Differentiation of active oxygen species for butane oxidation on vanadyl pyrophosphate

The contributions of lattice oxygen and adsorbed oxygen to the oxidation of butane by VPO catalysts were quantitatively determined by measurement of the reaction kinetics with a novel oscillating microbalance reactor. At 674 K, with the gas composition of butane/oxygen/Ar/He = 1.75/2.1/1.6/balance (vol%), and a gas hourly space velocity (GHSV) of 30 000 h(-1), oxidation of butane by lattice oxygen accounts for only about 5% of the butane oxidation rate, with the remainder carried out by adsorbed oxygen, most likely O-. Thus under steady state reaction conditions, the traditional Mars-van Krevelen mechanism is a minor contributor to the rate.