Supercritical ion exchange: a new player in Cu-zeolite catalyst synthesis towards NH3-SCR of NOx

Abstract

In this study, the effect of zeolite type, copper loading, and synthesis method/conditions on the performance of a range of Cu/Zeolites in the Standard Selective Catalytic Reduction (SCR) reaction was investigated via utilizing synthesis methods of Supercritical and Aqueous Ion Exchange (SCIE and AIE). Cu/MORS synthesized via SCIE outperformed the conventionally prepared catalyst, Cu-MORA. Cu/MORS and Cu/ZSM-5 exhibited higher NO conversion than Cu/SSZ-13 at low temperatures due to higher Cu loading. However, Cu/SSZ-13 ones surpassed the other catalysts in terms of NO conversion at temperatures above 450 °C. Selective nature of SCIE under different conditions resulted in an obvious difference between the catalyst's performance while the SCIE temperature varied from 40 to 80 °C. The results of this study showed that synthesis method/condition affects directly the Cu speciation and catalyst performance in NH3-SCR, calling for developing new synthesis methods of Cu/Zeolites to modify the catalysts performance in after-treatment systems.