Dual Effects of C 3 H 6 in Suppressing and Promoting NH 3 –SCR Performance over Cu-SSZ-16 Catalyst at Different Temperatures

Unburned hydrocarbons (HCs), particularly light HCs such as propene (C 3 H 6 ), have a significant effect on the performance of Cu-based small-pore zeolites in selective catalytic reduction with ammonia (NH 3 –SCR) for the control of nitrogen oxides (NO x ) emitted from diesel vehicles. During this process, the formation of highly toxic hydrogen cyanide (HCN) occurs, posing significant risks to both the environment and human health. In this work, the temperature-dependent poisoning mechanism of C 3 H 6 and the HCN formation pathway over the Cu-SSZ-16 catalyst were systematically investigated. It was found that C 3 H 6 has dual effects on SCR activity. Firstly, competitive adsorption between C 3 H 6 and NH 3 as well as NO x on the active sites results in a decline in catalytic activity at low temperatures (400 °C) SCR activity.