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 deNOx catalysts using small‐grain Beta supporting FeOx nanoparticles as the core and tunable CeO2 thin film thickness as sheaths were designed and controllably synthesized. Their catalytic performances were tested for selective catalytic reduction of NOx with NH3 (NH3‐SCR). It was found that CeO2 shell thickness plays an important role in influencing the acidity and redox properties of the catalysts. Fe‐Beta@CeO2 core‐shell catalysts exhibit excellent resistance to H2O and SO2 and high NOx conversion (above 90%) in the wide temperature range (225–565°C). The kinetics result indicates that the coating of CeO2 shell significantly increases the pore diffusion resistance of Fe‐Beta@CeO2 catalysts. Furthermore, in situ DRIFT results reveal that CeO2 shell can promote the formation of NO2 and cis‐ species. But too thick CeO2 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. © 2017 American Institute of Chemical Engineers AIChE J, 63: 4430–4441, 2017