Promotion effect of vanadium on oxygen vacancy formation over MnGa oxide for syngas conversion into light olefins

A series of XMnGa (X--Al, Zn, Ce and V) oxides and VMnGa(y) with various V/(V+Mn+Ga) atomic ratios were prepared by the co-precipitation method, and mixed with SAPO-34 to prepare bifunctional catalyst for syngas conversion to light olefins (STO). (In-situ) XRD, N2 physisorption, SEM, TEM, H2-TPR, CO-TPD, H2-TPD, XPS and in-situ DRIFTS were selected for characterization. VMnGa(0.1) oxide sample exhibits the highest CO conversion and olefins space-time yield, while the other ternary metal oxides show poor CO conversion or low selectivity. The introduction of suitable amount of V into MnGa oxide formed Mn2VO4 spinel structure. VMnGa(0.1) pos-sesses high amounts of desorbed CO, which is due to the formation of more oxygen vacancies on metal oxide surface. The structure evolution of VMnGa(0.1) in pretreatment atmosphere of H2 and syngas (H2/CO=2:1) was studied and the catalytic performance for STO was compared; moreover, the structure-activity and reaction intermediate during the reaction were revealed.