Effect of lean-oxygen treatment on the adsorption and activity of zirconium phosphate @ Ce0.75Z0.25O2 for NH3-SCR deNOx

As oxygen is one of the essential reactants in the standard SCR reactions, the ability of restoring and releasing oxygen is an important factor to determine the SCR activity of the catalyst. Ceria catalysts present an innate prospect in SCR reaction because of the facilitated redox cycles from Ce4+ to Ce3+. In the present study, zirconium phosphate @ Ce(0.75)Z(0.25)O(2) (ZP/CZ) catalysts were pre-treated by O-2, N-2 and H-2 to study the effects of lean-oxygen teatment on the structure, NH3/NOx adsorption and activity of catalysts. The catalysts were characterized by activity test, H-2-TPR, XPS, DRIFT, NOx-TPD and kinetics study. The results showed that H-2 treatment led to deeply reduced catalyst surface, resulting in mainly nitrites instead of nitrates adsorbed on catalyst in NO + O-2 reaction and reduced Bronsted acidity of catalyst, which were responsible for the lowered deNOx activity of H-2 treated catalyst. N-2 treatment had only negligible influence on catalyst compared to O-2 treated catalyst. Ammonium nitrate route was consolidated as possible NH3-SCR reaction mechanism over ZP/CZ catalyst by kinetics study. (C) 2016 Elsevier B.V. All rights reserved.