Regulation of A-site cations in AMn2Ox spinel catalysts on the deep oxidation of light alkanes VOCs

Abstract

Light alkane VOCs are currently the most difficult VOCs to deal with in the petroleum and coal chemical industries due to their short carbon chains and stable molecular structures. On account of the metal components of spinel are diverse and the structure can be adjusted. Thus, a series of A-site cations substituted AMn2Ox (A = Co, Cu, Ni, Zn, Ce) spinel catalysts were prepared and the impacts of A-site cations on the oxidation of alkane were revealed. It was found that A-site metal ions made a big difference in the low-temperature reduction, lattice oxygen activity, high-valent manganese ion content, and oxygen vacancies with NiMn2O4 had the highest catalytic activity with a conversion of 90 % at 232 °C. In addition, in-situ DRIFTs were performed to investigate the underlying oxidation mechanisms for propane oxidation. We found that propane is firstly dehydrogenated by adsorption on the active site and then oxidized to carboxylates and carbonates, which are further converted to CO2 and H2O. Moreover, the catalyst also showed good stability and robust resistance of H2O and SO2. The excellent activity exhibited by Ni-Mn-based spinels may shed light on the development of efficient catalysts for light alkanes catalytic oxidation.