Alkali-Poisoning-Resistant FeO/MoO/TiO Catalyst for the Selective Reduction of NO by NH: The Role of the MoO Safety Buffer in Protecting Surface Active Sites.

The exhaust gas contains harmful products, including fuel-additive elements such as compounds of sodium, which cause dramatic catalyst deactivation of catalysts during selective catalytic reduction (SCR) of NO with NH. There is an increasing demand to synthesize alkali-poisoning-resistant catalysts for industrial NH-SCR applications. In this study, the as-synthesized FeO/MoO/TiO exhibits a high degree of resistance toward NaSO poisoning during the NH-SCR reaction. With 500 μmol g Na poisoning, FeO/MoO/TiO showed approximately 95% (or more) of its original activity throughout the entire temperature rage. Even with 700 μmol g Na poisoning, FeO/MoO/TiO still performed well. The 500 and 700 μmol g Na loadings dictate that, on average, SCR catalysts could be exposed to alkali-rich and highly dusty environments for more than 14 000 and 20 000 h, respectively. The layered MoO building block is used as a binding buffer and sandwiched between the active phase and TiO support to provide sufficiently stable binding sites for NaSO poison and to present alkali blocking of the surface active phase. Our findings provide useful information regarding the use of MoO as a safety buffer for developing functional NH-SCR catalysts with enhanced alkali-poisoning-resistant performance and long lifetimes.