A study of Mn-Ti oxide powders and their behaviour in propane oxidation catalysis

Mn-Ti mixed oxides with composition Ti1-xMnxOy (x = 0, 0.1, 0.2, 0.5, 0.8, 0.9 and 1) were prepared. A Mn-TiO2 monolayer type sample was also prepared by impregnation, for comparison. Manganese is found to speed up the anatase-to-rutile phase transition, more clearly in the impregnated sample, while titanium tends to slightly hinder the thermodynamically reversible hausmannite-to-bixbyite phase transition upon cooling. The catalytic activity of all samples in propene oxidation decreases with increasing Ti content. Conversely, the catalytic activity in propane oxidation shows a maximum at intermediate composition. 53 refs.