Fractionation of shale oil

Hydroxy derivatives of benzofuran are also found in the phenolic fractions of shale oil tar such compounds are formed by thermal ring closure of phenol ethers with unsaturated side chains.113-115 2-(4-Methoxyphenyl)benzofuran has been isolated in small amounts from the depolymerization products of some tars (in the presence of phenol).114,115... 

Also important is the use of the modem chromatographic methods to separate and identify individual components in commercial cmde shale oil. The use of efficient gas chromatographic columns coupled with ancillary techniques such as mass spectrometry and vapor-phase IR spectroscopy allows the identification of individual shale oil components. A principal part of this study is the comparison of diflFerent types of open tubular columns for the separation of the alkane-alkene fraction of shale oil WCOT, SCOT, and PLOT columns are examined. Gas chromatographic separation of shale oil acids and bases also is performed allowing the identification of these components. The potential utility of subtractive pre-columns in HPLC analysis is illustrated also. 

APPROX. COLUMN TEMP..-C NONPOLAR FRACTION OF SHALE OIL... 

NONPOLAR FRACTION OF SHALE OIL OMOV-101 35 X. 03" PLOT COLUMN... 

Despite the usual preference in GC for the application of more polar stationary phases for the resolution of polar species, the former may be applied usefully for nonpolar separations. Figure 4 illustrates the resolution of the alkane-alkene pairs of the hydrocarbon fraction of shale oil (sample as in Figure 2), on a FFAP PLOT column (100ft). FFAP is Carbowax 20M terminated with terephthalic acid residues. This column selectively retains olefins and enables base-line resolution of the alkane-alkene pairs. The only disadvantage of this phase is its temperature limitation of ca. 250°C. Identification of the numbered peaks in Figure 4 was achieved by interfaced MS (components are listed in Table 1). 

On considering the optimal chromatographic conditions for analysis of the more polar constituents of shale oil it becomes apparent that both packed columns and PLOT columns have useful features. An example involves the acid-component fraction of shale oil obtained by sodium hydroxide extraction, removal of nonpolar species with benzene, methyl-... 

These chromatographic examples demonstrate the utility of PLOT columns for the resolution of the various chemical constituent fractions of shale oil and their compatibility with interfaced IR and mass spectral peak identification. The major advantage of the higher column peak capacity of the PLOT columns makes the latter measurements more feasible particularly for the minor components in the chromatogram. 

The PNA fraction of the shale oil was smaller (6%) than that fraction in the coal liquids (10- 29%). In shale oil, a larger fraction of the PNA compounds are alkylated than in coal-derived liquids. For example, C5 or higher-substituted aromatics were seen in shale oil but C3 substitution was rare in coal liquid. This characteristic difference in alkyl substitution was repeated also when the N-heterocyclic compounds were similarly compared. Few alkylated species were seen in the coal liquids but Ce and higher-substituted pyridines, quinolines, acridines, indoles, and carbazoles were detected in shale oil. For example, the PNA fraction of shale oil contained many indoles which can be seen in the gas chromatogram of this fraction see Figure 7). The different alkyl substitution patterns found in these two syncrude materials may well reflect the underlying structural differences in coal and kerogen. 

Pelroy and Petersen 41) recently demonstrated how complex organic mixtures such as shale oil may produce variable responses in the Ames Salmonella assay depending upon the composition of the chemical mixture. In the presence of the PAH fraction of shale oil, the mutagenicity of dimethylbenzacridine was inhibited by 75% however, in the presence of the basic fraction of shale oil, dimethylbenzacridine mutagenicity was reduced by only 22%. The basic fraction of shale oil contained primarily alkyl-substituted pyridines, anilines, pyrroles, and quinolines. The basic fraction was more mutagenic by itself than any of the other fractions (acidic, neutral, tar, PAH, crude shale oil) tested. 

TABLE 6. Sephadex LH-20 Fractionation of Shale Oil Coupled with Mutagenicity Testing... 

Figure 3. Content of Fractions of Crude Oil and Shale Oil by Silicon Gel Column.

Table IV. Chemical Analysis and Molecular Weights of Shale Oil Fractions...

Figure 7. 1H NMR spectra of aromatic fractions from shale oils...

Figure 9. Gas chromatogram of shale oil bases aper acid extraction and alumina column fractionation. 100 ft X. 03 in. i.a. FFAP PLOT column. Substrate Chromosorb R6470 l, Temperature program 50°-22S C at 6 C/...

Olefins Aromatics. The hydroboration and analysis of shale oil distillate fractions have been described previously (9). Whole shale oils were prepared for determination of olefin and aromatic content by the removal of the polar material on Florisil (30/60 mesh, used as received) by elution with cyclohexane. The Florisil-to-oil weight ratio was 20/1 and the elution was carried out for 24 hr with a solvent recycle chromatography column. 

The heavy distillate fractions of shale and coal liquids will require hydro-treating in the event that they were to be used as an FCC charge stock or a fuel oil. The hydro-treating of these heavy distillates does not appear to facilitate optimum application of these materials however, this program s primary objective was to study the hydro-treating of the complete full range distillates and their subsequent comparison with petroleum. 

Figure 6. Proportions of shale oil and coal liquid fractions...

Shale Oil and Solvent-Refined Coal Materials. The analysis of shale oil and coal liquids was carried out by application of the procedure outlined in Figure 3. The proportions of the resulting fractions obtained from our sample of Laramie shale oil (Run 13) are shown in the shale oil portion of Figure 6. A preliminary characterization is presented in Table X. It should be noted that the compounds listed are similar to those described in earlier work with other shale oils and other separation methods (12). 

Figure 7. Typical gas-liquid chromatogram of shale oil PNA fraction...

Some specific class analyses have been reported for whole samples and distillates of shale oil and synthetic coal liquids (e.g.. References 1, 2, 3, and 4). A few examples of specific class analyses recently reported include determination of hydrocarbon types in shale oil distillates by a hydroboration technique (5), aromatic-aliphatic group analyses in petroleum and coal liquids (6), nitrogen base types in high-boiling petroleum distillates (7), and PAH fractions in oils (8,9). 

Table II. Fractionation and Recovery of Shale Oil Lipophilic Fractions Using Sephadex LH—20 Gel...

G.F.Stmiste, J.M.Bingham, W.D.Spall, J.W.Nickols, R. J.Okinaka,andD.J.-C. Chen, Fractionation of an Oil Shale Retort Process Water Isolation of Photoactive Genotoxic Components, presented at the conference on Short Term Bioassays in the Analysis of Complex Environmental Mixtures, Chapel Hill, NC, 22 January 1982 Los Alamos National Laboratory report LA-UR-82-1272. 

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