Probing the promotional roles of lanthanum in physicochemical properties and performance of ZnZr/Si-beta catalyst for direct conversion of aqueous ethanol to butadiene

Here, the efficient synthesis of butadiene from aqueous ethanol was achieved over a series of x%LaZnZr/Si-beta multifunctional catalysts prepared by wet impregnation method. La species played a crucial role in improving the physicochemical properties and catalytic performance of the ZnZr/Si-beta catalyst. The structure and physicochemical properties of the synthesized catalysts were analyzed by multiple characterization technique. The characterization results revealed that the introduction of La species into ZnZr/Si-beta catalyst created a new La-O-Si bond, and rationally modified the acid-base properties. The La species substantially improved the main reaction of aldol condensation and inhibited the ethanol dehydration, as demonstrated by ethanol-TPD and TPSR studies. In addition, the adsorption capacity of water vapor was remarkably suppressed. A remarkable butadiene selectivity of 60.6 % and ethanol conversion of 83.4 % were achieved on the 5 %LaZnZr/Si-beta catalyst. This enhancement of butadiene selectivity and catalytic activity is very helpful for the development of novel efficient multifunctional catalysts for the direct synthesis butadiene from aqueous ethanol. ● The effect of water vapor on the catalytic performance was investigated. ● The La species rationally adjusted the physicochemical properties of the catalysts. ● Aldol condensation of acetaldehyde reaction was improved via La species. ● The promoting roles of La species on physiochemical properties and performance were clearly clarified. ● 5 %LaZnZr/Si-beta catalyst achieved excellent catalytic activity and butadiene selectivity.