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Issue 1, 2019
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Cu-exchanged RTH-type zeolites for NH3-selective catalytic reduction of NOx: Cu distribution and hydrothermal stability

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Abstract

The Cu-exchanged RTH-type zeolites (Cu-RTH) were applied in ammonia-selective catalytic reduction (NH3-SCR) of NOx. The effects of Cu loading and distribution on the NOx reduction efficiency were investigated. The hydrothermal stabilities of a series of Cu-RTH catalysts were also presented. Excellent NOx conversion activity was observed for Cu-RTH catalysts with high Cu loadings (2.5–4.4 wt%) in the temperature range from 150 °C to 550 °C. Two possible sites (α and β species) for Cu2+ species were proposed based on the analysis of H2-TPR and DRIFTS results. The α species next to the 8-membered rings showed significantly higher TOF (turnover frequency) of NO conversion than the β species present next to the rth cage. The Cu-RTH catalysts showed lower activation energies (30–40 kJ mol−1) compared with that of the Cu-SSZ-13 catalyst (∼54 kJ mol−1) due to the different zeolite framework structures. After undergoing hydrothermal aging, although the zeolite framework structure stayed stable, the active Cu2+ species migrated to inactive sites, which resulted in the loss of NOx conversion for the NH3-SCR reaction. The saturated Cu2+-exchanged Cu4.4-RTH catalyst showed the best hydrothermal stability due to the limited Cu2+ mobility, which stabilized the active Cu2+ species.

Graphical abstract: Cu-exchanged RTH-type zeolites for NH3-selective catalytic reduction of NOx: Cu distribution and hydrothermal stability

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Supplementary files

Article information


Submitted
17 Sep 2018
Accepted
13 Nov 2018
First published
13 Nov 2018

Catal. Sci. Technol., 2019,9, 106-115
Article type
Paper

Cu-exchanged RTH-type zeolites for NH3-selective catalytic reduction of NOx: Cu distribution and hydrothermal stability

Y. Shan, X. Shi, J. Du, Y. Yu and H. He, Catal. Sci. Technol., 2019, 9, 106
DOI: 10.1039/C8CY01933A

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