PNNL

Abstract

In this contribution, the most likely positions for Cu in Cu-SSZ-13 with a single charge compensating Al atom (ZCu) with a Si : Al ratio of 11 : 1 were investigated, including the effect of the adsorption of reactants, intermediates, and products that one would find in an NH3 SCR reaction by using first-principles calculations based on density functional theory. The 6-membered ring (6MR) site is the most energetically favorable, while the 8-membered ring (8MR) sites are less favorable with energy differences of about 0.5 eV with respect to the 6MR site for plain ZCu. Upon molecular adsorption, the energy differences between Cu in the 8MR and 6MR sites decrease and, in some cases, almost disappear. For the complex scenarios of NO or CO adsorption, the co-adsorption of 2 NO or 2 CO molecules, as well as NO or CO with OH and H2O, weakens the interaction between adsorbates and Cu. The X-ray absorption near edge structure (XANES) of Cu in Cu-SSZ-13 under different conditions was also modeled from first principles. This work was supported by institutional funds provided to JSM from the Voiland School of Chemical Engineering and Bioengineering and was partially funded by USDA/NIFA through Hatch Project #WNP00807 entitled: “Fundamental and Applied Chemical and Biological Catalysts to Minimize Climate Change, Create a Sustainable Energy Future, and Provide a Safer Food Supply”. Financial support was also provided by the National Science Foundation GOALI program under contract No. CBET-1258717. We thank Prof. Fabio Ribeiro for the experimental XANES data. We also thank Mr. Atish Parekh, Prof. W. F. Schneider, Mr. Christopher Paolucci, Mr. Trunjoyo Anggara, Dr. Vincent Kispersky and Prof. Jeff Miller for stimulating discussions on the modeling of the XANES spectrum and Dr. Alyssa Hensley for her comments on the manuscript. J. S. and F. G. acknowledge the financial support of their work by the U. S. Department of Energy (DOE), Office of Energy Efficiency and Renewable Energy, Vehicle Technologies Program. A portion of the computer time for the computational work was performed using EMSL, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at PNNL. PNNL is a multi-program national laboratory operated for the US DOE by Battelle.