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Title: In situ XAS of Ni-W hydrocracking catalysts.

Abstract

Ni-W based catalysts are very attractive in hydrotreating of heavy oil due to their high hydrogenation activity. In the present research, two catalyst samples, prepared by different methods, that exhibit significant differences in activity were sulfided in situ, and the local structure of the Ni and W were studied using X-ray absorption spectroscopy (XAS). The Ni XANES spectra were analyzed using a linear component fitting, and the EXAFS spectra of the WS{sub 2} platelets in the sulfided catalysts were modeled. The Ni and W are fully sulfided in the higher activity sample, and there are both unsulfided Ni ({approx}25%) and W (<10%) in the lower activity sample.

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
970772
Report Number(s):
ANL/XSD/CP-118911
TRN: US201003%%111
DOE Contract Number:
DE-AC02-06CH11357
Resource Type:
Conference
Resource Relation:
Conference: 13th International Conference on X-ray Absorption Fine Structure (XAFS 13); Jul. 9, 2006 - Jul. 14, 2006; Stanford, CA
Country of Publication:
United States
Language:
ENGLISH
Subject:
02 PETROLEUM; ABSORPTION; ABSORPTION SPECTROSCOPY; CATALYSTS; FINE STRUCTURE; HYDROCRACKING; HYDROGENATION; PETROLEUM; SPECTRA; VISCOSITY

Citation Formats

Yang, N., Mickelson, G. E., Greenlay, N., Kelly, S. D., Bare, S. R., UOP LLC, and EXAFS Analysis. In situ XAS of Ni-W hydrocracking catalysts.. United States: N. p., 2007. Web. doi:10.1063/1.2644625.
Yang, N., Mickelson, G. E., Greenlay, N., Kelly, S. D., Bare, S. R., UOP LLC, & EXAFS Analysis. In situ XAS of Ni-W hydrocracking catalysts.. United States. doi:10.1063/1.2644625.
Yang, N., Mickelson, G. E., Greenlay, N., Kelly, S. D., Bare, S. R., UOP LLC, and EXAFS Analysis. Mon . "In situ XAS of Ni-W hydrocracking catalysts.". United States. doi:10.1063/1.2644625.
@article{osti_970772,
title = {In situ XAS of Ni-W hydrocracking catalysts.},
author = {Yang, N. and Mickelson, G. E. and Greenlay, N. and Kelly, S. D. and Bare, S. R. and UOP LLC and EXAFS Analysis},
abstractNote = {Ni-W based catalysts are very attractive in hydrotreating of heavy oil due to their high hydrogenation activity. In the present research, two catalyst samples, prepared by different methods, that exhibit significant differences in activity were sulfided in situ, and the local structure of the Ni and W were studied using X-ray absorption spectroscopy (XAS). The Ni XANES spectra were analyzed using a linear component fitting, and the EXAFS spectra of the WS{sub 2} platelets in the sulfided catalysts were modeled. The Ni and W are fully sulfided in the higher activity sample, and there are both unsulfided Ni ({approx}25%) and W (<10%) in the lower activity sample.},
doi = {10.1063/1.2644625},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}

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  • Ni-W based catalysts are very attractive in hydrotreating of heavy oil due to their high hydrogenation activity. In the present research, two catalyst samples, prepared by different methods, that exhibit significant differences in activity were sulfided in situ, and the local structure of the Ni and W were studied using X-ray absorption spectroscopy (XAS). The Ni XANES spectra were analyzed using a linear component fitting, and the EXAFS spectra of the WS2 platelets in the sulfided catalysts were modeled. The Ni and W are fully sulfided in the higher activity sample, and there are both unsulfided Ni ({approx}25%) and Wmore » (<10%) in the lower activity sample.« less
  • The detailed structural characterization of the metal function of two fully formulated Ni-W hydrocracking catalysts was investigated by time resolved in situ X-ray absorption spectroscopy (EXAFS and XANES) at both the Ni K-edge and W L{sub 3}-edge, and by high resolution transmission electron microscopy. These two hydrocracking catalysts (designated as HCA and HCB) contained the same wt% of Ni and W, the same wt% of the other constituents ({gamma}-Al{sub 2}O{sub 3}/silico-aluminate), and were calcined at the same temperature, but were prepared by different methods in order to highlight the sensitivity of the characterization techniques to the structural differences. The morphologymore » of the WS{sub 2} particles in the sulfided catalyst is substantially different between the two catalysts: in the HCA catalyst there are many more particles with multiple WS{sub 2} layers whereas in HCB there are more single layers. The average diameter of the WS{sub 2} plates is similar in both. The catalysts show a difference in the amount of W sulfidation after the 410 C sulfidation treatment in 10% H{sub 2}S/H{sub 2}. The W of HCA catalyst was completely sulfided whereas 16% W of HCB catalyst was unsulfided. Similarly there is a difference in the amount of sulfided Ni: 16% Ni in HCA and 60% Ni in HCB remain unsulfided. In the sulfided form of both catalysts the Ni exists in three different morphologies: oxidized Ni (six-fold coordinate as a nickel aluminate), nanoparticulate Ni{sub 3}S{sub 2}, and Ni decorating the edge sites of the WS{sub 2}. In both the Ni{sub 3}S{sub 2}, and Ni decorating the edge sites of the WS{sub 2}, the Ni is in a tetrahedral coordination with sulfur. In both catalysts the sulfidation of the Ni and W occurs essentially simultaneously over most of the temperature range and the sulfidation of the W proceeds through the same tungsten oxysulfide in both samples. The characterization methodology presented here is a powerful one for elucidating the structural differences of complex heterogeneous catalysts.« less
  • We have been studying the hydrocracking of polyaromatic compounds over Ni-loaded zeolite catalysts (ZSM-5, mordenite, and Y-type) and found the fact that pore size of zeolite exerts an interesting effect on product distribution. In this study, we have conducted the hydrocracking of pyrene using Pd-modified Ni-loaded Y-type zeolite as catalyst. Addition of Pd-metal activated Ni-loaded Y-type zeolite at a great extent. 100% conversion of pyrene was attained under milder conditions like at 325{degrees}C for 1 h (H{sub 2} 70 kg/cm{sup 2}) while Ni-loaded Y-type zeolite can attain 100% conversion at 350{degrees}C for 1 h. Detailed analysis of product distribution suggestedmore » us to apply this catalyst for the hydrodesulfurization of dibenzothiophene. We have conducted hydrocracking of dibenzothiophene at 300{degrees}C for 1 h and found that almost all of dibenzothiophene was hydrocracked while both Ni-loaded Y-type zeolite and Pd-loaded Y-type zeolite show about 10-15% of starting materials remained. This result clearly indicates that modifier Pd-metal shows a kind of synergy for hydrodesulfurization of dibenzothiophene.« less
  • The performance of a NiMoW/Al{sub 2}O{sub 3} catalyst for promoting various reactions during residual oil hydroprocessing is reported. Catalyst performance and properties are compared to that of conventional NiMo and NiW catalysts. Performance evaluation tests were conducted in a high pressure fixed bed reactor system using Kuwait vacuum residue as feed. Hydrodesulfurization, hydrodenitrogenation, hydrodemetalization, hydroconversion to distillates, asphaltene removal and CCR reduction reactions were monitored. The NiMoW catalyst was more active for various conversions than the NiMo and NiW catalysts. The addition of W to NiMo/Al{sub 2}O{sub 3} enhanced the hydrogenation function of the catalyst. 11 refs., 3 figs., 2more » tabs.« less