(148d) Carbon Monoxide Oxidation and Preferential Oxidation on Pt Alloy Nanoparticle Catalyst with Engineered Surface

Carbon monoxide oxidation and preferential oxidation (PROX) are two important reactions for environmental control and for applications requiring the use of clean hydrogen, for instance hydrogen fuel cell technology and ammonia synthesis. It is because that the typical hydrogen production processes by reforming hydrocarbons and diesel fuels generate CO as a byproduct, which is notorious poisoning species and readily deactivating many catalysts. There is thus a need for selective removal of CO before hydrogen can be used for these applications.
 
We report the study of Pt alloy nanoparticles with well-engineered surfaces as low temperature CO oxidation and PROX catalyst. In particular, the researched octahedral Pt3Ni alloy nanoparticle catalysts, which are exclusively enclosed by the (111) surface, exhibit both high PROX activity and 100% selectivity from RT all the way till around 100 °C. The much promoted CO oxidation kinetics on octahedral Pt3Ni was attributed to significantly decreased Ea comparing to spherical Pt3Ni and Pt (~40.0 kJ/mol vs. 56.9 and 66.3 kJ/mol) and the presence of both Pt and Ni active sites on the engineered (111) surface, which can work synergistically to activate and react CO and O2. The 100% PROX selectivity was associated with the unique (111) surface geometry of the octahedral Pt3Ni and the big difference in the adsorption energy of CO and H2 on the surface, which help with suppressing H2 from adsorption and oxidation.