Au nanoparticles deposited on the external surfaces of TS-1: Enhanced stability and activity for direct propylene epoxidation with H2 and O2
•First direct evidence of pore blocking for the deactivation of Au/TS-1 catalysts.•Uncalcined TS-1 with blocked micropores has higher gold loading efficiency.•Au/TS-1-B catalyst exhibits enhanced stability for over 30 h.•Au/TS-1-B catalyst prepared by DP method shows high PO formation rate.
Au/TS-1 catalysts prepared by deposition–precipitation method are very promising for direct propylene epoxidation with H2 and O2. However, the catalysts usually suffer from rapid deactivation. In this work, calcined TS-1 with open micropores (TS-1-O) is first used to support Au catalysts, and then the used catalysts at different time-on-streams are characterized to understand the deactivation mechanism. The micropore blocking by carbonaceous deposits is found to be responsible for the deactivation. We therefore suggest a principle of catalyst design to improve the long term stability by depositing Au nanoparticles on the external surfaces of TS-1. For this purpose, uncalcined TS-1 with blocked micropores (TS-1-B) is used to support Au catalyst. As expected, the designed catalyst is not only very stable because of the elimination of pore blocking and the more accessible active sites, but also highly active with the PO formation rate of 125 gPO h−1 kgCat−1 for over 30 h.
Graphical abstractThe calcined TS-1 with open micropores (TS-1-O) supported gold catalyst is found to suffer from deactivation of the micropores blocking by carbonaceous deposits. However, the uncalcined TS-1 with blocked micropores (TS-1-B) supported gold catalysts exhibit high stability and activity.Figure optionsDownload full-size imageDownload as PowerPoint slide
Journal: Applied Catalysis B: Environmental - Volumes 150–151, 5 May 2014, Pages 396–401