THE SULPHUR CONTENT OF CRUDE NAPHTHA FROM TURNER VALLEY IN RELATION TO REFINING PRACTICE

Typical samples of Turner Valley naphtha were examined for their sulphur content and for their behavior towards common refining treatments. The sulphur content ranged from 0.15 to 0.19% and consisted of sulphides, organic disulphides and mercaptans. Thiophenes were present, but in very small amounts. No free sulphur or peroxides were detected. Distillation concentrated the color and color producing compounds and the gum and gum producing compounds in a small high-boiling residual fraction. Exposure to light, even in the absence of air, led to the development of a yellow color and to gum formation in all undistilled samples, treated or untreated. Distillation up to 165 °C. yielded a fraction (95% by volume) which remained colorless and free from gum formation when exposed to the air and to light for over eight months.Recovery of the propane and butane is recommended, and the treatment of the crude naphthas with sodium hydroxide solution or with sodium hydroxide and sodium sulphide solutions followed by distillation is suggested as a means of producing a fairly satisfactory gasoline. The caustic wash alone reduces the sulphur content to about 0.1%, while the alkaline-sodium sulphide wash reduces it to about 0.05%.Sulphuric acid, sodium hypochlorite, caustic wash, sodium plumbite and cupric chloride treatments were examined and the refined products compared for sulphur content, sweetness, corrosion, gum formation and color. None of these treatments prevented gum formation or the development of color when the treated samples were exposed to light.