Heterogeneous Catalytic Synthesis Of Propylene Glycol Monomethyl Ether

In this paper,nanometer iron oxide and nano-copper oxide were prepared by simple sol-gel method and XRD,SEM and TEM were used to characterize the structure,size,composition and structure.The catalytic performance of ethylene glycol monomethyl ether which synthesized by the reaction of propylene oxide and methanol was evaluated by using prepared nano-iron oxide as catalyst.The results indicated that nano iron oxide was an excellent catalyst for the synthesis of ethylene glycol monomethyl ether,and it obtained a high conversion of propylene oxide and a high selectivity of 1-methoxy-2-propanol.The optimum reaction conditions were determined by studying the reaction temperature,time,catalyst dosage,molar ratio of methanol and propylene oxide to the synthesis of ethylene glycol monomethyl ether.The reaction time was 8 h,the amount of catalyst was 1.5 g,the alkanol ratio was 36:1,and the reaction temperature was 160°C.Under these optimum conditions,the conversion of propylene oxide was 97.7%and the selectivity of 1-methoxy-2-propanol was 82.6%.The reusability of nanometer iron oxide catalyst was discussed.After four repeated experiments,the catalytic activity was almost constant and indicated that the catalyst had better reproducibility.Based on the experimental results obtained by the catalytic synthesis of nano-iron oxide,the catalytic effects of other oxide catalysts such as Fe₃O₄,ZnO,CuO,NiO and SnO₂ on the synthesis of ethylene glycol monomethyl ether were also discussed.In contrast,CuO exhibited higher catalytic activity,but the selectivity of1-methoxy-2-propanol was only 54.0%and the selectivity of 2-methoxy-1-propanol was only 46.0%.The process conditions for the synthesis of ethylene glycol monomethyl ether catalyzed by copper oxide were optimized.The optimum reaction conditions were obtained using copper oxide as catalyst.The reaction time was 8 h,the amount of catalyst was 1 g,the ratio of alkoxides was 72:1,and the reaction temperature was 160°C.Under these most process conditions,the conversion of propylene oxide was 98.9%,the selectivity of 1-methoxy-2-propanol was 53.7%,and the selectivity of 2-methoxy-1-propanol was 46.3%.After repeated of four times,the catalytic activity remained essentially unchanged.This kind of metal oxide catalyst has the advantages of simple preparation process,high reactivity and easy separation,excellent catalyst reusability and so on.