Consequences of the Mass Spectrometric and Infrared Analysis of Oils and Asphaltenes for the Chemistry of Coal Liquefaction

Abstract

Oils and asphaltenes are generally assumed to be key intermediates in coal liquefaction. Since fundamental chemical/ mathematical principles require compositionally unique fractions, mass spectrometry and infrared spectroscopy were employed to obtain detailed molecular analyses of fractionated coal-liquid-derived oils and asphaltenes. The asphaltenes contain higher molecular weight homologs in many specific-Z series and different compound types than do the oils. However, both fractions contain appreciable quantities of compound types equivalent in molecular formula and, hence, assumably in molecular structure. The chemical/physical properties of oils and asphaltenes are not describable in terms of average (hypothetical) molecular structures. The lack of unique oil and asphaltene compositions necessitates detailed molecular analysis as a prerequisite for understanding, assessing, and controlling the chemical/physical phenomena intrinsic to production and processing of coal liquids.T he concept of preasphaltenes, asphaltenes, and oils is of historical significance in the development of the science and technology of coal liquefaction (J). This concept is routinely employed in attempts to understand, assess,

Catalytic hydroprocessing of SRC-II heavy distillate fractions. 1. Preparation of the fractions by liquid chromatography

“…Ruberto et al (1976) adapted the SARA method for analysis of synthetic liquids derived from coal, tar sands, and oil shales. The suitability of the procedures to synthetic fuels has also been confirmed by other workers (Scheppele et al, 1979;.…”

Molecular weight distribution for heavy fossil fuels from gel-permeation chromatography and characterization data

“…As new methods of chemical analysis became available, new proposals were advanced for characterizing fossil-fuel mixtures; these include group-contribution methods and structural details obtained from sophisticated state-ofthe-art analytical techniques (Allen et al, 1984; Charleswork, 1980;Clutter et al, 1972;Petrakis et al, 1983; Poirier and Das, 1984;Scheppele et al, 1981;Schwager and Yen, 1979;Speight, 1970;Thompson et al, 1973). Such methods, however, are too cumbersome for typical engineering work.…”

Low-voltage, high-resolution mass spectrometric methods for fuel analysis: application to coal distillates

“…In this publication, quantitative data were given for nearly 1100 homologues found in coal-derived products, along with bulk chemical information, such as elemental analyses, number average molecular weights, carbon number distributions, and Z (a measure of aromaticity)-all derived from LVHRMS spectra. Scheppele et al (19) compared the group-type mass spectrometric analyses obtained from field ionization mass spectrometry (FIMS) and LVHRMS data on oils and asphaltenes from coal liquefaction. In this report, the effect of using sensitivities and approximations to sensitivities on the quantitative results calculated from FIMS were also discussed.…”