Novel Fe-doped CePO4 catalyst for selective catalytic reduction of NO with NH3: The role of Fe3+ ions.

Novel Fe-doped CePO4 (FexCe1-x) catalyst was firstly successfully synthesized via a simple co-precipitation method and demonstrated excellent NH3-SCR performance in comparison with FePO4 and CePO4. In order to study the promoting effects of Fe3+ ion on the NH3-SCR activity of CePO4 catalyst, various characterizations were conducted. It was found that NH3 capacity of FexCe1-x catalyst was controlled by P sites and depended on their specific surface area. Interestingly, Fe species in FexCe1-x were not a Lewis acid site for NH3 adsorption, but it could promote the activation of NH3. More importantly, Fe3+ doping could induce the redox equilibrium of Fe3+ + Ce3+ ⇆ Fe2+ + Ce4+, which significantly improved redox properties of CePO4 catalyst. Accordingly, improved catalytic activity of FexCe1-x catalysts could be attributed to the collective effects of the higher surface area, better redox properties and easily activated NH3. Among them, superior redox property of FexCe1-x catalysts was the main reason boosting their high catalytic activity. Finally, the reaction process analyzed by in situ DRIFT proposed that the NH3-SCR reaction over CePO4 and FexCe1-x occurred mainly via Eley-Rideal mechanism. We anticipated this work could promote the development of novel NH3-SCR catalyst.