Catalytic decomposition of nitric oxide over Cu-zeolites

Journal Article · Wed May 01 00:00:00 EDT 1991 · Journal of Catalysis; (USA)

DOI:https://doi.org/10.1016/0021-9517(91)90024-X· OSTI ID:5756963

Li, Yuejin; Hall, W K ^[1]

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1. Univ. of Pittsburgh, Pennsylvania (USA)

Cu-exchanged zeolites have been under investigation as catalysts for NO decomposition. Among the zeolites tested Cu-ZSM-5 had the highest turnover frequency. The Arrhenius plots for all the catalysts leveled off or inverted near 773 K, and these curves were entirely reversible on decreasing the temperature. The NO decomposition rate was first order in NO pressure and was inhibited by O{sub 2}. The kinetics could be described in the Langmuir-Hinshelwood form, with the inhibition being half order in O{sub 2} pressure. The redox capacitites of Cu-ZSM-5 measured in microbalance experiments were near 0.5 O/Cu, i.e., 1e{sup {minus}}/Cu. Interestingly, O{sub 2}could be desorbed isothermally from an initially oxidized catalyst upon flushing the catlayst with He. ESR spectra confirmed that the Cu{sup 2+} in the catalysts was being reduced to Cu{sup 1+} during the spontaneous desorption of a corresponding amount of O{sub 2}. This spontaneous desorption of O{sub 2} was also observed when pure O{sub 2} in the microbalance was replaced by an O{sub 2}/He mixture, i.e., when the partial pressure of O{sub 2} over the catalyst was lowered. This phenomenon is regarded as a key requirement for a sustained NO decompositon activity. An interpretation of the kinetics in light of these findings is presented.

• OSTI ID: 5756963
• Journal Information: Journal of Catalysis; (USA), Journal Name: Journal of Catalysis; (USA) Vol. 129:1; ISSN 0021-9517; ISSN JCTLA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
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Atmospheric-- Chemicals Monitoring & Transport-- (1990-)
CATALYSIS
CATALYST SUPPORTS
CATALYSTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
COPPER
DECOMPOSITION
DESORPTION
ELECTRON SPIN RESONANCE
ELEMENTS
EQUATIONS
FLUIDS
GASES
HELIUM
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
KINETIC EQUATIONS
KINETICS
MAGNETIC RESONANCE
MATERIALS
METALS
MINERALS
NITRIC OXIDE
NITROGEN COMPOUNDS
NITROGEN OXIDES
NONMETALS
OXIDES
OXYGEN
OXYGEN COMPOUNDS
PRESSURE DEPENDENCE
RARE GASES
REACTION KINETICS
RESONANCE
TRANSITION ELEMENTS
ZEOLITES