Diesel and Burner Fuels from Hydrocracking in Situ Shale Oil

Abstract

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. 99Downloaded by UNIV OF CALIFORNIA SAN DIEGO on August 24, 2015 |

Catalytic Hydroprocessing of Shale Oil to Produce Distillate Fuels

“…High wax contents have been noticed in the past (8,9) in shale oil products. The 350°-650°F diesel cut is similar in inspections to diesel fuels made by acid treating (5) and hydrocracking (6) shale oil, as shown in Table IV. The 180°-350°F heavy naphtha is compared in Table V with a raw naphtha derived from Arabian light crude oil.…”

“…However, as produced from a retort, shale oil is too high in nitrogen, sulfur, and arsenic content to allow direct utilization as a fuel in most current applications. The goals of many research groups over the years have been to reduce the amounts of these contaminants and crack the shale oil into lighter products (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22). Many of the earlier reports have concentrated on the hydroprocessing of either the raw shale oil, distillate fractions from the raw shale oil, or coker distillates from shale oil and have not tied together the various process units that would be needed in a complete refinery.…”

Comparison of physical and chemical characteristics of shale oil fuels and analogous petroleum products

“…These analyses have been carried out to study health effects, and, in the case of nitrogenous compounds, to assist in proper design of refining operations and to improve understanding of the factors responsible for product instability. Tables 5 through 8 present the reported PNA data for crude and hydrotreated shale oil samples by compound type and by nitrogenous compound fractions, using a four-step sequential analytical protocol involving chromatographic separations ( S range for 800 U.S. crudes [7,8] Paraho [l I , [25][26][27]311 In situ, Rock Springs, WY [12, Paraho are not available for petroleum crudes. As expected, however, the data in Tables 5 through 8 indicate that hydrotreatment of shale oil results in significant reductions in nearly all nitrogenous compounds.…”