Jamal Abdul Nasir, University College London
The copper-exchanged zeolite Cu-CHA has received considerable attention in recent years, owing to its application in the selective catalytic reduction (SCR) of NOx species. We have studied the NH3-SCR reaction mechanism on Cu-CHA using a high-level hybrid quantum mechanical/molecular mechanical (QM/MM) technique as implemented in ChemShell and state-of-the-art Diffuse Reflectance Infrared Fourier-Transform Spectroscopy (DRIFTS) experiments to investigate the effects of solvent molecules (both NH3 and H2O) on the reactivity of Cu-CHA active sites.
The results show the promoting effect of solvent on the oxidation component of the NH3-SCR cycle, while there is an inhibition effect on the reduction component of the NH3-SCR cycle. The computational mechanistic study focuses on these results which complement and give insight to the experimental findings. From the data collected from experiments together with hybrid QM/MM results, we then establish an assignment of the key vibrational signatures of the important species. Our study provides additional understanding of the influence of solvent on the energetics of the active sites and provides guidance for optimizing the NH3-SCR process.
J. Abdul Nasir, J. Guan, T. W. Keal, A. W. Desmoutier, Y. Lu, A. M. Beale, C. R. A. Catlow and A. A. Sokol, “Influence of Solvent on Selective Catalytic Reduction of Nitrogen Oxides with Ammonia over Cu-CHA Zeolite”, J. Am. Chem. Soc., 2023, 145, 247. DOI: 10.1021/jacs.2c09823