Kinetics and mechanism of desulfurization and denitrogenation of coal-derived liquids. Fourteenth quarterly report, September 21, 1978-December 20, 1978

Quantitative measurement of the reactivities of methyl-substituted dibenzothiophenes, under high pressure reaction conditions (102 atm, 300/sup 0/C) representative of industrial practice, has been accomplished. The catalyst was sulfided commercial Co-Mo/..gamma..-Al/sub 2/O/sub 3/. Methyl groups in the 2 and 8 or 3 and 7 positions show little effect. Methyl groups in the 4 position, however, reduced the reactivity by an order of magnitude and methyl groups in the 4 and 6 positions reduced it somewhat more. Dibenzothiophene (DBT) was found to be self-inhibiting and results with the methyl-substituted compounds implies that there is competitive adsorption of DBT and the methyl-substituted DBT. The reaction network involving benzonaphthothiophene and hydrogen has been determined. As before, the catalyst was typical commercial cobalt molybdate (sulfided CoO-MoO/sub 3//..gamma..-Al/sub 2/O/sub 3/). The reaction conditions were 68 atm and 300/sup 0/C. The important result was that in contrast to dibenzothiophene, benzonaphthothiophene experiences extensive hydrogenation accompanying hydrodesulfurization, even with Co-Mo/..gamma..-Al/sub 2/O/sub 3/, the most selective of the available hydrodesulfurization catalysts. The sulfur-containing compounds having 3 rings or fewer experience nearly stoichiometric hydrodesulfurization (hydrogenolysis without hydrogenation), whereas the sulfur-containing compounds having 4 rings or more experience hydrogenation and hydrodesulfurization at roughly equal rates, giving products which experience further hydrogenation (and/or hydrodesulfurization - as the compound allows), again at roughly the same rates