The Study Of Solid Alkali Metal Catalysts Used For The Synthesis Of Diethyl Carbonate By Transesterification

Diethyl carbonate (DEC) is an important organic compound. Much attention has been paid to the synthesis and application of DEC because it's low toxic and versatile, and is used as intermediate and starting material for organic synthesis to substitute the poisonous phosgene and dimethyl sulfate in carbonylation and methylation reaction. There are several preparation routes for it, in which oxidative carbonylation method and transeaterification method are the focus of present research. In this paper, the process to prepare DEC from ethanol and dimethyl carbonate (DMC) is studied as follows:Firstly, the free energy change of the reactionΔrGmθ, equilibrium constant Kθwere evaluated according to the chemical thermodynamics principle. The results show that it is helpful for generating DEC when temperature is not too high.Secondly, several solid alkali metals catalysts for the transesterification reaction between EtOH and DMC were examined. The carbonates, hydroxides, alkoxides and halogens of the alkali metals have good catalytic activity in the transesterification reaction. The most active catalyst for the reaction studied was modified potassium salt. Potassium salts showed higher activity than sodium salts and lithium salts among the same anion compounds. Of the potassium halogens tested potassium iodide was proved to be the most active. Therefore, the hardness and softness of acids and bases influence their chemical behavior on the catalytic performance.Finally, the factors affecting their actions including the catalyst concentration the reactant ratio, and the reaction temperature were investigated. Under the optimized condition for industrialization by father optimize research: reaction temperature 78-82℃, mole ratio of EtOH/DMC 6:1, reflux ratio 6:1, catalyst amount 1.0wt.%, reaction time 5h, the conversion of DMC is 75.0%, the yield of DEC is 64.3%.