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Title: HDS and deep HDS activity of Co/Mo/S-mesostructured synthetic clays.

Abstract

The goal of this work is to identify more promising supports from synthetic clay materials to advance hydrotreating catalyst development. Silica sol can be used as the silicon-containing starting material when creating nanoporous layered silicate catalysts with a certain portion of unreacted sol particles incorporated into the final matrix. The resulting structure then has mesoporosity and a unique morphology. Hectorite-based clays have been prepared using different silica sols in order to ascertain the importance of sol characteristics on the final matrix. Several techniques have been applied to characterize the materials, including XRD, TGA, N2 porosimetry, and TEM. For hydrodesulfurization (HDS), the conversion of dibenzothiophene (DBT) to biphenyl was examined at 400 degrees C using CoMoS-loaded mesostructured clay supports. No hydrogenation or hydrocracking was observed with any of the clay supports. The most active clay was derived from Ludox silica sol AS-30 with an activity of 65% DBT conversion and 100% selectivity to biphenyl (BP). For comparison, a reference commercial catalyst displayed 94% BP selectivity. For deep HDS, the conversion of 4,6-dimethyldibenzothiophene was tested at 325 and 350 degrees C. At 325 degrees C, conversions are 92% of commercial catalysts for a CoMoS-loaded mesostructured clay derived from Ludox AM-30 silica sol.more » A commercially available synthetic hectorite called laponite has very low activity, indicating that the unique morphology of the mesostructured clays is important. Hydrogenolysis vs. hydrogenation pathways are compared for the deep HDS reaction. HR-TEM of the most active deep HDS catalyst revealed a multilayered MoS2 morphology.« less

Authors:
; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
982017
Report Number(s):
ANL/CHM/CP-114858
TRN: US201013%%869
DOE Contract Number:
DE-AC02-06CH11357
Resource Type:
Conference
Resource Relation:
Journal Name: Catal. Today; Journal Volume: 116; Journal Issue: 4 ; 2006; Conference: 229th American Chemical Society National Meeting; Mar. 13, 2005 - Mar. 17, 2005; San Diego, CA
Country of Publication:
United States
Language:
ENGLISH
Subject:
36 MATERIALS SCIENCE; BIPHENYL; CATALYSTS; CLAYS; CONVERSION; HYDROCRACKING; HYDROGENATION; MATERIALS; MEETINGS; MONTMORILLONITE; MORPHOLOGY; PARTICLES; SILICA; SILICATES; SOLS; SUPPORTS; WORK; X-RAY DIFFRACTION

Citation Formats

Carrado, K. A., Song, C., Kim, J. H., Castagnola, N., Fernandez-Saavedra, R., Marshall, C. L., Schwartz, M. M., Penn State Univ., and ICMM-CSIC. HDS and deep HDS activity of Co/Mo/S-mesostructured synthetic clays.. United States: N. p., 2006. Web. doi:10.1016/j.cattod.2006.06.033.
Carrado, K. A., Song, C., Kim, J. H., Castagnola, N., Fernandez-Saavedra, R., Marshall, C. L., Schwartz, M. M., Penn State Univ., & ICMM-CSIC. HDS and deep HDS activity of Co/Mo/S-mesostructured synthetic clays.. United States. doi:10.1016/j.cattod.2006.06.033.
Carrado, K. A., Song, C., Kim, J. H., Castagnola, N., Fernandez-Saavedra, R., Marshall, C. L., Schwartz, M. M., Penn State Univ., and ICMM-CSIC. Sun . "HDS and deep HDS activity of Co/Mo/S-mesostructured synthetic clays.". United States. doi:10.1016/j.cattod.2006.06.033.
@article{osti_982017,
title = {HDS and deep HDS activity of Co/Mo/S-mesostructured synthetic clays.},
author = {Carrado, K. A. and Song, C. and Kim, J. H. and Castagnola, N. and Fernandez-Saavedra, R. and Marshall, C. L. and Schwartz, M. M. and Penn State Univ. and ICMM-CSIC},
abstractNote = {The goal of this work is to identify more promising supports from synthetic clay materials to advance hydrotreating catalyst development. Silica sol can be used as the silicon-containing starting material when creating nanoporous layered silicate catalysts with a certain portion of unreacted sol particles incorporated into the final matrix. The resulting structure then has mesoporosity and a unique morphology. Hectorite-based clays have been prepared using different silica sols in order to ascertain the importance of sol characteristics on the final matrix. Several techniques have been applied to characterize the materials, including XRD, TGA, N2 porosimetry, and TEM. For hydrodesulfurization (HDS), the conversion of dibenzothiophene (DBT) to biphenyl was examined at 400 degrees C using CoMoS-loaded mesostructured clay supports. No hydrogenation or hydrocracking was observed with any of the clay supports. The most active clay was derived from Ludox silica sol AS-30 with an activity of 65% DBT conversion and 100% selectivity to biphenyl (BP). For comparison, a reference commercial catalyst displayed 94% BP selectivity. For deep HDS, the conversion of 4,6-dimethyldibenzothiophene was tested at 325 and 350 degrees C. At 325 degrees C, conversions are 92% of commercial catalysts for a CoMoS-loaded mesostructured clay derived from Ludox AM-30 silica sol. A commercially available synthetic hectorite called laponite has very low activity, indicating that the unique morphology of the mesostructured clays is important. Hydrogenolysis vs. hydrogenation pathways are compared for the deep HDS reaction. HR-TEM of the most active deep HDS catalyst revealed a multilayered MoS2 morphology.},
doi = {10.1016/j.cattod.2006.06.033},
journal = {Catal. Today},
number = 4 ; 2006,
volume = 116,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2006},
month = {Sun Jan 01 00:00:00 EST 2006}
}

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  • From Mossbauer spectroscopy studies of catalysts of typical industrial compositions and activity measurements it was shown that catalysts containing the ''Co-Mo-S'' phase have relatively higher hydrodesulfurization (HDS) activities. It was also found that the use of Co in the first impregnation step favored the formation of Co/sub 9/S/sub 8/ (in addition to Co in alumina), while the reverse impregnation order produced mainly the ''Co-Mo-S'' phase. Avoiding Co/sub 3/O/sub 4/ formation in the oxide precursor was important for the formation of the ''Co-Mo-S'' phase and this was achieved by the impregnation of Mo before Co. There was also evidence that whenmore » Co was used in the second impregnation step, there was significant Mo, Co interaction. This interaction my produce a CoMo surface phase which is disordered and well dispersed and sulfides to the ''Co-Mo-S'' phase. (JMT)« less
  • A series of Mo/TiO{sub 2} catalysts ranging from 1 to 15 wt% MoO{sub 3} was prepared by incipient wetness impregnation. The catalysts were characterized by laser Raman spectroscopy (LRS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS, ESCA), and gravimetric analysis. The Mo interaction species and MoO{sub 3} were identified and quantitated by Raman spectroscopy. The Mo interaction species increased with Mo loading up to 6 wt% MoO{sub 3} and leveled off at higher Mo loadings. MoO{sub 3} is detected at 7.5 wt% MoO{sub 3}/TiO{sub 2} and increased linearly with further Mo additions. The molybdenum speciation determined from Raman data ismore » shown to correlate with ESCA and XRD measurements. The reduction characteristics of molybdenum on titania depend on Mo loading, and a lower average Mo oxidation state is found for Mo/TiO{sub 2} than previously reported for comparable loadings of Mo/Al{sub 2}O{sub 3} catalysts. Correlation between structure and thiophene hydrodesulfurization activity is presented for the Mo/TiO{sub 2} series. The influence of nickel (cobalt) addition on the surface structure and the reactivity of the Mo/TiO{sub 2} catalysts is also examined.« less
  • The structure of the active sites of the catalysis employed in the hydrodesulfurization process has been source of some controversy in the literature. To explain the catalytic synergy between metals of group VI (Mo and W) and those of group VIII (Co, Ni), at least 12 theoretical models have been proposed. However, at the present time, the problem has not yet been resolved. Recently, Delmon has analyzed in detail the basis of each one of the theoretical models. Based on experimental evidence from various sophisticated surface techniques, ten of the models have been eliminated. Nevertheless, despite the intensive development ofmore » the use of the surface analysis in catalyst studies, Delmon has concluded that the sensitivity and resolution of these techniques are still insufficient to give a decisive advantage to either of the two remaining models, namely the amorphous Co-Mo-S structure proposed by Topsoee and the contact synergy-remote control model proposed by Delmon. This communication reports some new results of a research program aimed at characterizing the active sites of a hydrodesulfurization catalyst, and their relation to catalytic activity.« less
  • A series of Co-Mo/..gamma..-Al/sub 2/O/sub 3/ catalysts of typical commercial compositions were characterized by emission Moessbauer spectroscopy and x-ray photoelectron spectroscopy (XPS). Diffuse reflectance spectroscopy (DRS) was used to study the precursor oxide form. The activities for the catalyzed hydrodesulfurization (HDS) of dibenzothiophene and the hydrogenation of cyclohexene to cyclohexane were measured, and these activities are discussed in relation to the results of the catalyst characterization studies. (BLM)