Redox properties of various bismuth molybdate phases in the catalytic oxidation of but-1-ene

Abstract

The redox properties of four bismuth molybdate catalysts (α, β and γ phases and a mixture of β and γ phases) have been investigated in atmospheres of oxygen and but-1-ene at different temperatures using the electrical-conductivity technique. It has been shown that these solids are intrinsic semiconductors in the oxidized state and become highly conductive when in contact with but-1-ene. The only source of active oxygen is the surface lattice anions of the solid, whose anionic vacancies are replenished by oxygen from the gas phase. The qualitative classification of the relative reduction rates found by conductivity measurements is identical to that found by kinetic measurements carried out in a pulse reactor (γ > α > β).