The promotion effect of Cr additive on CeZr2Ox catalyst for the low-temperature selective catalytic reduction of NOx with NH3

A sequence of Cr-modified CeZr 2 O x catalysts were synthesized through the co-precipitation way and applied in selective catalytic reduction (SCR) of NO x with ammonia. The optimal catalyst (Cr 1 CeZr 2 O x ) exhibited the excellent NH 3 -SCR activity and high SO 2 resistance. From the characterization results, Cr species in Cr 1 CeZr 2 O x could suppress the formation of ZrO 2 crystals, which could also contribute to stronger surface acidity and reducibility . Besides, more Ce 3+ and surface adsorbed oxygen species were observed on Cr 1 CeZr 2 O x catalyst. On the basis of in situ DRIFT experiments, it could be confirmed that the NH 3 -SCR process on Cr 1 CeZr 2 O x was promoted through Langmuir-Hinshelwood (L-H) mechanism. Besides, the improved NO oxidation and more ad-NO x and ad-NH 3 also played a vital role for the superior low-temperature SCR activity of Cr 1 CeZr 2 O x .