skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: The adsorption of NO and reaction of NO with O{sub 2} on H-, NaH-, CuH-, and Cu-ZSM-5: An in situ FTIR investigation

Abstract

The adsorption of NO and the reaction of NO with O{sub 2} on H-, NaH-, CuH-, and Cu-ZSM-5 zeolites were studied at 300 K using in situ Fourier transform infrared spectroscopy (FTIR). At this temperature, NO readily adsorbs on the Cu{sup +} sites of CuH- and Cu-ZSM-5 catalysts and decomposition of NO is observed for all catalysts, although the rate of decomposition is vastly different on these materials. In comparison, this reaction is negligible over the H- and NaH-ZSM-5 samples. The time evolution of several nitrogen-containing molecules after controlled O{sub 2} exposure to the NO/ZSM-5 systems has allowed the spectral correlation of these species. These nitrogen-containing species can interact with either the protonic sites of bridging hydroxyls forming hydrogen bonding complexes or the metal cations producing primarily surface nitrates and nitrites. The hydrogen bonded N{sub x}O{sub y} complexes were characterized with their IR absorption features: (1) NO{sub 2}, 2133 cm{sup {minus}1}; (b) N{sub 2}O{sub 3}, 1875 and 1587 cm{sup {minus}1}; and (c) N{sub 2}O{sub 4}, 2185 and 1745 cm{sup {minus}1}. The stretching vibrational frequency of the acidic OH groups of ZSM-5 red-shifts due to the interaction with nitrogen-containing molecules and forms {open_quotes}ABC{close_quotes} band structures characteristic of medium and strong hydrogenmore » bonding complexes. Although the adsorbed N{sub x}O{sub y} species (N{sub 2}O{sub 3}, N{sub 2}O{sub 4}) interacting with the Bronsted protons exhibit characteristics of a strong Lewis base, adsorption enthalpies are sufficiently weak that their existence is not observed even after brief evacuation. Nitric oxide, oxygen coadsorption produces metal cation (Na{sup +} and Cu{sup n+}) bonded surface species possessing IR absorption bands between 1400 and 1650 cm{sup {minus}1} characteristic of nitrite and nitrate species. 46 refs., 9 figs.« less

Authors:
;  [1]
  1. Los Alamos National Lab., NM (United States)
Publication Date:
OSTI Identifier:
486391
Resource Type:
Journal Article
Journal Name:
Journal of Catalysis
Additional Journal Information:
Journal Volume: 164; Journal Issue: 1; Other Information: PBD: Nov 1996
Country of Publication:
United States
Language:
English
Subject:
33 ADVANCED PROPULSION SYSTEMS; 20 FOSSIL-FUELED POWER PLANTS; 40 CHEMISTRY; NITRIC OXIDE; ADSORPTION; CHEMICAL REACTIONS; ZEOLITES; SORPTIVE PROPERTIES; COPPER COMPOUNDS; SODIUM COMPOUNDS; OXYGEN; ABSORPTION SPECTROSCOPY; VIBRATIONAL STATES; LEWIS ACIDS; BROENSTED ACIDS

Citation Formats

Szanyi, J, and Paffett, M T. The adsorption of NO and reaction of NO with O{sub 2} on H-, NaH-, CuH-, and Cu-ZSM-5: An in situ FTIR investigation. United States: N. p., 1996. Web. doi:10.1006/jcat.1996.0378.
Szanyi, J, & Paffett, M T. The adsorption of NO and reaction of NO with O{sub 2} on H-, NaH-, CuH-, and Cu-ZSM-5: An in situ FTIR investigation. United States. https://doi.org/10.1006/jcat.1996.0378
Szanyi, J, and Paffett, M T. Fri . "The adsorption of NO and reaction of NO with O{sub 2} on H-, NaH-, CuH-, and Cu-ZSM-5: An in situ FTIR investigation". United States. https://doi.org/10.1006/jcat.1996.0378.
@article{osti_486391,
title = {The adsorption of NO and reaction of NO with O{sub 2} on H-, NaH-, CuH-, and Cu-ZSM-5: An in situ FTIR investigation},
author = {Szanyi, J and Paffett, M T},
abstractNote = {The adsorption of NO and the reaction of NO with O{sub 2} on H-, NaH-, CuH-, and Cu-ZSM-5 zeolites were studied at 300 K using in situ Fourier transform infrared spectroscopy (FTIR). At this temperature, NO readily adsorbs on the Cu{sup +} sites of CuH- and Cu-ZSM-5 catalysts and decomposition of NO is observed for all catalysts, although the rate of decomposition is vastly different on these materials. In comparison, this reaction is negligible over the H- and NaH-ZSM-5 samples. The time evolution of several nitrogen-containing molecules after controlled O{sub 2} exposure to the NO/ZSM-5 systems has allowed the spectral correlation of these species. These nitrogen-containing species can interact with either the protonic sites of bridging hydroxyls forming hydrogen bonding complexes or the metal cations producing primarily surface nitrates and nitrites. The hydrogen bonded N{sub x}O{sub y} complexes were characterized with their IR absorption features: (1) NO{sub 2}, 2133 cm{sup {minus}1}; (b) N{sub 2}O{sub 3}, 1875 and 1587 cm{sup {minus}1}; and (c) N{sub 2}O{sub 4}, 2185 and 1745 cm{sup {minus}1}. The stretching vibrational frequency of the acidic OH groups of ZSM-5 red-shifts due to the interaction with nitrogen-containing molecules and forms {open_quotes}ABC{close_quotes} band structures characteristic of medium and strong hydrogen bonding complexes. Although the adsorbed N{sub x}O{sub y} species (N{sub 2}O{sub 3}, N{sub 2}O{sub 4}) interacting with the Bronsted protons exhibit characteristics of a strong Lewis base, adsorption enthalpies are sufficiently weak that their existence is not observed even after brief evacuation. Nitric oxide, oxygen coadsorption produces metal cation (Na{sup +} and Cu{sup n+}) bonded surface species possessing IR absorption bands between 1400 and 1650 cm{sup {minus}1} characteristic of nitrite and nitrate species. 46 refs., 9 figs.},
doi = {10.1006/jcat.1996.0378},
url = {https://www.osti.gov/biblio/486391}, journal = {Journal of Catalysis},
number = 1,
volume = 164,
place = {United States},
year = {1996},
month = {11}
}