For several years, the Laramie Energy Research Center has conducted research in recovering shale oil through in situ retorting by the underground combustion method. Crude shale oils produced by this method normally have lower specific gravities, viscosities, and pour points than do crude shale oils produced in the gas combustion or N-T-U retorts. They also contain somewhat less nitrogen, but the sulfur content is not greatly different from that of the crude oils from these aboveground retorts. Percentages of both elements are higher than desirable in liquid fuels or in feedstocks that are to be processed to high-quality liquid fuels by most catalytic refining processes.Catalytic hydrogenation at cracking conditions, referred to here as "hydrocracking," has been found by previous experiments to be a suitable method for producing low-sulfur, low-nitrogen "synthetic crude" oils from in situ crude shale oils (1,2,1). One of the primary objectives of these previous experiments has been to increase the quantity of gasoline contained in the hydrocracked synthetic crudes. A limited investigation of the suitability of fractions of the hydrocracked oils as catalytic reforming and catalytic cracking feedstocks for the production of gasoline has been made however, little attention has been given to the types of diesel fuels and fuel oils that can be prepared from the fractions.The purpose of the present work was to investigate the quantity and quality of diesel fuels and fuel oils that could be prepared from the liquid product obtained by hydrocracking of in situ combustion shale oil. A sample of the in situ crude oil was hydrocracked at operating conditions that had been found by previous experiments to be effective in eliminating most of the nitrogen and sulfur from the oil and in greatly reducing the average boiling point of the oil. The hydrocracked oil was distilled into a 350° F end-point reforming stock and small-volume heavier fractions. Diesel fuels, suitable for use also as fuel oils, were prepared by blending small-volume fractions.
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