Deactivation Mechanism of an Ionic Liquid Catalyst in Transesterification to Dimethyl Carbonate

The catalytic activity of an ionic liquid catalyst decreased during the transesterification of propylene carbonate (PC) with methanol to dimethyl carbonate (DMC). The interaction between the strong basic sites of ionic liquid catalyst and carbonyl compounds of PC and/or DMC was considered to attribute to this deactivation. The presence of H 2 O accelerated this process by the formation of OH – . The strong basic ionic liquid reacted with the trace amount of H 2 O in the reaction system to generate OH – , which then reacted with the carbonyl structure in PC and/or DMC to form the inactive compound HCO 3 – , resulting in the deactivation of the ionic liquid catalyst. A plausible mechanism was proposed for the deactivation of the ionic liquid catalyst in this reaction.