Manganese catalysts for methane transformations in the absence of oxygen .2. Catalysts characterization by toluene, methylcyclohexane and cyclohexane transformations

Catalytic properties of supported manganese oxide catalysts were studied using cyclohexane, methylcyclohexane and toluene test reactions. It was found that silicaalumina/MnOx systems possess both acid and redox centres of moderate strength. These sites are able to activate sigma C-H bonds of cyclohexane and methylcyclohexane as well as sigma C-Aryl-C-Alk bonds in toluene and they undergo a slow deactivation. Alumina supported manganese oxide is able to activate sigma C-H and sigma C-C bonds, but it undergoes fast deactivation. The GC-MS analyses of minor reaction products allow to propose detailed reaction schemes and to correlate fast deactivation of alumina based catalysts with the action of redox sites, which catalyze radical transformations of test molecules.