Insight into Deactivation Reasons for Nanogold Catalysts Used in Gas-Phase Epoxidation of Propylene

摘要

Gas-phase epoxidation of propylene over nanogold catalysts has attracted extensive attention in recent years. Among the Au/Ti-based catalysts, Au/titanium silicalite-1 (denoted as Au/TS-1) shows excellent activity of PO generation. However, Au/TS-1 is reported to suffer from rapid deactivation. To prolong its lifetime, the main deactivation reason was investigated. In this work, Au/TS-1 and Au/TS-1 coated with silicalite-1 (denoted as Au/TS-1@S-1) were prepared. Compared to the traditional Au/TS-1, Au/TS-1@S-1 exhibits better catalytic stability during the same reaction time. This is most likely due to the confinement effect of TS-1@S-1 channels on Au clusters. Multiple types of characterization further confirm that the deactivation of Au/TS-1 is mainly caused by the agglomeration of Au clusters. Moreover, higher reaction temperature as well as longer reaction time results in greater Au particles and the gradual catalyst deactivation.