'Desulfurizationof Heptane Solutions Using Nitrogen Diogide-Sulfuric Acid Mixtures J. R. MEADOW AND R. H. GRAVES University of Kentucky, Lexington, Ky.
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DE SULFUR1ZATION PROCEDURE
REVIOUS work by Meadow and White (6) suggested the possibility of using a mixture of nitrogen dioxide dissolved in concentrated sulfuric acid as a desulfurizing agent for heptane solutions of organic sulfur compounds. Further investigation by the authors of this Paper on the use of this treating agent has included a study of the optimum concentrations of nitrogen dioxide in 95.5% sulfuric acid for use a desulfurizing mixture for solutions of some typical sulfur compounds, the effect of making other variations in the composition of the treating agent such as the use of nitric acid, and the influence of some aromatic solvents on the desulfurization results obtained in n-heptane.
The procedure used in this work was the same as that described of the +heptane by Meadow and White (6). Portions ( 5 0 solutions were stirred vigorously 10 minutes at room temperature with varying amounts of treating agent, usually 1, 2, 4, or 6 ml. These different volumes of treating agent, when used with a 50-mI. sample of solution represented 1.96,3.85,7.4,and 10.7 volume %, respectively. The upper layer or raffinatewas easily separated from the lower layer O r extract, and after washing out traces of acid this represented a recovery of about 92 t o 98% of the volume of the original solution. Slight mechanical losses of from 2 t o 3% were unavoidable, and in addition, a slight loss to the extract was to be expected. The latter would, of course, depend on the efficiency of the desulfurizing agent, the molecular weight of the sulfur compound removed, and the extent t o which entrainment of any solvent in t h e extract had occurred.
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MATERIALS
Xormal heptane, ASTM reference fuel, was selected as the primary solvent for various sulfur compounds listed i n Table I. A few of its physical properties are listed below: Purity, mole % Refractive indexo(20' C.) Freezing point, C. Sulfur content, %
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99 5 1 3878 -90 68
