Precisely Engineered Supported Gold Clusters as a Stable Catalyst for Propylene Epoxidation

Abstract

Designing a stable and selective catalyst with high H 2 utilisation is of pivotal importance for the direct gas‐phase epoxidation of propylene. This work describes a facile one‐pot methodology to synthesise ligand‐stabilised sub‐nanometre gold clusters immobilised onto a zeolitic support (TS‐1) to engineer a stable Au/TS‐1 catalyst. A non‐thermal O 2 plasma technique is used for the quick removal of ligands with limited increase in particle size. Compared to untreated Au/TS‐1 catalysts prepared using the deposition precipitation method, the synthesised catalyst exhibits improved catalytic performance, including 10 times longer lifetime (>20 days), increased PO selectivity and hydrogen efficiency in direct gas phase epoxidation. The structure‐stability relationship of the catalyst is illustrated using multiple characterisation techniques, such as XPS, 31 P MAS NMR, DR‐UV/VIS, HRTEM and TGA. It is hypothesised that the ligands play a guardian role in stabilising the Au particle size, which is vital in this reaction. This strategy is a promising approach towards designing a more stable heterogeneous catalyst.