Influence of decomposition time and H2 pressure on properties of unsupported ammonium tetrathiomolybdate-derived MoS2 catalysts

Jamie Whelan, Ionut Banu, Gisha E. Luckachan, Nicoleta Doriana Banu, Samuel Stephen, Anjana Tharalekshmy, Saleh Al Hashimi, Radu V. Vladea, Marios S. Katsiotis, Saeed M. Alhassan

Research output: Contribution to journalArticle

Abstract

Background: Molybdenum sulfide (MoS2) catalysts to be used for hydrodesulfurization (HDS) processes were prepared via the reductive thermal decomposition of ammonium tetrathiomolybdate at fixed temperature (653 K) by varying decomposition times and H2 pressures. Both parameters were found to strongly influence textural and catalytic properties of the resulting MoS2 catalysts. Methods: Nitrogen sorption, FT-IR, and XRD analyses revealed the effect of varying decomposition times (3 to 7 h) and H2 pressure (20 to 1,000 psig) on the morphology and structure of the catalysts. Dibenzothiophene (DBT) was used to assess catalytic efficiency for HDS reactions. Results: The influence of time on specific surface was minimal at low pressures but increased at higher decomposition pressures. Vibrational energies of Mo-S bonds in FT-IR indicate that MoS2 catalysts prepared at higher pressures exhibit weaker Mo-S bonds. Analysis of XRD patterns point towards an increase in stacking and crystallite size with increasing pressure; interlayer rotation about both the a- and c-axes of the stacks was also observed. Catalytic testing results show that conversion increases at higher values of decomposition time and pressure. Partially hydrogenated products were also observed at higher pressures, and the ratio of partially to fully hydrogenated DBT was calculated as an additional measure of catalytic efficiency. Conclusions: Decomposition time and H2 pressure during ammonium tetrathiomolybdate (ATM) thermal decomposition have a significant impact on the morphological and catalytic properties of the derived MoS2 catalysts. Samples prepared for 5 h at 1,000 psig exhibited the highest conversion of DBT and the lowest ratio of partially to fully hydrogenated products.

Original languageEnglish (US)
Article number8
JournalJournal of Analytical Science and Technology
Volume6
Issue number1
DOIs
StatePublished - Dec 1 2015

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ammonium
catalyst
decomposition
Decomposition
Pressure
catalysts
Catalysts
thermal decomposition
Hydrodesulfurization
X-ray diffraction
molybdenum sulfides
minimal surfaces
Pyrolysis
products
Hot Temperature
molybdenum
stacking
sorption
tetrathiomolybdate
low pressure

Keywords

  • Ammonium tetrathiomolybdate
  • Hydrodesulfurization
  • MoS
  • Reductive decomposition pressure

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Chemistry(all)
  • Environmental Science(all)
  • Materials Science(all)
  • Physics and Astronomy(all)

Cite this

Influence of decomposition time and H2 pressure on properties of unsupported ammonium tetrathiomolybdate-derived MoS2 catalysts. / Whelan, Jamie; Banu, Ionut; Luckachan, Gisha E.; Banu, Nicoleta Doriana; Stephen, Samuel; Tharalekshmy, Anjana; Al Hashimi, Saleh; Vladea, Radu V.; Katsiotis, Marios S.; Alhassan, Saeed M.

In: Journal of Analytical Science and Technology, Vol. 6, No. 1, 8, 01.12.2015.

Research output: Contribution to journalArticle

Whelan, J, Banu, I, Luckachan, GE, Banu, ND, Stephen, S, Tharalekshmy, A, Al Hashimi, S, Vladea, RV, Katsiotis, MS & Alhassan, SM 2015, 'Influence of decomposition time and H2 pressure on properties of unsupported ammonium tetrathiomolybdate-derived MoS2 catalysts', Journal of Analytical Science and Technology, vol. 6, no. 1, 8. https://doi.org/10.1186/s40543-014-0043-0
Whelan, Jamie ; Banu, Ionut ; Luckachan, Gisha E. ; Banu, Nicoleta Doriana ; Stephen, Samuel ; Tharalekshmy, Anjana ; Al Hashimi, Saleh ; Vladea, Radu V. ; Katsiotis, Marios S. ; Alhassan, Saeed M. / Influence of decomposition time and H2 pressure on properties of unsupported ammonium tetrathiomolybdate-derived MoS2 catalysts. In: Journal of Analytical Science and Technology. 2015 ; Vol. 6, No. 1.
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abstract = "Background: Molybdenum sulfide (MoS2) catalysts to be used for hydrodesulfurization (HDS) processes were prepared via the reductive thermal decomposition of ammonium tetrathiomolybdate at fixed temperature (653 K) by varying decomposition times and H2 pressures. Both parameters were found to strongly influence textural and catalytic properties of the resulting MoS2 catalysts. Methods: Nitrogen sorption, FT-IR, and XRD analyses revealed the effect of varying decomposition times (3 to 7 h) and H2 pressure (20 to 1,000 psig) on the morphology and structure of the catalysts. Dibenzothiophene (DBT) was used to assess catalytic efficiency for HDS reactions. Results: The influence of time on specific surface was minimal at low pressures but increased at higher decomposition pressures. Vibrational energies of Mo-S bonds in FT-IR indicate that MoS2 catalysts prepared at higher pressures exhibit weaker Mo-S bonds. Analysis of XRD patterns point towards an increase in stacking and crystallite size with increasing pressure; interlayer rotation about both the a- and c-axes of the stacks was also observed. Catalytic testing results show that conversion increases at higher values of decomposition time and pressure. Partially hydrogenated products were also observed at higher pressures, and the ratio of partially to fully hydrogenated DBT was calculated as an additional measure of catalytic efficiency. Conclusions: Decomposition time and H2 pressure during ammonium tetrathiomolybdate (ATM) thermal decomposition have a significant impact on the morphological and catalytic properties of the derived MoS2 catalysts. Samples prepared for 5 h at 1,000 psig exhibited the highest conversion of DBT and the lowest ratio of partially to fully hydrogenated products.",
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AU - Whelan, Jamie

AU - Banu, Ionut

AU - Luckachan, Gisha E.

AU - Banu, Nicoleta Doriana

AU - Stephen, Samuel

AU - Tharalekshmy, Anjana

AU - Al Hashimi, Saleh

AU - Vladea, Radu V.

AU - Katsiotis, Marios S.

AU - Alhassan, Saeed M.

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AB - Background: Molybdenum sulfide (MoS2) catalysts to be used for hydrodesulfurization (HDS) processes were prepared via the reductive thermal decomposition of ammonium tetrathiomolybdate at fixed temperature (653 K) by varying decomposition times and H2 pressures. Both parameters were found to strongly influence textural and catalytic properties of the resulting MoS2 catalysts. Methods: Nitrogen sorption, FT-IR, and XRD analyses revealed the effect of varying decomposition times (3 to 7 h) and H2 pressure (20 to 1,000 psig) on the morphology and structure of the catalysts. Dibenzothiophene (DBT) was used to assess catalytic efficiency for HDS reactions. Results: The influence of time on specific surface was minimal at low pressures but increased at higher decomposition pressures. Vibrational energies of Mo-S bonds in FT-IR indicate that MoS2 catalysts prepared at higher pressures exhibit weaker Mo-S bonds. Analysis of XRD patterns point towards an increase in stacking and crystallite size with increasing pressure; interlayer rotation about both the a- and c-axes of the stacks was also observed. Catalytic testing results show that conversion increases at higher values of decomposition time and pressure. Partially hydrogenated products were also observed at higher pressures, and the ratio of partially to fully hydrogenated DBT was calculated as an additional measure of catalytic efficiency. Conclusions: Decomposition time and H2 pressure during ammonium tetrathiomolybdate (ATM) thermal decomposition have a significant impact on the morphological and catalytic properties of the derived MoS2 catalysts. Samples prepared for 5 h at 1,000 psig exhibited the highest conversion of DBT and the lowest ratio of partially to fully hydrogenated products.

KW - Ammonium tetrathiomolybdate

KW - Hydrodesulfurization

KW - MoS

KW - Reductive decomposition pressure

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