Tailored activity of Cu–Fe bimetallic Beta zeolite with promising C3H6 resistance for NH3-SCR

Abstract

The application of Beta zeolites in the selective catalytic reduction of NO_x with NH₃ in diesel engines is limited to some extent by catalyst deactivation due to hydrocarbons, especially in the case of Fe-Beta. One possible solution is to introduce an oxidative component that can facilitate the partial oxidation of hydrocarbons and prevent their deposition in the form of polyene, therefore improving the hydrocarbon resistance of Beta zeolites. Herein, copper ions with better redox ability cooperated with Fe ions in a Beta zeolite, and this is demonstrated to improve the NH₃-SCR performance in the presence of C₃H₆. Cu_6.8-Fe-Beta possesses NO_x conversion higher than 80% over a wide temperature range (200–550 °C) and preferable N₂ selectivity in the presence of C₃H₆. The introduction of Cu inhibited the polymerization of C₃H₆ and promoted the oxidation of C₃H₆, which alleviated competitive adsorption between C₃H₆ and NO_x. Furthermore, Cu_6.8-Fe-Beta can maintain great NO_x conversion levels after hydrothermal aging at 750 °C, giving this bimetallic Cu-Fe-Beta zeolite conspicuous practical application prospects.