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An Australian bituminous coal has been heated, both alone and in the presence of bentonite, from 200 to 360°C over a period of 4 days. The heating sequence was designed to simulate coalification in a subsiding basin in which volatiles are confined to the generating sequence. The clay particles act as centres for catalytic cracking of volatile matter which cannot then adsorb within the coal on cooling. Evidence for deposition of “carbon” within the clay comes from thermal analysis, light microscopy and transmission electron microscopy. GC-MS data show that polycyclic aromatic hydrocarbons are only present in the free oil that is generated during maturation when clay is available as a catalyst. more...

Rundle oil shale containing 12.9 wt.% of organic carbon was retorted using a combustion-type retort. It was possible to quantify the reduction in oil yield (compared with Fischer assay) due to the combustion of oil vapour during retorting. The oil yield was only 7.2 wt.%, compared with a Fischer assay oil yield of 8.7 wt.%, when retorting was carried out with excess air but no additional source of carbon. Oil yields could be improved by mixing lignite, available from within the Rundle deposit, with oil shale before retorting. Oil yields, based on charge, from mixtures containing more than 10% lignite decreased with increasing lignite content, but were virtually identical with Fischer assay oil yields from the mixtures. The maximum oil yield was about 8.5 wt.% for 6 wt.% lignite in the mixtures. The resulting oils were slightly heavier and more aromatic than the oils obtained by Fischer assay, but showed no significant difference in oxygen content. more...

Oil shale and lignite from the Rundle/Stuart deposit and a range of mixtures of the two, have been pyrolysed in a Fischer retort. Oil yields decreased linearly from 8.67 to 5.19 wt% as the lignite content increased from 0 to 100%. Yields of gas, water and spent shale also varied linearly. H C atomic ratios of the resulting oils varied from 1.70 to 1.47 and, when plotted against oil shale percentage, a slightly concave curve resulted. Similarly, carbon aromaticity determined by n.m.r. varied from 0.33 to 0.48 and resulted in a slightly convex curve when graphed against oil shale content. It appears that oil produced by blending shale and lignite is more aromatic than expected for non-interacting components. Results show that oil from an intimate geological mixture is more aromatic than that from a comparable synthetic mixture. more...

The Permo-Triassic Bowen Basin (Figure 1) is a backarc extentional foreland basin that contains up to 6500 m of mainly terrigenous siliciclastic felsic sediments. The basin is heavily intruded by mafic intrusions and lesser dykes and sills as a result of intense magmatism which accompanied the breakup of the supercontinent of Gondwana in the middle to late Mesozoic (Veevers, 1989). Magmatism continued episodically throughout the Cretaceous and Tertiary (Baker et al., 1995; Raza et al., 1995; Golding et al., 1996). more...

The oxidation of carbon nanotubes and nanoparticles has been studied by thermogravimetric analysis (TGA) in air. The maximum rate of weight loss took place at 695[degrees]C at a heating rate of 1[degrees]C/min. This result shows that the nanotubes and nanoparticles are more resistant to oxidation than other forms of carbon diamond, soot, graphite, and C[sub 60] studied previously under identical conditions. The TGA of the nanotubes/nanoparticles in argon showed no weight change or detectable thermal transformation up to 1000[degrees]C. 18 refs., 1 fig. more...

The authors study the oxidation properties of purified C{sub 60}, in air. They find almost no weight gain due to the addition of oxygen, prior to the onset of weight loss. Rates of weigh loss are studied as a function of the heating rate for temperature rises varying from 1 to 20{degrees} per minute. The authors compare their results with other recent work, and offer explanations for the observed discrepancies. more...

Pyrolysis—hydrogenation—gas chromatography (PHGC) has been used to compare the carbon-skeleton structures of kerogens before and after demineralisation. Coals were demineralised by either of two processes involving successive extractions with organic solvents, hydrochloric acid, hydrofluoric acid and then either nitric acid or lithium aluminium hydride. The last two reagents are necessary to remove minerals such as pyrite, by either oxidation or reduction respectively. Both processes cause some change in the kerogen. HNO 3 treatment leads to a general loss of organic material, especially high in lower-rank coal, and infrared spectroscopy gives evidence of some nitration; the products of PHGC indicate considerable change to the carbon-skeleton structure of the kerogen. LiAlH 4 treatment results in much smaller losses of organic material, particularly in lower-rank coal and PHGC shows that only minor changes in kerogen structure occur. Neither demineralisation process is perfect but that involving LiAlH 4 is preferable. Some general features of the chemical structure of the kerogen in the original coal are proposed. These proposals are based on comparisons of the quantities of individual PHGC products from each coal and its HNO 3 -treated kerogen. The kerogen structures have in turn been related to the rank of the coals, which ranged from peat to anthracite. more...

Shale oil recovered from Fischer assays of fresh and artificially weathered oil shales have been compared using 1 H and 13 C nuclear magnetic resonance spectroscopy and elemental analyses. Rundle, Julia Creek and Green River shales were exposed to air at 100 °C for 60 weeks to simulate either geological weathering, or oxidation during drying or stockpiling prior to retorting. As a result of oxidation, the oils became more aromatic, with higher oxygen contents and shorter average aliphatic chain lengths. Variations in the distribution of phenols, acids and ketones, as well as heterocyclic compounds containing nitrogen and sulphur, have been detected. more...

An attempt has been made over 60 weeks to simulate experimentally the weathering of Rundle, Julia Creek and Green River oil shales. Finely-ground shales were subjected to three types of ‘weathering’: 1. (1) 22 °C in air without water or sunlight (‘internal’ conditions) 2. (2) 10–35 °C under water with sunlight (‘external’ conditions) 3. (3) 100 °C in air without water or sunlight (‘extreme’ conditions). All shales exhibited decreases in oil yields by Fischer assay, the highest loss being 90 wt % for Julia Creek shale under extreme conditions for 60 weeks. Solid-state 13C n.m.r. spectra of kerogens before and after weathering under extreme conditions for 60 weeks confirm increased aromaticity and greater concentrations of oxygenated functional groups. Elemental analyses show that, for these kerogens, H/C ratios decreased by ≈ 30% and O/C ratios increased by ≈ 300%. The results are important when considering natural geological weathering of shale seams, oxidation of stockpiled shale and prolonged drying of shale at elevated temperatures. more...

Vanadyl porphyrins have been detected in a series of oil shale and weathered coquinite samples from the Toolebuc Formation, Queensland, Australia. Concentrations of soluble vanadyl porphyrins range from < 1 to 730 μg g−1. Organically bound vanadium has also been found in kerogens isolated from oil-shale samples taken at locations up to several hundred kilometres apart. Variations in the concentration of both vanadyl porphyrins and kerogen-bound V are probably due to recent weathering. By preferentially removing smaller aliphatic molecules, weathering progressively renders the remaining kerogen more aromatic and ultimately solubilizes all organic matter in the shales. At the same time, organically bound V is released and becomes associated with the inorganic fraction of the weathered shale. more...

A technique consisting of pyrolysis at 700°C in hydrogen, followed by catalytic hydrogenation and gas chromatography of the products, has been developed for studying the carbon-skeleton structure of coal or kerogen. As a result of the hydrogenation step, the only organic compounds produced were saturated and aromatic hydrocarbons. Pyrolysis-hydrogenation of coal produced light hydrocarbon gases, n-alkanes from pentane to pentadecane, benzene, toluene, xylenes and other unidentified hydrocarbons. Samples of some coals were used to show the quantitative and qualitative reproducibility of the technique and to examine the relationship between the yields of various hydrocarbons and the usual coal parameters. The results indicated that coals have an appreciable component of long unbranched carbon chains. This component is decreased, and the aromatic component is increased, with increasing coal rank, although the relationship is complicated, probably by variations in maceral composition. The total yield of hydrocarbons from a coal was found to bear a linear relationship to its hydrogen content. This relationship could be explained on the basis of stoichiometry. more...

Differing degrees of oxidation, caused by weathering at the surface, are evident in the Julia Creek oil shale deposit. Weathering results in decreased oil yields and its extent is indicated by the oil/organic carbon ratio. In a series of carefully selected samples, this ratio (by weight) varies from 0.55 for ‘fresh’ shale to 0.38 for appreciably altered shale. Oxidation of kerogen is reflected in the elemental composition of kerogens obtained by demineralization of the samples. FT-i.r. spectra of kerogens show that CH concentrations decrease and COOH contents increase with in situ oxidation. Nuclear magnetic resonance spectroscopy gives clear evidence that, as well as oil quantity, oil quality progressively changes with shale weathering. Results are, in general, directly comparable with those for artificially weathered shales. more...

The hydrocarbon secreting alga Botryococcus has been identified in organic remains of sediments ranging from Precambrian to Recent, and is believed to have been a major source material for petroleum generation throughout the geological time. In some petroleum source rocks of Lower Palaeozoic and Precambrian age, identification of the alga is only possible by electron microscopy. Transmission electron microscopy (TEM) has been used in the present study to identify microstructures of the algal remains in a range of oil shales and petroleum source rocks. It has been established that Botryococcus is the predominant alga in the Kukersite oil shale of Estonia. Similarly, the alga has been shown to be a major contributor to petroleum source rocks in Cambrian and Precambrian sedimentary basins in Australia. TEM has been applied to observations of Botryococcus in torbanites and to products from simulated maturation experiments on torbanite. A comparison with algal remains from Cambrian and Precambrian sediments ranging from undermature to overmature, enabled the distinction of organic matter in various stages of oil generation. Maturation/thermal effects on alginite have been established by reflectance and fluorescence, and compared with experimental results. more...

A fresh sample of Rundle shale oil, recovered during retorting, was subjected to a variety of storage conditions for 26 weeks. Changes in chemical composition were investigated by Chromatographic and n.m.r. techniques. Subsamples of the fresh shale oil were stored at 1. (a) −4 °C under nitrogen 2. (b) 22 °C in air, in the dark 3. c) 22 °C in air, exposed to artificial light 4. (d) 10–35 °C in air, exposed to sunlight. The most significant changes were observed in the ‘sunlight’ sample. Exposure to sunlight caused a marked decrease in the aliphatic and mono-aromatic fractions in the aged shale oil with a corresponding increase in polar constituents. The ratio of straight-chain 1-alkenes to alkanes was significantly lower in this sample, while the ratio of 1-alkenes to internal alkenes was greatly increased. The reactivity of cis and trans -2-alkenes appeared to be similar during ageing experiments. more...

Dry samples of torbanite and soft brown coal, from which mineral matter and material soluble in chloroform have been removed, have been artificially matured in an attempt to simulate conditions in a subsiding sedimentary basin with a constant geothermal gradient. Sealed tubes were increased in temperature by 1°C per week beginning at 100°C. A tube containing each source material was opened and analysed at yearly intervals for six years. Olefins and carbon monoxide were not significant products at any stage. At less than 300°C torbanite generated a paraffinic crude oil in 35% yield, while the brown coal gave a wet, CO2-rich natural gas. In most respects, these experiments, which are possibly as slow as can be realistically planned within a human time-scale, appear to have duplicated geochemical hydrocarbon generation. more...

Elemental analyses, X-ray diffraction, thermal and isotopic analyses, gas chromatography-mass spectrometry, electron spin resonance, nuclear magnetic resonance spectroscopy and demineralizing techniques have been used to evaluate the effect of a small igneous intrusion on Rundle oil shale. Each set of results contributes to an overall appreciation of how in situ pyrolysis of a highly aliphatic kerogen occurs. As in previous studies, application of a range of methods gives a better understanding than any of the techniques on its own. Significant conclusions are as follows: (1) the shale samples closest to the intrusion contain the least organic matter; (2) a “micro-reservoir” for expelled volatiles was identified ∼ 1 m below the intrusion; (3) the hydrogen-deficient carbonaceous residue remaining close to the intrusion produces no oil on further heating; and (4) the major effect of the intrusive event was the in situ pyrolysis of the oil shale, the severity of alteration decreasing with distance from the contact. more...

The amount of oil that can be generated from a kerogen under natural conditions is an important parameter in source rock assessment. Similarly, the quantity of oil able to be formed from a coal or kerogen during much more rapid pyrolysis is a crucial factor in oil shale and coal conversion studies. An approximate relation based on atomic ratios is derived for slow geological heating but is also valuable for comparing samples under other conditions. The percentage of oil, on a weight basis, that can be generated is given by: Oil = 66.7 H C − 57.0 O C −33.3 . Typical results for twelve Australian coals and twelve world oil shales are given as examples. more...

A simple method is proposed for using gas Chromatographic data on the high molecular weight saturated fractions of crude oils to make comparisons of source materials, migration mechanisms and, in particular, alteration processes within reservoirs. The preferential loss of normal alkanes by bacterial attack on a light crude is one of several processes readily followed using this scheme. more...

Molar Kerr constant, dipole moment, and dielectric relaxation measurements of (p-C6H4Cl)3Bi in benzene solution indicate a C–Bi–C bond angle of 93 ° and an average rotation (in the same sense) of each C6H4Cl group about its C–Bi bond of 45° from a model in which the aromatic planes intersect along the symmetry axis. A similar configuration in solution is likely in the case of Ph3Bi, for which a C–Bi–C bond angle of 94° has been reported in the solid state. more...