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Title: In Situ EXAFS Studies on Ni2P Hydrodesulfurization Catalysts in the Presence of High Pressure and High Temperature Oil

Abstract

A Ni2P/SiO2 catalyst that is highly active for hydrodesulfurization (HDS) reaction was studied by in situ extended x-ray absorption fine structure (EXAFS) under the real reaction conditions. The measurements were conducted at realistic conditions of high pressure (3 MPa) and high temperature (613 K) in the presence of model oil. We used a low-volume cell with cubic boron nitride windows. The obtained spectra revealed that the bulk Ni2P structure was stable at reaction conditions and that the active surface had Ni-S bonds under reaction conditions, which played an important role for HDS reactions.

Authors:
;  [1];  [2]; ;  [3];  [1]
  1. Catalysis Research Center, Hokkaido University, Sapporo 001-0021 (Japan)
  2. National Institute of Advanced Industrial Science and Technology, 16-1, Onogawa, Tsukuba, 305-8569 (Japan)
  3. Department of Chemical Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061 (United States)
Publication Date:
OSTI Identifier:
21054696
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: 10.1063/1.2644609; (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 SPECTRA; ABSORPTION SPECTROSCOPY; BORON NITRIDES; CATALYSIS; CATALYSTS; FINE STRUCTURE; INTERFACES; NICKEL PHOSPHIDES; OILS; PRESSURE DEPENDENCE; PRESSURE RANGE MEGA PA 10-100; REFINING; SILICON OXIDES; SURFACES; TEMPERATURE DEPENDENCE; X-RAY SPECTRA; X-RAY SPECTROSCOPY

Citation Formats

Kawai, Toshihide, Asakura, Kiyotaka, Bando, Kyoko K., Lee, Yong-Kul, Oyama, S. Ted., and Chun, Wang-Jae. In Situ EXAFS Studies on Ni2P Hydrodesulfurization Catalysts in the Presence of High Pressure and High Temperature Oil. United States: N. p., 2007. Web. doi:10.1063/1.2644609.
Kawai, Toshihide, Asakura, Kiyotaka, Bando, Kyoko K., Lee, Yong-Kul, Oyama, S. Ted., & Chun, Wang-Jae. In Situ EXAFS Studies on Ni2P Hydrodesulfurization Catalysts in the Presence of High Pressure and High Temperature Oil. United States. doi:10.1063/1.2644609.
Kawai, Toshihide, Asakura, Kiyotaka, Bando, Kyoko K., Lee, Yong-Kul, Oyama, S. Ted., and Chun, Wang-Jae. Fri . "In Situ EXAFS Studies on Ni2P Hydrodesulfurization Catalysts in the Presence of High Pressure and High Temperature Oil". United States. doi:10.1063/1.2644609.
@article{osti_21054696,
title = {In Situ EXAFS Studies on Ni2P Hydrodesulfurization Catalysts in the Presence of High Pressure and High Temperature Oil},
author = {Kawai, Toshihide and Asakura, Kiyotaka and Bando, Kyoko K. and Lee, Yong-Kul and Oyama, S. Ted. and Chun, Wang-Jae},
abstractNote = {A Ni2P/SiO2 catalyst that is highly active for hydrodesulfurization (HDS) reaction was studied by in situ extended x-ray absorption fine structure (EXAFS) under the real reaction conditions. The measurements were conducted at realistic conditions of high pressure (3 MPa) and high temperature (613 K) in the presence of model oil. We used a low-volume cell with cubic boron nitride windows. The obtained spectra revealed that the bulk Ni2P structure was stable at reaction conditions and that the active surface had Ni-S bonds under reaction conditions, which played an important role for HDS reactions.},
doi = {10.1063/1.2644609},
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}
}
  • No abstract prepared.
  • A Ni{sub 2}P catalyst supported on a high-surface area SiO{sub 2} (350 m{sup 2} g{sub -1}) was prepared by temperature-programmed reduction, and its structural and surface properties were studied. X-ray diffraction and extended X-ray absorption fine structure measurements were used to obtain structural parameters for the supported Ni{sub 2}P phase, and Fourier transform infrared (FTIR) analysis with the probe molecules CO and pyridine was carried out to characterize the surface properties. The catalytic activity was measured at 573 K and 3.1 MPa in a three-phase fixed-bed reactor for hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) using a model liquid feed. At standardmore » conditions using 500 ppm S as 4,6-dimethyldibenzothiophene (4,6-DMDBT), 3000 ppm S as dimethyldisulfide, 200 ppm N as quinoline, and 1% tetralin in a tridecane solvent, the Ni{sub 2}P/SiO{sub 2} gave an HDS conversion of 85%, an HDN conversion of 100%, and a tetralin conversion of 37%, which were much higher than those of a commercial Ni-Mo-S/Al{sub 2}O{sub 3} catalyst, which gave an HDS conversion of 41%, an HDN conversion of 98%, and a tetralin conversion of 20% based on equal numbers of sites (240 {micro}mol) loaded in the reactor. The sites were counted by CO chemisorption for the phosphide and by low-temperature O{sub 2} chemisorption for the sulfide. The Ni{sub 2}P/SiO{sub 2} catalyst favored the hydrogenation (HYD) pathway for 4,6-DMDBT HDS to generate methylcyclohexyltoluene and dimethylbicyclohexane with a relative HYD selectivity of 95%. It also favored hydrogenation for tetralin to give decalin with a relative HYD selectivity of 89%. The Ni{sub 2}P/SiO{sub 2} catalyst also showed better resistance to N-compounds than the Ni-Mo-S/Al{sub 2}O{sub 3} catalyst. The FTIR spectra of adsorbed CO showed that the Ni site in the Ni{sub 2}P phase gave rise to considerable {pi}-back bonding, which was related to the high activity of the Ni{sub 2}P/SiO{sub 2} catalyst in the hydrogenation of aromatics. The FTIR spectra of adsorbed pyridine showed that the Ni{sub 2}P phase had a P{single_bond}OH group associated with Br{o}nsted acidity that was active for the protonation of N compounds. These results thus suggest that the supported Ni{sub 2}P catalyst has bifunctional properties that are beneficial for catalytic activity in hydroprocessing.« less
  • Information regarding the structure and type of phases present in sulfided alumina-supported, as well as unsupported, Co-Mo catalysts is obtained from in situ Moessbauer emission spectroscopy (MES) studies. The results give the first direct evidence of the presence of a Co-Mo-S phase in alumina-supported and unsupported catalysts with similar Co/Mo ratios. Information regarding the nature of the Co-Mo-S phase is obtained from a detailed study of the Moessbauer parameters, their temperature dependence, and their sensitivity to changes in the gaseous environment. Previously proposed structural models cannot explain all the observed features of the Co-Mo-S phase. It is proposed that inmore » alumina-supported catalysts the Co-Mo-S phase is present as single S-Mo-S slabs (i.e., one layer of the MoS/sub 2/ structure) with cobalt most likely present at molybdenum sites. For unsupported catalysts the Co-Mo-S phase consists of several slabs with bulk MoS/sub 2/-like structure. The present observations suggest that the previously observed similarities between supported and unsupported catalysts are associated with the presence of the Co-Mo-S phase in both catalyst systems. A possible reaction mechanism for hydrodesulfurization involving cobalt in the Co-Mo-S phase is proposed. Information regarding other phases in the catalysts is obtained by MES studies of Co/Al/sub 2/O/sub 3/, CoMo/sub 2/S/sub 4/, Co/sub 9/S/sub 8/, CoS/sub 2/, Co/sub 3/S/sub 4/, and CoS/sub 1+x/ samples. It is observed that for a sulfided Co-Mo/Al/sub 2/O/sub 3/ catalyst with a composition typical of those used industrially, part of the cobalt is located in the alumina. For unsupported catalysts the effect of changing the cobalt concentration and preparation method is investigated and it is observed that under certain conditions also the thermodynamically stable cobalt sulfide, Co/sub 9/S/sub 8/, may be formed.« less
  • A series of sulfided Co-Mo/Al/sub 2/O/sub 3/ catalysts with different Co/Mo ratios but with constant molybdenum content is investigated. The catalysts are characterized by in situ Moessbauer emission spectroscopy (MES) and investigated for their thiophene hydrodesulfurization activity. The catalytic activity shows a pronounced maximum at a Co/Mo ratio of about 1.0. The MES spectra reveal that cobalt may be present in three distinctly different phases: cobalt located in the alumina lattice (Co:Al/sub 2/O/sub 3/), cobalt in Co/sub 9/S/sub 8/, and cobalt located in the Co-Mo-S surface phase discussed in the preceeding paper. It is found that the relative amounts ofmore » the three phases depend strongly on the Co/Mo ratio. The Co:Al/sub 2/O/sub 3/ phase and the Co-Mo-S phase are observed in all catalysts studied, whereas Co/sub 9/S/sub 8/ is observed only in catalysts with Co/Mo > 0.4. It is shown that the presence of Co/sub 9/S/sub 8/ cannot explain the promoting role of cobalt in the Co-Mo/Al/sub 2/O/sub 3/ catalysts. However, a linear relation between the catalytic activity and the amount of Co in the Co-Mo-S phase leads to the conclusion that the promoting effect of cobalt is associated with the presence of this phase.« less