Effect of ammonia treatment on Pt catalyst used for lowtemperature reaction

Platinum based catalysts are well known as the most active ones among noble metals for oxidation of hydrocarbons as well as hydrogen. Microcombustion experiments using bare Pt foil catalyst have shown that hydrocarbon fuels (e.g. propane) can be oxidized at low-temperature (< 60 °C) by treating the catalyst surface by burning propane-air mixtures with ∼ 5 % of the propane replaced by ammonia for half an hour. This NH₃pre-treatment creates step-like structures on the scale of few μm_s, after hydrocarbon combustion testing, completely unlike those without NH₃treatment. This change in structure with NH₃treatment is noteworthy in that it increases the performance of the catalyst by a factor of 3, but only for low-temperature reactions characteristic of microcombustors. This is not merely a surface area effect, since increasing bulk catalyst area had almost no effect on combustion performance.