Yuan-Gen Yin

Temperature Program Desorption and Reduction Studies of Octahedral Molecular Sieves

Publisher Summary The reactivity of oxygen species in single or mixed transition metal oxides plays an important role in determining the catalytic performance of an oxide as a consequence of the Mars–van Krevelen redox mechanism. Manganese dioxides, such as octahedral molecular sieves (OMSs), are a family of promising compounds for studying relationships between solid and catalytic properties. The incorporation of additional transition metal(s) into OMS materials lends great variability for adjusting oxidative and reductive stoichiometry and, consequently, the valency states and Mn–O binding strengths. Three or more oxygen species can be discriminated in the tunnel structure of both doped OMS 1 and OMS 2 in view of the emerging temperature of peaks during temperature-programmed desorption (TPD) in He. The doping cations do not markedly affect the evolution of TPD peaks. The predominance of oxygen species related to the high-temperature (HT) region peaks in TPD suggests that they are mainly under the influence of Mn ions in the framework because of their relative interatomic distances from Mn and from doping cations.