Role of Sm3+ and Ce4+ on mesoporous rice husk silica for selective oxidation of benzyl alcohol to benzaldehyde

Abstract

Silica was prepared from rice husk—agricultural waste—by soaking and pyrolysis method. Ceria and samaria were impregnated on silica by rotavapor-assisted impregnation method. The physicochemical properties of Ce–Sm/Si catalyst were determined by BET, FT-IR, XRD, SEM, EDX, and n-butylamine titration. Catalytic activity was evaluated by oxidation of benzyl alcohol (Bzl-OH) to benzaldehyde (B-CHO) using H2O2 as an oxidant in acetonitrile medium. Different reaction parameters like time, temperature, solvent, and catalyst amount on the reaction were also studied. Among the various catalysts, 50Ce50Sm/Si showed the impressive catalytic performance with a selectivity of 91.4% to benzaldehyde. The improved catalytic performance was attributed to the well dispersion of ceria–samaria on the surface of silica. These materials can be reused effectively up to four cycles without significant loss in their selectivity. Moreover, excellent selectivity of benzaldehyde in shorter duration using modified rice husk silica catalysts makes this protocol highly attractive and practically beneficial.