Single-site Pt/La-Al₂O₃ stabilized by barium as an active and stable catalyst in purifying CO and C₃H₆ emissions

High-temperature operations present a substantial challenge for developing industrial-capable precious metal catalysts (e.g. Pt/alumina), where the scarce metal atoms easily become wasted as sintered nanoparticles. Using fully dispersed precious metal atoms to deliver the catalysis remains an elusive goal. On a widely used La-stabilized alumina support, we find that the atomically dispersed Pt₁(II)-O_x- species, rather than the much more visible large metal particles, are the actual catalytic sites for the CO and C₃H₆ oxidation reactions. Unfortunately, the La dopants in alumina support will not hinder the sintering of the active Pt₁(II)-O_x- species. As a natural next step, the Ba-O_x- species were introduced to specifically stabilize the single-atom Pt on the La-stabilized alumina support. By implementing this improved formulation, the atomically dispersed Pt on alumina retains the original full dispersion even after 650 °C hydrothermal aging. Intriguingly, with or without the barium additives and/or sintered platinum particles in the catalysts, the intrinsic activity per Pt atom stays intact. Along with other experimental evidence, this leads to the finding that the single-atom Pt is the true catalytic site for the oxidation of CO and C₃H₆ in the widely-used Pt/La-Al₂O₃ material system. This work provides a new perspective for efficient precious metal utilization under demanding catalytic conditions.