Insight into the effects of Cu2+ ions and CuO species in Cu-SSZ-13 catalysts for selective catalytic reduction of NO by NH3

Different Cu precursors were adopted to adjust the isolated Cu2+ ions and CuO species in the Cu-SSZ-13 catalysts. The Cu2+ ions were mainly located at eight-member rings in the catalysts with the Cu precursors of Cu(NO3)(2) (Fresh-I) and CuSO4 (Fresh-II), while that located at six-member rings in the catalysts with the Cu precursors of CuCl2 (Fresh-III) and Cu(CH3COO)(2) (Fresh-IV). All catalysts showed>90% of NO conversion and 100% of N-2 selectivity at 200-680 degrees C. Fresh-I and Fresh-II catalysts showed an unexpected increase of the high-temperature activity after hydrothermal treatment. The characterizations revealed that the hydrothermal treatment promoted the production of CuO species, which accelerated the adsorption of NOx species to enhance the high-temperature SCR activity. Moreover, the SCR reaction pathway changed from Langmuir-Hinshelwood to Eley-Rideal mechanisms for the Fresh-II catalyst after the hydrothermal treatment, which was verified by in situ DRIFTS. (C) 2022 Elsevier Inc. All rights reserved.

Automated summary

In this study, different Cu precursors were used to adjust the isolated Cu2+ ions and CuO species in the Cu-SSZ-13 catalysts. It was found that the high-temperature activity of the catalysts unexpectedly increased after hydrothermal treatment. The characterization results showed that hydrothermal treatment promoted the production of CuO species and changed the SCR reaction mechanism in the catalysts.