Pt 4d binding energy as an electronic descriptor for ignition temperature in Pt–Re/Al2O3 catalysts

Pt–Re catalysts exhibit strong metal–metal interaction effects in reforming and hydrogenolysis, yet their use in catalytic combustion has been limited by concerns over the oxidative instability and volatility of rhenium oxides. In this work, Pt–Re/Al2O3 catalysts are revisited for low-temperature hydrocarbon combustion, demonstrating that appropriate synthesis and thermal treatment modify the surface oxidation state distribution of rhenium, accompanied by changes in the Pt 4d binding energy and improved catalytic performance. Catalysts prepared by co-impregnation and calcined between 550 and 1000 °C showed the disappearance of detectable Re7+ species together with increased proportions of Re4+ and Re6+ surface species, as revealed by X-ray photoelectron spectroscopy (XPS). These changes were accompanied by systematic shifts in the Pt 4d binding energy, whereas sequential impregnation was associated with different Pt electronic states and inferior catalytic activity. In temperature-programmed n-butane combustion, Pt–Re catalysts exhibited substantially lower ignition temperatures than Pt/Al2O3 and ignition performance comparable to the Pt–Sn reference catalysts under the present experimental conditions. A clear relationship between ignition temperature and Pt 4d binding energy suggests that the electronic state of platinum may serve as a useful electronic descriptor for combustion onset. These results demonstrate the potential of Pt 4d binding energy as an electronic descriptor for catalytic ignition and highlight appropriately prepared Pt–Re catalysts as promising candidates for low-temperature combustion.