Glycerol carbonation with CO2 and La2O2CO3/ZnO catalysts prepared by two different methods: Preferred reaction route depending on crystalline structure

Abstract

La2O2CO3/ZnO catalysts for glycerol carbonation with CO2 to produce glycerol carbonate were prepared by two different methods – co-precipitation (conventional method) and ethylene glycol combustion (novel method) – and investigated their catalytic properties and performance through characterization and reaction tests. La2O2CO3/ZnO prepared by the novel method (NLZ) showed higher yields of glycerol carbonate than La2O2CO3/ZnO prepared by the conventional method (CLZ) due to extremely high selectivity of glycerol carbonate by NLZ, even though NLZ exhibited lower glycerol conversions. Depending on the preparation method, predominant La2O2CO3 phases were different: monoclinic La2O2CO3 for NLZ and hexagonal La2O2CO3 for CLZ. From characterization of the spent catalysts, zinc glycerolate, an intermediate in this reaction, was formed in a large aggregate of nanoparticles over the spent CLZ, while the spent NLZ contained a trace amount of zinc glycerolate. These different catalytic behaviors were explained on the basis of catalytic reaction routes and La2O2CO3 structures.