用管式反应技术制备乙二醇乙醚乙酸酯

Chinese j.Chcm.Eng-11(3)338-340(2003)RESEARCH NOTESPreparation of Ethylene Glycol Monoethyl Ether AcetateUsing a Tubular reactorCAI Zhenyun(蔡振云), LU Zuguo(卢祖国) and LI Xiaobo(李小波)Engineering, Zhejiang University, Hangzhou 310027, Chinaact Ethylene glycol monoethyl ether acetate(EGEA), an excellent solvent, is prepared with ethylene oxidend ethyl acetate(EA) in a tubular reactor under suitable reaction condition. The single circulation yield canThis technology is not only safe but also makes it possible to continuously produce EGEA in industrycontent of high boiling point by-productsKeywords ethylene glycol monoethyl ether acetate, ethyl acetate, tubular reactor1 INTRODUCTIONly prepared through a two-step reaction in the presEthylene glycol monoalkyl ether carboxylic acids, ence of a strongly acidic cationic exchange resin asa series of compounds used as important solvents, were catalyst 21. 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 year!. Its chemical structure can be exIn recent. years, one-step reaction was widely re-pressedsearched and exploited, in which Eo directly reactswith ea to produce EGEA in a tank reactor in thepresence of catalyst 3. This technology has been ap-H3C-C-OCH2, CH2-0-CH2, CHslied 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 andHowever, the disadvantage is that it will bring abotty fragment, as contribute much to the good solubility lots of by-products of diethylene glycol, triethyleneof EGEA, which can dissolve not only low molecular 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 experiit can be well dissolved in water. EGEA is a highly ments, we found that one-step reaction process couldffective solventbe 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 worldction. 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 beproducts come out at the same time. In this study H2C-CH2+Clla COCH CH3 aicuassured in the presence of EO, moreover, lots of byI3 COCHl2 CH2 CH3we industrialize the synthesis of EGEA by exploitinga new process and adopting a tubular reactor.2.2 The reaction process2 EXPERIMENTALA simple fow chart for the reaction is shown inIt is known that EGEA can't be produced by aThe pre-mix unit whose structure and measure areone-step reaction with EO and EA, which is gener- shown in Table I together with those of the tubularReceived 2002-09-19, accepted 2003-01-10.中国煤化工To whon correspondence should be addressedCNMHGPreparation of Ethylene Glycol Monoethyl Ether Acetate Using a Tubular Reactor2.3 Experimental results分团-[6EGEAThe results are shown in Table 2, in which dgeaFigure 1 A simple process chartis the main by- product and the yield of EGEA is cal-I--inetering pump: 2--pre-mix unit; 3--tublar reactorculated only based on a single circulation4-buffer tank; 5-Hlash evaporator: 6--rectification towerIn this technology, anhydrous aluminium trichlo-ride is selected as catalyst, and triethyl amine as co-Table 1 The structure and dimension of tubularcatalyst. Hence, water should be excluded from thereactor and pre-mix unit(whole reacting system, no matter in raw materials orin catalyst, or in the tubular reactor. generally, no410×15中15×2water 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 ofThe amount of the catalyst used can range fromwhich can be measured and controlled by metering 6% to 8% based on the reactant EO os clpump. 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(2-4):1tion 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 200C, 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 pickPressure 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 fash evaporator in the liquid phase, to assure high reaction rate. Inrecover a part of unreacted EA. Remanent EA is general, the pressure between 1.0 MPa and 1.5 MPa isseparated 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 51. 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 Ratio of AlCl3Yield of byto triethyl TempproducttimeEGEADGEA(by nole) % (by mass) %(by mass) %(by mass21,43333333l60l.549,1767777778777754.91.52.315423160TYHe图Chinese J.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 eA to EO increases while lower than that in a tank reactorthe yield of DGEA falls. When the ratio exceeds 8During the whole reaction, EA and EO are fullythe variation becomes unconspicuous. The preferable dispersed and move forward along the tube. It is inratio 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 anine 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 EOand NH3). As we predicted, it should be also suitablefor large-scale production of EGEA(2)Water contained in the raw materials and cat-lysts 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 pumpsing to the hydrolyzing deposits; secondly, eo also re-acts with water to produce ethylene glycol, so the rawraho of EA to Eo(by mole)materials and catalysts should be treated in dry nitro-Figure 2 Effect oftants on theten gas before being fed in a dried tubular reactoryield of EGEA and DGEA暑- yield of EGEA;-·- vield of dgeAREFERENCES3 DISCUSSIONEthylene glycol monoalkyl ether carboxylates", Fin(1)The content of high boiling point by-productsPetroleum Chemical Engineering, 1(3),60-64(1991).(incan be greatly decreased with tubular reactor. The2 Karmetaka, N, Marumo, K,"Process for the controduction of ethylene glycol monoethyl ether acetate",UStent of high boiling point by-products will rise by 20% 3 Hu, w. Yan MLa, synthesis of ethylene glycol mousing traditional tank reactor under the same reactChem. Eng. Chinese Univ, 12(3):277-282,(1998)g condition. Owing to the restriction of pressure inin Chinesa tank reactor. EO must be fed to the tank reactorYoshihara, H, "Process for the production of alkylene gly-at a time. When reactants are heated and agitatedcol ether ester of organic carboxylic acid", US Pat.,4115415though EO can be dispersed sufficiently in the sur- 5 Cai, Z.Y., Xie, R.J., "Analysis of Eo in the preparat ion pro-rounding of EA, egea is apt to re-react with Eoess of ethanolamine", Petrochemical Technology, 23(10).to produce DGEA, a high boiling point by-product676678(1994).( in Chinese)Whereas in a tubular reactor raw materials flow for6 Hu, wQ,"The research of synthesis of alkylene glyceether ester of organic carboxylic acid", MS Thesis, Zhejiangward and react each other after fully pre-mixing,soUniversity, China(1995).(in Chinese中国煤化工CNMHG