Improvement of low-temperature NH3-SCR performance of Cu-zeolite and vanadium catalysts through ozone injection

Selective catalytic reduction (SCR), a widely used technology to mitigate NO x emissions from diesel engines, faces the challenge of improving NO x reduction efficiency at low temperatures. O 3 can improve the low-temperature NO x reduction performance of SCR by oxidizing NO in exhaust gas to NO 2 , a more reactive molecule. This study investigates the potential of O 3 assisted SCR reaction in real exhaust gas condition of diesel engine and compares the differences of two catalysts, Cu-zeolite and vanadium. The results show that NO x reduction performance at low temperature can be improved by assisting O 3 in the both catalysts. The improvement of NO x reduction performance was slightly better for the Cu-zeolite catalyst than for the vanadium catalyst. This is because Cu-zeolite catalysts have a larger NO 2 or HNO 3 adsorption capacity and stronger bonding strength than vanadium catalysts, undergoing better SCR reaction and forming more NH 4 NO 3 . • The low-temperature denitrification performance of O 3 -assisted SCR for was evaluated. • NH 4 NO 3 formation is the main pathway for denitrification at low temperatures. • Cu-zeolite forms more NH 4 NO 3 than vanadium due to its superior adsorption capacity. • Only a fraction of adsorbed NO 3 is converted to NH 4 NO 3 . • Partial decomposition of NH 4 NO 3 into N 2 O hinders denitrification efficiency.