Oxidative dehydrogenation of propane over (Mo)-Sm-V-O catalytic system. Role of the different phases

The (Mo)-Sm-V-O catalytic system has been exhaustively studied in the propane oxidative dehydrogenation reaction. In order to obtain different surface arrangements, simple oxides (V2O5, SM2O3 and MoO3), SMV mixed oxides with different Sm/V molar ratio and SMVO4 impregnated with vanadium, samarium or molybdenum were prepared. The function that the possible arrangements play has been identified. A slight samarium excess favors total combustion causing a strong drop of selectivity, therefore, it is necessary to avoid it. On the other hand, vanadium excess constituting surface vanadium oxide species (VOx) notably increases the catalytic activity while a higher vanadium amount leads to crystalline V2O5 formation and the catalyst behavior tends to that of bulk V2O5, Molybdenum at low concentrations constitutes surface molybdenum oxide species (MoO.) which showed to be highly selective in propane ODH. High contents of molybdenum favor the formation of crystalline MoO3, thus, causing an important catalyst deactivation. Finally, a comparison with other known efficient vanadium based catalysts is made and hence, the potentiality of (Mo)-Sm-V-O catalysts is shown