Thermally Stable, Regenerable Single Atom Catalysts Via Atom Trapping

Thermally Stable, Regenerable Single Atom Catalysts via Atom Trapping

Abhaya Datye

University of New Mexico, Albuquerque, NM, USA

Single atom catalysts show great promise in terms of efficient utilization of precious metals, improved reactivity and selectivity.  However, single atom catalysts can deactivate due to sintering and formation of nanoparticles when the catalyst is exposed to harsh reaction conditions.  Stabilization of single atom catalysts and their regeneration requires suitable trapping sites on the catalyst support.  Our work has focused on alumina supports, which are extensively used in industrial catalysis. 

In recent work we found that La-stabilized alumina was able to stabilize atomically dispersed Pd, leading to high activity for CO oxidation[1].  The Pd when atomically dispersed is bound to the alumina through surface oxygen atoms on the alumina surface.  Lanthanum oxide which is added to alumina to stabilize the support helps to anchor the atomically dispersed Pd, making it possible to regenerate the catalyst. In the case of the Pt-Sn/alumina catalysts, we noticed a similar behavior, where the presence of Sn in atomically dispersed form on the alumina made it possible to regenerate the catalyst and restore catalyst activity and selectivity [2].  The Pt/alumina treated under similar conditions could not be regenerated to a significant extent.  The major difference between these two catalysts is the presence of atomically dispersed Sn which is stable after multiple cycles of propane dehydrogenation and provides sites for trapping the Pt [2]. 

This lecture will provide additional examples how atom trapping can help in the generation of single atom catalysts that are thermally stable and regenerable. 

References

[1] E.J. Peterson, A.T. DeLaRiva, S. Lin, R.S. Johnson, H. Guo, J.T. Miller, J. Hun Kwak, C.H.F. Peden, B. Kiefer, L.F. Allard, F.H. Ribeiro, A.K. Datye, Low-temperature carbon monoxide oxidation catalysed by regenerable atomically dispersed palladium on alumina, Nat Commun, 5 (2014).

[2] H.N. Pham, J.J.H.B. Sattler, B.M. Weckhuysen, A.K. Datye, Role of Sn in the Regeneration of Pt/γ-A_l2O₃ Light Alkane Dehydrogenation Catalysts, ACS Catal., 10.1021/acscatal.5b02917  (2016).