Platinum catalyzed reduction of nitric oxide by n-butane in the presence of oxygen: Role of the hydrocarbon

The mechanism of the catalytic reduction of nitric oxide by n-butane in an oxidizing atmosphere has been investigated at temperatures from 373 to 723 K. The reaction was carried out with a TAP (temporal analysis of products) reactor on a platinum sponge catalyst. When admitting pulses of NO alone on a reduced surface until reaching a steady surface coverage, the processes of NO reduction into N-2 and N2O occur on time scales noticeable under TAP conditions according to the well accepted decomposition mechanism. When admitting oxygen and n-butane, the nitric oxide reduction is promoted: the N-2 yield reached 74% at 633 K compared to 6% only when admitting NO alone. The role of the hydrocarbon is not limited to the creation of free sites where NO can adsorb and dissociate. Carbon containing surface species formed during the hydrocarbon combustion increase the NO reduction by direct reaction between NO and these carbon containing species.