Kinetics and mechanism of desulfurization and denitrogenation of coal-derived liquids. Twelfth quarterly report, March 21-June 20, 1978

Technical Report · Fri Oct 20 00:00:00 EDT 1978

DOI:https://doi.org/10.2172/5669971· OSTI ID:5669971

Gates, B. C.; Katzer, J. R.; Olson, J. H.; Kwart, H.; Stiles, A. B.

All the data reported previously have been reevaluated to determine the quantitative reaction network for dibenzothiophene hydrodesulfurization at about 100 atm and 300/sup 0/C. This network shows the high selectivity of the catalyst for simple hydrodesulfurization (biphenyl + H/sub 2/S formation). When methyl groups are present in the 4 and 6 positions of dibenzothiophene, the primary hydrogenation reaction is approximately as fast as the primary hydrodesulfurization reaction. Ni and Mo or Ni and W used instead of Co and Mo in the catalyst, or H/sub 2/S in the reactant mixture, also favor hydrogenation relative to hydrodesulfurization. Previous results have been evaluated in light of the recent literature to provide a new interpretation of the reaction mechanism of catalytic hydrodesulfurization on surfaces of sulfided Co-Mo/Al/sub 2/0/sub 3/. It has often been assumed that catalytic hydrodesulfurization of thiophene and related compounds proceeds via a one-point end-on adsorption involving bonding of the sulfur atom with Mo ions at an anion vacancy on the catalyst surface. This interpretation is inadequate, failing to account for deuterium-exchange results, the reactivities of benzothiophene and dibenzothiophene, and the small steric effects of methyl substituents affecting the adsorption and reaction of compounds in the thiophene, benzothiophene, and dibenzothiophene families of homologs. An alternative mechanism, presented, here, involves a multipoint adsorption of the reactant, with a C=C bond interacting with the Mo cation and the S atom of the reactant interacting with a S ion on the surface. The new mechanism accounts for the observed deuterium exchange and hydrodesulfurization reactions and is consistent with the observed steric effects.

• Research Organization: Delaware Univ., Newark (USA). Dept. of Chemical Engineering; Delaware Univ., Newark (USA). Dept. of Chemistry
• Sponsoring Organization: US Energy Research and Development Administration (ERDA)
• DOE Contract Number: EX-76-C-01-2028
• OSTI ID: 5669971
• Report Number(s): FE-2028-14-T6
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
010402* -- Coal
Lignite
& Peat-- Purification & Upgrading
010405 -- Coal
Lignite
& Peat-- Hydrogenation & Liquefaction
CATALYSTS
CHEMICAL REACTIONS
COAL LIQUEFACTION
COAL LIQUIDS
DENITRIFICATION
DESULFURIZATION
HETEROCYCLIC COMPOUNDS
HYDROGENATION
LIQUEFACTION
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
SPECIFICITY
THERMOCHEMICAL PROCESSES
THIOPHENE