用管式反应技术制备乙二醇乙醚乙酸酯

J. Chem.Eng,11(3)338-340(2003)SEARCH NOTESPreparation of ethylene Glycol Monoethyl Ether AcetateUsing a Tubular ReactorCAI Zhenyun(蔡振云), LU Zuguo(卢袒国) and LI Xiaobo(李小波)Department of CheneerIejiang University, Hangzhou 310027, ChinaAbstract Ethylene glycol monoethyl ether acetate(EGEA), an excellent solvent, is prepared with ethylene oxide(EO) and ethyl acetate(EA) in a tubular reactor under suitable reaction condition. The single circulation yield canreach $%. This technology is not only safe but also makes it possible to continuously produce EGEA in industryh low content of high boiling point by-productsKeywords ethylene glycol monoethyl ether acetate, ethyl acetate, tubular reactor1 INTRODUCTIONally prepared through a two-step reaction in the pres-Ethylene glycol monoalkyl ether carboxylence of a strongly acidic cationic exchange resin as aa series of compounds used as important solventscatalyst, However, for this two-step process it needsexploited and developed in early 1970s, which not only a long time to complete the reaction, furthermore, wa-have better capability than comnon solvents such as ter and alcohol are produced as by-products, whichbenzene, acetone and EA, but also have better solvent form azeotrope with the reactants and products andproperties than ethylene glycol ether. Among them, it is very difficult to separate the mixture to obtainEGEA was the first to reach a yield of ten thousand the pure producttons per yearl. Its chemical structure can be exIn recent years, one-step reaction was widely re-pressed assearched and exploited, in which Eo directly reactswith EA to produce EGEA in a tank reactor in thepresence of catalyst 3. This technology has been apHa CC-OCH2 CH2-0-CH2 CH3olied extensively in industry owing to the advantagethat no water and alcohol are produced during the re-There are cther, carbonyl and alkyl structure in action, so it is convenient to refine the react mixturethe molecule, including non-polarity part and polaHowever, the disadvantage is that it will bring aboutity fragment, as contribute much to the good solubility lots of by-products of diethylene glycol, triethyleneof EGEA, which can dissolve not only low molccular glycol and diethylene glycol monoethyl ether acetateorganic substance, but macro-molecular materials as (DGEA), together with relevant ramificationswell, such as cellulose and high polymer. FurthermoreAfter several years'research work and experi-nents, we found that one-step reaction process couldit can be well dissolved in water. EGEA is a highly be well promoted using a tubular reactor, in whichIn the recent several decades, large-scale manu- almost no by-product is formed during the whole re-facture equipment has been set up over the world action. In this paper, we propose a new process toto exploit and synthesize a variety of relevant prod- synthesize EGEa by carrying out the one-step reac-ucts, for inst ance ethylene glycol methyl ether acetate tion in a tubular reactor. The reaction formula of EOand ethylene glycol butyl ether acetate. However, the and EA is as followssecurity of the traditional tank reactor could not beassured in the presence of EO, moreover, lots of byproducts come out at the same time. In this study H2 C- CH2+ CI3COCH2CH3-CH3COCIl2CH2OCH2CHwe industrialize the synthesis of EGEA by exploitinga new process and adopting a tubular reactor.2.2 The reaction process2 EXPERIMENTALA sinple fow chart for the reaction is shown in2.1 SynthesisFig1.It is known that EGEA can't be produced by aThe pre-mix unit whose structure and mcasure areone-step reaction with EO and EA, which is gener- shown in Table 1 together with those of the tubulareceived 2002-09-19, accepted 2003-01-10To whont correspondence should be addrPreparation of Ethylene Glycol Monoethyl Ether Acetate Using a Tubular Reactor2.3 Experimental resultsFO-①团EEAThe results are shown in Table 2, in which DGEAis the main by- product and the yield of EGEA is cal-1--metering pump: 2--pre-mix unit; 3--tublar reactorculated only based on a single circulation4--buffer tank; 5-flash evaporator: 6--rectification towerIn this technology, anhydrous aluminium trichlo-Table 1 The structure and dimension of tubularcatalyst. Hence, water should be excluded from thereactor and pre-mix unit(mrwhole reacting system, no matter in raw materials orin catalyst, or in the tubular reactor. Generally, no中15water exists in industrial EO, so it is necessary to en-ube length4U0O0sure that mass content of water in ea is less than0. 1%. As shown in Table 2, the yield of EGEA wouldreactor, is charged with raw materials(EA and Eo) be very low if the water content exceeds 0. 1%and catalysts in a certain proportion, the amount of The amount of the catalyst used can range fromwhich can be measured and controlled by metering 6% to 8% based on the reactant eo by mass in ac-pump. After mixed sufficiently, the mixtures are fed cordance with related patent! and based on manyinto a tubular reactor, at 10-20 g. min- afflux, then experiments. The most preferable molar ratio of alu-increase the temperature by 0.5C per min. The reac- minium trichloride to triethyl amine is about(24):1ion temperature is well controlled by an oil bath, andIn the process the reaction is at a temperaturethe pressure is dominated by a reducing valve. The about 150--200oC. At temperature above 200 C, thebuffer tank is used to increase the retention time of reaction is too fast to control and by-products will as-the reactants and to prevent the remanent EO from cend. At temperature below 150%C, reaction rate isentering the separating system. There is a fixed appa. low and satisfactory results can not be obtainedratus at the back of the reactor, which is used to pick Pressure should be high enough for the reaction toup sample for analyzing the content of the remain- proceed at the indicated temperature. However, theng EO, in order to accordingly control the reaction reaction pressure is desired to be as high as possibletemperature and the retention time. After fully react. to ensure the minimum pressure to proceed reactioning, mixtures are pumped into the flash evaporator in the liquid phase to assure high reaction rate. Into recover a part of unreacted EA Remanent EA is general, the pressure between 1.0 MPa and 1.5 MPa iseparated by distillation under atmospheric pressure, more appropriatethen re-circulated to a middle tank after being con- The tubular reactor should be long enough to as-densed and liquefied, and sent back to Ea tank to sure the retention time not less than 2h, so that eojoin the next reaction. Finally the mixture is distilled is completely reacted( 5. As shown in Table 2, thein the rectification tower under vacuum to obtain pure longer the retention time is, the higher the yield ofEGEAEGEA and the less the by-product DGEATable 2 Results of the experimentsRatio of Water Ratio of Ratio of alclYield ofExp. EA to content incat, toto triethyl Temp. Pressure Retention Yield of-productEOMPaEGEAA49,11521605086160.08577.816073.21.57416081.072.3Chinese 3.ch.E.11(3)338(2003)Chinese J. Ch. E.(Vol 11, No. 3)The amount of EA should be in excess of that of that EO is uniformly dispersed in the superfluous EAEO to avoid the repeating reaction of product and su- and the probability of EGEA to re-react with EO isperfluous EO. According to Fig. 2, the yield of EGEa greatly reduced. The content of by-products is muchincreases when the ratio of e,A to EO increases while lower than that in a tank reactorthe yield of DGEA falls. When the ratio exceeds 8uring the whole reaction, EA and EO are fullyt he variation becomes unconspicuous. The preferable dispersed and move forward along the tube. It is imratio of EA to EO is in the range of 6: 1 to 8: 1possible for EO to gather together, which also avoidsWe controlled the reaction at temperature 160c the danger of explosion and makes it practical to reactand pressure 1.5 MPa, and adjusted the mass ratio of in liquid environment with high temperature and highcatalysts to EO at 7. The mass ratio of aluminium pressuretrichloride to triethyl amine is 2. 3, and the ratio ofThis technology has been well applied in indus-ea to EO is varied gradually, as shown in Fig. 2.al synthesis of ethanolamine (the reaction of EOnd NH3). As we predicted, it should be also suitabler large-scale production of EGEA.(2)Water contained in the raw materials and cat-alysts greatly affects the yield of EGEA. First, alu-minium trichloride is prone to hydrolyze in the pres-euce of water, which not only reduces the content ofeffective catalyst, but also jams valves and pumps ow-g to the hydrolyzing deposits; secondly eo also reacts with water to produce ethylene glycol, so the rawraho of Ea to eo (by mole)materials and catalysts should be treated in dry nitro-2 Effect ofratio of reactants on thegen gas before being fed in a dried tubular reactoryield of EGEA and DGEA暑- yield of EGEA;-·- vield of dgeaREFERENCES3 DISCUSSIONEthylene glycol monoalkyl ethe(1)The content of high boilingby-productsPetroleum Chemical Engineering, 164(1991).(inan be greatly decreased with tubular reactor. The 2 Kametaka, N, Marumo, K. "Process for the continuoushigher the molar ratio of Ea to Eo, the less byoduction of ethylene glycol monoethyl ether acetate", USproducts. According to related literature[), the con-Pat,4260813(1981tent of high boiling point by-products will rise by 20%noether acetate by one step process from ethyusing traditional tank reactor under the same react-a tank reactor. Eo must be fed to the tank reactor 4 Yoshihara, H, "Process for the production of alkylene glyat a time. When reactants are heated and agitated(1976)though EO can be dispersed sufficiently in the sur- 5 Cai, Z Y, Xie, R.J., "Analysis of EO in the preparationrounding of EA, egea is apt to re-react with Eocess of ethanolamine", Petrochemical Technology, 23(to produce DGEA, a high boiling point by-product676678(1994). (in Chinese)Whereas, in a tubular reactor raw materials fow for-6 Hu, wQ,The research of synthesis of alkylene glycolether ester of organic carboxylic acid", MS Thesis, Zhejiangward and react each other after fully pre-mixing, so University,June, 2003