Catalytic performance of micro-mesoporous zirconosilicates prepared by non-hydrolytic sol-gel in ethanol-acetaldehyde conversion to butadiene and related reactions

Abstract

The open porosity and number of Lewis acid sites in metal silicates (M = Zr, Ta) have been reported as key factors enabling reaching high butadiene (BD) productivity from ethanol. However, some microporous zeolites recently displayed very high BD yields. To gain a deeper insight, we have applied non-hydrolytic sol-gel (NHSG) in the preparation of micro-mesoporous zirconosilicates. The porosity, structure, and acidity of these materials have been described and compared to a benchmark sample prepared by dry impregnation. The detailed characterization proved that NHSG preparation provided highly homogeneous Zr dispersion in silica leading to almost doubled Lewis acid site numbers and higher activity in ethanol-acetaldehyde conversion to BD, Meerwein-Ponndorf-Verley (MPV) reaction, and aldol condensation, in comparison to the catalyst prepared by dry impregnation. The selectivity and stability were similar for catalysts prepared by NHSG and dry impregnation.