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Title: Reduction of NO with CH{sub 4} effected by copper oxide clusters in the channels of ZSM-5

Abstract

Nitrogen oxides (NO{sub x}) are the main air pollutants that cause photochemical smog formation, acid rain, and general atmospheric visibility degradation. Worldwide, over 3 x 10{sup 7} tons of nitrogen oxides are vented to the atmosphere each year. Reduction of NO{sub x} emission has become one of the major problems to be solved for environmental protection. Many methods for reduction of NO{sub x} emissions such as reduction absorption, chelation absorption, catalytic decomposition, and catalytic reduction have been widely studied. Selective catalytic reduction with ammonia (NH{sub 3}-SCR) has been put to practical uses; however, the system is expensive in terms of handling the toxic ammonia. It has been recognized that the selective catalytic reduction of NO with hydrocarbons (HC-SCR) using copper-exchanged ZSM-5 (Cu-ZSM-5) catalysts is very effective. Fine structures of the copper oxide clusters involved in catalytic reduction of NO were studied by X-ray absorption spectroscopy. The Extended X-ray absorption fine structural (EXAFS) spectra indicate that about 2.89 nearest oxygen atoms bond to the Cu central atoms with a Cu-O bond distance of 1.96 {angstrom} for the oxidized Cu-ZSM-5 catalyst. Reduction of the catalyst in hydrogen at 573 K led to the formation of mainly Cu-Cu (2.54 {angstrom}) species with themore » coordination number (CN) of 2.91. The Cu{sub 4}O{sub 2} clusters in the channels of ZSM-5 observed by EXAFS were formed in the NO reduction process via incorporation of oxygen into the metallic copper matrix with desorption of N{sub 2}. Due to the restricted channel structure of ZSM-5, the Cu{sub 4}O{sub 2} clusters were reduced promptly by CH{sub 4}.« less

Authors:
;
Publication Date:
Research Org.:
National Cheng Kung Univ., Tainan (TW)
OSTI Identifier:
20003182
Resource Type:
Journal Article
Journal Name:
Journal of Physical Chemistry A: Molecules, Spectroscopy, Kinetics, Environment, amp General Theory
Additional Journal Information:
Journal Volume: 103; Journal Issue: 33; Other Information: PBD: 19 Aug 1999
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; 01 COAL, LIGNITE, AND PEAT; SELECTIVE CATALYTIC REDUCTION; NITRIC OXIDE; COPPER OXIDES; CATALYSTS; ZEOLITES; METHANE; AIR POLLUTION CONTROL

Citation Formats

Huang, Y.J., and Wang, H.P. Reduction of NO with CH{sub 4} effected by copper oxide clusters in the channels of ZSM-5. United States: N. p., 1999. Web. doi:10.1021/jp9906177.
Huang, Y.J., & Wang, H.P. Reduction of NO with CH{sub 4} effected by copper oxide clusters in the channels of ZSM-5. United States. doi:10.1021/jp9906177.
Huang, Y.J., and Wang, H.P. Thu . "Reduction of NO with CH{sub 4} effected by copper oxide clusters in the channels of ZSM-5". United States. doi:10.1021/jp9906177.
@article{osti_20003182,
title = {Reduction of NO with CH{sub 4} effected by copper oxide clusters in the channels of ZSM-5},
author = {Huang, Y.J. and Wang, H.P.},
abstractNote = {Nitrogen oxides (NO{sub x}) are the main air pollutants that cause photochemical smog formation, acid rain, and general atmospheric visibility degradation. Worldwide, over 3 x 10{sup 7} tons of nitrogen oxides are vented to the atmosphere each year. Reduction of NO{sub x} emission has become one of the major problems to be solved for environmental protection. Many methods for reduction of NO{sub x} emissions such as reduction absorption, chelation absorption, catalytic decomposition, and catalytic reduction have been widely studied. Selective catalytic reduction with ammonia (NH{sub 3}-SCR) has been put to practical uses; however, the system is expensive in terms of handling the toxic ammonia. It has been recognized that the selective catalytic reduction of NO with hydrocarbons (HC-SCR) using copper-exchanged ZSM-5 (Cu-ZSM-5) catalysts is very effective. Fine structures of the copper oxide clusters involved in catalytic reduction of NO were studied by X-ray absorption spectroscopy. The Extended X-ray absorption fine structural (EXAFS) spectra indicate that about 2.89 nearest oxygen atoms bond to the Cu central atoms with a Cu-O bond distance of 1.96 {angstrom} for the oxidized Cu-ZSM-5 catalyst. Reduction of the catalyst in hydrogen at 573 K led to the formation of mainly Cu-Cu (2.54 {angstrom}) species with the coordination number (CN) of 2.91. The Cu{sub 4}O{sub 2} clusters in the channels of ZSM-5 observed by EXAFS were formed in the NO reduction process via incorporation of oxygen into the metallic copper matrix with desorption of N{sub 2}. Due to the restricted channel structure of ZSM-5, the Cu{sub 4}O{sub 2} clusters were reduced promptly by CH{sub 4}.},
doi = {10.1021/jp9906177},
journal = {Journal of Physical Chemistry A: Molecules, Spectroscopy, Kinetics, Environment, amp General Theory},
number = 33,
volume = 103,
place = {United States},
year = {1999},
month = {8}
}