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Title: XAS Study at Mo and Co K-Edges of the Sulfidation of a CoMo / Al2O3 Hydrotreating Catalyst

Abstract

Because of its impact on environment, the removal of sulfur is an indispensable step, called hydrotreatment, in the refining of petroleum. One of the most commonly used hydrotreating catalysts is CoMo-type catalyst which is composed of molybdenum disulfide slabs promoted by cobalt atoms (CoMoS phase) and well dispersed on a high specific area alumina. As far as the highest sulfur content allowed in gasoline and diesel is continually decreasing, more and more efficient and active hydrotreating catalysts are required. In order to optimize the reactivity of the CoMo-type catalyst in hydrotreatment, a better understanding of the processes used to produce the active phase (CoMoS slabs) of the catalyst is necessary. The study reported here deals with the sulfiding mechanism of the slabs and the influence of temperature on the phenomenon. Ex situ X-ray absorption spectroscopy (XANES and EXAFS) was used to study the evolution of the structure of CoMo-type catalyst sulfided at various temperatures (from 293 to 873 K). XAS analysis was performed at both molybdenum and cobalt K-edges to obtain a cross-characterization of the sulfidation of the slabs. It evidenced the formation of various compounds, including two molybdenum oxides, MoS3 (or MoS3-like compound) and Co9S8, at specific steps ofmore » the sulfiding process. It showed the role of intermediate played by MoS3 (or MoS3-like compound) during the formation of the slabs and the competition between the appearance of promoted slabs (CoMoS phase) and Co9S8. At last, it leaded to the proposal of a mechanism for the sulfidation of the catalyst.« less

Authors:
; ;  [1];  [2]
  1. IFP-Lyon, Physics and Analysis Division, Materials Characterization Department, BP3, 69390 Vernaison (France)
  2. IFP-Lyon, Catalysis and Separation Division, Heterogeneous Catalysis Department, BP3, 69390 Vernaison (France)
Publication Date:
OSTI Identifier:
21054718
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 882; Journal Issue: 1; Conference: XAFS13: 13. international conference on X-ray absorption fine structure, Stanford, CA (United States), 9-14 Jul 2006; Other Information: DOI: 10.1063/1.2644631; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ABSORPTION SPECTROSCOPY; ALUMINIUM OXIDES; CATALYSTS; COBALT; COBALT COMPOUNDS; FINE STRUCTURE; HYDROGENATION; MOLYBDENUM; MOLYBDENUM OXIDES; MOLYBDENUM SULFIDES; PETROLEUM; REFINING; SULFIDATION; TEMPERATURE DEPENDENCE; X-RAY SPECTROSCOPY

Citation Formats

Pichon, C., Gandubert, A. D., Legens, C., and Guillaume, D. XAS Study at Mo and Co K-Edges of the Sulfidation of a CoMo / Al2O3 Hydrotreating Catalyst. United States: N. p., 2007. Web. doi:10.1063/1.2644631.
Pichon, C., Gandubert, A. D., Legens, C., & Guillaume, D. XAS Study at Mo and Co K-Edges of the Sulfidation of a CoMo / Al2O3 Hydrotreating Catalyst. United States. doi:10.1063/1.2644631.
Pichon, C., Gandubert, A. D., Legens, C., and Guillaume, D. Fri . "XAS Study at Mo and Co K-Edges of the Sulfidation of a CoMo / Al2O3 Hydrotreating Catalyst". United States. doi:10.1063/1.2644631.
@article{osti_21054718,
title = {XAS Study at Mo and Co K-Edges of the Sulfidation of a CoMo / Al2O3 Hydrotreating Catalyst},
author = {Pichon, C. and Gandubert, A. D. and Legens, C. and Guillaume, D.},
abstractNote = {Because of its impact on environment, the removal of sulfur is an indispensable step, called hydrotreatment, in the refining of petroleum. One of the most commonly used hydrotreating catalysts is CoMo-type catalyst which is composed of molybdenum disulfide slabs promoted by cobalt atoms (CoMoS phase) and well dispersed on a high specific area alumina. As far as the highest sulfur content allowed in gasoline and diesel is continually decreasing, more and more efficient and active hydrotreating catalysts are required. In order to optimize the reactivity of the CoMo-type catalyst in hydrotreatment, a better understanding of the processes used to produce the active phase (CoMoS slabs) of the catalyst is necessary. The study reported here deals with the sulfiding mechanism of the slabs and the influence of temperature on the phenomenon. Ex situ X-ray absorption spectroscopy (XANES and EXAFS) was used to study the evolution of the structure of CoMo-type catalyst sulfided at various temperatures (from 293 to 873 K). XAS analysis was performed at both molybdenum and cobalt K-edges to obtain a cross-characterization of the sulfidation of the slabs. It evidenced the formation of various compounds, including two molybdenum oxides, MoS3 (or MoS3-like compound) and Co9S8, at specific steps of the sulfiding process. It showed the role of intermediate played by MoS3 (or MoS3-like compound) during the formation of the slabs and the competition between the appearance of promoted slabs (CoMoS phase) and Co9S8. At last, it leaded to the proposal of a mechanism for the sulfidation of the catalyst.},
doi = {10.1063/1.2644631},
journal = {AIP Conference Proceedings},
number = 1,
volume = 882,
place = {United States},
year = {Fri Feb 02 00:00:00 EST 2007},
month = {Fri Feb 02 00:00:00 EST 2007}
}