Performance study of extraction and oxidation–extraction coupling processes in the removal of thiophenic compounds

• Desulfurisation of model fuel containing thiophenic compounds were done.
• Oxidation, extraction and single pot oxidation–extraction modes were applied.
• Acetonitrile, DMSO and immidazolium ethyl sulfate ionic liquid were used as extractant.
• Effects of different process parameters on extraction were investigated.

Thiophenic sulfur removal was attempted in three different modes of operation, such as extraction, oxidation and simultaneous oxidation–extraction for a model fuel. Extraction was done using different solvents, viz., acetonitrile, dimethyl sulfoxide and 1-ethyl 3-methyl imidazolium ethyl sulfate at near ambient condition. The sulfur compounds tested were thiophene, benzothiophene and dibenzothiophene in iso-octane. Titanium silicate-1 and titanium-beta catalysts were used for oxidation of the compounds. A detailed parametric study was performed varying stirring time, extraction temperature and amount of solvent, to investigate their effects on the extraction of the three sulfur compounds. Simultaneous oxidation–extraction process showed a significant amount of sulfur removal. Dimethyl sulfoxide was found to be the best solvent for extraction.