In Situ Preparation of Gold-Silica Particles from a Mixture of Oil Palm Leaves and Chloroauric Acid for Reduction of Nitroaromatic Compounds in Water

Abstract

Gold-silica composites were prepared via a simple green approach using oil palm leaves (OPL) as sustainable source of natural silica. The presence of peaks at 2 theta = 21.7 degrees, 38.1 degrees, 44.2 degrees, 64.5 degrees, and 77.4 degrees in X-ray diffraction (XRD) analysis indicated that gold metal was incorporated into the solid silica-containing product. The as-prepared solid material, Au-SiO2(OPL), was effective as a heterogeneous catalyst for 4-nitrophenol and 4-nitrobenzaldehyde reduction in the presence of sodium borohydride to give the corresponding amino compounds. The good catalytic activity of Au-SiO2(OPL) for the reduction of nitro compounds can be ascribed to the presence of active sites in the ligand-free gold surface supported by green silica. The catalyst exhibited good stability, as confirmed by the consistency of the XRD pattern of the catalyst before and after being used in the 4-nitrophenol reduction reaction.