Cu‐ERI Zeolite Catalysts With Tailored Properties for the Removal of N‐Containing Compounds

A series of ERI‐type zeolite materials of different properties was prepared, which led to the obtaining of Cu‐containing ERI materials of distinct catalytic properties in the selective catalytic reduction of NO _x with ammonia (NH ₃ ‐SCR‐DeNO _x ) and the selective catalytic oxidation of ammonia (NH ₃ ‐SCO). Various characterization techniques were employed to describe the copper species in the synthesized ERI zeolite in order to understand its NH ₃ ‐SCR‐DeNO _x and NH ₃ ‐SCO activity as well as N ₂ selectivity. Cu‐ERI_1 and Cu‐ERI_2 possess the highest amount of active sites (i.e., Cu ²⁺ species) and thus enhanced activity in the low‐temperature range of NH ₃ ‐SCR‐DeNO _x (with NO conversion of 83%–93% and N ₂ selectivity of 93%–95% at 250 °C). Especially, Cu‐ERI_2 possesses easily reducible Cu ²⁺ species that are responsible for activation and oxidation of NH ₃ . Indeed, steady‐state isotopic transient kinetic analysis of NH ₃ ‐SCO revealed the shortest average surface lifetime and the lowest surface concentration of NH ₃ over the Cu‐ERI_2 sample. Further, modulation excitation experiments confirmed that NO preferentially consumes NH ₃ adsorbed on the Brønsted acid sites on this sample. For other samples, the experiments of NO absorption followed by NH ₃  + O ₂ exposure and around (NH ₃ adsorption and NO + O ₂ exposure) indicated that NH ₃ adsorbed on Lewis acid sites is preferentially consumed during the reaction process.