Hydrodesulfurization of dibenzothiophene in a monolithic catalyst reactor

The liquid-phase hydrodesulfurization of dibenzothiophene was studied on a Co-Mo/[gamma]-Al[sub 2]O[sub 3] catalyst. The catalyst support was a monolith with a cell density of 200 cells/in.[sup 2]. The flow pattern was segmented gas-liquid flow. The hydrogen pressures were in the range 6-8 MPa, and the temperatures were in the range 543-573 K. A kinetic model consistent with the experimental rate data was developed. The rate expressions are of the Langmuir-Hinshelwood type, assuming two different types of active sites: one active in the hydrodesulfurization reaction and the other active in the hydrogenation reaction. The reaction scheme proposed is a parallel-serial one in which dibenzothiophene desulfurizes to cyclohexylbenzene, either directly or via biphenyl which subsequently undergoes ring hydrogenation. A simple power law model is also presented.