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

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 (0.9–6.6 wt%), 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 (1–5 h), indicating that styrene oxide did not undergo secondary reactions under these conditions.

Gold nanoparticles deposited on Yb2O3 by the homogeneous deposition precipitation method shows high thermal stability against sintering at high temperatures and also showed high catalytic activity and excellent reusability in the epoxidation of styrene by TBHP.Figure optionsDownload high-quality image (47 K)Download as PowerPoint slideHighlights
► Prepared Au/Yb2O3 by DP and HDP methods.
► Au/Yb2O3 (HDP) showed better performance in the epoxidation.
► The epoxidation was strongly influenced by Au loading and calcination temperature of Au/Yb2O3 (HDP).
► Au/Yb2O3 catalysts were characterized by HRTEM and XPS.
► The catalyst calcination temperature strongly influenced the Au particle size and surface gold species.