Surface reactions and catalysis at alcoholvapour/3dtransitionmetaloxide interfaces at T ≤ 475 K. Part I. Dehydration and dehydrogenation of isopropanol over V2O5 and V2O3

Abstract

Pseudo steady-state conversions of alcohol vapours observed in a differential flow microcatalytic reactor provide the basis for comparing catalytic activities for a minor dehydrogenation (−H2) process and for a dominant dehydration (−H2O) process over both oxygenated and deoxygenated alcoholvapour/vanadiumoxide interfaces. Effects of surface pre-reduction or pre-oxidation upon sample activity and ir spectra are consistent with an involvement of quadrivalent vanadium in the surface sites responsible for (−H2) and (−H2O) activities. Different sensitivities towards poisoning by phenol point to important differences in the environment of VIV in the (−H2) and (−H2O) sites. Observations by ir and X-ray diffraction show extensive reduction by alcohol vapour at deoxygenated, but not at oxygenated interfaces.