KINETIC-STUDY OF THE SELECTIVE REDUCTION OF NITRIC-OXIDE OVER VANADIA-TUNGSTA-TITANIA SEPIOLITE CATALYST

A kinetic study of the reduction of nitric oxide by ammonia in the pre sence of oxygen on a novel catalyst prepared as a physical mixture of V2O5-WO3/TiO2 catalyst and a natural silicate (sepiolite) was carried out. The steady-state differential reactor data were fitted to several equations using a discriminating method based on physical and statist ic criteria. The best fit was obtained from a model involving adsorpti on of ammonia and oxygen which react with nitric oxide from the gas ph ase following an Eley-Rideal mechanism. The equation considered for th is model reproduces well the experimental results obtained in a differ ential regime. Important limitations by internal diffusion were determ ined when the reaction took place in an integral regime.