TY - JOUR
T1 - Catalytic reduction of NO on copper/MCM-41 studied by in situ EXAFS and XANES
AU - Huang, Y. J.
AU - Wang, H. Paul
AU - Lee, Jyh Fu
N1 - Funding Information:
The financial support of the National Science Council, Taiwan is gratefully acknowledged. We also thank Professor Y.W. Yang of the Taiwan SRRC and Dr. A.C. Wei of the National Tsing Hua University for their EXAFS experimental assistance.
Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.
PY - 2003/3
Y1 - 2003/3
N2 - Speciation of copper in the channels of MCM-41 during reduction of NO with CO at 473-773 K was studied by in situ extended X-ray absorption fine structural (EXAFS) and X-ray absorption near edge structural (XANES) spectroscopies in the present work. The component fitted (in situ) XANES spectra of the catalyst showed that about 72% of metallic copper (Cu(O)) in MCM-41 was oxidized to higher oxidation state coppers (Cu(II) (46%) and Cu(I) (26%)) during the NO reduction process (at 473 K). By EXAFS, we also found that in the NO reduction process, oxygen was inserted into the metallic copper matrix and led to a formation of the copper oxide species with a Cu-O bond distance of 1.93 Å which was greater than that of the model compound Cu2O (typically 1.86 Å). At 573-673 K, mainly Cu(II) was found in the channels of MCM-41. Nevertheless, at a higher temperature (e.g., 773 K), about 61% Cu(I), 31% Cu(II), and 8% Cu(O) with averaged Cu-Cu and Cu-O bond distances of 3.04 and 1.88 Å, respectively were observed, that might account for the high selectivity-to-decomposition (S/D) ratios for yields of N2 and CO2 in the catalytic reduction of NO with CO.
AB - Speciation of copper in the channels of MCM-41 during reduction of NO with CO at 473-773 K was studied by in situ extended X-ray absorption fine structural (EXAFS) and X-ray absorption near edge structural (XANES) spectroscopies in the present work. The component fitted (in situ) XANES spectra of the catalyst showed that about 72% of metallic copper (Cu(O)) in MCM-41 was oxidized to higher oxidation state coppers (Cu(II) (46%) and Cu(I) (26%)) during the NO reduction process (at 473 K). By EXAFS, we also found that in the NO reduction process, oxygen was inserted into the metallic copper matrix and led to a formation of the copper oxide species with a Cu-O bond distance of 1.93 Å which was greater than that of the model compound Cu2O (typically 1.86 Å). At 573-673 K, mainly Cu(II) was found in the channels of MCM-41. Nevertheless, at a higher temperature (e.g., 773 K), about 61% Cu(I), 31% Cu(II), and 8% Cu(O) with averaged Cu-Cu and Cu-O bond distances of 3.04 and 1.88 Å, respectively were observed, that might account for the high selectivity-to-decomposition (S/D) ratios for yields of N2 and CO2 in the catalytic reduction of NO with CO.
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U2 - 10.1016/S0045-6535(02)00645-8
DO - 10.1016/S0045-6535(02)00645-8
M3 - Article
C2 - 12531709
AN - SCOPUS:0037332550
SN - 0045-6535
VL - 50
SP - 1035
EP - 1041
JO - Chemosphere
JF - Chemosphere
IS - 8
ER -