title: The mechanism of selective catalytic reduction of NOxon Cu-SSZ-13 - a computational study.
abstract: The copper-exchanged aluminosilicate zeolite SSZ-13 is a leading catalyst for the selective catalytic reduction of NO. Density functional theory calculations are used to construct a complete catalytic cycle of this process paying special attention to the coordination geometries and redox states of copper. N2can be produced in the reduction half-cycle via a nitrosamine intermediate generated from the reaction of the additive reductant NH3with a NO+intermediate stabilized by the zeolite lattice. The decomposition of this nitrosamine species can be assisted by incipient Brønsted acid sites generated during catalysis. Our calculations also suggest that the reoxidation of Cu(i) to Cu(ii) requires the addition of both NO and O2. The production of a second equivalent of N2during the oxidation half-cycle proceeds through a peroxynitrite intermediate to form a Cu-nitrite intermediate, which may react with an acid, either HNO2or NH4+to close the catalytic cycle. Models of copper neutralized by an external hydroxide ligand are also examined. These calculations form a key basis for understanding the mechanism of NO reduction in Cu-SSZ-13 in order to develop strategies for rationally optimizing the performance in future experiments.
authors.affiliation: Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, IN 47405, USA. mbaik2805@kaist.ac.kr.
authors.forename: Douglas W
authors.initials: DW
authors.lastname: Crandell
authors.affiliation: BASF Corporation, 25 Middlesex/Essex Turnpike, Iselin, NJ 08830, USA. xiaofan.yang@basf.com.
authors.forename: Haiyang
authors.initials: H
authors.lastname: Zhu
authors.affiliation: BASF Corporation, 25 Middlesex/Essex Turnpike, Iselin, NJ 08830, USA. xiaofan.yang@basf.com.
authors.forename: Xiaofan
authors.initials: X
authors.lastname: Yang
authors.affiliation: BASF Corporation, 25 Middlesex/Essex Turnpike, Iselin, NJ 08830, USA. xiaofan.yang@basf.com.
authors.forename: John
authors.initials: J
authors.lastname: Hochmuth
authors.affiliation: Department of Chemistry, Indiana University, 800 E. Kirkwood Avenue, Bloomington, IN 47405, USA. mbaik2805@kaist.ac.kr and Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS), Daejeon 305-701, South Korea and Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, South Korea.
authors.forename: Mu-Hyun
authors.initials: MH
authors.lastname: Baik