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

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.