Dynamic structure of Mo-O species in Ag-Mo-P-O catalyst for oxidative dehydrogenation of propane

In order to understand the relationship between catalytic performance and structure of Ag-Mo-P-O caalyst for oxidative dehydrogenation of propane, the dynamic structure of Mo-O species in the catalyst was studied by in-situ confocal microprobe LRS and XRD. The catalyst was mainly Composed Of MoO3 and AgMoO2PO4 phases. The Mo-O species was monitored by in-situ confocal microprobe LRS in different atmosphere. 3C(3)H(8)-lO(2)-N-2 flow, only the Raman hands of Mo-O species in AgMoO2PO4 were detected at 773 K. In O-2 flow, the Mo-O species in MoO3 and in AgMoO2PO4 could be detected at all the investigated temperatures. In 7C(3)H(8)-43N(2) flow, the intensity of Raman bands belonging to Mo-O species in both MoO3 and AgMoO2PO4 gradually decreased and finally disappeared as temperature increasing. At that time, the catalyst was exposed to 3C(3)H(8)-lO(2)-4N(2) flow, the Raman bands belonging to Mo-O species in AgMoO2PO4 was detected. Subsequently, the catalyst was switched to O-2 flow, the Raman bands of Mo-O species in MoO3 and in AgMoO2PO4 were detected again, The results of catalytic test showed higher conversion of propane with higher selectivity for propene in 3C(3)H(8)-IO2-4N(2) flow at 773 K. The transformation of Mo-O species is due to the intrinsic properties of Mo-O species. The Mo-O species of AgMoO2PO4 might be active species for Oxidative dehydrogenation of propane.