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Title: Activation of unsupported Co-Mo catalysts in thiophene hydrodesulfurization

Abstract

A series of unsupported oxidic Co-Mo catalysts with different mole fractions r = Co/(Co + Mo) was prepared by coprecipitation of solutions of (NH{sub 4}){sub 6}Mo{sub 7}O{sub 24} and Co(NO{sub 3}){sub 2}. The calcined catalysts contain a-CoMoO{sub 4} (r = 0.5) mixed with MoO{sub 3} (r < 0.5) or with Co{sub 3}O{sub 4} (r > 0.5) according to X-ray diffraction (XRD) and electron diffraction. The a-CoMoO{sub 4} transforms partially into b-CoMoO{sub 4} upon grinding. The higher the cobalt (r) and b-CoMoO{sub 4} contents, the higher are the surface area increase and the degree of reduction of calcined catalysts during hydrogen treatment at 673 K. Electron microscopy (EM) data agree well with the surface area increase observed after reduction. X-ray photoelectron spectroscopy (XPS) shows the reduction of molybdenum rather than that of cobalt. Reduced crystalline phases cannot be identified by these techniques. Sulfidation with a mixture of H{sub 2}/thiophene following reduction caused a drastic drop in surface area but the particle size seen by EM does not increase. Weak oxythiomolybdate XRD bands appeared after slight sulfidation, most XRD signals disappeared after massive sulfidation of samples with r = 0.5. Cobalt promotes sulfidation of molybdenum in the bulk, but the maximum sulfidationmore » degree was about half of the stoichiometric value. XPS shows surface cobalt enrichment, XRD and EM traces of Co{sub 9}S{sub 8} in samples with r = 0.38 and 0.50. A pronounced maximum was observed in initial hydrodesulfurization (HDS) activity and hydrogenation (HYD) selectivity at medium Co content. On used catalysts, this synergism disappeared. The authors attribute the highest HDS activity of short-living cobalt-oxythiomolybdate(s) formed initially during sulfidation. HYD was promoted by sulfided molybdenum and by less surface cobalt.« less

Authors:
; ;  [1]; ;  [2]
  1. Institute of Isotopes of the Hungarian Academy of Sciences, Budapest (Hungary)
  2. Univ. of Zuerich (Switzerland)
Publication Date:
OSTI Identifier:
6356231
Resource Type:
Journal Article
Journal Name:
Journal of Catalysis; (USA)
Additional Journal Information:
Journal Volume: 116:2; Journal ID: ISSN 0021-9517
Country of Publication:
United States
Language:
English
Subject:
01 COAL, LIGNITE, AND PEAT; 02 PETROLEUM; CATALYSTS; CHEMICAL ACTIVATION; COBALT; CATALYTIC EFFECTS; MOLYBDENUM SULFIDES; THIOPHENE; DESULFURIZATION; CALCINATION; CHEMICAL PREPARATION; COBALT COMPOUNDS; COBALT SULFIDES; ELECTRON DIFFRACTION; ELECTRON MICROSCOPY; HYDROGENATION; MOLYBDATES; PARTICLE SIZE; PHASE TRANSFORMATIONS; PHOTOELECTRON SPECTROSCOPY; QUANTITY RATIO; REDUCTION; SULFIDATION; SURFACE AREA; SURFACE PROPERTIES; X-RAY DIFFRACTION; X-RAY SPECTROSCOPY; CHALCOGENIDES; CHEMICAL REACTIONS; COHERENT SCATTERING; DECOMPOSITION; DIFFRACTION; ELECTRON SPECTROSCOPY; ELEMENTS; HETEROCYCLIC COMPOUNDS; METALS; MICROSCOPY; MOLYBDENUM COMPOUNDS; ORGANIC COMPOUNDS; ORGANIC SULFUR COMPOUNDS; OXYGEN COMPOUNDS; PYROLYSIS; REFRACTORY METAL COMPOUNDS; SCATTERING; SIZE; SPECTROSCOPY; SULFIDES; SULFUR COMPOUNDS; SYNTHESIS; THERMOCHEMICAL PROCESSES; TRANSITION ELEMENT COMPOUNDS; TRANSITION ELEMENTS; 010402* - Coal, Lignite, & Peat- Purification & Upgrading; 020400 - Petroleum- Processing

Citation Formats

Koranyi, T I, Manninger, I, Paal, Z, Marks, O, and Guenter, J R. Activation of unsupported Co-Mo catalysts in thiophene hydrodesulfurization. United States: N. p., 1989. Web. doi:10.1016/0021-9517(89)90109-7.
Koranyi, T I, Manninger, I, Paal, Z, Marks, O, & Guenter, J R. Activation of unsupported Co-Mo catalysts in thiophene hydrodesulfurization. United States. https://doi.org/10.1016/0021-9517(89)90109-7
Koranyi, T I, Manninger, I, Paal, Z, Marks, O, and Guenter, J R. 1989. "Activation of unsupported Co-Mo catalysts in thiophene hydrodesulfurization". United States. https://doi.org/10.1016/0021-9517(89)90109-7.
@article{osti_6356231,
title = {Activation of unsupported Co-Mo catalysts in thiophene hydrodesulfurization},
author = {Koranyi, T I and Manninger, I and Paal, Z and Marks, O and Guenter, J R},
abstractNote = {A series of unsupported oxidic Co-Mo catalysts with different mole fractions r = Co/(Co + Mo) was prepared by coprecipitation of solutions of (NH{sub 4}){sub 6}Mo{sub 7}O{sub 24} and Co(NO{sub 3}){sub 2}. The calcined catalysts contain a-CoMoO{sub 4} (r = 0.5) mixed with MoO{sub 3} (r < 0.5) or with Co{sub 3}O{sub 4} (r > 0.5) according to X-ray diffraction (XRD) and electron diffraction. The a-CoMoO{sub 4} transforms partially into b-CoMoO{sub 4} upon grinding. The higher the cobalt (r) and b-CoMoO{sub 4} contents, the higher are the surface area increase and the degree of reduction of calcined catalysts during hydrogen treatment at 673 K. Electron microscopy (EM) data agree well with the surface area increase observed after reduction. X-ray photoelectron spectroscopy (XPS) shows the reduction of molybdenum rather than that of cobalt. Reduced crystalline phases cannot be identified by these techniques. Sulfidation with a mixture of H{sub 2}/thiophene following reduction caused a drastic drop in surface area but the particle size seen by EM does not increase. Weak oxythiomolybdate XRD bands appeared after slight sulfidation, most XRD signals disappeared after massive sulfidation of samples with r = 0.5. Cobalt promotes sulfidation of molybdenum in the bulk, but the maximum sulfidation degree was about half of the stoichiometric value. XPS shows surface cobalt enrichment, XRD and EM traces of Co{sub 9}S{sub 8} in samples with r = 0.38 and 0.50. A pronounced maximum was observed in initial hydrodesulfurization (HDS) activity and hydrogenation (HYD) selectivity at medium Co content. On used catalysts, this synergism disappeared. The authors attribute the highest HDS activity of short-living cobalt-oxythiomolybdate(s) formed initially during sulfidation. HYD was promoted by sulfided molybdenum and by less surface cobalt.},
doi = {10.1016/0021-9517(89)90109-7},
url = {https://www.osti.gov/biblio/6356231}, journal = {Journal of Catalysis; (USA)},
issn = {0021-9517},
number = ,
volume = 116:2,
place = {United States},
year = {1989},
month = {4}
}