Selective catalytic reduction of NO with C3H6 over Rh alumina in the presence and absence of SO2 in the feed

The selective catalytic reduction of NO in excess Oz with C3H6 as reductant was studied over a Rh/alumina catalyst. The effect of SO2 on the extent of NO reduction and product formation was extensively examined. TPD and FT-IR studies using different feeds aimed at the identification of species adsorbed on alumina and Rh/alumina samples. Experiments were also carried out in a differential fixed-bed reactor to estimate apparent orders of reaction and activation energies. The rate-controlling step of the proposed reaction mechanism for the NO reduction is the reaction of Rh-NCO and Rh-NO+ for an SO2-free feed. In the presence of SO2 in the feed the NO and C3H6 oxidation over the catalyst were inhibited and a less complicated reaction mechanism is proposed, based on the reaction of Rh-NOf and partially oxidized C3H6 (C) 1999 Elsevier Science B.V. All rights reserved.