(582h) Elucidating Effect of Support Acidity Using Platinum Nanoparticles on Propane Combustion

Catalytic combustion of hydrocarbons is an important process involved in reducing air pollutant emissions from automotive exhaust due to its efficiency. However, improvements are continuously required as stable lower alkanes such as propane require relatively high temperatures to be completely oxidized over the most active noble metal catalysts. To improve combustion activity, research work has been performed to find suitable supports or promoters for noble metals. However, these studies led to challenges in identifying changes from particle size and phase, causing somewhat contrasting conclusions and observations on what the active species are.

Herein, we report a systematic study of the effects of Pd/Pt compositions, size and support on propane combustion with the goal of understanding these effects, clarifying contradictory reports, and learning how to improve the performance. Well-defined noble metal nanoparticles were employed to prepare catalysts that could be compared while varying only one parameter at a time as an important advantage in contrast to conventional impregnation methods. With this approach, we confirmed Pt is the most active component, and the interface between metal nanoparticle and support is critical for propane combustion. Besides, a positive relation between reactivity and support acidity was observed. We further demonstrated that water, a common inhibitor in hydrocarbon combustion, plays an important role to understand the mechanism behind the effect of support acidity. We therefore provide opportunities for the rational design of efficient catalytic combustion materials.