Constitution of tars from the flash pyrolysis of Australian coals: 1. Separation

Separation of the maltene fraction of Millmerran flash-pyrolysis coal tar by ion-exchange and adsorption chromatography produced coal-tar resins, aromatic hydrocarbons (AH) and an alkane/alkene fraction. The coal-tar resins comprise acid, base, neutral and polyfunctional fractions. Derivatives of benzene and naphthalene are the main volatile constituents of the AH fraction, while the alkane/alkene fraction consists mainly of straight-chain hydrocarbons from C₁₀ to C₃₄ and small amounts of isoprenoid hydrocarbons, steranes and triterpanes. Fuller's Earth, used in the separation of the maltenes, suffers from the disadvantage of irreversibly adsorbing organic material.     

Low-temperature pyrolysis of Texas lignite,basic extracts and some related model compounds

Low-temperature (400 °C) pyrolysis of Texas lignite produced volatile products typical of coal tars, with tar evolution beginning at about 300 °C. n-Alkanes up to about C₃₀ were observed among the products and these were accompanied by smaller but significant amounts of 1 -alkenes. Similar pyrolyses were performed on pyridine extracts and sodium hydroxide extracts of lignite. The alkanes and alkenes were seen among the pyrolysis products from the pyridine extracts and from the residual lignite from both types of extractions, but they were not seen among the pyrolysis products from the sodium hydroxide extracts. Pyrolyses of some model compounds suggested that dealkylation of alkyl-substituted arenes can be significant at 400 °C and can account for the production of the alkanes and alkenes from the lignite.     

Characterization of the highest optically active fraction of shale oil

A shale oil sample from an above-ground 150 ton retort, designed to simulate the in-situ retort process, was vacuum distilled to obtain narrow distillate fractions. The optical rotation was measured for each distillate cut. The fraction with the highest optical rotation (470 °–485 °C) was subjected to elution chromatography using hexane, benzene and methanol, respectively. The resulting saturated fraction (hexane cut) was investigated by computerized gas chromatography-mass spectrometry. Three steranes, four pentacyclic triterpanes and five normal alkanes were identified, and the partial structures of two other compounds have been suggested.     

Composition of natural bitumens and asphalts from Iran: 2. Bitumens from the Posteh Ghear valley,south-west Iran

Vein, lens and stratiform natural sedimentary bitumen deposits were analysed by combined geochemical and micropetrographic techniques. Reflectances in oil, air and water, fluorescence spectral properties, solubility in dichloromethane, elemental analysis and bulk chemical composition of soluble fractions by chromatographic separation indicate that these materials are generally gilsonite bitumen, although some, showing evidence of significant alteration and weathering, are closer to albertite in composition. Optical properties show that the bitumens are immature and fall within the field of asphaltites on the bituminization curve. Fluorescence spectra generally show two maxima, again a feature associated with immature gilsonite bitumen. Capillary-column g.c. of saturates fractions indicates the absence of normal and acyclic isoprenoid alkanes, these fractions being dominated by a series of C₂₇-C₃₄ pentacyclic triterpanes of the hopane family. The saturates fraction composition is characteristic of biodegraded crude oils, and molecular biomarker stereochemistry indicates a moderately mature petroleum source. All the bitumens are shown to have a common genetic origin and are thought to be the result of in situ alteration and biodegradation of oil infillings in joints, fractures and bedding planes, resulting from fracturing and faulting of reservoir and overlying cap rocks associated with a period of Neogene tectonism.     

Flash pyrolysis of coals. 1. Devolatilization of a Victorian brown coal in a small fluidized-bed reactor

The devolatilization behaviour of finely-ground (< 0.2 mm) Loy Yang brown coal was investigated under rapid heating conditions using a small-scale fluidized-bed pyrolyser. The pyrolyser operated continuously, coal being fed at rates of 1–3 g/h directly into a bed of sand fluidized by nitrogen. Particle heating rates probably exceeded 10⁴ °C/s. The yields of tar, C₁-C₃ hydrocarbons and total volatile matter are reported for a pyrolyser-temperature range of 435 to 900 °C. A maximum tar yield of 23% w/w (dry ash-free coal), 60% more than the Fischer assay, was obtained at 580 °C. Yields of C₁-C₃ hydrocarbons increased with increasing temperature, reaching 8% at 900 °C. Elemental analyses showed that the composition of the tar and char products was strongly dependent on pyrolysis temperature. The effects on the devolatilization behaviour of the coal produced by the moisture associated with the coal, by hydrogen, and by the replacement of the sand by a fluidized bed of petroleum coke were investigated.     

Semicoking of Kansko-Achinsk lignite and applications of tar fractions

The semicoking of regular lignite from the Berezovsk field in Kansko-Achinsk Basin (moisture content 1.6–19.6 wt %) at 450–550°C in a reactor with solid heat carrier is studied. The products are semicoke (up to 68.1%), tar (up to 9.5%), gas (up to 31.9%), and pyrogenetic water. The composition of the semicoking gas is quantitatively determined. Its main components are hydrogen (up to 71.7%) and methane (up to 17.2%). The heat of combustion of the semicoking gas is 12.39–16.25 MJ/m³. The yield of phenolic fractions in the semicoking tar, consisting of phenol and its alkyl derivatives with one or two short substituents (C₁–C₃), is 10.5–14.6%. After hydraulic purification of the gasoline fraction in the semicoking tar (below 180°C), gasoline with octane rating 75.8 (by the motor method) is obtained. It consists of aromatic, saturated, and unsaturated hydrocarbons (C₅–C₈). The diesel fuel derived from tar fractions distilled off at temperatures up to 350°C are of good quality, except for their low cetane rating. The high-boiling tar fractions may be used to produce lignite pitch and pitch coke. The semicoke obtained is a very effective reducing agent in the production of phosphorus. It may also be used as a lean additive in coking batch and as a component in enriched domestic coal briquets.     

Characterization of liquid product from the reaction of coal with hydrogen atoms

An oily product formed by the reaction of a domestic subbituminous coal (Taiheiyo coal) with hydrogen atoms at 200 °C, has been characterized. The material is essentially composed of C₅-C₂₂ alkanes and cycloalkanes. The $\text{H}\text{C}$ ratio, specific gravity and refractive index were 1.81, 0.855 and 1.447, respectively. The absence of heteroatoms, alkenes and aromatics in the product is the outstanding feature of the coal liquefaction induced by hydrogen atoms.     

Comparative characterization of the distribution of biomarker hydrocarbons in the chemical transformation products of oxygen-containing precursors of petroleum

The distribution of biomarker hydrocarbons in the thermolysis and thermocatalysis products of oxygen-containing compounds (possible petroleum hydrocarbon precursors) was studied by gas chromatography-mass spectrometry. It was found that n-alkylcyclohexanes and steranes were generated in the course of thermolysis along with expected hydrocarbons—n-alkanes and isoprenes, which resulted from the loss of a functional group. In this case, the molecular-weight distributions of n-alkanes and n-alkylcyclohexanes correlated well with each other. In the course of thermocatalysis, the homologous series of n-alkanes and n-alkylcyclohexanes were also generated; however, an n-alkylcyclohexane distribution maximum had an even number of carbon atoms in the molecule (C₁₈). It was experimentally found that the sterane fragments of oxygen-containing compounds formed upon thermolysis were thermodynamically unstable; this was supported by the formation of biological C₂₇–C₂₉ 5α, 14α, 17α, 20S, and 20R and 5β, 14α, 17α, and 20R (coprostane) steranes as a result of thermolysis. Unlike thermolysis, all of the four epimers of regular C₂₇–C₂₉ (5α, 14α, 17α, 20S, and 20R and 5α, 14β, 17β, 20S, and 20R) steranes were formed as a result of thermocatalysis. It was found that the relative distribution of biomarker hydrocarbons in the thermolysis products of various oxygen-containing compounds largely reflected the structure of the parent organic substance, as compared with that upon thermocatalysis in the presence of active aluminosilicate.     

Distribution modes and possible origins of sheep wool hydrocarbons

An unusual mode of distribution of low-molecular-weight n-alkanes (C₁₁-C₁₅) with a slight even carbon-number predominance has been observed in the gas Chromatographic analysis of the paraffin fraction which was extracted from the wool of live sheep. This is in addition to the other two modes of medium-, C₁₅-C₂₄, and high-, C₂₄-C₃₃, molecular-weight alkanes usually present in wool wax which have also been found in sheep’s manure. The high-molecular-weight hydrocarbons (predominantly odd carbon-numbered) are presumed to be derived from the diet (pasture plants) whereas the other two hydrocarbon distributions probably result from the combined action of animal and microbial metabolism.     

Flash pyrolysis of coals: influence of cations on the devolatilization behaviour of brown coals

The influence of cations on the pyrolysis behaviour of brown coals under flash heating conditions was investigated by means of a small fluidized-bed pyrolyser. A stream of coal particles in nitrogen was injected at rates of 1–3 g coal/h directly into a heated bed of sand fluidized by nitrogen. Yields of tar, C₁–C₃ hydrocarbons and total volatile matter from four Gelliondale brown coals and a Montana lignite were determined as a function of pyrolysis temperature. With all coals the maximum tar yield was obtained at 600 °C. Removal of cations present in the coals markedly increased the yields of tar and total volatile matter, with little effect on the yields of hydrocarbon gases. The converse was also observed in that the addition of Ca²⁺ to a cation-free coal decreased the yields of tar and total volatile matter. The extent of the reduction in tar yield at 600 °C in the presence of cations was found to be similar for all coals. After acid washing, tar yields appear to correlate with the atomic $\text{H}\text{C}$ ratios of the coals in a manner similar to that observed previously with bituminous coals.     

New Long Chain Bases in Lipophosphonoglycan of Acanthamoeba Castellanii

The polymer called lipophosphonoglycan (LPG) was isolated from Acanthamoeba castellanii membranes after exhaustive delipidation and butanol extraction. A novel extremely long phytosphingosine was revealed in glycoinositolphosphosphingolipid (GIPSL). All data obtained by gas–liquid chromatography coupled with MS analyses of products liberated during acid methanolysis and products of sodium metaperiodate and permanganate–periodate oxidations showed an unusual pattern of long chain bases (LCB) with branched bases (anteiso-C₂₄, anteiso-C₂₅, anteiso-C₂₆, iso-C₂₆, anteiso-C₂₇, and anteiso-C₂₈) and normal ones (C₂₄, C₂₅, C₂₆, C₂₇). The phytosphingosines with hexa-, hepta-, and octacosanoic chains have not been detected in Acanthamoeba cells up to now. Also, the isomer configuration of long chain bases in LPG of A. castellanii was not defined in earlier reports. In the GC–MS chromatograms, the component forming a peak corresponding to anteiso-C₂₅ phytosphingosine was the most abundant and constituted more than 50 % of all LCB.     

Isolation and identification of constituents of Jasminum auriculatum (Vahl) leaves

Jasminum auriculatum (Vahl) (family: Malvaceae) widely grown in India was analysed for its fatty acids and waxy constituents. Straight-chain hydrocarbons (C₂₀-C₃₄), fatty acids (C₁₄-C₂₃) and fatty alcohols (C₂₁-C₃₂) were found in the 95% aqueous ethanol extract of the leaves of the plant. Malvalic acid was the only cyclic acid identified. Hydrocarbons (C₂₉ and C₃₁), fatty acids (C₁₆, C₁₈, C_18:1, C_18:2, C_18:3 and C₂₂) and fatty alcohols (iso-C₂₆, C₂₈ and C₃₀) were the major components. Four polyalcohols, namely D-mannitol, xylitol, inositol and sorbitol, have also been found in the alcoholic extract of the leaves.     

Compositional Changes of Hydrocarbons of Residual Oil in Contaminated Soil During Ozonation

Ozonation is an effective method to remove recalcitrant weathered oil in contaminated soil. The purpose of this study was to characterize the compositional changes of hydrocarbons in residual oil during ozonation. A bioremediated soil containing residual oil was ozonated for up to 15 h. A total of 102 compounds in the residual oil were analyzed by GC/MS and 36 diagnostic ratios (DRs) were calculated based on quantitative or semi-quantitative results in order to evaluate the susceptibility of the residual oil compositions to ozonation and the effects of ozonation on the fingerprint profile of the residual oil. The total ozonation removal rates were in the following order: triaromatic steranes (TAS) > steranes, polycyclic aromatic hydrocarbons, terpanes > alkanes. Ozone kept the fingerprints of n-alkanes, C₂₇- to C₃₄-terpanes, steranes and TAS, separately. Branched alkanes (i.e., pristane and phytane) showed a higher removal rate than n-alkanes. Ozone reactivity of PAHs depended on the number of rings, presence of heteroatoms and level of alkylation. Four- to six-ring PAHs and PAHs with a high level of alkylation showed higher reactivity, while dibenzothiophene and alkylated dibenzothiophenes were found to be resistant to ozonation. Some of the biomarker source ratios remained stable and could still be used for source identification even after some of the biomarkers were removed by >90% by ozonation.     

Supercritical fluid extracts from brown coal lithotypes and their group components—molecular composition of non-polar compounds

The two Tertiary brown coals, i.e. xylitic brown coal (XBC) and humodetritous brown coal (HBC), from the ‘Turów’ and ‘Konin’ deposits in Poland and their group components were investigated on their behaviour to Soxhlet and supercritical fluid (SFE process) extractions. The raw coals were Soxhlet pre-extracted to remove unbound lipids (bitumens). Humic acids, lignin and cellulose were obtained from the pre-extracted XBC, while humic acids and residual coal were separated from the HBC. Raw coals and their group components were extracted under supercritical conditions with toluene (653 K, 8 MPa, 1 h). The yield of non-polar fractions from the Soxhlet and supercritical extracts were determined and analysed by gas chromatography-mass spectrometry (GC-MS).The diversity in biomarker compositions (n-alkanes, n-alkylbenzenes, iso-alkanes, fatty acids, diterpanes and pentacyclic triterpanes and their aromatised derivatives, methylphenanthrenes) of the supercritical fluid extracts (SFEs) were compared and contrasted with the Soxhlet extracts. The biomarker geochemical indices in Soxhlet extracts are typical of low maturity, while these released by SFE process have characteristic of a higher maturation level. The Soxhlet extracts of both coals show a dominance of 17α(H),21β(H)-homohopane with the precursor configuration of 22R. The pentacyclic triterpanes found in the SFEs are diverse structures, i.e. 17α(H),21β(H)-hopanes, moretanes and small amounts of benzohopanes, as well as geochemically unaltered homohopane with the biological configuration of 17β(H),21β(H)-(22R). Isopimarane is the characteristic of SFEs from humic acids of the coals. Partially aromatised pentacyclic triterpanes related to α- and β-amyrin are characteristic of free lipids and SFEs of humic acid fractions from both coals. The diversity in the phenanthro[4,5-bcd]furan, methylphenanthrenes and 2-methylanthracene compositions is dependent on chemical nature of the brown coal group component.     

Nature of alkanes in beef heart lipids

n-Alkanes have been found to be the major saturated hydrocarbon components in the fatty tissues on beef heart. These alkanes consist of a homologous series C₁₄–C₃₅, with the C₂₉ and C₃₁ n-alkanes being most abundant. C₁₆, C₁₉, and C₂₀ isoprenoid alkanes also were identified. A C₁₇ isoprenoid alkane tentatively was identified. The fatty tissues on beef heart contained 32 μg/g saturated hydrocarbons. The distribution pattern of these saturated hydrocarbons is in marked contrast to the alkane distribution in beef liver where branched and cyclic alkanes are predominant. The enrichment and the similarity of the n-alkane distribution in the fatty tissues on heart and in pasture plants may have implications for the physiological aspects of hydrocarbons in the diet.     

Role of cuticular hydrocarbons of aphid parasitoids in their relationship to aphid-attending ants

Lysiphlebus cardui, the dominant aphidiid parasitoid of the black bean aphid,Aphis fabae cirsiiacanthoidis (Afc), on creeping thistle, is able to forage in ant-attended aphid colonies without being attacked by ants. Several behavioral observations and experimental studies led to the hypothesis thatL. cardui mimics the cuticular hydrocarbon profile of its host aphid. Chemical analysis of the cuticular extracts revealed that bothL. cardui and Afc exclusively possess saturated hydrocarbons:n-alkanes, monomethyl (MMA), dimethyl (DMA), and trimethyl alkanes (TMA). Comparison of the hydrocarbon profiles of parasitoid and aphid showed great qualitative resemblance between parasitoid and host:L. cardui possesses almost all host-specific compounds in addition to species-specific hydrocarbons of mainly higher molecular weight (>C₃₀). However, there is a lesser quantitative correspondence between parasitoid and host aphid. Furthermore, we analyzed the cuticular hydrocarbon profile of another parasitoid of Afc,Trioxys angelicae. This aphidiid species is vigorously attacked and finally killed by honeydewcollecting ants when encountered in aphid colonies. Its cuticular hydrocarbon profile is characterized by the presence of large amounts of (Z)-11-alkenes of chain lenghts C₂₇, C₂₉, C₃₁, and C₃₃, in addition to alkanes and presumably trienes. The role of the unsaturated hydrocarbons onT. angelicae as recognition cues for aphid-attending ants is discussed.     

Effects of methane concentration on hydrocarbon release during the pyrolysis of coal

The weight-loss characteristics of Longkou lignite were studied by means of thermogravimetric analysis in methane ambience. Pyrolysis experiments of the sample coal in different concentrations of methane were carried out on a tube reactor to study the characteristics of hydrocarbon released. The results show that methane can promote the pyrolysis of lignite in a certain temperature range and the coal can also improve the pyrolysis of methane further. The influence of methane concentration on hydrocarbon release during the pyrolysis of coal is obvious. The hydrocarbon released from the pyrolysis of lignite is intensive within the temperature range from 400°C to 500°C and the release of hydrocarbon components dramatically increased as the concentration of methane decreased. This indicates that the release of C₂, C₃ and C₄ has a close relationship with methane pyrolysis and proves that a synergistic effect does exist between the coal and methane.     

Comparison of the diffusion coefficients of linear and cyclic alkanes

Monte Carlo simulations of linear and cyclic alkanes were performed on a coarse-grained high coordination lattice. The simulations were performed at 473 K for C_NH_2N+2 and C_NH_2N where N had the values of 60, 100, and 316. The results indicated: (i) at low molecular weights, cyclic alkanes have lower diffusion coefficients than linear alkanes, and (ii) at high molecular weights, they have higher diffusion coefficients than linear alkanes. The lower diffusion coefficient of the small cyclic alkanes was attributed to the high local density within the volume defined by the smaller mean square radius of gyration of the cyclic alkanes. The high local density of cyclic alkane segments resulted in a decrease in the mobility of the beads. The crossover in diffusion coefficients was observed around the entanglement molecular weight of linear alkanes, which suggests that the linear alkanes are more susceptible to the effects of entanglements than are the cyclic alkanes.     

Chemical composition of the distillate fractions of coal tar from OAO Altai-Koks

The chemical composition of the distillate fractions with boiling points of to 180, 180–230, and 230–280°C separated from undehydrated coal tar from OAO Altai-Koks was studied by gas chromatography-mass spectrometry. A list of identified aromatic compounds (including N-, O-, and S-containing compounds) and their alkyl derivatives is given. It was found that, upon the complete processing of tar with the recirculation of residual raw materials at the stage of coking and its hydrogenation refining in the presence of suspended Mo- and Ni-containing catalysts and a hydrogen donor (tetralin), the yields of chemical products were the following (wt %): coke, 50–55; absorption oil, 9–12; benzene, naphthalene, tetralin, dimethylnaphthalenes, and other hydrocarbons, 25–30; BTX fraction 4–5; and C₁-C₄ and CO₂, 10–12.     

Gas evolution kinetics of two coal samples during rapid pyrolysis

Quantitative gas evolution kinetics of coal primary pyrolysis at high heating rates is critical for developing predictive coal pyrolysis models. This study aims to investigate the gaseous species evolution kinetics of a low rank coal and a subbituminous coal during pyrolysis at a heating rate of 1000 °C s^− 1 and pressures up to 50 bar using a wire mesh reactor. The main gaseous species, including H₂, CO, CO₂, and light hydrocarbons CH₄, C₂H₂, C₂H₄, C₂H₆, C₃H₆, C₃H₈, were quantified using high sensitivity gas chromatography. It was found that the yields of gaseous species increased with increasing pyrolysis temperature up to 1100 °C. The low rank coal generated more CO and CO₂ than the subbituminous coal under similar pyrolysis conditions. Pyrolysis of the low rank coal at 50 bar produced more gas than at atmospheric pressure, especially CO₂, indicating that the tar precursor had undergone thermal cracking during pyrolysis at the elevated pressure.