Method for removing nitrogen from shale oil by hydrogenation and liquid sulfur dioxide extraction

摘要

A method is disclosed for reducing the nitrogen content of shale oil using mild hydrogenation followed by liquid sulfur dioxide extraction of the hydrogenated shale oil. The mild hydrogenation is effective for increasing the fraction of shale oil that is insoluble in the liquid sulfur dioxide. The mild hydrogenation is sufficient for saturating unsaturated compounds present in the shale oil to the substantial exclusion of adding hydrogen to the nitrogen of the nitrogen-containing compounds. Following hydrogenation of the shale oil, it is extracted with liquid sulfur dioxide at a temperature from about 14 DEG F. to about 60 DEG F. forming two fractions, a liquid sulfur dioxide insoluble fraction containing a relatively low nitrogen content and a liquid sulfur dioxide soluble fraction containing a relatively high nitrogen content. The liquid sulfur dioxide fraction is separated from the insoluble shale oil fraction. The liquid sulfur dioxide can be recovered for recycling to another extraction step.