The enhanced resistance to K deactivation of Ce/TiO2 catalyst for NH3-SCR reaction by the modification with P

Highlights: • The modification of Ce/TiO₂ catalyst with P could enhance its K tolerance. • The addition of P would broaden the temperature window under the control of L-H mechanism. • The NH₃-SCR reaction over P-Ce/TiO₂ catalyst could be accelerated through L-H pathway. The deactivation of SCR catalyst caused by K species contained in the fly ash would suppress its DeNOx performance. In this study, it was manifested that the modification of Ce/TiO₂ catalyst with P could enhance its K tolerance. To understand the promotion mechanism, the fresh and poisoned catalyst samples were subjected to the characterization techniques including BET, XRD, XPS, H₂-TPR, NH₃-TPD and in situ DRIFT. The results elucidated that the introduction of P species could increase the reducibility of Ce species and generate more surface chemisorbed oxygen, along with the strengthened surface acidity for NH₃ adsorption. It seemed that the NH₃-SCR reaction mechanism over Ce/TiO₂ catalyst was a combination of L-H mechanism (< 200 °C) and E-R mechanism (≥ 200 °C). After the addition of P species, the NO oxidation over Ce/TiO₂ catalyst was also accelerated, accompanied by the broadened temperature window for the NH₃-SCR reaction under the control of L-H mechanism. The promoted NH₃ species adsorption and the generated more NO₂ over P-Ce/TiO₂ catalyst were conducive to the NH₃-SCR reaction through L-H pathway, which might be the primary reason for its good K resistance.