Single-atom alloy (SAA) catalysts have well defined active sites, and we are now at the point where we have predictive capabilities in the design of new SAA heterogenous catalysts. I will describe the first example of the design and testing of a single atom heterogeneous catalyst from first principles. Specifically, rhodium is well known to be a poor catalyst for alkane dehydrogenation due to its tendency to over-bind reactants leading to hydrogenolysis. However, our first-principle calculations indicated that single rhodium atoms in a copper surface should be stable and selective for non-oxidative propane to propene conversion, a reaction of great interest industrially. Guided by these predictions we performed surface science and microscopy studies to probe rhodium/copper single-atom alloys and their ability to activate C-H groups and resist coking that plagues many alkane dehydrogenation catalysts. Our results indicated that rhodium atoms are indeed capable of facile C-H activation and the production of alkenes. This then informed our design and synthesis of nanoparticle catalysts that exhibited high activity and stability for non-oxidative propane to propene conversion. Our single-atom alloy catalysts are in fact more active than the industrial Pt analogues and more selective to propene (100% vs. 85% on Pt) while containing just 1% the amount of precious metal as a typical Pt-based system. Furthermore, due to the site isolation of the Rh atoms our new developed RhCu catalyst exhibits remarkable resilience to coking that plagues Pt-based systems due to the isolation of the active Rh atom sites in the Cu host metal.

Single-atom alloy catalysts for non-oxidative propane dehydrogenation

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.