Effect of oxygen concentration on the NOx reduction with ammonia over V2O5–WO3/TiO2 catalyst

The catalytic reduction of NOx in the typical operation temperatures and oxygen concentrations of diesel engines has been studied in the presence of V3W9Ti in a tubular flow reactor. The results have shown that the selective catalytic reduction is strongly affected by the oxygen concentration in low temperature range (150–275 °C). At higher temperatures, the reaction becomes independent of the O2 concentration. The rate of the selective catalytic reduction of NO with ammonia may be considerably enhanced by converting part of the NO into NO2. DRIFT measurements have shown that NH3 and NO2 are adsorbed on the catalyst surface on the contrary of NO. The experiments have shown that the decrease in N2 selectivity of the SCR reaction is mainly due to the SCO of ammonia and to the formation of nitrous oxide.