Fe-Beta@CeO2 core-shell catalyst with tunable shell thickness for selective catalytic reduction of NOx with NH3

Abstract

A series of core-shell structural deNO x catalysts using small-grain Beta supporting FeO x nanoparticles as the core and tunable CeO 2 thin film thickness as sheaths were designed and controllably synthesized. Their catalytic performances were tested for selective catalytic reduction of NO x with NH 3 (NH 3 -SCR). It was found that CeO 2 shell thickness plays an important role in influencing the acidity and redox properties of the catalysts. Fe-Beta at CeO 2 core-shell catalysts exhibit excellent resistance to H 2 O and SO 2 and high NO x conversion (above 90%) in the wide temperature range (225-565°C). The kinetics result indicates that the coating of CeO 2 shell significantly increases the pore diffusion resistance of Fe-Beta at CeO 2 catalysts. Furthermore, in situ DRIFT results reveal that CeO 2 shell can promote the formation of NO 2 and cis- N2O2- species. But too thick CeO 2 shell (~20 nm) would result in the formation of inactive nitrate species, and thereby lead to a decrease of high-temperature activity of the catalysts.