Selective reduction of NO{sub x} by methane on Co-ferrierites. II. Catalyst characterization

Journal Article · Thu Dec 01 00:00:00 EST 1994 · Journal of Catalysis

DOI:https://doi.org/10.1006/jcat.1994.1357· OSTI ID:47983

Li, Yuejin; Slager, T L; Armor, J N ^[1]

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1. Air Products and Cheimicals, Inc., Allentown, PA (United States)

Co-ferrierite, active for the selective NO reduction by CH{sub 4}, was characterized by X-ray photon spectroscopy and magnetic susceptibility measurements. The adsorption of NO and NO{sub 2} was studied by diffuse-reflectance FTIR spectroscopy to discover which intermediates participate in the NO{sub x} reduction. The valence state of cobalt in Co-ferrierite and other Co-zeolite catalysts was found to be 2+. The dominant NO species adsorbed on Co-Y, Co-ZSM-5, and Co-ferrierite is in a dinitrosyl form appearing at 1810 and 1897 cm{sup -1} for Co-Y and 1810 and 1890 cm{sup -1} for Co-ZSM-5 and Co-ferrierite. The mononitrosyl form of the adsorbed NO is a minor species appearing at 1930-1935 cm{sup -1} on all three samples. The mononitrosyl species on all samples is extremely weakly adsorbed. The dinitrosyl species adsorbed on Co-ferrierite is strongly adsorbed and needs to be heated above 300{degrees}C to desorb. Interestingly, the weakly adsorbed mononitrosyl species is enhanced in an O{sub 2} environment (100 Torr of O{sub 2}) and is now stable to 200{degrees}C. However, in an oxygen environment, the dinitrosyl species is less stable, desorbing at {approximately}200{degrees}C. All adsorbed NO species disappear at >200{degrees}C in 100 Torr O{sub 2}, and adsorbed NO{sub 2} species were observed. NO{sub 2} adsorbed on Co-ferrierite shows a weakly adsorbed, covalent N{sub 2}O{sub 5} in addition to stable species, such as nitro, nitrito, and nitrato species. Together with earlier kinetic and reaction studies, the authors suggest a mechanism for the selective reduction of NO{sub x} by CH{sub 4}. 44 refs., 9 figs., 4 tabs.

• OSTI ID: 47983
• Journal Information: Journal of Catalysis, Vol. 150, Issue 2; Other Information: PBD: Dec 1994
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
20 FOSSIL-FUELED POWER PLANTS
ZEOLITES
CATALYTIC EFFECTS
NITROGEN OXIDES
SELECTIVE CATALYTIC REDUCTION
COBALT OXIDES
REACTION INTERMEDIATES
METHANE
ACTIVATION ENERGY
COMBUSTION
CHEMICAL REACTION KINETICS
X-RAY SPECTROSCOPY
MAGNETIC SUSCEPTIBILITY
SORPTIVE PROPERTIES
ABSORPTION SPECTROSCOPY