A new class of alloy catalysts called Single-Atom Alloys has emerged in recent years in which precious, reactive metals are utilized at the ultimate limit of efficiency. These catalysts were discovered by combining atomic-scale scanning probes with more traditional approaches to study surface-catalyzed chemical reactions. This research has provided links between the atomic scale surface structure and its reactivity which are key connections in understanding and ultimately controlling important catalytic processes. The work conducted at Tufts University combining surface science and catalysis has identified and exploited often unexpected synergies that pave the way for the rational design of new heterogeneous catalysts. In Part I of the two presentations, key findings from the surface science investigations by the Sykes group will be discussed and showcased with a number of model single crystal Single-Atom Alloy surfaces. These findings are then tested in high pressure reactors using Single-Atom Alloy nanoparticle catalysts that can perform industrially relevant reactions at realistic reaction conditions. The activity, selectivity, and stability of these controlled catalyst structure and composition systems are investigated by the Flytzani-Stephanopoulos group and will be showcased in Part II of the two presentations. For example, alloying elements like platinum and palladium with less reactive host metals like copper enables 1) more selective chemical reactions, 2) reduced susceptibility to CO poisoning, and 3) higher resistance to deactivation by coking, which leads to designs of more stable catalysts for reactions as demanding as alkane dehydrogenation. Model surfaces and nanoparticles that can host isolated atoms in the surface layers behave similarly in escaping the linear scaling relationships that limit traditional catalysts and enable rational fine-tuning of activity and selectivity. Good stability is imparted by the strong metal-metal bonds in Single-Atom Alloys between the host and the minority metal, and atomic dispersion can be maintained at high temperatures. Furthermore, dramatic cost savings in catalyst manufacture are envisioned with Single-Atom Alloy catalysts. Our work illustrates that surface science and catalysis can no longer be considered separate non-interacting areas, but can together enhance and hasten the design and development of new heterogeneous catalysts.

Single-atom alloy catalysts; Part I: Birth and formative years spent in a chilly vacuum; Part II: Coming of age and transition into a fiery reactor

2019 Fall National Meeting

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