FeO/HY Catalyst: A Microporous Material with Zeolite-Type Framework Achieving Highly Improved Alkali Poisoning-Resistant Performance for Selective Reduction of NO with NH.

The commercially available VO/WO-TiO is a well-known catalyst for selective catalytic reduction (SCR) of NO with NH. When alkali ions are present in the exhaust (e.g., as impurities such as dust) of a reactor containing commercial VO/WO-TiO, alkali poisoning occurs, deactivating the catalyst. Consequently, there is substantial interest in the development of better-performing and more durable NH-SCR catalysts with an improved resistance to alkali deactivation. For the present study, the protonated (H) form of zeolite Y, HY, was used as a support and acted as buffer zone, leading to trapping (sticking) of foreign alkali poisons in the zeolite pore structure, preventing alkali poisoning of the FeO/HY catalyst. Catalytic tests showed that the FeO/HY retained 100% of its original catalytic reactivity for NH-SCR reaction even after 1000 μmol Na g poisoning. 1000 μmol Na g treatment indicates a 26 000-h exposure under an alkaline dust-containing condition. In contrast, upon 1000 μmol Na g treatment, severe alkali deactivation occurred for a commercial VO/WO-TiO. The catalyst activity of FeO/HY remained unchanged because of the intercalation of Na in the internal HY zeolite pores that impedes the blocking of Na poison to the external active sites of FeO. The findings in this work suggest that the zeolite HY may be revealed as an attractive building block for designing an alkali poisoning-resistant catalyst.