Effect of acidic components (SO42-and WO3) on the surface acidity, redox ability and NH3-SCR activity of new CeO2-TiO2 nanoporous aerogel catalysts: A comparative study

Selective catalytic reduction (SCR) of nitrogen oxide (NO) by ammonia (NH3) was studied in this work over new sulfate (SO42-) or tungsta (WO3) modified CeO2-TiO2 aerogel catalysts. The catalytic systems were elaborated via sol gel method then characterized by: XRD, N2-Physisorption at 77 K, DRUV-vis, NH3-TPD and H2-TPR. It was revealed that the nature of acidic components influences differently the texture, surface oxygen concentration, acidity, reducibility and NH3-SCR activity of new Ce-based catalysts. Hence, the incorporation of sulfate modifies the nature of Ce species, improves their dispersion through the Ce-SO42- interactions and, particularly, generates new strong acid sites which display superior catalytic performance at high temperature NO reduction (NO conversion into N2 > 90 % between 450 and 500 degrees C over CeO2-TiO2-SO42- catalyst). However, the addition of tungsta affects slightly the surface acidity of CeO2-TiO2 catalyst but it induces the creation of more reactive surface oxygen and new redox sites at its surface (mainly due to the existence of W-Ce interactions) leading to highly active WO3-CeO2-TiO2 system for the low temperature NH3-SCR reaction with above 90 % NO conversion into N2 between 320 and 400 degrees C.

Automated summary

Selective catalytic reduction of nitrogen oxide by ammonia was studied over new sulfate or tungsta modified CeO2-TiO2 aerogel catalysts. The incorporation of sulfate improved the dispersion of Ce species and generated new strong acid sites, while the addition of tungsta enhanced the surface oxygen activity and created new redox sites. Both modifications resulted in highly active catalysts for NO reduction.