NO sub x reduction by urea under lean conditions over single step sol-gel Pt/alumina catalyst

We prepared 2% Pt on alumina catalyst using a single step sol-gel process (designated as 2% Pt-SG) and tested its activity for NO sub x reduction with aqueous urea solutions under oxidizing conditions. Our results show that approx =99% NO sub x conversion was obtained as low as 150 deg C but above 350 deg C, the conversion became negative because of the additional formation of NO and NO sub 2 from the oxidation of nitrogen-containing compounds. We also found that NO sub x conversion activity of 2% Pt-SG is strongly dependent on water content rather than on urea amount and the presence of 7% oxygen in the feed lowers the maximum NO sub x conversion temperature from 250 to 150 deg C. (Relevance to the reduction of NO sub x from diesel engine exhaust and power plant flue gas noted.)