Pt catalysts supported on H-type zeolites for the catalytic combustion of chlorobenzene

The deep oxidation of chlorobenzene was investigated over Pt catalysts supported on H-type zeolites (H-ZSM5 and H-beta). Pt/zeolite catalysts showed a higher activity compared to Pt/gamma-Al(2)O(3) samples which were tested for comparison. Within each class of zeolite, the activity of Pt/zeolite catalysts was found to be higher on the samples with lower SiO(2)/Al(2)O(3) ratio. Amounts of polychlorinated benzenes (PhCl(x)) were produced in the order Pt/H-ZSM5 < Pt/H-beta < Pt/gamma-Al(2)O(3) and were found to be roughly independent of the SiO(2)/Al(2)O(3) ratio of the zeolitic support. The trend in the PhCl(x) formation observed on Pt/zeolite samples, both in terms of total amount and relative distribution, was explained on the basis of a product shape selectivity effect induced by the zeolite, a lower size of zeolite channels hindering the further chlorination of PhCl to PhCl(x). (C) 2003 Elsevier Science B.V. All rights reserved.