Enhanced Low-temperature NH3-SCR Activity over Ce-Ti Oxide Catalysts by Hydrochloric Acid Treatment

The effect of hydrochloric acid treatment on Ce-Ti oxides was investigated for selective catalytic reduction of NO with NH3. The results showed that hydrochloric acid treatment had a positive effect on the low-temperature activity of Ce-Ti oxides. The improved activity of Ce-Ti oxides could be attributed to the increase in the concentration of Ce as well as the amount of Ce3+ and chemisorbed oxygen on the catalyst surface. In addition, the enhanced Lewis acidity could improve NH3 absorption, and was also a key factor to enhance the low-temperature activity of Ce-Ti oxides.