Comparison of Industrial and Lab-Scale Ion Exchange for the DeNOx-SCR Performance of Cu Chabazites: A Case Study

Abstract

The efficiency and robustness of selective catalytic reduction (SCR) by NH3 catalysts for exhaust gas purification, especially of heavy-duty diesel engines, will continue to play a major role, despite the increasing electrification of powertrains. With that in mind, the effect of the synthesis scale on commercially available Cu-exchanged chabazite catalysts for SCR was investigated through physicochemical characterizations and catalytic tests. During hydrothermal aging, both industrial and lab-scale prepared catalysts underwent structural dealumination of the zeolite framework and redistribution of the Al sites. Although both catalysts demonstrated similar NO conversion activity under SCR conditions, the lab-scale catalyst showed higher selectivity and lower activity in NH3 oxidation. Variations in N2O formation and NH3 oxidation rate were found to correlate with the formation of different copper species, and the compositions become less controllable in industrial-scale process. This case study focused on routes of ion exchange, and the results provide new insights into catalytic performance of the industrially-produced zeolites.

OSDA-Free Seeded Cu-Containing ZSM-5 Applied for NH3–SCR-DeNOx

“…The activity of the materials significantly dropped above 300 °C without water due to a side reaction of ammonia oxidation. 56 Thus, in the presence of H 2 O in the feed, the activity was improved for all samples due to competitive adsorption between NH 3 and H 2 O. All catalysts maintained their stability for 24 h at 250 °C during the time-on-stream in the presence of 5 vol % H 2 O (panel d).…”

“…Cu-ZSM-5_4, based on the ZSM-5 seeds prepared at 170 °C, showed significantly lower activity, while both samples based on silicalite-1 possess the lowest activity. The activity of the materials significantly dropped above 300 °C without water due to a side reaction of ammonia oxidation . Thus, in the presence of H 2 O in the feed, the activity was improved for all samples due to competitive adsorption between NH 3 and H 2 O.…”