Catalytic property of AII2BIIBVIO6 double perovskites (BVI = Mo, W) for the reduction of nitric oxide with propane in the presence of oxygen

Systematic series of double perovskites containing W and Mo, AII2BIIBVIO6 (AII = Ba, Sr, Ca; BII = Mg, Ca, Co, Ni, Cu, Cd; BVI = W, Mo, W1−xMox) were synthesized, and their catalytic activities for NO–C3H8–O2 reaction were investigated. All the oxides crystallized in the ordered double perovskite structure with the rock-salt arrangement of BII and BVI cations, and the unit cell symmetry was almost exclusively determined by AII cations. The double perovskites catalyzed the nonselective reduction of NO into N2O and occasionally N2 specifically at 600°C in the gaseous mixture of NO (0.44%), C3H8 (0.29%) and O2 (4.4%). The reduction activity of NO into N2O and N2 depended on the sort of AII, BII, and BVI cations, but the effect of BII cations was the most remarkable. The NO reduction activity increased monotonically with an increase in the enthalpy of formation of BIIO (−ΔHf°), suggesting that the strength of BII–O bond or the redox property of BII ions is of primary importance for the NO reduction activity in the NO–C3H8–O2 reaction.