CN116730839A - Method for preparing methyl ethyl carbonate and diethyl carbonate by transesterification - Google Patents
Method for preparing methyl ethyl carbonate and diethyl carbonate by transesterification Download PDFInfo
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- CN116730839A CN116730839A CN202310725154.6A CN202310725154A CN116730839A CN 116730839 A CN116730839 A CN 116730839A CN 202310725154 A CN202310725154 A CN 202310725154A CN 116730839 A CN116730839 A CN 116730839A
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- carbonate
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- methyl ethyl
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- ionic liquid
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- OIFBSDVPJOWBCH-UHFFFAOYSA-N Diethyl carbonate Chemical compound CCOC(=O)OCC OIFBSDVPJOWBCH-UHFFFAOYSA-N 0.000 title claims abstract description 29
- JBTWLSYIZRCDFO-UHFFFAOYSA-N ethyl methyl carbonate Chemical compound CCOC(=O)OC JBTWLSYIZRCDFO-UHFFFAOYSA-N 0.000 title claims abstract description 29
- 238000000034 method Methods 0.000 title claims abstract description 22
- 238000005809 transesterification reaction Methods 0.000 title claims abstract description 18
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims abstract description 73
- 238000006243 chemical reaction Methods 0.000 claims abstract description 40
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 claims abstract description 31
- 239000003054 catalyst Substances 0.000 claims abstract description 26
- 239000002608 ionic liquid Substances 0.000 claims abstract description 17
- -1 alkyl imidazole carboxylate Chemical compound 0.000 claims abstract description 13
- 239000002994 raw material Substances 0.000 claims abstract description 9
- 230000008569 process Effects 0.000 claims description 8
- 125000000217 alkyl group Chemical group 0.000 claims description 4
- 125000002947 alkylene group Chemical group 0.000 claims description 4
- 239000000047 product Substances 0.000 claims description 3
- 230000035484 reaction time Effects 0.000 claims description 3
- 239000006227 byproduct Substances 0.000 claims description 2
- 238000004821 distillation Methods 0.000 claims description 2
- 125000001183 hydrocarbyl group Chemical group 0.000 claims description 2
- 239000000376 reactant Substances 0.000 claims description 2
- 238000007670 refining Methods 0.000 claims description 2
- 150000002148 esters Chemical class 0.000 abstract description 7
- 230000000694 effects Effects 0.000 abstract description 6
- 230000008901 benefit Effects 0.000 abstract description 5
- 238000004519 manufacturing process Methods 0.000 abstract description 3
- 238000004064 recycling Methods 0.000 abstract description 3
- 230000009849 deactivation Effects 0.000 abstract description 2
- 238000001556 precipitation Methods 0.000 abstract description 2
- 230000002779 inactivation Effects 0.000 abstract 1
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 30
- 235000019441 ethanol Nutrition 0.000 description 22
- 238000003756 stirring Methods 0.000 description 8
- 239000003792 electrolyte Substances 0.000 description 6
- 239000002904 solvent Substances 0.000 description 6
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 5
- 229910001416 lithium ion Inorganic materials 0.000 description 5
- 238000010438 heat treatment Methods 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 239000002002 slurry Substances 0.000 description 4
- 238000003786 synthesis reaction Methods 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- ZMANZCXQSJIPKH-UHFFFAOYSA-N Triethylamine Chemical compound CCN(CC)CC ZMANZCXQSJIPKH-UHFFFAOYSA-N 0.000 description 3
- 229910052783 alkali metal Inorganic materials 0.000 description 3
- 150000001340 alkali metals Chemical class 0.000 description 3
- 238000012856 packing Methods 0.000 description 3
- 238000000066 reactive distillation Methods 0.000 description 3
- 238000000926 separation method Methods 0.000 description 3
- 230000002194 synthesizing effect Effects 0.000 description 3
- 239000010409 thin film Substances 0.000 description 3
- HCGMDEACZUKNDY-UHFFFAOYSA-N 1-butyl-3-methyl-1,2-dihydroimidazol-1-ium;acetate Chemical compound CC(O)=O.CCCCN1CN(C)C=C1 HCGMDEACZUKNDY-UHFFFAOYSA-N 0.000 description 2
- 239000002585 base Substances 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 239000002815 homogeneous catalyst Substances 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 150000007529 inorganic bases Chemical class 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 150000007530 organic bases Chemical class 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- OIWSIWZBQPTDKI-UHFFFAOYSA-N 1-butyl-3-methyl-2h-imidazole;hydrobromide Chemical compound [Br-].CCCC[NH+]1CN(C)C=C1 OIWSIWZBQPTDKI-UHFFFAOYSA-N 0.000 description 1
- RLUSZXYOUSSDLA-UHFFFAOYSA-N 1-ethyl-2,3-dimethyl-1,2-dihydroimidazol-1-ium;acetate Chemical compound CC([O-])=O.CC[NH+]1C=CN(C)C1C RLUSZXYOUSSDLA-UHFFFAOYSA-N 0.000 description 1
- ZXLOSLWIGFGPIU-UHFFFAOYSA-N 1-ethyl-3-methyl-1,2-dihydroimidazol-1-ium;acetate Chemical compound CC(O)=O.CCN1CN(C)C=C1 ZXLOSLWIGFGPIU-UHFFFAOYSA-N 0.000 description 1
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 1
- GSEJCLTVZPLZKY-UHFFFAOYSA-N Triethanolamine Chemical compound OCCN(CCO)CCO GSEJCLTVZPLZKY-UHFFFAOYSA-N 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 229910000288 alkali metal carbonate Inorganic materials 0.000 description 1
- 150000008041 alkali metal carbonates Chemical class 0.000 description 1
- 150000008044 alkali metal hydroxides Chemical class 0.000 description 1
- 229910052784 alkaline earth metal Chemical class 0.000 description 1
- 150000001342 alkaline earth metals Chemical class 0.000 description 1
- 125000003545 alkoxy group Chemical group 0.000 description 1
- 150000001412 amines Chemical class 0.000 description 1
- QGYGRQGZDRVWRP-UHFFFAOYSA-N butanoate;1-butyl-3-methyl-1,2-dihydroimidazol-1-ium Chemical compound CCCC([O-])=O.CCCC[NH+]1CN(C)C=C1 QGYGRQGZDRVWRP-UHFFFAOYSA-N 0.000 description 1
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 1
- 125000002915 carbonyl group Chemical group [*:2]C([*:1])=O 0.000 description 1
- 238000006555 catalytic reaction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000003254 gasoline additive Substances 0.000 description 1
- 239000002638 heterogeneous catalyst Substances 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000002894 organic compounds Chemical class 0.000 description 1
- 150000002989 phenols Chemical class 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 230000036632 reaction speed Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000010992 reflux Methods 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 230000002441 reversible effect Effects 0.000 description 1
- 238000001308 synthesis method Methods 0.000 description 1
- 239000012209 synthetic fiber Substances 0.000 description 1
- 229920002994 synthetic fiber Polymers 0.000 description 1
- 229920003002 synthetic resin Polymers 0.000 description 1
- 239000000057 synthetic resin Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C68/00—Preparation of esters of carbonic or haloformic acids
- C07C68/06—Preparation of esters of carbonic or haloformic acids from organic carbonates
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J31/00—Catalysts comprising hydrides, coordination complexes or organic compounds
- B01J31/02—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides
- B01J31/0277—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides comprising ionic liquids, as components in catalyst systems or catalysts per se, the ionic liquid compounds being used in the molten state at the respective reaction temperature
- B01J31/0278—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides comprising ionic liquids, as components in catalyst systems or catalysts per se, the ionic liquid compounds being used in the molten state at the respective reaction temperature containing nitrogen as cationic centre
- B01J31/0281—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides comprising ionic liquids, as components in catalyst systems or catalysts per se, the ionic liquid compounds being used in the molten state at the respective reaction temperature containing nitrogen as cationic centre the nitrogen being a ring member
- B01J31/0284—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides comprising ionic liquids, as components in catalyst systems or catalysts per se, the ionic liquid compounds being used in the molten state at the respective reaction temperature containing nitrogen as cationic centre the nitrogen being a ring member of an aromatic ring, e.g. pyridinium
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J31/00—Catalysts comprising hydrides, coordination complexes or organic compounds
- B01J31/02—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides
- B01J31/0277—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides comprising ionic liquids, as components in catalyst systems or catalysts per se, the ionic liquid compounds being used in the molten state at the respective reaction temperature
- B01J31/0298—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides comprising ionic liquids, as components in catalyst systems or catalysts per se, the ionic liquid compounds being used in the molten state at the respective reaction temperature the ionic liquids being characterised by the counter-anions
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
Abstract
A method for preparing methyl ethyl carbonate and diethyl carbonate by transesterification uses dimethyl carbonate and ethanol as raw materials and alkyl imidazole carboxylate ionic liquid as a catalyst for reaction, wherein the ionic liquid has higher solubility in carbonic ester, can avoid the deactivation of the catalyst caused by reaction with a large amount of carbonic ester, and is not easy to separate out in a reboiler to block a pipeline. The catalyst has the advantages of high activity, difficult inactivation and recycling after continuous use, large solubility in carbonic ester, difficult precipitation, adjustable proportion of the methyl ethyl carbonate and the diethyl carbonate and the like, and reduces the production cost of producing the methyl ethyl carbonate and the diethyl carbonate by a transesterification method.
Description
Technical Field
The invention relates to a method for synthesizing methyl ethyl carbonate and diethyl carbonate by transesterification of dimethyl carbonate and ethanol, in particular to a catalyst adopted in the synthesis process.
Background
Methyl ethyl carbonate (EMC for short) is a widely used asymmetric carbonate compound, mainly used as a solvent and an organic synthesis intermediate, and particularly used as a solvent for a water-insoluble electrolyte in a lithium ion battery. The EMC as the electrolyte solvent of the lithium ion battery has the advantages of being capable of improving the energy density and the discharge capacity of the battery, improving the safety performance, prolonging the service life, and being good in low-temperature use performance and the like. The EMC as the electrolyte solvent of the lithium ion battery has the advantages that the EMC is discovered in recent years, the ion conductivity of lithium ion conduction can be obviously improved, the energy density and the discharge capacity of the battery are improved, the service life of the battery can be prolonged, and the safety performance is high, so that the methyl ethyl carbonate electrolyte has the irreplaceable advantage in the electrolyte industry of the lithium ion battery. Because the high price and purity of EMC affect the application of the EMC, the development of a good synthesis method, the reduction of production cost and the improvement of purity are key to the wide use of EMC.
The diethyl carbonate is an organic compound with very wide application, contains alkoxy and carbonyl in the molecule, has active chemical properties, can react with various alcohols, phenols, amines, esters and the like, is a solvent with excellent performance and an important organic synthesis intermediate, is widely applied to industries such as electrolyte solvents of lithium batteries, synthetic fibers, synthetic resins, pharmacy and the like, and is also an excellent gasoline additive, thus having very high industrial application value.
The transesterification method is a main method for synthesizing methyl ethyl carbonate and diethyl carbonate, dimethyl carbonate and ethanol are used as raw materials, and most of catalysts adopted in the transesterification process are alkaline substances, and can be homogeneous phase or heterogeneous phase. Strong base resins and rare metal impregnated SiO as proposed in patent US 4691041 2 Etc., organic bases such as triethylamine and triethanolamine as proposed in US 4062884, organic phosphorus as proposed in US 4734518, etc., naOH, KOH, naOCH as proposed in US 3803201 3 、KOCH 3 And alkali metal and alkaline earth metal derivatives. Among these catalysts, heterogeneous catalysts do not have the problem of subsequent separation, but are the least active; although the organic base catalyst has certain activity, the activity is still 10-100 times lower than that of inorganic base. Thus, in many cases, inorganic bases remain the catalyst of choice due to their high activity and low cost.
In the chinese patent 01105822.6, the inventor proposes a new process for synthesizing diethyl carbonate by transesterification of dimethyl carbonate and ethanol, in which a strong base such as alkali metal hydroxide, alkali metal methylate or ethylate is used as a catalyst, the reaction speed is high, and in the practical application process, it is found that the alkali metal derivative catalyst has low solubility in diethyl carbonate, and is easy to react with a large amount of existing carbonate to generate alkali metal carbonate, so that the catalyst is deactivated, and is easy to precipitate in a reboiler to block a pipeline. Therefore, further improvement of the Chinese patent 011055822.6 is necessary. For this reason, it has been an effort to develop a catalyst which is compatible with carbonates, has high activity and has a long life. Industrial catalysis (2013,21 (3): 58-62) discloses that dimethyl carbonate and ethanol are catalyzed to be transesterified to synthesize methyl ethyl carbonate by using 1-butyl-3-methylimidazole bromide, the reaction temperature is 90 ℃, the reaction time is 12h, the DMC conversion rate is 71.1%, the selectivity is 81.8%, and the catalyst can be circulated for 3 times.
The invention aims to disclose a method for preparing methyl ethyl carbonate and diethyl carbonate by using a homogeneous catalyst formed by alkyl imidazole carboxylate ionic liquid, so as to overcome the defects in the prior art, and the proportion of the methyl ethyl carbonate to the diethyl carbonate in the product can be adjusted.
Disclosure of Invention
According to the invention, dimethyl carbonate and ethanol are used as raw materials, and transesterification is carried out in the presence of a homogeneous catalyst alkyl imidazole carboxylate ionic liquid to obtain diethyl methyl carbonate, and the ionic liquid has higher solubility in carbonic ester, so that the reaction with a large amount of carbonic ester existing can be avoided, the catalyst is deactivated, and the catalyst is not easy to separate out in a reboiler to block a pipeline.
In the invention, dimethyl carbonate and ethanol are used as raw materials, methyl ethyl carbonate is prepared through transesterification in the presence of an alkyl imidazole carboxylate ionic liquid catalyst, and diethyl carbonate is combined, and the reaction of the dimethyl carbonate and the ethanol can be represented by the following formula:
2CH 3 CH 2 OH + CH 3 OCOOCH 3 = C 2 H 5 OCOOC 2 H 5 + 2CH 3 OH (1)
the reaction is actually carried out in two steps:
CH 3 CH 2 OH + CH 3 OCOOCH 3 = CH 3 CH 2 OCOOCH 3 + CH 3 OH (2)
CH 3 CH 2 OH + CH 3 CH 2 OCOOCH 3 = C 2 H 5 OCOOC 2 H 5 + CH 3 OH (3)
therefore, the reaction of dimethyl carbonate and ethanol is a series reversible reaction, namely, under the action of a catalyst, ethanol firstly reacts with dimethyl carbonate to generate intermediate methyl ethyl carbonate and methanol, and then methyl ethyl carbonate and ethanol continuously react to generate diethyl carbonate and methanol. Reaction (2) is a fast reaction, reaction (3) is a slow reaction, and the rate of the whole reaction is determined by (3). By controlling the reaction progress, the transesterification reaction is allowed to produce methyl ethyl carbonate in a large amount, or diethyl carbonate in a large amount.
The catalyst is alkyl imidazole carboxylate ionic liquid, and the dosage of the ionic liquid is 0.1-10% of the total mass of the raw materials; wherein the structural formula of the alkyl imidazole carboxylate ionic liquid is
Wherein R is 1 、R 2 Is one of H, alkyl and alkylene; r is R 3 Is one of hydrocarbon groups; r is R 4 Is one of H, alkyl and alkylene.
The transesterification reaction temperature of the dimethyl carbonate and the ethanol is 25-130 ℃, the reaction time is 10-120 min, and the reaction is carried out under normal pressure or vacuum.
The molar ratio of the dimethyl carbonate to the ethanol is 1: 1-5: 1.
after the reaction is finished, separating reactant dimethyl carbonate and product methyl ethyl carbonate and part of byproduct diethyl carbonate by distillation, refining in the subsequent process, and returning the rest diethyl carbonate and alkyl imidazole carboxylate ionic liquid for reuse.
Compared with the existing transesterification catalyst, the alkyl imidazole carboxylate ionic liquid catalyst provided by the invention has the advantages of high activity, difficult deactivation in continuous use, recycling, large solubility in carbonic ester, difficult precipitation and the like, further reduces the production cost of producing methyl ethyl carbonate and diethyl carbonate by a transesterification method, and improves and perfects the synthesis process of methyl ethyl carbonate and diethyl carbonate by the transesterification method. The present invention will be further illustrated by the following examples, which are not intended to limit the scope of the invention.
Example 1
In a 250ml jacketed reaction kettle, a super constant temperature tank is used for water bath heating, and an electric stirring slurry is used for stirring, so that the rotating speed is more than 500 revolutions per minute, and mass transfer and heat transfer resistance can be eliminated. 46 g of absolute ethyl alcohol, 90 g of dimethyl carbonate and 1.36 g of 1-butyl-3-methylimidazole acetate are added into a reaction kettle and reacted at 75 ℃. After 40 minutes of reaction, the composition of the solution was 15.14% by weight of methanol (mass content is not specified below), 12.06% by weight of ethanol, 29.77% by weight of dimethyl carbonate, 34.90% by weight of ethyl methyl carbonate and 8.13% by weight of diethyl carbonate.
Example 2
In a 250ml jacketed reaction kettle, a super constant temperature tank is used for water bath heating, and an electric stirring slurry is used for stirring, so that the rotating speed is more than 500 revolutions per minute, and mass transfer and heat transfer resistance can be eliminated. 46 g of absolute ethyl alcohol, 90 g of dimethyl carbonate and 0.80 g of 1-ethyl-2, 3-dimethyl imidazole acetate are added into a reaction kettle to react at 70 ℃. After 50 minutes of reaction, the solution consisted of 14.95% (wt%) methanol, 12.58% ethanol, 33.25% dimethyl carbonate, 33.25% ethyl methyl carbonate, and 7.96% diethyl carbonate.
Example 3
In a 250ml jacketed reaction kettle, a super constant temperature tank is used for water bath heating, and an electric stirring slurry is used for stirring, so that the rotating speed is more than 500 revolutions per minute, and mass transfer and heat transfer resistance can be eliminated. 23 g of absolute ethyl alcohol, 90 g of dimethyl carbonate and 1.70 g of 1-ethyl-3-methylimidazole acetate are added into a reaction kettle and reacted at 65 ℃. After 60 minutes of reaction, the solution composition was 8.5% (wt%) methanol, 4.07% ethanol, 60.1% dimethyl carbonate, 25.31% ethyl methyl carbonate, and 2.02% diethyl carbonate.
Example 4
In a 250ml jacketed reaction kettle, a super constant temperature tank is used for water bath heating, and an electric stirring slurry is used for stirring, so that the rotating speed is more than 500 revolutions per minute, and mass transfer and heat transfer resistance can be eliminated. 46 g of absolute ethyl alcohol, 90 g of dimethyl carbonate and 2.72 g of ionic liquid 1-butyl-3-methylimidazole butyrate are added into a reaction kettle and reacted at 78 ℃. After 30 minutes of reaction, the solution composition was 15.2% (wt%) methanol, 11.9% ethanol, 29.4% dimethyl carbonate, 35.2% ethyl methyl carbonate, and 8.3% diethyl carbonate.
Example 5
The transesterification of dimethyl carbonate with ethanol is carried out in a reactive distillation column.
The reaction rectifying tower is a combined tower of packing material with the diameter of 500mm and the height of 26000mm and a plate tower, the rectifying tower section is provided with structured packing materials, the number of theoretical plates is 10, the reaction section is provided with 30 plates, the stripping section is structured packing materials, and the number of theoretical plates is 10.
Reaction rectifying tower operating condition:
raw material ethanol enters the top of a reaction section of the reactive distillation tower at the rate of 92kg/h, dimethyl carbonate at the rate of 209kg/h and a circulating catalyst at the rate of 10.2kg/h (wherein ionic liquid 1-butyl-3-methylimidazole acetate 6kg/h and diethyl carbonate 4.2 kg/h), and the total energy required by the reactive distillation process is provided by a tower kettle reheater through external heat. Operating at normal pressure, wherein the reflux ratio of the tower top is 2, the temperature of the tower bottom is 100-115 ℃, and the temperature of the tower top is 64-65 ℃. The top discharge amount of the column was 91.38kg/h, which consisted of 29.95% (wt) methanol and 70.05% (wt) DMC, and was fed to the subsequent methanol/DMC azeotrope separation column. The discharge amount of the tower kettle is 219.82kg/h, wherein the methyl ethyl carbonate is 66.91%, the DMC content is 17.74%, the rest is 2.76% of catalyst, the diethyl carbonate is 12.57%, and the methanol and the ethanol are trace. In the reactive rectifying column, the conversion of the raw material ethanol was 99.9%, and the selectivity of methyl ethyl carbonate was 85.84%. And feeding the tower kettle material liquid into a thin film evaporator.
Operating conditions of the thin film evaporator:
the feed liquid from the tower bottom of the reactive rectifying tower enters the upper part of the thin film evaporator at the speed of 219.92kg/h, the energy required by the separation process is provided by an evaporator jacket, the top temperature of the evaporator is 88-120 ℃, the temperature of the tower bottom is 120-135 ℃, and the operating pressure is normal pressure. Dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, trace methanol, ethanol and other light components are arranged at the top of the reaction rectifying tower, and the gas phase flow is 209.72kg/h and returns to the reaction rectifying tower; the catalyst-containing DEC solution of 10.2kg/h can be obtained at the tower bottom, wherein the DEC content is 41.2%, the catalyst content is 58.8%, and the DEC solution is returned to the reaction rectifying tower for recycling.
Claims (5)
1. A method for preparing methyl ethyl carbonate and diethyl carbonate by transesterification comprises the steps of taking dimethyl carbonate and ethanol as raw materials, and performing transesterification reaction in the presence of a catalyst to synthesize the methyl ethyl carbonate, and is characterized in that: the catalyst is alkyl imidazole carboxylate ionic liquid, and the dosage of the ionic liquid is 0.1-10% of the total mass of the raw materials; wherein the structural formula of the alkyl imidazole carboxylate ionic liquid is
2. Wherein R is 1 、R 2 Is one of H, alkyl and alkylene; r is R 3 Is one of hydrocarbon groups; r is R 4 Is one of H, alkyl and alkylene.
3. The method of claim 1, wherein: the reaction temperature is 25-130 ℃, the reaction time is 10-120 min, and the reaction is carried out under normal pressure or vacuum.
4. The method of claim 1, wherein: the molar ratio of the dimethyl carbonate to the ethanol is 1: 1-5: 1.
5. the method of claim 1, wherein: after the reaction is finished, separating reactant dimethyl carbonate and product methyl ethyl carbonate and part of byproduct diethyl carbonate by distillation, refining in the subsequent process, and returning the rest diethyl carbonate and alkyl imidazole carboxylate ionic liquid for reuse.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202310725154.6A CN116730839A (en) | 2023-06-19 | 2023-06-19 | Method for preparing methyl ethyl carbonate and diethyl carbonate by transesterification |
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