Utilization of Silver Silicate for the Formation of Highly Dispersed Silver on Silica Catalysts

Abstract

Supported silver catalysts with small and uniform particle sizes are promising for selective hydrogenation or oxidation reactions. However, during catalyst preparation, transport of the silver precursors often leads to large silver particles, especially at higher silver loadings. In this paper, the use of silver silicate as an intermediate for the preparation of silica-supported silver nanoparticles is reported. Supported silver silicate was prepared by reacting silver nitrate with silica. Subsequently, the silver silicate was reduced to prepare supported silver nanoparticles of ~2 nm in size at a loading of 15 wt% Ag. The utilization of silver silicate limited the transport of silver species during precursor decomposition, resulting in silver nanoparticles 20 times smaller than those formed by direct reduction of a supported silver nitrate precursor. The catalysts were applied in carbon monoxide oxidation, which confirmed the high dispersion as well as the excellent stability of the supported silver nanoparticles thus prepared.