Vitrinite extract

Figure 2. Noncatalytic hydrogenation—product yields vs. vitrinite + exinite content. Curve a, total conversion (X) Curve b, extract ( ) (10). (Note Lines a and b relate to coals where the mean maximum reflectance (R0 max) of the vitrinite fall in the range 0.43-0.68%. Values in parenthesis refer to R0 max for...

In coals alkylated in this manner, the number of acidic sites is substantially reduced, and acid-base associations are virtually precluded. Extracts from alkylated coals should, therefore, be amenable to GPC fractionation. Such fractionation, conducted on Bio Beads S-Xl and S-X2, results in separation by molecular weight and indicates that both benzene and chloroform extracts contain substantial amounts of high ( 6000) and fairly low (560-640) molecular weight fractions (Figure 2). While the extract yields from non-reductively ethylated vitrinite increase in the order benzene extr. chloroform extr. - pyrid. extr > the molecular weights determined by VPO in pyridine, decrease in this order. 

Figure 3 shows GPC fractionation of the benzene extract of a vitrinite which, before a single non-reductive ethylation, was treated with tetrahydronaphthalene at 390°C. Although hydrogenation reduced the -OH contents (from 4.9 to 1.7%), non-reductive alkylation increased the benzene-solubility of the solvolyzed material from 53% to 80.2%. It appears that this effect is due to ethylation of acidic atoms. 

Analysis of the results presented in Figures 2 and 4 appears to indicate that hydrogenation of the vitrinite is also accompanied by polymerization (see pyridine extract, Figure 4). If this can be confirmed, it would be worth investigating whether it involves specific fractions in the original vitrinite or has a random character. Solvolysis of different molecular weight fractions of a non-reductively alkylated vitrinite (or coal) may furnish some insight. 

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). 

It has been proposed (17) that the portion of coal which is mobile under liquefaction conditions, contributes to the stabilization of thermally-generated radicals. Thus, coals which are highly fluid or contain large contents of extractable material might be expected to provide hydrogen and thus promote conversion. Collins has reported that vitrinite is a better donor of hydrogen than is Tetralin (20). Our own measurements of the aromatic content and elemental analyses of the coals (16,21) (or coal products) before and after conversion at short time are insufficient to confirm or deny the supposition that coal acts as its own H-donor even at short times. 

Figure 5. Peak fluorescence intensity of raw (A) and extracted (A) vitrinites versus yield of chloroform extractables. Also shown are data for thermally pretreated vitrinite before ( ) and after ( ) prolonged chloroform extraction. (Data are from ref. 7.)...

In Curie-point Py-LVMS studies of maceral concentrates (22). vitrinitic moieties were shown to be the main source of the hydroxy aromatic components. Thus, the hydroxy aromatic signals observed in Figure 2d appear to be primarily derived from vitrinite-like components by means of pyrolytic processes. Presumably, therefore, the "nonmobile phase", rather than the "mobile phase , is the main source of the phenols observed in TG/MS and Py-MS studies of Pittsburgh 8 coal (9,16). Further support for this conjecture comes from the observation that phenolic products are also observed in Py-MS analysis of pyridine extracts of Pittsburgh 8 coal known to contain colloidal matter whereas the corresponding tetrahydrofuran extracts, free of colloidal material, produced no phenols (21). 

Given and coworkers studying the "British Macerals" took more of an organic chemist s approach to characterization. The macerals were subjected to solvent extraction, lithium reduction, hydroxyl determination, oxidation, and reaction with various reagents. N-bromosuccinimide (NBS) was used to bromin-ate aliphatic carbons which in the case for four macerals from an Aldwarke Silkstone coal yielded per 100 carbon atoms the following distribution of hydrogen which is replaced by bromine (61) vitrinite 16, exinite 25 1/2, micrinite 12, and fusinite... 

Table V. Electron Microprobe Analysis on Organic Maceral (Vitrinite) Level of Raw and Leached Coals and of Residues After Extraction by HC1 and HN0. a...

Samples taken within 2 m of the sill varied from light brown at — 0.17 m to black at — 1.93 m. The black samples contained some extractable organic material and coke however, essentially all of the vitrinite was coked and no organic material was detected in the light brown sample. On this basis temperature limits of 880° and 1060°K are estimated (26), The upper limit of the magma was set at the usual geology textbook temperature of 1473°K (1200°C). The estimate of the... 

Present-day reservoir or source rock temperature. 1 ppm — 1 pg g of rock. Hydrogen index HI — mg hydrocarbons produced per gram of TOC by ROCK EVAL pyrolysis of pre-extracted rock powder. ROCK EVAL parameter. Vitrinite reflectance. 

It is interesting that a bituminous coal (Sample 4) gave organic acids qualitatively similar to those of lignite coal see Figure Id). Major identified compounds were p-hydroxybenzoic acid and two isomers of hydroxybenzenedicarboxylic acid, benzene di- and tricarboxylic acids. No ortho or meta isomer of hydroxybenzoic acid was detected. We have found that solvent-extractable hydrocarbons obtained from this raw coal consist mainly of n-alkanes (Cjj to 3 ). This is quite different from other results which showed that aromatic hydrocarbons were the major solvent-extractable material of several bituminous and anthracite coals (21). Indeed, petrographic analysis shows that this coal has a high content of sporinite (14.3 wt %) and a low content of vitrinite (30.2 wt %) (33). 

Locally, over a short depth interval in lJ-14 SWCs, the concomitant shift in isotopes and LCAA removal supports a biodegradation effect. The most tar-filled core or SWC extracts tend to also have the lowest values for maturity parameters, MPI-1 or estimated vitrinite reflectance equivalent Rc (Radke 1987). The observed... 

FIGU RE 11.5 Extraction using different solvents with carbon content for vitrinites. (From Van Krevelen, D.W.,... 

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