La-Doped Mg-Al Composite Oxides: Efficient Catalysts for the synthesis of Diethyl Carbonate via Transesterification of Ethylene Carbonate with Ethanol

Series of La-doped Mg-Al composite oxides were prepared by co-precipitation method and used as catalysts for the synthesis of diethyl carbonate (DEC) via transesterification of ethylene carbonate (EC) with ethanol (EtOH). SEM, XRD, FT-IR and XPS results confirmed that the introduction of La enhanced the interaction with MgO. The 8 mol % La-doped Mg-Al composite oxide (calcined catalyst named HTC-0.8 La) produced strong interactions and improved lattice oxygen content (27.84 %). Based on the N2 adsorption-desorption and CO2-TPD results, the HTC-0.8 La catalysts possessed abundant multistage mesoporous structure, high strong base density and strength (0.941 mmol & sdot; g-1). Therefore, the HTC-0.8La catalyst exhibited high catalytic activity with 58.5 % yield of DEC and 94.7 % selectivity to DEC (EC: EtOH molar ratio=1 : 6, reaction time=1.5 h, reaction temperature=150 degrees C and catalyst amount=3.2 wt %). Based on the correlation between catalytic activity and alkalinity, the yield of DEC was positively and linearly related to the strong alkali density of the catalyst. After five replicate experiments, the DEC yield after recovery and roasting reached 54.1 %, indicating that HTC-0.8La is a renewable heterogeneous catalyst. La-doped Mg-Al composite oxides were prepared by co-precipitation method. The introduction of La enhanced the interaction with MgO, which further increased the density and strength of the strong base sites of the catalysts and improved the lattice oxygen content of the catalysts. The material showed high catalytic performance for the synthesis of diethyl carbonate via transesterification of ethylene carbonate with ethanol. image