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. Metal catalysts often lose activity when their particles grow, so dispersion is usually maximized. This study shows that larger platinum particles resist oxygen poisoning and improve light alkane oxidation.