Confirmation of isolated Cu 2+ ions in SSZ-13 zeolite as active sites in NH 3-selective catalytic reduction

Deka, U. and Juhin, A. and Eilertsen, E.A. and Emerich, H. and Green, M.A. and Korhonen, S.T. and Weckhuysen, B.M. and Beale, A.M. (2012) Confirmation of isolated Cu 2+ ions in SSZ-13 zeolite as active sites in NH 3-selective catalytic reduction. Journal of Physical Chemistry C, 116 (7). pp. 4809-4818. ISSN 19327447 (ISSN). (doi:https://doi.org/10.1021/jp212450d) (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided)

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Abstract

NH 3-Selective Catalytic Reduction (NH 3-SCR) is a widely used technology for NO x reduction in the emission control systems of heavy duty diesel vehicles. Copper-based ion exchanged zeolites and in particular Cu-SSZ-13 (CHA framework) catalysts show both exceptional activity and hydrothermal stability for this reaction. In this work, we have studied the origin of the SCR activity of Cu-SSZ-13 as evidenced from a combination of synchrotron-based and laboratory techniques. Synchrotron-based in situ XAFS/XRD measurements were used to provide complementary information on the local copper environment under realistic NH 3-SCR conditions. Crucial then to the catalytic activity of Cu-SSZ-13 is the local environment of the copper species, particularly in the zeolite. Cu-SSZ-13 contains mononuclear Cu 2+ species, located in the face of the double-6-ring subunit of the zeolite after calcination where it remains under reaction conditions. At lower temperatures (with low activity), XAFS and XRD data revealed a conformational change in the local geometry of the copper from a planar form toward a distorted tetrahedron as a result of a preferential interaction with NH 3. This process appears necessary for activity, but results in a stymieing of activity at low temperatures. At higher temperatures, the Cu 2+ possess a local coordination state akin to that seen after calcination. © 2012 American Chemical Society.

Item Type: Article
Additional information: Unmapped bibliographic data: LA - English [Field not mapped to EPrints] J2 - J. Phys. Chem. C [Field not mapped to EPrints] AD - Materials Innovation Institute (M2i), Mekelweg 2, 2628 CD Delft, Netherlands [Field not mapped to EPrints] AD - Inorganic Chemistry and Catalysis Group, Debye Institute of Nanomaterials Science, Utrecht University, Universiteitsweg 99, 3584 CA Utrecht, Netherlands [Field not mapped to EPrints] AD - Institut de Minéralogie et de Physique des Milieux Condensés, CNRS, Université Pierre et Marie Curie, Case courier 115, 4 place, Jussieu 75252, Paris Cedex 05, France [Field not mapped to EPrints] AD - SMN/INGAP, Department of Chemistry, University of Oslo, Sem Selands vei 26, 0315 Oslo, Norway [Field not mapped to EPrints] AD - Swiss Norwegian Beamline (SNBL, BM01), ESRF, BP 220, F-38043 Grenoble, France [Field not mapped to EPrints] AD - Beamline BT1, NIST Center for Neutron Research, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20878, United States [Field not mapped to EPrints] AD - Department of Materials Science and Engineering, University of Maryland, College Park, MD 20742, United States [Field not mapped to EPrints] DB - Scopus [Field not mapped to EPrints]
Uncontrolled keywords: Active site, Conformational change, Copper environments, Copper-based, Heavy duty diesel vehicles, Higher temperatures, Hydrothermal stabilities, In-situ, Ion exchanged zeolites, Laboratory techniques, Local coordination, Local environments, Local geometry, Low temperatures, Preferential interaction, Reaction conditions, XAFS, XRD, Calcination, Catalyst activity, Copper, Emission control, Selective catalytic reduction
Subjects: Q Science > QC Physics > QC173.45 Condensed Matter
Q Science > QD Chemistry > QD478 Solid State Chemistry
Divisions: Faculties > Sciences > School of Physical Sciences > Functional Materials Group
Depositing User: Giles Tarver
Date Deposited: 14 Oct 2015 11:31 UTC
Last Modified: 14 Oct 2015 11:31 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/50970 (The current URI for this page, for reference purposes)
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