Vitrinite samples

ESR of Different Rank Vitrinites. The vitrinite samples provide the opportunity to study the systematics of radical chemistry as a function of the extent of coalification. Perhaps the most striking first observation is that the type of radical is different in subbituminous coals than it is for bituminous coals (with some intermediate behavior for high volatile C vitri-... 

Samples. Two of the coals used 1n this study were obtained from the Penn State Coal Sample Bank, an HVA bituminous coal (PSOC 1103) from the Upper Elkhorn 3 seam in Eastern Kentucky and an HVA bituminous coal (PSOC 828) from the Brazil Block seam in Indiana. A third coal from which vitrinite and fusinite were hand picked was an Illinois No. 2 seam HVC bituminous coal from Northern Illinois. Also, resinite and vitrinite samples were hand picked from a Hiawatha seam bituminous coal from the King 6 mine in Utah. Finally, the alginite sample was obtained from an Ohio No. 5 seam (PSOC-297) coal by 06C (2,5). All of the elemental and petrographic analyses are presented in Table I. The details of the sink-float technique have been reported previously (1). Typically, a 3 micron particle size demineralized coal Ts centrifuged in aqueous CsCl2 solution of the appropriate density with a small amount of surfactant added to disperse the coal particles. The exinites in the float are... 

Once again we see sulfur compounds present in some macerals but not in others, and indeed sulfur compounds in macerals which appear to be absent in the floated (unfractionated) coal. For instance, sulfur compounds III and IV contribute significantly to the FPD traces of oxidized Herrin No.6 floated and vitrinite samples and the Indiana No.5 sporinite sample, but are very weak or apparently absent in the remaining samples. Also sulfur compound number VII appears in the Herrin No.6 inertinite sample but no other. We attribute the fact that certain sulfur compounds appear in the sporinite and inertinite chromatograms but not in the chromatograms of their parent floated coals to the presence of a large excess of vitrinite in the floated coal samples. 

Sample Separation and Characterization. Three vitrinite samples (Silkstone, High Hazels, and Westfield) were obtained by hand-picking of macroscopic vitrain bands in Carboniferous coals. Selected vitrain particles were crushed to pass a B. S. 100 mesh sieve (250 y) and polished mounts were prepared. Sample purity was determined by point-counting (sample reflectivity) 500 points, giving a + 2% (by volume) accuracy (18). 

Six vitrinite samples from the Lower Kittaning seam were hand-picked to represent a wide range of vitrinite reflectance. These samples exhibited a minimum of 97% vitrinite and were used without further purification. Samples were supplied by Professor Alan Davis of Pennsylvania State University. 

The vitrinite samples from the Lower Kittaning seam were run as received. The chemical analysis is given in Table III. 

Figure 7. CP /MAS spectra of vitrinite samples from the Lower Kittanning Seam. The spectra represent changes that occur with rank progression. V refers to vitrinite reflectance values.

At the conclusion of each run, the oxygen buffer was examined petrographically to ensme the presence of all members of the solid buffer assemblage. In some experiments, a fetid odor was detected on opening the mn capsule. The vitrinite sample was removed—but not washed—and dried at 105°C for about 10 min at atmospheric pressure. 

The elemental composition of the three maceral groups varies. The vitrinite, which frequently is about 85% of the sample in the United States, is similar to the patent coal. The liptinites are richer in hydrogen, whereas the inertinites are relatively deficient in hydrogen and richer in carbon. The liptinites also contain more aliphatic materials the inertinites are richer in aromatics. The term inertinite refers to the relative chemical inertness of this material, making it especially undesirable for Hquefaction processes because it tends to accumulate in recycled feedstock streams. 

Vitrinite Reflectance. The amount of light reflected from a poHshed plane surface of a coal particle under specified illumination conditions increases with the aromaticity of the sample and the rank of the coal or maceral. Precise measurements of reflectance, usually expressed as a percentage, ate used as an indication of coal rank. 

Given, P. H., Cronaucr, D. C., Spackman, W., Lovell, H. L., Davis, A., and Biswas, B., Dependence of coal liquefaction behavior on coal characteristics 1. vitrinite-rich samples. Fuel, 1975, 54, 34 39. 

To test this approach, 5 g samples -300 mesh Tyler, of a low-rank vitrinite, were stirred for 6 hrs in liquid ammonia (150 ml -33°C) containing 5 gms of potassium amide and 5 g of sodium amide. (The amides were formed in the medium, before introducing the coal, by action of anhydrous ferric oxide (1 g) or ferric chloride (1.5 g) on alkali metals.) Thereafter, 100 ml of anhydrous ethyl ether was added, the suspended coal material ethylated with C2H5Br (32 ml), and the reaction mixture stirred until all ammonia and ether had evaporated. Following... 

For example, Beynon and Cwm coals when digested in anthracene oil give extraction yields of 68% and 47% respectively. This variation can be explained by reference to the maceral composition of the coals. Beynon coal contains a lower concentration of inertinite than the Cwm coal (Table V). In experiments where relatively pure samples of petrographic species were digested in anthracene oil, exinite and vitrinite were shown to be highly soluble, whilst in comparison the inertinite was almost completely insoluble. Similar variations in reactivity of macerals have been reported from studies of solubility in pure organic solvents (1(3). 

Bed Sample No. Vitrinite Exinite Micrinite fusinite Fusinite Ash inches... 

Samples of banded coals show in the vitrinite portion transversal bands of high relief (owing to polishing) with a fine median crack filled with uranium minerals (Figure 4a, b). 

Let us take another example. At the U.S. Gulf Coast, the Pleistocene and the Upper Tertiary (Pliocene and Miocene) reach a thickness of more than 6000 meters. Nevertheless, the coaliflcation has only reached the stage of high volatile bituminous at this depth. This observation resulted from our studies of samples from a deep borehole located in Terrebonne Parish, La. By reflectance measurements on humic inclusions in claystones of the uppermost Middle Miocene encountered at a depth of 5440 meters, we obtained a mean value (under oil) of 0.95% reflectance, which is equivalent to the reflectance of vitrinites (out of deep boreholes) with 35-40% volatile matter (daf). On the other hand, we found low volatile bituminous coals (14-16% volatile matter, daf) at a depth of 5100 meters in a borehole in the Lower... 

It was considered likely that any fine structure present might not be obvious owing to lack of contrast. In an attempt to reveal any structures present, samples of vitrinite were evacuated at 10" mm. Hg for several days and then impregnated with a saturated aqueous solution of lead acetate. The solution was allowed to dry over a period of several days and then some of the vitrinite was freed from the encrusting lead acetate, crushed finely, and dispersed on a carbon-collodion filmed grid. 

Sample Locality Equivalent vitrinite C H O Atomic ratios H/C O/C ... 

Several of the resinite samples were carbonized in nitrogen at various temperatures up to 800°C. using a heating rate of 1.75°C. for one hour. The alterations in the infrared absorption curves of Duxite and resinite from bituminous coals have already been reported (18) and shown to be similar to one another and comparable to the changes produced in the spectrum of carbonized low rank vitrinite. 

The values in Table VII show that 12 nonaromatic rings should be present for nine mean structural units in the case of exinite, 10 in the case of vitrinite, and 16 in the case of micrinite. Since all faiIt -Rnnr) values are higher than the highest ones obtained from the aliphatic group distribution (see Table IV), all samples must contain nonaromatic rings even if the most probable / values... 

R(min) — Rar(max) — 0.8. If it is taken into account that only CH2 and CH groups can form alicyclic rings and that these rings contain not more than four and not less than two C atoms, limits for Cun eye 1 (alicyclic C atoms per unit) can be calculated. Results are exinite R[Pg.342]

Samples Studied. From British Seams. The suite of samples was collected and separated by the Coal Survey of the National Coal Board under the direction of Dr. G. W. Fenton, and the authors are indebted to Dr. Fenton for the gift of the samples. The suite consisted of the vitrinites, spore-rich exinites, fusinites and, in one case, the micrinite from five British coal seams of Carboniferous age together with the vitrinites from two coals of higher rank from which it was impracticable to separate the other macerals. The exinites were separated by float-and-sink methods from selected black durain bands, as also... 

Range of reflectance values, 1.5-6.5% sample contained roughly 5% vitrinite as impurity. 

Results on Unheated Samples. The results obtained in Southampton for the set of British samples are shown in Figures 2 and 3. In Figure 2 the spin concentration of each maceral is plotted against the carbon content (daf) of the associated vitrinite, and the points for each set of macerals from one coal are joined by a vertical line. It can be seen that the vitrinite series forms a well-defined narrow band which curves upwards sharply at about 90% carbon, and the data resemble closely those presented earlier by Austen and Ingram for whole coals. The values of exinites form a wider, approximately horizontal band lying a little below the vitrinite band, while the fusinite data appear to vary at random but lie consistently well above the vitrinite band and are appreciably higher than vitrinites of the same carbon content (90-92%) would be. 

Results for Pyrolyzed Samples. The complete set of data obtained is collected in Table III and some typical trends are shown in Figures 4 and 5. For consistency, the figures shown for unpyrolyzed samples are all data obtained by the Penn State group. At 550°C. the vitrinites suffered about 25%... 

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