FUEL 29 |
| To obtain insight into the HDS mechanism of dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene, two hydrogenated intermediates of DBT, tetrahydro- and hexahydro-DBT, were synthesized, and their HDS was investigated over sulfided Mo/g-Al2O3 at 300 °C and 5.0 MPa. The interconversion of tetrahydro- and hexahydro-DBT was fast and the two compounds quickly came to equilibrium. H2S strongly inhibited the desulfurization of DBT and its two hydrogenated intermediates. 2-Methylpiperidine strongly inhibited the interconversion of the tetrahydro- and hexahydro-DBT and their desulfurization. With the inhibition of 2-methylpiperidine, 1-cyclohexen-1-yl-benzene was observed. Tetrahydro-DBT mainly undergoes hydrogenation to hexahydro-DBT and desulfurization to 1-cyclohexen-1-yl-benzene, which is then hydrogenated to cyclohexylbenzene. The breaking of two C-S bonds occurs by hydrogenolysis. Hexahydro-DBT mainly undergoes dehydrogenation to tetrahydro-DBT and then desulfurization of tetrahydro-DBT occurs to produce 1-cyclohexen-1-yl-benzene and cyclohexylbenzene. At the same time, hexahydro-DBT also undergoes desulfurization and its C-S bonds breaking occurs by hydrogenolysis. The desulfurization of tetrahydro-DBT is faster than that of hexahydro-DBT. |
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Green Chemistry for Sustainable Energy Supply and Conversion
1:45 PM-5:40 PM, Sunday, April 6, 2008 Morial Convention Center -- Rm. 242, Oral
Division of Fuel Chemistry |