DESULFURIZATION OF PETROLEUM FRACTIONS BY OXIDATION AND SOLVENT-EXTRACTION

The known ability of several solvents to extract sulfur compounds sele ctively from petroleum fractions can be dramatically improved by oxidi zing the sulfur from the divalent state (sulfide) to the hexavalent (s ulfone). The oxidation process itself leads to the removal of a substa ntial portion of the existing sulfur and makes the remaining sulfur co mpounds amenable to efficient removal even by solvents such as methano l which are not effective in selective extraction of the unoxidized su lfur compounds. Thus this combination process is capable of removing u p to 90% of the sulfur compounds in petroleum fractions at acceptable yields. The oxidation process has no deleterious effects on the distil lation profile and other characteristics of the middle distillate frac tions that were examined.