Understanding the high hydrothermal stability and NH3-SCR activity of the fast-synthesized ERI zeolite

Abstract

ERI zeolite is a small-pore zeolite that has been rarely explored as a catalyst in the selective catalytic reduction of NOx with ammonia (NH3-SCR) as the performance has been considered to be limited by its insufficient hydrothermal stability. We herein report that a fast-synthesized ERI zeolite, which can be synthesized in only 2 h at a high temperature (210 °C), shows much enhanced hydrothermal stability than the conventional ERI zeolite due to the presence of less silanol defects. The fast-synthesized ERI zeolite with an optimal copper loading (equaling a Cu/Al ratio of 0.20) is demonstrated to be highly active in the NH3-SCR, which even rivals Cu-SSZ-13 – the benchmark NH3-SCR catalyst. Various characterization techniques are employed to characterize the copper species in the fast-synthesized ERI zeolite in order to understand its high hydrothermal stability and NH3-SCR activity. The results indicate that the copper species sitting at different locations exhibit variant hydrothermal stability and NH3-SCR activity, suggesting the importance of the interplay between the copper species and the zeolite host. With a deep understanding into the structure-activity relationship, this work presents that the fast-synthesized ERI zeolite holds potential to emerge as a robust NH3-SCR catalyst for emission control.