Efficient and durable light-alkane oxidation over sintered Pt catalysts.

Nanoparticle sintering is typically regarded as a deactivation mechanism for supported metal catalysts, motivating efforts to maximize metal dispersion. Here we demonstrate the opposite trend for platinum catalysts in light-alkane oxidation. Intentionally pre-sintered platinum particles, tens of nanometers in size and supported on thermally stable magnesium aluminate, show higher activity than highly dispersed platinum species for propane oxidation. Theory-guided adsorption calculations suggest that oxygen-resistant metallic facets prevalent on large platinum particles mitigate oxygen poisoning, a concept validated by controlled calcination. The sintered catalyst delivers a turnover frequency of 0.1625 s-1 at 220 °C, 116-fold higher than platinum nanoclusters, and lowers the temperature for 90% propane conversion from 360 to 245 °C. It remains stable for 48 hours in dry and water-containing feeds and after hydrothermal aging. Mechanistic analyses reveal that low-index metallic facets sustain propane activation, while oxygen-rich feeds drive reconstruction toward less active stepped surfaces.