Effect of Catalyst Oxidation State and Structure on Thiophene Hydrodesulfurization over Model Molybdenum Catalysts

Activity and product selectivity have been measured for thiophene hydrodesulfurization (HDS) over model silica-supported molybdenum catalysts at a pressure of 1 atm and at temperatures ranging from 398 to 673 K. The model catalysts feature isolated molybdenum atoms in the +2, +4, and +6 oxidation st...

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Bibliographic Details
Published inJournal of catalysis Vol. 172; no. 1; pp. 64 - 75
Main Authors Sullivan, David L., Ekerdt, John G.
Format Journal Article
LanguageEnglish
Published Amsterdam Elsevier Inc 01.11.1997
Elsevier
Subjects
Catalysis
Catalysts: preparations and properties
Chemistry
Exact sciences and technology
General and physical chemistry
Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry
Five membered ring
Catalyst selectivity
Temperature effect
Thiophene
Experimental study
X ray diffraction
Molybdenum IV
Molybdenum
Silica
Supported catalyst
Heterogeneous catalysis
Sulfur heterocycle
Molybdenum VI
Molybdenum II
Oxidation number
Photoelectron spectrometry
Dimer
Catalyst activity
Catalyst
Hydrodesulfurization
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Summary:Activity and product selectivity have been measured for thiophene hydrodesulfurization (HDS) over model silica-supported molybdenum catalysts at a pressure of 1 atm and at temperatures ranging from 398 to 673 K. The model catalysts feature isolated molybdenum atoms in the +2, +4, and +6 oxidation states and molybdenum dimers with each molybdenum atom in the +4 oxidation state. Silica-supported MoS2, prepared by deposition and decomposition of (NH4)2MoS4, was used for reference. There is a correlation between thiophene HDS activity and molybdenum oxidation state, with Mo(II) most active. Thiophene HDS activity does not show a significant structure dependence for isolated Mo(IV) versus dimeric Mo(IV) catalysts. Activation energies of 51.5 and 49.9 kJ/mol were determined for thiophene HDS over Mo(II) and MoS2/SiO2catalysts, respectively. Butane and butenes are the major products of thiophene HDS with little butadiene detected. Activity and selectivity trends suggest the HDS reaction is initiated by ηlbinding of thiophene on the supported metal catalysts.
ISSN:0021-9517
1090-2694
DOI:10.1006/jcat.1997.1867