A study of anatase-supported Mn oxide as catalysts for 2-propanol oxidation

Several samples of TiO(2) (anatase)-supported Mn oxide XMn-TiO(2) (with X = 0.5, 1.0, 1.5 and 2.0, the theoretical monolayer fractions) have been prepared by a wet impregnation method and characterised by conventional techniques. Mn oxide was found to be well dispersed on the support surface as Mn(3+) species, while part of it is stabilised into the TiO(2) bulk as Mn(4+) species. This cation seem to hinder the support sintering and to favour the anatase to rutile phase transition at higher temperatures: Mn oxides supported on TiO(2) are stable and retain medium-high surface area in the 600-900 K range. They are less active than pure Mn oxides in the isopropanol oxidation but, above 600 K, allow complete oxidation of isopropanol to CO(2) only. FT-IR studies and the GC-MS analysis of some intermediate products allow us to confirm the 2-propanol total oxidation occurs through the previously proposed 2-propoxide/acetate/formate surface pathway. (C) 1999 Elsevier Science B.V. All rights reserved.