A superior cerium-tungsten bimetal oxide catalyst with flower-like structure for selective catalytic reduction of NO by NH3

• 0.1%WO 3 /CeO 2 (f) with flower-like morphology exhibited a wonderful NH 3 -SCR performance. • W loading strengthened the acidity while the structure of CeO 2 optimized the reducibility. • A strong interaction existed between surface WO x species and CeO 2 support. • NH 3 oxidization/deformation species could react with the gaseous or adsorbed NO x . • Bridged nitrates participated in the reaction via a L-H route over 0.1%WO 3 /CeO 2 (f). A novel flower-like 0.1%WO 3 /CeO 2 (f) catalyst with high-efficiency was fabricated for the selective reduction of NO x by NH 3 . In contrast to traditional WO 3 /CeO 2 , this catalyst exhibited a significant SCR performance of 90% NO x conversion and 95% N 2 selectivity within a wide temperature range of 175–450 °C and great H 2 O and/or SO 2 resistance under a high GHSV of 177,000 h −1 . A variety of analytical techniques including SEM, XRD, XPS, NH 3 -TPD, H 2 -TPR and in situ DRIFTS-MS were employed for the catalysts characterization to fully understand the reaction mechanism over WO 3 /CeO 2 catalysts. It was found that the flower-like structure promoted a more uniform dispersion of tungsten species on the support and a stronger interaction between WO 3 and CeO 2 , thereby increasing the acid sites and surface vacancies. Moreover, more chemical active oxygen and trivalent cerium species were presented on 0.1% WO 3 /CeO 2 (f). In situ DRIFTS-MS and H 2 -TPR revealed that the reducibility was optimized for 0.1% WO 3 /CeO 2 (f). Then NH 3 oxidation species could react with gaseous or adsorbed NO x during Eley-Rideal (E-R) pathway for 0.1%WO 3 /CeO 2 (f) at a high temperature (300 °C). Meanwhile, NO x was reduced into more active bridged nitrates participating in the reaction via Langmuir-Hinshelwood (L-H) route, contributing to its superior deNO x performance. In comparison, the formation of inert adsorbed NH 3 oxidization/deformation species and bridged nitrates suppressed the SCR reaction over 0.1%WO 3 /CeO 2 , resulting in its inferior deNO x activity. This study not only provides a new strategy for developing high-efficiency ceria supported NH 3 -SCR catalyst, but also lays a foundation for investigating the reaction mechanism of cerium-based catalyst for further practical applications.