Synthesis of glycerol carbonate from glycerol and diethyl carbonate over Ce-NiO catalyst: The role of multiphase Ni

A series of Ce-NiO catalysts prepared by co-precipitation method were tested for glycerol trans-esterification with diethyl carbonate (DEC) to produce glycerol carbonate (GC). The microstructural and physicochemical properties of the catalysts were determined by XRD, XPS, SEM, EDX, CO2-TPD, N-2-adsorption, FT-IR, and TG-DTG. The results showed that the particle size (100-350 nm) of the Ce-NiO was smaller than that of pure NiO (400-900 nm), suggesting addition of Ce in the catalyst synthesis could lessen the aggregation or facilitate the dispersion of NiO particles. The highest catalyst activity was observed over the Ce-NiO catalyst with Ce/Ni atomic ratio of 0.2 and calcined at 400 degrees C. 94.14% of glycerol conversion and 90.95% selectivity to GC were obtained over this catalyst under the optimum conditions (5 wt.% catalyst of glycerol, 85 degrees C, 8 h, glycerol/DEC ratio of 1:3). This catalyst can be reused up to three cycles with a slight decrease in its catalytic activity. It was found the well dispersed NiO particles and the strong basic sites derived from the substitution of Ce4+ by Ni2+ in the CeO2 lattices synergistically promoted the glycerol conversion. (C) 2017 Elsevier B.V. All rights reserved.