Structure–reactivity relationship in isolated Zr sites present in Zr-zeolite and ZrO2 for the Meerwein–Ponndorf–Verley reaction

Abstract

The influence of the crystallographic phase of ZrO₂ on its catalytic performance in the MPV reduction of cyclohexanone with propan-2-ol has been systematically investigated by combining accurate synthesis procedures, XRD and HRTEM characterization, kinetic measurements and DFT calculations, and compared to that of Zr-beta zeolite. The higher intrinsic activity of monoclinic zirconia as compared to other ZrO₂ phases is not due to a lower activation energy for the rate-determining step, but to an adequate distribution of reactant fragments on the catalyst surface, indicating a structure–activity relationship for this reaction when catalyzed by ZrO₂ and also by Zr-beta zeolite. Inexpensive and stable ZrO₂ catalysts for the MPV reaction have been obtained by controlling the crystallographic phase of the synthesized material.