Nitrogen Compound Types in Hydrotreated Shale Oils

摘要

The nitrogen content of retorted shale oils needs to be reduced if the oils are to be used as transportation fuels. The nitrogen compound-type compositions in oils and fuels are dependent on shale source as well as on upgrading conditions. The identification of the nitrogen-containing species in shale oil aids in understanding the effects of fuel processing and fuel stability. This research is directed towards examining the nitrogen-type distribution in several oils and fuels. Nitrogen compound distributions in retorted, hydrotreated, and acid-clay-treated shale oils have been determined from data obtained by nuclear magnetic resonance (NMR) and mass spectrometry, infrared spectroscopy, alumina/silica adsorption chromatography, gas chromatography, and potentiometric titration. Catalytic hydrotreated oils contained alkyl-substituted pyridines, anilines, indoles, carbazoles, quinolines, and tetrahydroquinolines, predominantly 1,2,3,4 tetrahydroquinoline. Different hydrodenitrogenation reactivities were determined for different nitrogen compound types. Less reactive compound types such as sterically hindered alkylpyridines and nonbasic alkylindoles/carbazoles were found in oils that had undergone moderate hydrotreating conditions. The deleterious effects of certain nitrogen compounds on fuel storage stability and thermal oxidation are well known. Acid and clay selectively removed basic nitrogen from hydrotreated shale oils. Carbazole and alkyl-substituted carbazoles were the only nitrogen species present in the acid-clay-treated (finished) fuel from shale oil. Based upon model compound studies, these nitrogen species are not expected to be problematic for fuel storage. 19 refs., 5 figs. 8 tabs. (ERA citation 10:038775)