The Synthesis And Purification Of Methyl Glycolate

The synthesis of methyl glycolate from one-step oxidative esterification of ethylene glycol with methanol and the preparation of highly active Au/Al2O3 catalyst were studied in this paper. With the research, the optimum reaction conditions were determined, and also the purification scheme was obtained.The catalyst supports and preparation methods for gold catalyst were discussed in the screening stage. The experimental results exhibited that Au/Al2O3 catalyst prepared by deposition-precipitation method, using NaOH as the precipitating agent, Au weight loading between 0.5% and 1.0%, calcined under 300～400℃for 2h, showed the most favorable performance. Then, based on the former researches, the reaction conditions were optimized according to the thermodynamic analysis and reaction mechanism. Over 97% conversion of ethylene glycol and 60% selectivity of methyl glycolate could be achieved under the optimum conditions as follow:120℃,0.45 MPa and O2:N2=1:2 (volume).With the analysis of the reaction compound, the main by-products were determined as dimethyl oxalate and methyl oxalate. Through the physical-chemical properties of every compound, the separation method was processed as follows:the dimethyl oxalate can be distilled out as azeotrope by the adding of H2O; the methyl oxalate can be removed as precipitation by the using of precipitator B, at last, the purity of methyl glycolate could reach up to 88% by vacuum distillation.