Kinetic evaluation of perovskites-type catalysts in the reduction of 4-nitrophenol: A mechanistic elucidation study

Abstract

• The effect of electron scavengers helps determine the type of surface mechanism in 4NP reduction. • 4NP reduction by borohydride is a surface catalytically driven reaction. • Perovskites, are alternatives to noble metal-containing heterogeneous catalysts for degradation of environmental pollutants. Herein, we report on the catalytic activity of ABO 3 perovskites (A = La or Sr, B = Co, Sn, Fe, or Al) synthesized by nanocasting technique with silica-based KIT-6 as a hard template. The physical and chemical characteristics of the perovskites were determined using various techniques such as powder X-ray diffraction, nitrogen sorption, transmission and scanning electron microscopes and temperature programmed desorption. The synthesized ABO 3 perovskites were used as heterogeneous catalysts in the reduction of 4-nitrophenol (4NP) by sodium borohydride (NaBH 4 ) to 4-aminophenol (4AP). The perovskites exhibit surface areas ranging from 19 to 101 m 2 /g. Among the as-synthesized perovskites SnAlO 3 was the most acidic catalyst and exhibited the highest catalytic activity towards 4NP reduction. We further explored the role of electron scavengers in elucidating the catalytic mechanism and postulate that the reduction of 4NP follows a surface-driven electron transfer mechanism.