A Niobia-Ceria based multi-purpose catalyst for selective catalytic reduction of NOx, urea hydrolysis and soot oxidation in diesel exhaust

Abstract

We report about a novel niobia-ceria based catalyst that may be applied for the selective catalytic reduction (SCR) of NOx as well as the catalytic regeneration of diesel particulate filters (DPF) in diesel engines. The material proved to be active in model gas experiments for a series of important reactions in these processes: (1) the SCR of NO with NH3, (2) the hydrolysis of urea to NH3 and (3) the oxidation of soot. The catalyst was able to convert 72% NO already at 250°C and showed almost full NO reduction between 300 and 450°C. The new niobia-ceria exhibited a similar urea hydrolysis activity as compared to a conventional TiO2 catalyst. A significant decrease of the soot oxidation temperature was also noticed with this catalyst.