Search

Oil shale is a raw material that is considered to be an alternative fossil fuels and it is widely used in producing energy and chemicals. Oil shale bitumen identification are not widely described in literature. This article tackles the structural elucidation of oil shale bitumen using gas chromatography-mass spectrometry (GC-MS) and nuclear magnetic resonance (NMR) spectroscopy with a short sample preparation step, based on ultrasonic-assisted liquid extraction. The ultrasonic-assisted extraction was examined in terms of solvent type and volume, sample size, sonication time and temperatures. A bitumen recovery of 17.7 wt% dmmf (dry-mineral-matter-free) was achieved when 0.50 g of shale was mixed with 20 mL THF and sonicated for 10 min at ultrasonic power of 120 W at 45°C. GC-MS of the bitumen showed high polar oxygenated compounds with more than 20 wt% being esters and ethers. Small concentrations of thiols and amides have been also found. The structural identification of bitumen was carried out using 1H-NMR and 13C-NMR and the results showed highly aliphatic character bitumen, consisting of aromatic, paraffinic, naphthenic and olefinic hydrogen and carbon atoms. These results suggested that ultrasonic solvent extraction could be an efficient and environment-friendly method for obtaining of bitumen from oil shale. [ABSTRACT FROM AUTHOR]

Few comparisons have been made between low-aromaticity marine and lacustrine oil shales and their kerogens, because the reliability of structural analyses has been limited by a reliance on only one method of kerogen isolation, HCl-HF. Therefore, a detailed analysis by 13C NMR and X-ray photoelectron spectroscopy (XPS) was made for Attrat marine oil shale (Jordan) and Colorado (Green River) lacustrine oil shale (USA) and their NaOH-HCl kerogens. Some differences between oil shales and their kerogens were noted, but many structural features were considered to be true characteristics of the organic matter. The results emphasise the importance of comparing the analyses of kerogens isolated by different methods to ensure that features of the organic matter are not an artefact of the method of kerogen isolation. For both oil shales, the predominantly aliphatic character of the organic part was confirmed and the long average chain length of the aliphatic hydrocarbons was established. All shales and their kerogens showed a small cluster size for the aromatic rings. The elemental analysis obtained by XPS, compared with the bulk elemental analysis, indicated major differences between the near-surface region sampled by XPS and the bulk. The organic S was determined to be aliphatic and aromatic S with possibly small amounts of sulfoxide. Most of the N was pyrrolic with smaller amounts in pyridinic or quaternary form. Nearly all of the surface organic C in both kerogens was bonded to C and H. Two major forms of organic O were distinguishable. A good correlation between the proportion of aliphatic S and pyrolysis reactivity is suggested. This paper studies the comparison between low-aromaticity marine (Attrat-Jordan) and lacustrine (Colorado-USA) oil shales and their kerogens. Kerogens were extracted using NaOH-HCl method. The characterisations were performed using elemental analysis, Rock Eval, 13C NMR, and XPS. This work reveals some differences in the organic structure between the two kerogens. [ABSTRACT FROM AUTHOR]

• Shale carbonate content influenced change in oil yield from shale to kerogen. • Higher S can explain higher reactivity for marine kerogens. • Lower S can explain greater polymerization of N in lacustrine kerogens. • Average aliphatic chain length was similar for both kerogen liquids. • More substituted aromatics in kerogen hydrogen liquids than in nitrogen liquids. The reactivity of kerogens from two different types of oil shales, marine Attrat oil shale from Jordan (type II kerogen, high sulfur) and lacustrine Colorado from USA (type I kerogen, low sulfur) has been studied. The kerogens were obtained using the NaOH/HCl demineralization method. The reaction products from the kerogens were compared with those from the raw shales. The reactivity of Attrat and Colorado kerogens was measured using sealed autoclaves at 355 and 390 °C for 1–5 h under N 2 or H 2 pressure. Attrat kerogen showed a higher conversion than Colorado kerogen, probably due to its high sulfur content. Except for Colorado at 390 °C under N 2 , kerogen was more reactive than the raw shale. The reactions under H 2 produced higher oil yields for Attrat raw shale and kerogen when compared to their reactions under N 2. The reactions of Colorado under H 2 showed the opposite effect in most cases. The yields of CH 2 Cl 2 -solubles + water + hydrocarbon gas + sulphide gas increased with temperature whereas those of asphaltene and asphaltol decreased. CH 2 Cl 2 -solubles from both kerogens showed high atomic H/C ratios, with high sulphur content (Attrat) and nitrogen content (Colorado), as expected from the properties of the original kerogens. The proton nuclear magnetic resonance (1H NMR) indicated the highly aliphatic character of both CH 2 Cl 2 -solubles and, in contrast to what was observed for the raw oil shales, no significant change when H 2 was substituted for N 2. The aromaticity of CH 2 Cl 2 -solubles was higher for Attrat than Colorado (0.4 vs 0.3) as for the original kerogens, and the aromatic rings in both cases were heavily substituted. The gas chromatography-mass spectrometry (GC–MS) for both kerogen reaction products indicated highly aliphatic character; Attrat kerogen reaction products were distinguished by the presence of substituted thiophenes and benzothiophenes while these compounds could not be detected in Colorado kerogen reaction products. The marked differences between the reactions of the two kerogens did not appear to be due to effects of marine/lacustrine character, as such, but rather to the high S content of Attrat kerogen. [ABSTRACT FROM AUTHOR]

Oil shales from two different continents (Australia and North America) of different ages (100 and 40 million years) and origins (one marine, one lacustrine) have been reacted in the range 355–425 °C under H 2 or N 2 for 1 or 5 h with or without the addition of catalyst. The shales differed in S content, and the nature of the mineral matter, but both had high atomic H/C ratios. The overall reactivity of the two shales was similar and high yields of soluble products could be obtained under relatively mild conditions with only small CO 2 yields, but the temperature dependence of reactivity and the effect of potential catalysts differed markedly. Increasing the temperature and time led to increases in conversion but of different extents. Substituting H 2 for N 2 led to a large increase to conversion for the lower-atomic-H/C ratio marine oil shale. The CH 2 Cl 2 solubles from the marine oil shale showed a larger range of compounds than those from the lacustrine oil shale which resembled the CH 2 Cl 2 solubles from torbanite, a coal-like material derived from lacustrine algae. [ABSTRACT FROM AUTHOR]

Four oil shales from different locations and origins have been reacted in a flow-through system (425 °C, with N 2 or H 2 as sweep gases at 1 atm pressure) with a view to more closely simulating a practical process for oil shale conversion than can be achieved with a sealed autoclave system. It was observed that there was no general correlation between the yields in the two systems, nor was there a general correlation between the amount of condensate and the amount of volatiles obtained by thermogravimetric analysis. For all four oil shales, the condensate gave more complex gas chromatography–mass spectrometry total ion chromatograms (GC–MS TICs) than the CH 2 Cl 2 -solubles from sealed autoclave reactions. Surprisingly, the products from one of the Jordanian oil shales, Yarmouk, and an Australian Julia Creek oil shale were remarkably similar. The product from the lacustrine Colorado oil shale was much more similar to that from a lacustrine algal coal (torbanite) than to those from marine oil shales. The differences in yields and product characteristics between sealed autoclave and flow-through reactions suggest that yields and product distributions obtained from sealed autoclave reactions should be treated with caution. [ABSTRACT FROM AUTHOR]

A high sulfur Jordanian oil shale was converted into liquid hydrocarbons by reaction at 390°C under N2, and the dichloromethane soluble fraction of the products was isolated then analyzed by using gas chromatography (GC). Comprehensive two-dimensional GC (GC×GC) and multidimensional GC (MDGC) were applied for component separation on a polar – non-polar column set. Flame-ionization detection (FID) was used with GC×GC for general sample profiling, and mass spectrometry (MS) for component identification in MDGC. Multidimensional GC revealed a range of thiophenes (th), benzothiophenes (bth) and small amounts of dibenzothiophenes (dbth) and benzonaphthothiophenes (bnth). In addition, a range of aliphatic alkanes and cycloalkanes, ethers, polar single ring aromatic compounds and small amounts of polycyclic aromatics were also identified. Some of these compound classes were not uniquely observable by conventional 1D GC, and certainly this is true for many of their minor constituent members. The total number of distinct compounds was very large (ca.>1000). GC×GC was shown to be appropriate for general sample profiling, and MDGC-MS proved to be a powerful technique for the separation and identification of sulfur-containing components and other polar compounds. [ABSTRACT FROM AUTHOR]

Abstract: Reactions of a Jordanian El-Lajjun oil shale under N2 or H2 for 1h results in almost complete conversion of the organic material to liquid products at 355°C or 390°C. In contrast, reactions for 1h of the algal coal, torbanite, give minimal conversion at 390°C, but almost total conversion if the reaction time is extended to 5h. At 355°C reactions of torbanite are minimal at 1 and 5h reaction times, however at 425°C for 1h almost complete conversion is observed. In addition, the oil to asphaltene ratio for the products from the Jordanian oil shale increases in the temperature range 355–390°C, whereas the oil to asphaltene ratio for the products from torbanite strongly favours oil at all temperatures. The oil from both materials is highly aliphatic. The torbanite oil is mainly long chain, saturated hydrocarbons with few aromatic compounds. The oil from the Jordanian shale also has a high aliphatic content but a much wider range of aromatics. In addition, significant amounts of sulfur-containing compounds are present. [Copyright &y& Elsevier]

[Display omitted] • Novel extraction of oil from a Jordanian oil shale using supercritical propane with a co-solvent. • High oil yields achieved at very low temperature. • Above the critical temperature of propane (100 °C), higher yields obtained at high pressure. • The oil had more oxygen and less sulfur than high-temperature oil. • Oil was easily hydrogenated to reduce sulfur and oxygen contents dramatically. The only method currently used for producing oil from oil shale is high temperature retorting, which is wasteful of energy and gives oil with a high content of heavy oil. The novel method of extraction used in this study, involving supercritical propane with tetrahydrofuran as a co-solvent, solves the problem of the high cost of producing oil by conventional high temperature retorting. El-Lajjun oil shale from Jordan was used to evaluate the reaction yield and the characteristics of the product. At supercritical propane temperature and pressure (100 °C and 4.3 MPa), the yield was high and comparable to that for the conventional retorting method (>350 °C). As the temperature increased to 200 °C, the oil yield increased with pressure. The oil obtained was high in aliphatic hydrocarbons but with significant amounts of ethers, some carbonyls and sulfur-oxygen compounds. Hydrodeoxygenation and hydrodesulfurization of the produced oils using NiMo-Al-SBA-15 catalysts significantly enhanced the quality of the oil by decreasing the oxygen and sulfur contents and increasing the aliphatic and diesel fractions. This work leads to an enduring breakthrough technology that substantially reduces costs, waste, energy and the environmental impact of using oil shale as a raw material for liquid fuel production using Green Technology. Recovery of THF is high (>95%) and re-use of THF and propane would be essential for commercial application. [ABSTRACT FROM AUTHOR]

[Display omitted] • Oil shales and their HCl-HF and NaOH-HCl kerogens gave generally similar pyrolysis yields. • Asphaltol yields from NaOH-HCl kerogens were higher. • Characteristics of products from HCl-HF and NaOH-HCl kerogens were similar. • The flow-through products were more complex than sealed autoclave products. • NaOH-HCl extraction is a suitable alternative to the more dangerous HCl-HF method. The inherent reactivity of kerogens isolated from marine oil shales has not been extensively studied. Determining the conversion and products of demineralized oil shales simplifies modelling of oil shale pyrolysis because the complications introduced by the mineral matter are removed. Accordingly, the reactive behaviour of demineralized products (kerogens) isolated from two marine oil shales (type II kerogen) by NaOH-HCl and HCl-HF methods have been compared with each other and with those of untreated shales. Pyrolysis experiments have been carried out under N 2 and H 2 in a sealed system, and also in a flow through autoclave system, which is closer to practical pyrolysis conditions, at temperatures in the range 355 °C to 425 °C. The two isolation methods gave a similar conversion in sealed autoclaves and the only major difference was the higher asphaltol yield for the NaOH-HCl kerogens, so that asphaltol yield cannot be used to characterize the intrinsic reactivity of the shale organic matter. The El-Lajjun shale gave higher conversion to organic materials than the kerogens but the opposite was noted for Julia Creek, especially for pyrolysis under N 2. Pyrolysis experiments in a flow through system gave similar overall conversion for the kerogens and their untreated shales but the yields of condensates for the Julia Creek shale were significantly lower for the oil shales than for the kerogens. The chemical complexity of the condensates from the flow through experiments was much greater than that for the CH 2 Cl 2 soluble samples from the sealed autoclave pyrolysis experiments. The product compositions for the NaOH-HCl and HCl-HF kerogens were, as for the total yields, very similar, suggesting that the NaOH-HCl method is a valuable alternative in countries where the use of HF is severely restricted. Further, determining the reactive behaviour of kerogens isolated by two different methods makes it likely that features of the reactivity common to both types of kerogens are features of organic matter reactivity rather than of the isolation method and thus provides a firm foundation for future work. The isolated kerogen could also be considered as a source material for the production of fine chemicals and other applications. [ABSTRACT FROM AUTHOR]

• Reactivity of the two oil shale differed significantly. • More reaction time was required to obtain higher oil yield. • There were no significant variations in the composition of the liquid products. • The diesel fraction was higher at higher reaction temperature. Two oil shales from Jordan, El-Lajjun (EL) in the centre of the country and Isfir Al-Mahata (IA) in the south, have been analysed by elemental analysis, XRF, XRD, FTIR, TGA and 13C NMR. Both oil shales have high S contents and atomic H/C ratios. The calorific value of EL (1630 ± 10 kcal/kg) was similar to that of IA (1571 ± 13 kcal/kg). IA has higher moisture content (7.1 ± 0.3 wt% db) than EL shale (0.7 ± 0.2 wt% db); higher CaCO 3 content (XRF, XRD) and lower P content (XRF, XRD). FTIR and 13C NMR indicated a high content of aliphatics for both oil shales, especially for IA shale. These oil shales have been pyrolysed at 300 °C and 320 °C for 7, 14 and 21 days under a constant flow rate of N 2. The lower-temperature, long-time reaction yields and analyses of the products were compared with those obtained from the standard Fischer Assay method (520 °C for 90 min). EL oil shale was less reactive than IA oil shale, particularly at lower reaction time. For both oil shales, as the reaction time increased from 7 to 21 days, the oil yield increased to 83–90 wt% of the Fischer Assay oil yield. Fischer assay and lower-temperature, long-time reaction products were analysed using gas chromatography-mass spectrometry (GC–MS) and 1H NMR. The GC–MS results for both shales showed that all the reaction products were similar and of high aliphatic content. Higher diesel fraction was obtained for 21 day reactions at 320 °C. Homologous series of sulfur-containing organic compounds (thiophenes and benzothiophenes) were present in considerable amounts in both EL and IA reaction products. The 1H NMR measurements suggested that the Fischer assay and long-time, lower-temperature reaction products all had high aliphatic content, matching the results obtained from GC–MS measurements. [ABSTRACT FROM AUTHOR]

Abstract: A Jordanian oil shale from the El Lajjun deposit has been reacted with N2, H2 and CO in the presence and absence of water in the temperature range 300–425°C. The effect of adding Fe, Cu, Ni, Sn and NaAlO2 as potential catalysts to some of these reactions has been studied but none led to improved oil yields. Most of the organic material in the oil shale was converted to asphaltene at 355°C, but the oil yield was low at this temperature. At 425°C nearly all the organic product was in the form of oil. [Copyright &y& Elsevier]