Interface modulation of Pt/Al2O3 catalyst and their roles in thermal stability

Abstract

Interfacial local environment of noble metal nanoparticles (NPs) and support is crucial for the development and design of thermally and chemically stable noble metal heterogeneous catalysts. The unique chemical environment can strengthen the NPs interaction with the support surface, which can effectively avoid the agglomeration of NPs. The strategy is developed to modulate the interfacial chemical environment of supported Pt NPs with the help of the unsaturated Al3+ in Al2O3N (nanobelt) support, resulting in a sintering-resistant Pt/Al2O3N catalyst. Al solid-state MAS NMR characterization shows that Al2O3N support contains a large amount of unsaturated Alpenta3+ (about 22.6%). XAS confirms that Pt NPs deposited on the surface of Al2O3 with rich unsaturated pentahedral coordinated Al3+ sites have a unique coordination structure at the interface (more Pt-O coordination). When catalyzing the CO oxidation as a probe reaction, the catalytic activity and the particle sizes of Pt NPs do not change significantly even after the reaction at 400 °C for 15 days, and the complete CO conversion temperature increases only by 40 °C when the catalyst is screened at 600 °C for 5 days. This work demonstrates a new strategy to develop stable large-scale anti-sintering noble metal-based heterogeneous catalysts for many important high-temperature industrial applications.