A Study of the Catalytic Reduction of NOx in Diesel Exhaust 962042

Reduction of nitrogen oxides in Diesel exhaust gas is a challenging task. This paper reports results from an extensive study using Pt-based catalysts involving synthetic gas activity testing (SCAT), engine bench testing and tests on passenger cars. Preliminary SCAT work highlighted the importance of Pt-dispersion, and both SCAT and bench engine testing yielded comparable NO_x conversions under steady state conditions at high HC:NO_x ratios. On passenger cars in the European cycle without secondary fuel injection NO_x conversion was lower than obtained in the steady state tests. Better conversion was obtained in the FTP cycle, where secondary injection was employed. Higher HC:NO_x, ratios and more favourable temperature conditions which were present in the exhaust contributed to this higher conversion.