Synthesis of Trigonal Mo-V-M3rd-O (M3rd = Fe, W) Catalysts by Using Structure-Directing Agent and Catalytic Performances for Selective Oxidation of Ethane

Crystalline Mo-V-M(3)rd-O (M(3)rd = Fe, W) catalysts (MoVFeO and MoVWO) with trigonal symmetry were successfully obtained by a hydrothermal method in the presence of structure-directing agents (ammonium cation and ethylammonium cation) and their catalytic performances for selective oxidation of ethane were compared with trigonal Mo3VOx catalyst (MoVO). Fe and W were uniformly distributed throughout the rod-shaped crystals. XRD, Raman, XRD simulation, and Rietveld analysis revealed that MoVFeO contained Fe in a heptagonal channel and W in MoVWO substituted Mo in {Mo6O21}(6-) pentagonal unit in the structure. MoVWO catalyst showed comparable catalytic activity with MoVO for the selective oxidation of ethane. On the other hand, catalytic performance of MoVFeO was far less compared with those of MoVO and MoVWO. The picture that the catalytic reaction occurs at the specific part in the structure could be visualized.