The interaction of NO with copper ions in ZSM5: An EPR and IR investigation

• Published in: Journal of catalysis 1992-08, Vol.136 (2), p.510-520
• Main Authors: Giamello, E., Murphy, D., Magnacca, G., Morterra, C., Shioya, Y., Nomura, T., Anpo, M.
• Format: Article
• Language: English
• Subjects: 01 COAL, LIGNITE, AND PEAT; 010800 - Coal, Lignite, & Peat- Waste Management; 330701 - Emission Control- Nitrogen Oxides; 400201 - Chemical & Physicochemical Properties; 540120 - Environment, Atmospheric- Chemicals Monitoring & Transport- (1990-); ACID RAIN; ADVANCED PROPULSION SYSTEMS; ATMOSPHERIC PRECIPITATIONS; Catalysis; CATALYST SUPPORTS; CATALYSTS; CATALYTIC EFFECTS; Catalytic reactions; CHALCOGENIDES; CHEMICAL REACTIONS; Chemistry; CONFIGURATION INTERACTION; COPPER; DECOMPOSITION; DENITRIFICATION; ELEMENTS; ENVIRONMENTAL SCIENCES; Exact sciences and technology; General and physical chemistry; INORGANIC ION EXCHANGERS; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ION EXCHANGE MATERIALS; MAGNETISM; MATERIALS; METALS; MINERALS; NITRIC OXIDE; NITROGEN; NITROGEN COMPOUNDS; NITROGEN OXIDES; NITROUS OXIDE; NONMETALS; OXIDES; OXYGEN; OXYGEN COMPOUNDS; PARAMAGNETISM; RAIN; REACTION INTERMEDIATES; REDUCTION; SELECTIVE CATALYTIC REDUCTION; SILICATE MINERALS; SURFACE PROPERTIES; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; TRANSITION ELEMENTS; VALENCE; ZEOLITES
• ISSN: 0021-9517; 1090-2694
• DOI: 10.1016/0021-9517(92)90081-R

The interaction of nitric oxide with copper ZSM5 zeolites at room temperature has been studied by EPR and FT-IR spectroscopy in the aim of investigating the surface intermediates involved in the decomposition of NO to N 2 and O 2. Particular care has been devoted to obtaining a catalyst in a well-defined oxidation state, i.e., with one of the two ionic forms of copper (Cu 2+ or Cu +) clearly prevailing on the other. The interaction of NO with Cu 2+/ZSM5 yields a reversibly adsorbed nitrosylic adduct easily desorbed upon pumping at 333 K. The species is diamagnetic and bears a partial positive charge. Cu + is unstable under NO pressure and undergoes oxidation at room temperature. In the early stages of the interaction a paramagnetic nitrosyl of Cu + is formed having a partial negative charge on NO. This species evolves with time (or NO pressure) towards a diamagnetic dinitrosyl capable of eliminating N 2 with simultaneous oxidation of the site to Cu 2+.