorption rate. However, maleic acid and fumaric acid produced by the reaction of maleic anhydride with water tend to corrode equipment to clog pipes, resulting in lower yields of maleic anhydride and a large amount of wastewater.
The organic solvent absorption process adopts an organic solvent as an absorbent to absorb maleic anhydride, and the organic solvent commonly adopted at present comprises dibutyl phthalate, dibutyl hexahydrophthalate and diisobutyl hexahydrophthalate. The organic solvent absorption process effectively overcomes the defects of easy corrosion of equipment, low maleic anhydride yield and large wastewater amount existing in the water absorption process, and gradually replaces the water recovery process to become a main recovery method of maleic anhydride. However, the organic solvent has higher cost, and the maleic anhydride product can be obtained only by rectification and separation after the maleic anhydride is absorbed, so that the organic solvent has higher energy consumption and 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 raw material cost and low energy consumption and is suitable for industrial production.
In order to achieve the above object, the present invention provides the following technical solutions:
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 heat-exchanged mixed gas containing maleic anhydride with the absorption liquid for countercurrent absorption to obtain a mixed liquid containing maleic anhydride;
mixing the mixed solution containing maleic anhydride with methanol from heat exchange to perform esterification reaction, and separating the obtained esterified solution to obtain the dimethyl maleate and a separation mother solution;
the separated mother liquor is used as absorption liquor for reutilization;
The absorption liquid comprises dimethyl maleate and an organic sulfonic acid catalyst;
the mixed gas containing maleic anhydride is obtained by oxidizing n-butane as a raw material.
Preferably, the temperature of the mixed gas containing maleic anhydride is 120-250 ℃;
the mass ratio of the dimethyl maleate in the absorption liquid to the maleic anhydride in the mixed gas containing maleic anhydride is 0.01-0.1: 1.0.
Preferably, the molar ratio of the heat-exchanged methanol to the maleic anhydride in the mixed solution containing maleic anhydride after heat exchange is 2.0-8.0: 1.
Preferably, the methanol from the heat exchange is in the form of methanol vapor;
the temperature of the methanol vapor is 80-160 ℃.
Preferably, the esterification reaction is carried out in an esterification reactor;
The esterification reactor is one or more esterification reactors of a packed tower, a bubble cap tower, a plate tower, a tubular reactor, a loop reactor, a reaction kettle and a heat exchanger which are connected in series.
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 benzenesulfonic acid preferably comprises linear alkylbenzenesulfonic acid and/or branched alkylbenzenesulfonic acid;
The linear alkylbenzene sulfonic acid comprises one or more of p-toluenesulfonic acid, dodecylbenzenesulfonic acid, tetradecylbenzenesulfonic acid and hexadecylbenzenesulfonic acid.
Preferably, the mixed solution containing maleic anhydride comprises maleic anhydride, dimethyl maleate and 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 heat-exchanged mixed gas containing maleic anhydride with the absorption liquid for countercurrent absorption to obtain a mixed liquid containing maleic anhydride; mixing the mixed solution containing maleic anhydride with methanol from heat exchange to perform esterification reaction, and separating the obtained esterified solution to obtain the dimethyl maleate and a separation mother solution; the separated mother liquor is used as absorption liquor for reutilization; the absorption liquid comprises dimethyl maleate and an organic sulfonic acid catalyst; the mixed gas containing maleic anhydride is obtained by oxidizing n-butane as a raw material. The maleic acid dimethyl ester absorption liquid containing the organic sulfonic acid catalyst is used for absorbing maleic anhydride in the mixed gas containing maleic anhydride tail, 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 raw materials is low; and the 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 heat-exchanged mixed gas containing maleic anhydride with the absorption liquid for countercurrent absorption to obtain a mixed liquid containing maleic anhydride;
mixing the mixed solution containing maleic anhydride with methanol from heat exchange to perform esterification reaction, and separating the obtained esterified solution to obtain the dimethyl maleate and a separation mother solution;
the separated mother liquor is used as absorption liquor for reutilization;
The absorption liquid comprises dimethyl maleate and an organic sulfonic acid catalyst;
the mixed gas containing maleic anhydride is obtained by oxidizing n-butane as a raw material.
In the present invention, all the preparation materials are commercially available products well known to those skilled in the art unless specified otherwise.
The invention carries 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.
In the invention, the mixed gas containing maleic anhydride is obtained by oxidizing n-butane as a raw material; the oxidation preferably comprises the steps of:
and (3) sequentially oxidizing and cooling n-butane serving as a raw material to obtain the mixed gas containing 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 process of the heat exchange is not particularly limited, and may be performed by a process well known to those skilled in the art. In a specific embodiment of the present invention, the heat exchange process is preferably: and (3) sequentially carrying out heat exchange on the mixed gas containing the maleic anhydride 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 maleic anhydride-containing gas mixture after heat exchange is preferably 120 to 250 ℃, more preferably 130 to 240 ℃, and even more preferably 140 to 230. In the present invention, the temperature of the methanol after heat exchange is preferably 80 to 160 ℃, more preferably 90 to 150 ℃, and even 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 secondary mixed raw material for esterification.
In the present invention, the mole percentage of maleic anhydride in the heat-exchanged maleic anhydride-containing gas mixture is preferably 1.0 to 5.0 mole%.
After the heat-exchanged mixed gas containing maleic anhydride and the heat-exchanged methanol are obtained, the heat-exchanged mixed gas containing maleic anhydride and the absorption liquid are mixed for countercurrent absorption, so that the mixed liquid containing maleic anhydride is obtained.
In the present invention, the absorption liquid includes dimethyl maleate and an organic sulfonic acid type catalyst. The absorption liquid preferably comprises 80.0 to 96.0wt% of dimethyl maleate and 0.1 to 5.0wt% of organic sulfonic acid catalyst in terms of mass percent. 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 present invention, the organic sulfonic acid catalyst preferably includes one or more of alkylsulfonic acid, haloalkylsulfonic acid, benzenesulfonic acid and substituted benzenesulfonic 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 benzenesulfonic acid preferably comprises linear alkylbenzenesulfonic acid and/or branched alkylbenzenesulfonic acid; the linear alkylbenzene sulfonic acid further preferably comprises one or more of p-toluene sulfonic acid, dodecylbenzene sulfonic acid, tetradecylbenzene sulfonic acid and hexadecylbenzene sulfonic acid. In the present invention, when the organic sulfonic acid catalyst is two or more of the above-mentioned choices, the proportion of the specific substances is not particularly limited, and any proportion may be used. 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 acid wastewater; and the cost is lower, and the method is suitable for industrial application.
In the present invention, the mass ratio of dimethyl maleate in the absorption liquid to maleic anhydride in the heat-exchanged maleic anhydride-containing mixed gas 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 mass percentage of maleic anhydride in the maleic anhydride-containing mixed solution is preferably 60%.
The mixing process is not particularly limited, and may be performed by a process well known to those skilled in the art.
In a specific embodiment of the present invention, the countercurrent absorption is preferably performed in an absorption column; the countercurrent absorption process preferably comprises the steps of:
Injecting the heat-exchanged mixed gas containing maleic anhydride from the bottom of the absorption tower, injecting the absorption liquid from the top of the absorption tower, and carrying out countercurrent contact on the heat-exchanged mixed gas containing maleic anhydride and the absorption liquid to absorb maleic anhydride by using the absorption liquid to obtain the mixed liquid containing maleic anhydride.
In the present invention, the temperature of the absorption liquid is preferably 20 to 60 ℃. In the invention, the heat exchange is carried out on the mixed gas containing maleic anhydride and the absorption liquid after the heat exchange through countercurrent absorption; the temperature of the maleic anhydride-containing mixed solution is preferably 60 to 100 ℃, and more preferably 70 to 90 ℃.
In the specific embodiment of the invention, the temperature of the bottom of the absorption tower is preferably 60 ℃ and the gauge pressure is 40KPa; the temperature of the top of the absorption tower is preferably 50 ℃, and the gauge pressure is normal pressure.
In a specific embodiment of the present invention, the absorption tower further preferably includes 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 is preferably returned to the top of the absorption tower through a circulating pump and is used as a raw material to continuously circularly absorb the maleic anhydride in the maleic anhydride tail gas until the mass concentration of the maleic anhydride in the mixed liquid reaches 60 percent. In the present invention, the absorption rate of maleic anhydride in maleic anhydride tail gas by the absorption liquid is preferably > 98%.
After the mixed solution containing maleic anhydride is obtained, the mixed solution containing maleic anhydride and methanol from heat exchange are mixed for esterification reaction, and the obtained esterified solution is separated to obtain the dimethyl maleate and the separation mother liquor.
In the present invention, the methanol from the heat exchange is preferably mixed with a mixed solution containing maleic anhydride in the form of methanol vapor.
In the present invention, the molar ratio of the maleic anhydride in the mixture liquid containing maleic anhydride and methanol after heat exchange 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, and may be performed by a process well 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 ℃, still more preferably 100 to 130 ℃; the time is preferably 30 to 720 minutes, more preferably 50 to 700 minutes, and still more preferably 100 to 650 minutes.
In the present invention, the separation means is preferably distillation under reduced pressure. The process of the reduced pressure distillation is not particularly limited, 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 the absorption liquid.
In a specific embodiment of the present invention, the esterification reaction preferably includes the steps of: injecting the mixed solution 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; and the mixed solution containing maleic anhydride and the methanol from heat exchange are in countercurrent contact in an esterification reactor to carry out esterification reaction.
In a specific embodiment of the present invention, after the esterification reaction is completed, unreacted methanol is preferably discharged 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 maleic anhydride. The rectification process is not particularly limited, 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 tray column, a tubular reactor, a loop reactor, a reaction vessel, and a heat exchanger, and is used in series.
In a specific embodiment of the present invention, when the esterification reactor is preferably two of the above-defined reactors connected in series, the esterification reaction preferably includes sequentially performing a primary esterification reaction and a secondary esterification reaction; the primary esterification reaction is carried out in a primary esterification reactor, and the secondary esterification reaction is carried out in a secondary esterification reactor. Specifically, injecting the mixed solution containing maleic anhydride from the top of a first-stage esterification reactor, injecting methanol from the bottom of the first-stage esterification reactor, and performing a first-stage esterification reaction in the first-stage esterification reactor to obtain a monoesterification product; and injecting the monoesterification product from the top in the secondary esterification reactor, and injecting the methanol from the heat exchange from the bottom of the secondary esterification reactor, wherein the monoesterification product and the methanol from the heat exchange generate 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 specific embodiment of the invention, the temperature of the primary esterification reaction is preferably 100-150 ℃ and the time is preferably 20-60 min. In a specific embodiment of the present invention, in the secondary esterification reaction, the mass ratio of the monoesterification product to methanol from heat exchange is preferably 7 to 10:3, more preferably 8 to 9:3. in the specific embodiment of the invention, the temperature of the secondary esterification reaction is preferably 100-150 ℃ and the time is preferably 0.5-10.0 h.
In the invention, the absorption liquid and the methanol are in heat exchange with the maleic anhydride tail gas, so that no extra 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.
In order to further illustrate the present invention, a method for preparing dimethyl maleate using maleic anhydride tail gas is provided in detail with reference to examples, which should not be construed as limiting the scope of the invention.
Example 1
N-butane is used as a raw material to carry out oxidation reaction at the temperature of 450 ℃, and the product is cooled to obtain mixed gas containing maleic anhydride; the mixed gas containing maleic anhydride sequentially passes through a methanol superheater and a methanol reboiler to exchange heat with methanol to obtain mixed gas containing maleic anhydride (the mole percentage content of maleic anhydride is 3.3mol percent) (the temperature is 125 ℃) after heat exchange and methanol (the temperature is 130 ℃);
Injecting the heat-exchanged mixed gas containing maleic anhydride from the bottom of an absorption tower, injecting an absorption liquid (comprising 86.0wt% of dimethyl maleate, 1.0 wt% of monomethyl maleate, 3.0wt% of hexadecyl benzenesulfonic acid and 10 wt% of dimethyl phthalate; the temperature is 35 ℃) from the top of the absorption tower, carrying out countercurrent contact, absorbing maleic anhydride by using the absorption liquid, returning the obtained mixed liquid to the top of the absorption tower by using a circulating pump, and continuously circularly absorbing maleic anhydride until the mass concentration of maleic anhydride in the mixed liquid reaches 60%, thereby obtaining the mixed liquid containing maleic anhydride (the absorption rate of 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 solution containing 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), and injecting the heat-exchanged methanol from the bottom of the packed tower (in the reaction process, the mole ratio of the heat-exchanged methanol to the maleic anhydride in the mixed solution containing maleic anhydride is 3.0:1.0); countercurrent contact is carried out between the mixed solution containing maleic anhydride and methanol in a packed tower, and esterification reaction is carried out for 4 hours, thus obtaining esterified solution (wherein the esterified solution comprises 92.17 weight percent of dimethyl maleate, 1.18wtwt weight percent of monomethyl maleate, 4.2 weight percent of methanol, 1.7 weight percent of dimethyl phthalate, 0.3 weight percent of water and 0.45 weight percent of hexadecyl benzene sulfonic acid); the obtained esterified liquid is distilled under reduced pressure to obtain dimethyl maleate (the conversion rate of maleic anhydride is 100%, the selectivity of the dimethyl maleate is 99.2%, and the purity is 99.5%) and separation mother liquor (comprising 86wt% of dimethyl maleate, 5.0wt% of monomethyl maleate, 1.9% of hexadecyl benzenesulfonic acid and 7.1wt% of dimethyl phthalate);
The obtained separated mother liquor is reused as absorption liquid.
Example 2
Carrying out oxidation reaction on n-butane serving as a raw material at the temperature of 450 ℃, cooling a product to obtain a mixed gas containing maleic anhydride, sequentially carrying out heat exchange on the mixed gas containing maleic anhydride and methanol through a methanol superheater and a methanol reboiler to obtain a mixed gas containing maleic anhydride after heat exchange (wherein the mole percentage content of maleic anhydride is 3.3 mol%) (the temperature is 145 ℃) and methanol after heat exchange (the temperature is 135 ℃);
Injecting the heat-exchanged mixed gas containing maleic anhydride from the bottom of an absorption tower, and injecting an absorption liquid (comprising 86wtwt% of dimethyl maleate, 5.0% of monomethyl maleate, 2.5% of dodecylbenzene sulfonic acid and 6.5% of dimethyl phthalate; the temperature is 35 ℃) from the top of the absorption tower for countercurrent contact, absorbing the maleic anhydride by using the absorption liquid, and returning the obtained mixed liquid to the top of the absorption tower by a circulating pump to continuously circularly absorb the maleic anhydride until the mass concentration of the maleic anhydride in the mixed liquid reaches 60%, thereby obtaining the mixed liquid containing the maleic anhydride (the absorptivity of the maleic anhydride is 98.5%); wherein, the mass ratio of the dimethyl maleate 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 solution containing maleic anhydride from the top of a packed tower (the temperature of the packed tower is 130 ℃, and the packed packing is 316L pall ring), and injecting the heat-exchanged methanol from the bottom of the packed tower (the mole ratio of the heat-exchanged methanol to the mixed solution containing maleic anhydride is 2.5:1.0 in the reaction process); countercurrent contact is carried out between the mixed solution containing maleic anhydride and methanol in a packed tower, and esterification reaction is carried out for 6 hours, thus obtaining esterified solution (wherein the esterified solution comprises 92.29 weight percent of dimethyl maleate, 0.61 weight percent of monomethyl maleate, 3.96 weight percent of methanol, 2.1 weight percent of dimethyl phthalate, 0.4 weight percent of water and 0.64 weight percent of deca-alkylbenzene sulfonic acid); the obtained esterified liquid is distilled under reduced pressure to obtain dimethyl maleate (the conversion rate of maleic anhydride is 100%, the selectivity of the dimethyl maleate is 99.0%, and the purity is 99.5%) and separation mother liquor (comprising 89wt% of dimethyl maleate, 2.0wt% of monomethyl maleate, 2.1% of deca-alkylbenzene sulfonic acid and 6.9wt% of dimethyl phthalate);
The obtained separated mother liquor is reused as absorption liquid.
Example 3
N-butane is used as a raw material to carry out oxidation reaction at the temperature of 450 ℃, and the product is cooled to obtain mixed gas containing maleic anhydride; the mixed gas containing maleic anhydride sequentially passes through a methanol superheater and a methanol reboiler to exchange heat with methanol to obtain mixed gas containing maleic anhydride after heat exchange (wherein the mole percentage of the maleic anhydride is 3.3 mol%) (the temperature is 120 ℃) and methanol after heat exchange (the temperature is 125 ℃);
Feeding the heat-exchanged mixed gas containing maleic anhydride from the bottom of an absorption tower, injecting an absorption liquid (comprising 87 wt% 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 liquid to the top of the absorption tower by a circulating pump, and continuously circularly absorbing maleic anhydride until the mass concentration of maleic anhydride in the mixed liquid reaches 60%, thereby obtaining the mixed liquid containing maleic anhydride (the absorption rate of maleic anhydride is 98.9%); wherein, the mass ratio of the dimethyl maleate 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 loop reactor (the temperature of the loop reactor is 125 ℃), injecting methanol from the bottom of the loop reactor (the mole ratio of the methanol to the maleic anhydride in the mixed solution containing maleic anhydride is 2.5:1 in the reaction process), and carrying out primary esterification for 1h to obtain a monoesterification product; injecting the obtained monoesterification product from the top of a bubble column (the temperature of the bubble column is 125 ℃), injecting the heat-exchanged methanol from the bottom of the bubble column (the mass ratio of the monoesterification product to the methanol from the heat exchange is 8:3 in the reaction process), and carrying out a secondary esterification reaction for 5 hours to obtain an esterification liquid (comprising 94.7wt% of dimethyl maleate, 0.2 wt% of monomethyl maleate, 3.56wt% of methanol, 0.74wt% of dimethyl phthalate, 0.5wt% of water and 0.3wt% of p-toluenesulfonic acid); the obtained esterified liquid is distilled under reduced pressure to obtain dimethyl maleate (the conversion rate of maleic anhydride is 100%, the selectivity of the dimethyl maleate is 99.3%, and the purity is 99.5%) and a separation mother liquor (which comprises 90.5wt% of dimethyl maleate, 1.5wt% of monomethyl maleate, 2.3% of p-toluenesulfonic acid and 5.7wt% of dimethyl phthalate);
The obtained separated mother liquor is reused as absorption liquid.
Example 4
N-butane is used as a raw material to carry out oxidation reaction at the temperature of 450 ℃, and the product is cooled to obtain mixed gas containing maleic anhydride; the mixed gas containing maleic anhydride sequentially passes through a methanol superheater and a methanol reboiler to exchange heat with methanol to obtain mixed gas containing maleic anhydride after heat exchange (wherein the mole percentage of the maleic anhydride is 3.3 mol%) (the temperature is 120 ℃) and methanol after heat exchange (the temperature is 125 ℃);
Injecting the heat-exchanged maleic anhydride tail gas 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 maleic anhydride by using the absorption liquid, returning the obtained mixed liquid to the top of the absorption tower by a circulating pump, and continuously carrying out circulating absorption on maleic anhydride until the mass concentration of maleic anhydride in the mixed liquid reaches 60%, thereby obtaining a mixed liquid containing maleic anhydride (the absorption rate of maleic anhydride is 98.9%); wherein, the mass ratio of the dimethyl maleate 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 maleic anhydride is 2.5:1 in the reaction process), and carrying out primary esterification for 1h to obtain a monoesterification product; injecting the obtained monoesterification product from the top of a bubble column (the temperature of the bubble column is 135 ℃), injecting the heat-exchanged methanol from the bottom of the bubble column (the mass ratio of the monoesterification product to the methanol from the heat exchange is 10:3 in the reaction process), and carrying out a secondary esterification reaction for 5 hours to obtain an esterification liquid (comprising 95.02wt% of dimethyl maleate, 0.21wt% of monomethyl maleate, 5.0wt% of methanol, 2.12 wt% of dimethyl phthalate, 0.3wt% of water and 0.35wt% of methane sulfonic acid); the obtained esterified liquid is distilled under reduced pressure to obtain dimethyl maleate (the conversion rate of maleic anhydride is 100%, the selectivity of the dimethyl maleate is 98.5%, and the purity is 99%) and a separation mother liquor (which comprises 87.0wt% of dimethyl maleate, 1.0wt% of monomethyl maleate, 1.7% of methane sulfonic acid and 10.3wt% of dimethyl phthalate);
The obtained separated mother liquor is reused as absorption liquid.
Example 5
N-butane is used as a raw material to carry out oxidation reaction at the temperature of 450 ℃, and the product is cooled to obtain mixed gas containing maleic anhydride; the mixed gas containing maleic anhydride sequentially passes through a methanol superheater and a methanol reboiler to exchange heat with methanol to obtain mixed gas containing maleic anhydride after heat exchange (wherein the mole percentage of the maleic anhydride is 3.3 mol%) (the temperature is 120 ℃) and methanol after heat exchange (the temperature is 125 ℃);
Feeding the heat-exchanged mixed gas containing maleic anhydride from the bottom of an absorption tower, injecting an absorption liquid (comprising 87wt% of dimethyl maleate, 1.0wt% of monomethyl maleate, 1.7wt% of propane sulfonic acid and 10.3wt% 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 liquid to the top of the absorption tower by a circulating pump, and continuously circularly absorbing maleic anhydride until the mass concentration of maleic anhydride in the mixed liquid reaches 60%, thereby obtaining the mixed liquid containing maleic anhydride (the absorption rate of maleic anhydride is 98.9%); wherein, the mass ratio of the dimethyl maleate 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 (the molar ratio of the methanol to the maleic anhydride in the mixed solution containing maleic anhydride is 2.0:1 in the reaction process), and carrying out primary esterification reaction for 1h to obtain a monoesterification product; injecting the obtained monoesterification product from the top of a bubble column (the temperature of the bubble column is 130 ℃), injecting the heat-exchanged methanol from the bottom of the bubble column (the mass ratio of the monoesterification product to the methanol from the heat exchange is 7:3 in the reaction process), and performing a secondary esterification reaction for 5 hours to obtain an esterification liquid (comprising 93.88wt% of dimethyl maleate, 0.12wt% of monomethyl maleate, 5.2wt% of methanol, 0.3wt% of water and 0.5wt% of propane sulfonic acid); the obtained esterified liquid was distilled under reduced pressure to obtain dimethyl maleate (conversion of maleic anhydride is 100%, selectivity of dimethyl maleate is 98.5%, purity is 99.0%) and a separation mother liquor (which includes 86.8wt% of dimethyl maleate, 0.6wt% of monomethyl maleate, 2.5% of propane sulfonic acid and 10.1wt% of dimethyl phthalate);
The obtained separated mother liquor is reused as absorption liquid.
Example 6
N-butane is used as a raw material to carry out oxidation reaction at the temperature of 450 ℃, and the product is cooled to obtain mixed gas containing maleic anhydride; the mixed gas containing maleic anhydride sequentially passes through a methanol superheater and a methanol reboiler to exchange heat with methanol to obtain mixed gas containing maleic anhydride after heat exchange (wherein the mole percentage of the maleic anhydride is 3.3 mol%) (the temperature is 120 ℃) and methanol after heat exchange (the temperature is 125 ℃);
Injecting the heat-exchanged mixed gas containing maleic anhydride from the bottom of an absorption tower, injecting an absorption liquid (comprising 86.8wt% of dimethyl maleate, 0.6wt% of monomethyl maleate, 2.5wt% of trifluoromethyl benzenesulfonic acid and 10.1wt% 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, and returning the obtained mixed liquid to the top of the absorption tower by a circulating pump to continuously circularly absorb maleic anhydride until the mass concentration of maleic anhydride in the mixed liquid reaches 60%, thereby obtaining the mixed liquid containing maleic anhydride (the absorption rate of maleic anhydride is 98.9%); wherein, the mass ratio of the dimethyl maleate 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 bubble column (the temperature of the bubble column is 135 ℃), and injecting the heat-exchanged methanol from the bottom of the bubble column (the molar ratio of the heat-exchanged methanol to the mixed solution containing maleic anhydride is 2.5:1 in the reaction process); countercurrent contact is carried out between the mixed solution containing maleic anhydride and methanol in a bubble column, and esterification reaction is carried out for 6 hours, thus obtaining esterified solution (wherein the esterified solution comprises 92.08 weight percent of dimethyl maleate, 0.14 weight percent of monomethyl maleate, 5.8 weight percent of methanol, 1.28 weight percent of dimethyl phthalate, 0.3 weight percent of water and 0.4 weight percent of trifluoromethyl benzenesulfonic acid); distilling the esterified liquid under reduced pressure to obtain dimethyl maleate (the conversion rate of maleic anhydride is 100%, the selectivity of the dimethyl maleate is 98.5%, and the purity is 99%) and a separation mother liquor (comprising 88.2wt% of dimethyl maleate, 0.9wt% of monomethyl maleate, 2.6% of trifluoromethylbenzenesulfonic acid and 8.3wt% of dimethyl phthalate);
The obtained separated mother liquor is reused as absorption liquid.
Example 7
N-butane is used as a raw material to carry out oxidation reaction at the temperature of 450 ℃, and the product is cooled to obtain mixed gas containing maleic anhydride; the mixed gas containing maleic anhydride sequentially passes through a methanol superheater and a methanol reboiler to exchange heat with methanol to obtain mixed gas containing maleic anhydride after heat exchange (wherein the mole percentage of the maleic anhydride is 3.3 mol%) (the temperature is 120 ℃) and methanol after heat exchange (the temperature is 125 ℃);
Injecting the heat-exchanged mixed gas containing maleic anhydride from the bottom of an absorption tower, injecting an 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 maleic anhydride by using the absorption liquid, and returning the obtained mixed liquid to the top of the absorption tower by a circulating pump to continuously circularly absorb maleic anhydride until the mass concentration of maleic anhydride in the mixed liquid reaches 60%, thereby obtaining the mixed liquid containing maleic anhydride (the absorption rate of maleic anhydride is 98.9%); wherein, the mass ratio of the dimethyl maleate 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 packed tower (the temperature of the packed tower is 125 ℃, and the packed packing is triangular spiral packing), and injecting the heat-exchanged methanol from the bottom of the packed tower (the mole ratio of the heat-exchanged methanol to the mixed solution containing maleic anhydride is 4.0:1 in the reaction process); countercurrent contact is carried out between the mixed solution containing maleic anhydride and methanol in a packed tower, and esterification reaction is carried out for 8 hours, thus obtaining esterified solution (comprising 91.9 weight percent of dimethyl maleate, 0.33 weight percent of monomethyl maleate, 5.67 weight percent of methanol, 1.5 weight percent of dimethyl phthalate, 0.3 weight percent of water and 0.3 weight percent of benzenesulfonic acid); the obtained esterified liquid is distilled under reduced pressure to obtain dimethyl maleate (the conversion rate of maleic anhydride is 100%, the selectivity of the dimethyl maleate is 98.4%, and the purity is 99%) and a separation mother liquor (which comprises 87.2wt% of dimethyl maleate, 2.0wt% of monomethyl maleate, 1.8% of benzenesulfonic acid and 9.0wt% of dimethyl phthalate);
The obtained separated mother liquor is reused as absorption liquid.
Although the foregoing embodiments have been described in some, but not all embodiments of the invention, other embodiments may be obtained according to the present embodiments without departing from the scope of the invention.
Claims (8)
1. A method for preparing dimethyl maleate by using maleic anhydride tail gas, which 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 heat-exchanged mixed gas containing maleic anhydride with the absorption liquid for countercurrent absorption to obtain a mixed liquid containing maleic anhydride; the mixed solution containing maleic anhydride comprises maleic anhydride, dimethyl maleate and organic sulfonic acid catalyst; the mass of the organic sulfonic acid catalyst is 0.1% -0.5% of that of maleic anhydride;
mixing the mixed solution containing maleic anhydride with methanol from heat exchange to perform esterification reaction, and separating the obtained esterified solution to obtain the dimethyl maleate and a separation mother solution;
the separated mother liquor is used as absorption liquor for reutilization;
The absorption liquid comprises dimethyl maleate and an organic sulfonic acid catalyst; the organic sulfonic acid catalyst is one or more of alkyl sulfonic acid, halogenated alkyl sulfonic acid, benzene sulfonic acid and substituted benzene sulfonic acid;
the mixed gas containing maleic anhydride is obtained by oxidizing n-butane as a raw material.
2. The process of claim 1, wherein the esterification reaction does not require additional heating.
3. The method according to claim 1, wherein the temperature of the maleic anhydride-containing gas mixture after heat exchange is 120-250 ℃.
4. The method according to claim 1, wherein the molar ratio of the methanol after heat exchange to the maleic anhydride in the maleic anhydride-containing mixed solution is 2.0 to 8.0:1.
5. The method according to claim 1, wherein the methanol from the heat exchange is in the form of methanol vapor;
the temperature of the methanol vapor is 80-160 ℃.
6. The process according to claim 1, wherein the esterification reaction is carried out in an esterification reactor;
The esterification reactor is one or more esterification reactors of a packed tower, a bubble cap tower, a plate tower, a tubular reactor, a loop reactor, a reaction kettle and a heat exchanger which are connected in series.
7. The method according to claim 6, wherein the esterification reaction is carried out at a temperature of 80 to 150 ℃ for a time of 30 to 720min.
8. The method according to claim 1, wherein the alkyl sulfonic acid is one or more of methane sulfonic acid, ethane sulfonic acid and propane sulfonic acid;
the haloalkylsulfonic acid is trifluoromethanesulfonic acid;
The substituted benzene sulfonic acid is linear alkylbenzene sulfonic acid and/or branched alkylbenzene sulfonic acid;
The straight-chain alkylbenzene sulfonic acid is one or more of p-toluenesulfonic acid, dodecylbenzenesulfonic acid, tetradecylbenzenesulfonic acid and hexadecylbenzenesulfonic acid.
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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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