EPR and Raman investigations into anionic redox chemistry of nanoporous 12CaO·7Al2O3 interacting with O2, H2 and N2O

摘要

EPR and Raman spectroscopy jointed with temperature-programmed reduction (TPR) and oxidation (TPO) were used to elucidate of the anionic redox processes occurring during the interaction of dioxygen, nitrous oxide and dihydrogen with nanoporous 12CaO·7Al2O3. The results showed that hydrogen and oxygen enter the mayenite cages following a dissociative pathway involving hydride, hydroxyl and peroxide intermediates, respectively. Generation and annihilation of the cage O 2 ? and O? radicals upon oxidative and reductive treatments, confined to the near to the surface region, were found to be reversible. The key intermediates of this process were identified and a detailed mechanism of the surface and cage reactions was proposed.