An investigation of oxygen-containing compounds - phenols and indanols - in coal liquid distillates
Creators: name: Metcalf, Gary Steven
Publisher: name: University of Utah
Year: 2012
Subjects: Coal liquefaction
Oxo compounds

description: A renewed emphasis on the development of liquid synthetic fuels  from coal has prompted an increase in the variety of analytical methods  employed for the chemical characterization of these products. These  characterizations have been necessitated as product composition directly  affects the choice of process variables, and inherently, the overall  success of the process. Complete characterization, however, is often  inhibited due to the complex nature of these liquids.  The successful operation of any coal liquefaction process is  ultimately dependent upon the efficiency of hydrogen consumption. Ideal  levels of hydrogen consumption involve not only increased hydrogen to  carbon (H/C) ratios of initially formed hydrocarbon fragments, but also  removal of heteroatoms in reduced form, principally as NHg, h^S and 1^0.  Of the major heteroatomic species found in coal, less attention has been  devoted to the analysis of oxygen-containing compounds, although recent  evidence indicates that oxygen functionalities may play important roles  in the effectiveness of hydrogen utilization as well as in the yield of  quality end-products.  Several distillates from the Exxon Donor Solvent (EDS) and H-Coal  processes were investigated for oxygen-containing compounds by a combination  of analytical techniques including open-column liquid  chromatography (LC), capillary gas chromatography (GC), gas chromatography  coupled with mass spectrometry (GC/MS) and pyrolysis mass spectrometry (Py/MS). These analyses resulted in the tentative identification  of several series of hydroxyaromatic and hydroxyhydroaromatic  compounds. The two major classes of oxygen-containing compounds found  in the distillates examined were a series of alkylphenols and a second  series thought to consist of 4-indanol, 5-indanol and their respective  homologs. This latter series was deemed noteworthy because of unexpectedly  high abundances and the apparent reactivity of 5-indanol (and  corresponding homologs) during hydrotreatment. Whether this reactivity  occurred with a correspondingly beneficial or detrimental effect on the  overall process has not been determined.  Exact identities of the indanols could not be confirmed directly  due to a lack of reference spectra. Since unambiguous identification  of mass spectra usually requires matching unknown spectra with spectra  obtained from standard compounds and/or reference libraries, and only  a limited number of suitable standards were available, computerassisted  pattern recognition was used in an attempt to assign mass  spectra of these "unknown" species to correct compound classes.  Selected spectra from GC/MS analyses were extracted to form two  sets of data. The first data set contained spectra of a variety of  hydrocarbons as well as spectra of suspected alkylphenols and alkylindanols  and was used to examine the degree of separation possible  between hydroxy- and nonhydroxy-containing compounds. The second data  set consisted of spectra of suspected alkylphenols, alkylindanols and  several reference compounds and was used to examine the degree of  separation possible between these classes and the indanol relationships  to isomers of differing molecular structure. Examinations were  achieved through the formation of data files of two types. From each original data file (containing fragment ion spectra) a corresponding  "reverse" file (containing neutral-loss spectra) was formed. Original  files were used to obtain molecular core information while the "reverse"  files were employed to investigate fragmentation tendencies of the  various classes.  Each data file was subjected to specific data processing routines,  as available in the ARTHUR computer program package, including factor  analysis, discriminant analysis and non-linear mapping. The combined  results obtained from these analyses indicated separation not only  between the various classes, but in certain instances, between class  homologs and isomers of the same molecular weight. In spite of the  absence of sufficient reference spectra, the classification of spectra  into correct categories was successful and further validated previously  assigned class identities.