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Title: (Co)MoS{sub 2}/ alumina hydrotreating catalysts : an EXAFS study of the chemisoption and partial oxidation with O{sub 2}.

Abstract

The adsorption of O{sub 2} on alumina-supported (Co)MoS{sub 2} catalysts and the subsequent mild oxidation of the (Co)MoS{sub 2} by O{sub 2} have been studied by extended X-ray absorption fine-structure (EXAFS) spectroscopy. By analyzing the difference between spectra before and after O{sub 2} exposure, small changes in the structure could be determined, which were not resolved using standard methods. At 20{sup o}C on MoS{sub 2}/alumina and (Co)MoS{sub 2}/alumina, O{sub 2} is chemisorbed at the edge of the MoS{sub 2} particles at a Mo-O distance of 1.73(2) {angstrom}. The O{sub 2} chemisorption results at the Mo edge indicate that, despite the large fraction of Co at the surface of the MoS{sub 2} crystallite in (Co)MoS{sub 2}/alumina, some of the Mo atoms are exposed to the reacting gases. At 100{sup o}C, there is partial substitution of S by O atoms in the Mo coordination sphere. The resulting decrease in both the Mo-S and Mo-Mo coordination numbers indicates partial disruption of the MoS{sub 2} crystallites. At 20{sup o}C, O{sub 2} chemisorption on (Co)MoS{sub 2}/alumina also leads to displacement of the terminal Co-S bond and the formation of one Co-O bond at a distance of about 2.01(5) {angstrom}. The terminal Co-S bond distance ismore » 2.26(2) {angstrom} and is significantly longer than the four bridging Mo-S-Co bonds, which are 2.18(2) {angstrom}. At 100{sup o}C, the latter are unreactive to O{sub 2}, although the Coion coordination increases to about six, i.e., four bridging Co-S and two terminal Co-O bonds. The Co chemisorption results suggest that the terminal Co-S is the reactive bond that has been displaced by the oxygen adsorbate.« less

Authors:
; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC); FE
OSTI Identifier:
943221
Report Number(s):
ANL/CMT/JA-38395
Journal ID: ISSN 0021-9517; JCTLA5; TRN: US200916%%664
DOE Contract Number:  
DE-AC02-06CH11357
Resource Type:
Journal Article
Journal Name:
J. Catal.
Additional Journal Information:
Journal Volume: 202; Journal Issue: 2001; Journal ID: ISSN 0021-9517
Country of Publication:
United States
Language:
ENGLISH
Subject:
36 MATERIALS SCIENCE; ABSORPTION; ADSORPTION; ALUMINIUM OXIDES; ATOMS; CATALYSTS; CHEMISORPTION; COBALT SULFIDES; COORDINATION NUMBER; CRYSTAL STRUCTURE; FINE STRUCTURE; GASES; HETEROGENEOUS CATALYSIS; MOLYBDENUM SULFIDES; OXIDATION; OXYGEN; PARTICLES; SPECTRA; SPECTROSCOPY; SURFACES; TRANSITION ELEMENTS

Citation Formats

Miller, J T, Marshall, C L, Kropf, A J, Chemical Engineering, and BP Research Center. (Co)MoS{sub 2}/ alumina hydrotreating catalysts : an EXAFS study of the chemisoption and partial oxidation with O{sub 2}.. United States: N. p., 2001. Web. doi:10.1006/jcat.2001.3273.
Miller, J T, Marshall, C L, Kropf, A J, Chemical Engineering, & BP Research Center. (Co)MoS{sub 2}/ alumina hydrotreating catalysts : an EXAFS study of the chemisoption and partial oxidation with O{sub 2}.. United States. https://doi.org/10.1006/jcat.2001.3273
Miller, J T, Marshall, C L, Kropf, A J, Chemical Engineering, and BP Research Center. Mon . "(Co)MoS{sub 2}/ alumina hydrotreating catalysts : an EXAFS study of the chemisoption and partial oxidation with O{sub 2}.". United States. https://doi.org/10.1006/jcat.2001.3273.
@article{osti_943221,
title = {(Co)MoS{sub 2}/ alumina hydrotreating catalysts : an EXAFS study of the chemisoption and partial oxidation with O{sub 2}.},
author = {Miller, J T and Marshall, C L and Kropf, A J and Chemical Engineering and BP Research Center},
abstractNote = {The adsorption of O{sub 2} on alumina-supported (Co)MoS{sub 2} catalysts and the subsequent mild oxidation of the (Co)MoS{sub 2} by O{sub 2} have been studied by extended X-ray absorption fine-structure (EXAFS) spectroscopy. By analyzing the difference between spectra before and after O{sub 2} exposure, small changes in the structure could be determined, which were not resolved using standard methods. At 20{sup o}C on MoS{sub 2}/alumina and (Co)MoS{sub 2}/alumina, O{sub 2} is chemisorbed at the edge of the MoS{sub 2} particles at a Mo-O distance of 1.73(2) {angstrom}. The O{sub 2} chemisorption results at the Mo edge indicate that, despite the large fraction of Co at the surface of the MoS{sub 2} crystallite in (Co)MoS{sub 2}/alumina, some of the Mo atoms are exposed to the reacting gases. At 100{sup o}C, there is partial substitution of S by O atoms in the Mo coordination sphere. The resulting decrease in both the Mo-S and Mo-Mo coordination numbers indicates partial disruption of the MoS{sub 2} crystallites. At 20{sup o}C, O{sub 2} chemisorption on (Co)MoS{sub 2}/alumina also leads to displacement of the terminal Co-S bond and the formation of one Co-O bond at a distance of about 2.01(5) {angstrom}. The terminal Co-S bond distance is 2.26(2) {angstrom} and is significantly longer than the four bridging Mo-S-Co bonds, which are 2.18(2) {angstrom}. At 100{sup o}C, the latter are unreactive to O{sub 2}, although the Coion coordination increases to about six, i.e., four bridging Co-S and two terminal Co-O bonds. The Co chemisorption results suggest that the terminal Co-S is the reactive bond that has been displaced by the oxygen adsorbate.},
doi = {10.1006/jcat.2001.3273},
url = {https://www.osti.gov/biblio/943221}, journal = {J. Catal.},
issn = {0021-9517},
number = 2001,
volume = 202,
place = {United States},
year = {2001},
month = {1}
}