Work

Inhibition of NH 3 -SCR over Cu-CHA at high partial pressures of water: Measurements and DFT-based kinetic modeling

Year: 2025

Type: article

Abstract: 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 H 2 -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 NO x 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 ( p H 2 O / p ∘ ) 0 . 76 . The experimental results are corroborated with DFT-based microkinetic modeling. The DFT calculations show that H 2 O 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.

Source: Journal of Catalysis

DOI: 10.1016/j.jcat.2025.116071

Authors: Shivangi Singh, Yingxin Feng, Ton V.W. Janssens, Henrik Grönbeck

Institution: Chalmers University of Technology

Language: English

Topic: Catalytic Processes in Materials Science

Subfield: Materials Chemistry

Field: Materials Science

Domain: Physical Sciences

SDG: Clean water and sanitation

Open Access status: hybrid

Estimated APC paid: $4,250