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

A hectorite, a montmorillonite and a saponite, all of them in their Al-pill ared forms, as well as unpillared saponite were considered as supports of p latinum catalysts (2.3 wt.% Pt) for the catalytic combustion of acetone and methyl-ethyl-ketone (MEK). The preparation of the catalysts modified the t extural properties of the Al-pillared clay supports, giving rise to a signi ficant loss of specific surface area and micropore volume. After hydrogen r eduction at 773 K, the presence of poorly dispersed metallic platinum with mean crystallite sizes in the 70-100 Angstrom range was detected by X-ray d iffraction (XRD). Good activity and stability performances were found under the reaction conditions used. Whatever be the catalyst considered, MEK res ulted 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 i n catalytic activity arose depending on the pillared or unpillared characte r of the support and the nature of the starting smectite clay used. Regardl ess of the ketone molecule, the following order of decreasing catalytic per formance was established with respect to the support nature: unpillared sap onite. > Al-pillared montmorillonite > Al-pillared saponite > Al-pillared h ectorite, (C) 2001 Elsevier Science B.V. All rights reserved.