INTRINSIC KINETICS OF NITRIC-OXIDE REDUCTION BY AMMONIA ON A VANADIA TITANIA CATALYST

The kinetics of the selective catalytic reduction of nitric oxide by ammonia on a vanadia-titania (anatase) model catalyst have been investigated. Stationary values of the reaction rates are measured as a function of the concentrations of NO, NH3 and H2O in a recirculation system. Up to values usually present in flue gases the water content only weakly affects the rate of the main reaction, the reduction of nitric oxide to nitrogen. On the other hand the possible side reactions, the oxidation of ammonia and the formation of nitrous oxide are largely suppressed by the presence of water. The investigation of transport phenomena has shown that a strong influence of inner mass transfer resistance is expected in catalysts of technically relevant dimensions. The intrinsic kinetics can be quantified by use of a Langmuir-Hinshelwood type rate equation.