Platinum catalysts supported on Al-pillared clays: Application to the catalytic combustion of acetone and methyl-ethyl-ketone

Abstract

A hectorite, a montmorillonite and a saponite, all of them in their Al-pillared forms, as well as unpillared saponite were considered as supports of platinum catalysts (2.3 wt.% Pt) for the catalytic combustion of acetone and methyl-ethyl-ketone (MEK). The preparation of the catalysts modified the textural properties of the Al-pillared clay supports, giving rise to a significant loss of specific surface area and micropore volume. After hydrogen reduction at 773 K, the presence of poorly dispersed metallic platinum with mean crystallite sizes in the 70–100 Å range was detected by X-ray diffraction (XRD). Good activity and stability performances were found under the reaction conditions used. Whatever be the catalyst considered, MEK resulted easier to oxidize than acetone, a fact which has been related to the strength of the weakest C–H bond in these ketones. Remarkable differences in catalytic activity arose depending on the pillared or unpillared character of the support and the nature of the starting smectite clay used. Regardless of the ketone molecule, the following order of decreasing catalytic performance was established with respect to the support nature: unpillared saponite> Al- pillared montmorillonite > Al- pillared saponite > Al- pillared hectorite .