A-site cation exfoliation of amorphous SmMnxOy oxides for low temperature propane oxidation

Propane removal is one of the critical challenges in reducing volatile organic compounds and automotive exhaust emission. Being a non-polar molecule with saturated C-H bonds, low temperature propane oxidation hinges on efficient dehydrogenation of terminal methyl by active lattice oxygen. We report here the fabrication of a multi-component MnOx/SmMn2Ox catalyst for propane combustion via A-site cation exfoliation of amorphous SmMn2Ox. The formation of surface mesostructured MnOx induced by partial removal of Sm cations greatly boosts C-H bond activation and formation of formate species. Amorphous SmMn2Ox base with rich oxygen conservation as well as robust connection between MnOx and support accelerates decomposition of formate species exhibiting one of the best propane catalytic activity with 90.7% conversion at 237 °C under 60,000 ml·g−1·h−1 space velocity, together with excellent thermal endurance and water resistance. Rate determining steps for propane oxidation over amorphous SmMnxOy, i.e. C-H bond activation and formate decomposition, were analyzed through propane temperature programmed surface reaction (C3H8-TPSR) and in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS), in which SmMnxOy showed the best surface lattice oxygen activity and eminent ability of propane deep oxidization.