Inhibition of NH3-SCR over Cu-CHA at high partial pressures of water: Measurements and DFT-based kinetic modeling

IF 6.5 1区 化学 Q2 CHEMISTRY, PHYSICAL
Shivangi Singh , Yingxin Feng , Ton V.W. Janssens , Henrik Grönbeck
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引用次数: 0

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 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.

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来源期刊
Journal of Catalysis
Journal of Catalysis 工程技术-工程:化工
CiteScore
12.30
自引率
5.50%
发文量
447
审稿时长
31 days
期刊介绍: The Journal of Catalysis publishes scholarly articles on both heterogeneous and homogeneous catalysis, covering a wide range of chemical transformations. These include various types of catalysis, such as those mediated by photons, plasmons, and electrons. The focus of the studies is to understand the relationship between catalytic function and the underlying chemical properties of surfaces and metal complexes. The articles in the journal offer innovative concepts and explore the synthesis and kinetics of inorganic solids and homogeneous complexes. Furthermore, they discuss spectroscopic techniques for characterizing catalysts, investigate the interaction of probes and reacting species with catalysts, and employ theoretical methods. The research presented in the journal should have direct relevance to the field of catalytic processes, addressing either fundamental aspects or applications of catalysis.
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