Desulfurization of high speed diesel using hydroperoxide and peroxy acid as oxidants and solvent extraction

Abstract

This study consists of desulfurization of high speed diesel by oxidation reaction using hydroperoxide and peroxy acid as oxidants and extraction of sulfur compound by solvent such as methanol, acetic acid, ammonia and ethanolamine at ratio of solvent per high speed diesel in the range of 0.25 to 4.00. Physical properties of high speed diesel such as sulfur content, density, viscosity, flash point, colour and distiallation temperature range are evaluated and compared. High speed diesels used in this study are taken from Rayong Refinery and Thaioil Refinery before they pass through desulfurization unit. Experimental results show that hydrogen peroxide is a suitable oxidant for oxidation reaction of sulfur compounds in high speed diesel using acetic acid as solvent at ratio of high speed diesel to acetic acid equal to 1:1 at 90 degree Celsius. Sulfur compounds are oxidized to sulfone and sulfoxide forms which have higher polarity than sulfur compound and transfer from high speed diesel to acetic acid layer, as solvent for oxidation reaction. Sulfur content in high speed diesel is reduced approximately 50 percent by weight in each oxidation reaction. The remaining is separated by solvent extraction. Methanol is the most efficient solvent for extraction of sulfone and sulfoxide. Solvent to high speed diesel ratio of higher than 4.0 can be efficientively removed sulfur compound comparable to three times of oxidation reaction. Reduction sulfur content in high speed diesel by this method also reduces aromatic contents in high speed diesel and increases its pour point approximately 3-9 degree Celsius. Other properties such as density, viscosity, flash point, colour and distillation range, remain.