Epoxidation of styrene by t-butyl hydroperoxide over gold nanoparticles supported on Yb2O3: Effect of gold deposition method, gold loading, and calcination temperature of the catalyst on its surface properties and catalytic performance

Abstract

Surface properties and epoxidation performance of Au/Yb2O3 catalyst are influenced by the method of gold deposition [viz. deposition–precipitation (DP), homogeneous deposition–precipitation (HDP) or impregnation], gold loading (0.9–6.6wt%), and the catalyst calcination temperature (400–900°C)]. The catalyst showed the best epoxidation performance when it was prepared by the HDP method and calcined at 500°C. The Au/Yb2O3 catalyst even after calcination at 900°C showed good activity and epoxide selectivity. Both Au0 and Au3+ surface species were found in the catalyst calcined at 800°C, but only Au0 species were observed at the lower calcination temperatures (<600°C). The selectivity for styrene oxide increased continuously with the reaction temperature (from 75°C to 97°C) and time (1–5h), indicating that styrene oxide did not undergo secondary reactions under these conditions.