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

Abstract

The redox properties of four bismuth molybdate catalysts (a,/? and y phases and a mixture of /? and y 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 ( y > a > /?).

Phase Composition and Charge Transport in Bismuth Molybdates

“…It has been accepted [6] that the anionic conductivity in these systems, under the notreduced condition in these systems, is realized by the oxygen ion transport. Bismuth molybdates, the properties of which have been investigated in the literature [7][8][9][10][11] up to now, were prepared essentially by the solid state reaction and precipitation. In the present study, we have studied the charge transport in three pure bismuth molybdate phases α -, β -and γ prepared by the spray HARTMANOVÁ et al . drying technique [12].…”