ETHYLENE-GLYCOL DIMETHYL CARBONATE COGENERATION

In this paper eight classes of effective, and in most cases novel, transesterification catalysts are identified for the cogeneration of ethylene glycol plus dimethyl carbonate from ethylene carbonate and methanol. They include: (a) macroreticular and gel-type exchange resins with tertiary amine and quaternary ammonium pendant groups, (b) zirconium, titanium and tin homogeneous catalysts, (c) homogeneous Group VB and VIB compounds, (d) alkali metal silicates on silica, (e) ammonium-exchanged zeolites, (f) acidic resins bearing sulfonic acid and carboxylic acid functional groups and (g) tertiary phosphine polymer catalysts. Liquid products comprising in many cases near-equilibrium concentrations of ethylene glycol and dimethyl carbonate have been cogenerated in greater-than-or-equal-to 98 mol% selectivity (based on EC converted) using continuous unit equipment under moderate conditions (60-150-degrees-C, 100 psi). Unreacted methanol plus EC make up > 99% of the remaining organics. The relative performance advantages and mechanistic pathways of these different classes of catalyst are compared and discussed.