Catalytic methane activation over La1−xSrxScO3−α proton-conducting oxide surface: A comprehensive study

Abstract The detailed investigation of the influence of strontium on the methane activation over the state-of-the-art proton-conducting oxide catalyst La1−xSrxScO3−α was carried out using a combination of the novel H/D isotopic exchange method, Raman Spectroscopy, 1H NMR and DFT studies in the temperature range 673 – 973 K, at 10 mbar of CH4 + H2 (95%+5%) mixture. It was found that methane activation occurs via the four parallel channels of the hydrogen adsorption and incorporation mechanism, followed by the formation of methane intermediates with different hydrogen content (CHx species). The dominant type of adsorbed intermediate is governed by the temperature and the surface defect structure, which is in close correlation with the strontium content. The increase of strontium content in La1−xSrxScO3−α drastically increases the catalytic activity due to the surface modification with oxygen deficiencies in the ScO6 octahedron, and stabilisation of the CHx species with a low amount of hydrogen.