Inhibition of NH3-SCR over Cu-CHA at high partial pressures of water: Measurements and DFT-based kinetic modeling
Artikel i vetenskaplig tidskrift, 2025

Cu-exchanged chabazite (Cu-CHA) is a widely applied catalyst for selective catalytic reduction of nitrogen oxides in oxygen excess. The application of Cu-CHA to exhaust from H2-fueled engines depends on the behavior of this material at high partial pressures of water. We have performed flow-reactor measurements, which show that the NOx conversion at 200 °C over a Cu-CHA (3.2 wt% Cu, Si/Al=6.7) catalyst decreases with increasing partial pressures of water from 2 to 25%. Simultaneously, the apparent reaction order in water decreases from −0.17 to −1.18, following the simple empirical equation −3.43(pH2O/p∘)0.76. The experimental results are corroborated with DFT-based microkinetic modeling. The DFT calculations show that H2O competes with NO adsorption on the Cu-sites and hinders the reaction. The kinetic model describes accurately the inhibiting effect of water after minor adjustments to the computed Gibbs free energies of water adsorption.

Water inhibition

NH -SCR 3

Cu-CHA

H combustion engine 2

Författare

Shivangi Singh

Umicore

Chalmers, Fysik, Kemisk fysik

Yingxin Feng

Chalmers, Fysik, Kemisk fysik

Ton Janssens

Umicore

Henrik Grönbeck

Chalmers, Fysik, Kemisk fysik

Journal of Catalysis

0021-9517 (ISSN) 1090-2694 (eISSN)

Vol. 446 116071

The Competence Centre for Catalysis, KCK 2022-2026

Umicore Denmark ApS (KCK2022-2026), 2022-01-01 -- 2026-12-31.

Scania AB (Dnr:2021-036543Pnr:52689-1), 2022-01-01 -- 2026-12-31.

Preem AB (KCK2022-2026), 2022-01-01 -- 2026-12-31.

Volvo Group (PO:2435702-000), 2022-01-01 -- 2026-12-31.

Johnson Matthey (2500123383), 2022-01-01 -- 2026-12-31.

Cu-CHA zeolite-based catalysts for the selective catalytic reduction of NOx in exhaust diesel gas: addressing the issue of Sulfur Stability (CHASS)

Europeiska kommissionen (EU) (EC/H2020/955839), 2021-06-01 -- 2025-05-31.

Ämneskategorier (SSIF 2025)

Teoretisk kemi

Oorganisk kemi

Organisk kemi

DOI

10.1016/j.jcat.2025.116071

Mer information

Senast uppdaterat

2025-04-04