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CN-117945864-B - Method for synthesizing alkyl glyceryl ether by glycerin etherification

CN117945864BCN 117945864 BCN117945864 BCN 117945864BCN-117945864-B

Abstract

A method for synthesizing alkyl glyceryl ether by glycerin etherification comprises the steps of adding a eutectic solvent into glycerin, introducing nitrogen to remove oxygen, introducing the mixture into a micro-channel reactor, introducing gas olefin into the micro-channel reactor, reacting the gas olefin with the micro-channel reactor, performing gas-liquid separation on a reaction product, and refining the liquid to obtain the alkyl glyceryl ether, wherein the eutectic solvent is a mixture of methylimidazole sulfonate and oxalic acid. The invention adopts the specific eutectic solvent and the micro-channel reactor to jointly promote the dissolution of olefin in the eutectic solvent, so that the multiphase reaction of gas-phase olefin and liquid-phase glycerin is converted into homogeneous reaction, the olefin polymerization side reaction is reduced under the condition that no additional polymerization inhibitor is required to be added, the product yield is improved, and the technical scheme of the invention can realize continuous production and improve the production efficiency of the product.

Inventors

  • CHENG JIN
  • CAO CHANGHAI
  • LI LANPENG
  • WANG SHOUZHANG
  • WANG YIDI

Assignees

  • 中国石油化工股份有限公司
  • 中石化（大连）石油化工研究院有限公司

Dates

Publication Date
20260505
Application Date
20221031

Claims (11)

  1. 1. A method for synthesizing alkyl glyceryl ether by glycerin etherification is characterized in that a eutectic solvent is added into glycerin, nitrogen is introduced into a microchannel reactor after deoxidization, gas olefin is introduced into the microchannel reactor for reaction, gas-liquid separation is carried out on reaction products, and liquid is refined to obtain the alkyl glyceryl ether, wherein the eutectic solvent is a mixture of methylimidazole sulfonate and oxalic acid.
  2. 2. The method according to claim 1, wherein the eutectic solvent is a mixture of methylimidazole sulfonate and oxalic acid in a molar ratio of 1:1-1:5.
  3. 3. The method according to claim 1, wherein the eutectic solvent is obtained by mixing methylimidazole sulfonate with oxalic acid, stirring for 30-90min at 60-150 ℃ until a homogeneous transparent liquid is formed, and cooling for use.
  4. 4. A method according to claim 1, wherein the eutectic solvent is used in an amount of 5% -30% by mass of glycerol.
  5. 5. The method according to claim 1, wherein the space velocity of the mixture of glycerol and eutectic solvent relative to the volume of the microchannel reactor is 1-10h -1 .
  6. 6. The process according to claim 1, wherein the olefin is isobutylene and/or isoamylene.
  7. 7. The method of claim 1, wherein the olefin and glycerol are introduced into the microchannel reactor at a gas-to-liquid molar ratio of from 10 to 20:1.
  8. 8. The process according to claim 1, wherein the reaction conditions in the microchannel reactor are such that the reaction temperature is from 20 to 100℃and the reaction pressure is from 0.2 to 2MPa.
  9. 9. The method of claim 1, wherein the microchannel reactor has an inner diameter of 0.2-1.2mm.
  10. 10. The process of claim 1 wherein the gas fraction is unreacted olefin after gas-liquid separation of the product effluent from the microchannel reactor, optionally being recycled as olefin feed.
  11. 11. The method according to claim 1, wherein after gas-liquid separation of the product from the microchannel reactor, the liquid fraction is separated by at least one method selected from the group consisting of water washing, extraction and distillation, the bottom effluent is unreacted trace glycerol, eutectic solvent and monoglyceride, and optionally recycled as recycle material, and the top is a small amount of monoglyceride and main diglyceride and triglyceride products.

Description

Method for synthesizing alkyl glyceryl ether by glycerin etherification Technical Field The invention relates to the technical field of fuel additives, in particular to a method for preparing alkyl glyceryl ether by glycerin etherification. Background Glycerol is a byproduct of the transesterification process of vegetable oils to produce biodiesel. With the development of the biodiesel industry, there is a large surplus of global glycerol supply. How to fully and reasonably utilize the low-cost glycerin becomes an important problem. In recent years, research focus has been on the use of glycerol to prepare glycerol ethers as fuel additives. The etherification reaction is carried out by using the low-cost glycerin and the alkylating reagent, so that the problem of excessive glycerin can be solved by using the glycerin which is a byproduct of biodiesel, the production cost is reduced, and meanwhile, the product alkyl glyceryl ether can be used as a fuel additive and added into diesel oil to improve performances such as cetane number and the like. Therefore, the research of the alkyl glyceryl ether is developed, and the method has positive and great practical significance. The prior art generally employs etherification of glycerol with an alcohol and an olefin. The generated glycerol ether is a mixture of tert-butyl glycerol monoether, tert-butyl glycerol diether and tert-butyl glycerol triether, wherein the glycerol diether and the glycerol triether can be well compatible with diesel oil, can be used as diesel oil additives, and can obviously reduce the contents of particulate matters, hydrocarbons and carbon monoxide in tail gas when being added into standard diesel oil fuel containing 30% -40% of aromatic hydrocarbon. As is known, the etherification reaction of glycerol and alcohol is more difficult than the etherification reaction of glycerol and olefin, the utilization rate of reaction atoms is lower than that of the etherification reaction of olefin, and meanwhile, when alcohol is used as an etherifying agent, the reaction balance is limited by byproduct water, and the water is required to be continuously removed in the reaction process. During etherification reaction of glycerin and olefin, the reaction is difficult due to heterogeneous catalytic reaction, and 20% -50% of monosubstituted glycerin alkyl ether (with poor quality) exists in the product, and meanwhile, because olefin is easy to self-polymerize, more olefin dimerization byproducts are generated in the reaction, so that the conversion rate of converting olefin into alkyl glycerin ether is reduced. CN102531852a discloses a process for preparing tert-butyl glyceryl ether by using rare earth modified molecular sieve, which is characterized in that soluble salts of lanthanum, cerium, neodymium, europium, samarium and praseodymium are selected to prepare rare earth salt solution, H beta molecular sieve is subjected to ion exchange in the rare earth salt solution by microwave heating stirring or conventional heating stirring, the rare earth modified beta molecular sieve catalyst obtained after filtering, drying and calcining is added into a reaction kettle, and tert-butyl glyceryl ether mixture containing mono-tert-butyl glyceryl ether (MTBGs), di-tert-butyl glyceryl ether (DTBG) and tri-tert-butyl glyceryl ether (TTBG) is synthesized under the reaction pressure of 1-2 mpa and the reaction temperature of 50-100 ℃. The method adopts a noble metal catalyst, the catalyst is expensive and difficult to recycle. CN103910612B discloses a process for preparing glycerin ether by catalytic etherification of glycerin, namely pure glycerin and isobutene are used as raw materials, glycerin monoether, glycerin diether and glycerin triether are generated under the catalysis of a sulfonated graphene catalyst, and the reacted mixed system is extracted and separated by glycerin raw materials. Adding glycerin into the mixture after reaction, carrying out mixed mass transfer and sedimentation layering, separating the system into two phases, taking the product containing the triglyceride and the diglyceride as the main product in the upper layer, recovering the product as the product, and taking the glycerin, a small amount of the glyceride and the catalyst in the lower layer, continuing the reaction after the isobutene is flushed, and realizing the synthesis of preparing the glyceride by catalytic etherification of the glycerin, the product collection and the catalyst recycling through the cyclic operation of reaction-extraction. The method adopts the multiphase reaction of isobutene gas and liquid-phase glycerin, the glycerin reaction conversion rate is low, the yield of target products is low, isobutene is easy to self-polymerize, more olefin dimerization byproducts are generated in the reaction, and the conversion rate of converting olefin into alkyl glycerin ether is reduced. CN105732332B discloses a method for producing glycerin alkyl ether based on heterogeneous