Organic geochemistry of the British Kimmeridge clay: 2. Acyclic isoprenoid alkanes in Kimmeridge shale oils

The C15---C20 isoprenoid alkane composition of Kimmeridge Clay shale oils produced by Fischer assay has been examined, and compared with the isoprenoid composition of corresponding bitumens. C16 and C18 isoprenoid alkanes are generally dominant in shale oils, while pristane (C19) and phytane (C20) dominate in bitumens. A significant proportion of the phytane in many shale oils is derived from simple evaporation of free (bitumen) phytane, while free pristane contributes less to shale oil composition. Some shale oil phytane and a large proportion of pristane is kerogen-derived. Certain shale oils contain lower concentrations of isoprenoid alkanes than corresponding bitumens, suggesting that some free alkane is thermally degraded during pyrolysis. Results thus indicate three sources for shale oil isoprenoid alkanes: thermal evaporation of free alkanes (particularly for phytane), kerogen decomposition, and possibly the cracking of higher homologues for C15---C19 alkanes. Kerogen-derived isoprenoids are suggested to arise by thermal desorption of adsorbed free alkane (particularly for phytane) and from C---O and C---C bonded species (excluding phytane) via postulated clay catalysed hydrogenation of initially formed alkenes. Comparison of shale oil and bitumen pristane/phytane ratios allows groups of oil shales to be defined, dependent on source composition, organic carbon content and maturity. Shale oil pristane/phytane ratios can also help to determine depositional environments and source composition, although maturity, shale mineralogy and competing alkene-forming pyrolytic reactions may also affect the ratios.     

Thermogravimetry and decomposition kinetics of British Kimmeridge Clay oil shale

The characteristics of volatile matter evolution and the kinetics of thermal decomposition of British Kimmeridge Clay oil shale have been examined by thermogravimetry. TG has provided an alternative to the Fischer assay for shale grade estimation. The following relation has been derived relating TG % volatiles yield to the shale gravimetric oil yield: oil yield (g kg^?1) = (TG volatiles, % × 5.82) ? 28.1 ± 14.5 g kg^?1. A relationship has also been established for volumetric oil yield estimation: oil yield (cm³ kg^?1) = (TG volatiles, % × 4.97) – 5.43. TG is considered to give a satisfactory estimation of shale oil yield except in certain circumstances. It is found to be less reliable for low yield shales producing <≈40 cm³ kg^?1 of oil (≈10 gal ton^?1) where oil content of the TG volatiles is low: volumetric yield estimation accuracy is affected by variations in shale oil specific gravity. First order rate constants, k = 4.82 × 10^?5s^?1 (346.3 cm³ kg^?1shale) and k = 6.78 × 10^?5s^?1 (44.6cm³ kg^?1shale) have been obtained for the devolatilization of two Kimmeridge oil shales at 280 °C using isothermal TG. Using published pre-exponential frequency factors, an activation energy of ≈57.9 kJ mol^?1 is calculated for the decomposition. Preliminary kinetic studies using temperature programmed TG suggest at least a two stage process in the thermal decomposition, with two maxima in the volatiles evolution rate at ≈450 and 325 °C being obtained for some samples. Use of published pre-exponential frequency factors gives activation energies of ≈212 and 43 kJ mol^?1 for these two stages in the decomposition.     

Analysis of the structures of the organic materials in Kimmeridge and Oxford clays

Two samples of oil shales, an Oxford clay and a Kimmeridge clay, have been demineralized and the organic matter characterized by ¹³C CPMAS n.m.r. and i.r. spectrometry. The demineralized material was then progressively solubilized utilizing methods used previously for the solubilization of coals. Eventually up to 90% of the Oxford clay and 70% of the Kimmeridge clay were solubilized. The soluble extracts were examined mainly by g.c.-m.s. The dominant volatile species found in the extracts were alkanes, alkylbenzenes, -naphthalenes and -phenols. Distributions of products detectable by g.c.-m.s. in the Kimmeridge clay were similar to those found by Williams and Douglas. The structures of the kerogens showed a close relation with those of coals in that fairly simple mobile molecules appeared to be trapped within a more rigid organic framework, and as diagenesis became more severe the oil shales became more aromatic and the rigid network less tractable.     

Organic geochemistry of the British Kimmeridge Clay: 1. Composition of shale oils produced from Kimmeridge sediments

A series of shale oils produced by Fischer assay of Upper Jurassic Kimmeridgian oil shales, claystones and cementstones from on-shore Britain has been analysed. Oil yields are related to lithology via the quantity of sedimentary organic matter present in each lithologic unit, and also to stratigraphic horizon for certain rich, laterally uniform and persistent units. Shale oils are dark and sulphurous, containing < 50% hydrocarbons. NSO compounds are relatively important in the chromatographically separable fractions, while aliphatic hydrocarbons are usually subordinate. Unimodal normal alkane distributions maximize around nC16, while bimodal distributions have a secondary maximum around nC29. Many alkane gas chromatograms are characterized by a prominent peak due to the nC23 alkane. Certain compositional features are of pyrolytic origin (aromatics, heterocompounds, alkenes), while others are determined by the organic sedimentary input (alkane distributions, prominent nC23 alkane). Broad similarity in geochemical parameters suggests a consistency in the composition of sedimented organic matter. Smaller-scale compositional variations are thought to result from minor fluctuations in the composition of the organic sedimentary input, for example changes in the amount of terrestrial organic detritus reaching the depocentre. Results suggest a dominantly algal or bacterial organic matter source continuously operative throughout much of the Upper Jurassic over the entire region, with a smaller, more variable magnitude contribution from terrestrial sources, probably deposited in a near-shore marine shelf-sea environment under anoxic conditions.     

Characterization of pyrolysis products of harbolite and Avgamasya asphaltites: comparison with solvent extracts

The products of pyrolysis at 525 and 840 °C of two asphaltites from South-Eastern Turkey have been analysed and compared with the bitumen obtained by solvent extraction. The yield of oil product is reasonably similar for all three treatments, with gas (hydrogen, ethene, C₁C₄ alkanes and hydrogen sulphide) being liberated during pyrolysis. Greater percentages of alkanes with shorter chain lengths (along with some alkenes), and of pentane-soluble aromatic oils with reduced molecular masses, are generated during pyrolysis, at the expense of asphaltenes. The extra alkanes are generated partly by the cracking of aromatic side-chains and also from kerogen. Pyrolysis reduces the number of sulphur linkages in the oil, but nitrogen- and oxygen-containing structures are liberated from kerogen during heating.     

N.m.r. study of US Eastern and Western shale oils produced by pyrolysis and hydropyrolysis

Shale oils produced from US Eastern and Western oil shales by pyrolysis and hydropyrolysis processes have been investigated by both ¹H and ¹³C high-resolution n.m.r. techniques. Eastern shale oils produced by hydropyrolysis, and subsequently hydrotreated, were also included. From the n.m.r. data of the shale oils, the average molecular structure parameters were calculated. These parameters quantitatively represent the differences observed in the n.m.r. spectra of the various shale oils because of changes in the chemical composition. Mol percentages of aromatics, olefins, and alkanes were also determined for the shale oils, and show that the composition of the shale oil is dependent upon the geographic origin of the oil shale, the pyrolysis method, and the hydrogenation process. In addition to the study of shale oils, solid-state ¹³C n.m.r. spectra of Eastern and Western oil shales before and after pyrolysis and hydropyrolysis were obtained. The spectral data show that the carbon aromaticities for the Eastern oil shales and shale oils are higher than for the Western oil shale and shale oils. The data also show that hydropyrolysis relative to pyrolysis reduces the amount of residual organic carbon remaining on the spent shales. Carbon aromaticity data for both oil shale and shale oil suggest that the organic moieties present in kerogen may be retained in the shale oils to a greater extent after hydropyrolysis than after pyrolysis.     

Characteristics of oil shale pyrolysis in a two-stage fluidized bed

Rapid pyrolysis of oil shale coupled with in-situ upgrading of pyrolysis volatiles over oil shale char was studied in a laboratory two-stage fluidized bed(TSFB) to clarify the shale oil yield and quality and their variations with operating conditions. Rapid pyrolysis of oil shale in fluidized bed(FB) obtained shale oil yield higher than the Fischer Assay oil yield at temperatures of 500-600 ℃. The highest yield was 12.7 wt% at 500 ℃ and was about1.3 times of the Fischer Assay oil yield. The heavy fraction(boiling point 350 ℃) in shale oil at all temperatures from rapid pyrolysis was above 50%. Adding an upper FB of secondary cracking over oil shale char caused the loss of shale oil but improved its quality. Heavy fraction yield decreased significantly and almost disappeared at temperatures above 550 ℃, while the corresponding light fraction(boiling point 350 ℃) yield dramatically increased. In terms of achieving high light fraction yield, the optimal pyrolysis and also secondary cracking temperatures in TSFB were 600 ℃, at which the shale oil yield decreased by 17.74% but its light fraction yield of 7.07 wt% increased by 86.11% in comparison with FB pyrolysis. The light fraction yield was higher than that of Fischer Assay at all cases in TSFB. Thus, a rapid pyrolysis of oil shale combined with volatile upgrading was important for producing high-quality shale oil with high yield as well.     

Pyrolysis behaviour of Australian oil shales in a fluidized bed reactor and in a material balance modified Fischer assay retort

The pyrolysis behaviour of several Australian oil shales was determined using the material balance modified Fischer assay and a bench-scale fluidized bed pyrolysis reactor, with nitrogen or steam as the sweep gas. The assay oil yield, which ranged from 5.3 to 15.7 wt% of the dry shale, did not correlate well with the organic carbon contents of the shales. However, under both assay and fluidized bed pyrolysis conditions, a shale of high kerogen H/C had high organic carbon conversions to oil. Compared with the Fischer assay, nitrogen pyrolysis gave 7 ± 4 wt% more oil for the shales studied, and steam pyrolysis gave 15 ± 4 wt% more oil for all shales except one, which showed a 35 wt% increase in oil yield. However, the oils from both nitrogen and steam pyrolysis had lower H/Cs, higher sulphur and nitrogen contents, and more high boiling point fractions than those from the Fischer assay. Nitrogen pyrolysis oils were of higher quality than those produced by steam pyrolysis. With steam as the sweep gas, much more hydrogen and hydrogen sulphide were produced for all shales; in most cases, there was also more carbon monoxide and less hydrocarbon gases.     

Aromatic and hetero-aromatic compositional changes during catalytic hydrotreatment of shale oil

Oil shale from the Kimmeridge Clay, of Jurassic age from the UK was pyrolysed in a 5 kg fixed bed reactor at 525°C in a nitrogen atmosphere. The derived shale oil was then hydrotreated at 15.0 Mpa pressure and 400°C in a stirred reactor with a nickel–molybdenum (Ni–Mo) catalyst and residence times from 8 to 56 h. The shale oils were analysed for polycyclic aromatic hydrocarbons (PAH) and for nitrogen-PAH (PANH) and sulphur-PAH (PASH), before and after hydrotreatment. The results showed that generally the higher molecular weight three and four ring PAH decreased with increasing hydrotreatment time, however, single ring aromatic compounds and two ring PAH were increased. Nitrogen and sulphur containing PAH were significantly reduced in concentration in the oils with increasing hydrotreatment time to reach negligible concentrations after 56 h. The reduction in PANH and PASH coincided with a reduction in the overall nitrogen and sulphur contents of the oils.     

Studies on the oxidation of enamines with molecular oxygen. I. Oxidation of Some Piperidino Alkenes

In the autoxidation of 1-piperidinocyclohex-1-ene ( 1 ), 1-piperidinobut-1-ene ( 2 ), 3-piperidinopent-2-ene ( 3 ), and 1-piperidino-2-methyl-prop-1-ene( 4 ) only products of an oxidative attack at the CC-double bond are formed. Both α-aminoketones, the products of the rearrangement of primarily formed epoxides, and products of the oxidative session of the CC double bond are obtained. As a side reaction some hydrolysis of the starting enamines takes place. This hydrolysis proves that some water must be formed during the enamine oxidation.     

Compositional and structural variations of bitumen and its interactions with mineral matters during Huadian oil shale pyrolysis

Thermal bitumen is an important intermediate derived from kerogen decomposition during oil shale pyrolysis. In this study, free bitumen (FB) and bound bitumen (BB) were obtained by extracting oil shale chars (300–550 °C) before and after demineralization, and then analyzed by liquid chromatography fractionation, Fourier transform infrared spectroscopy, and gas chromatography/mass spectrometry. The FB yield first increased and then decreased with increasing temperature, and the maximum value was 2.10% at 400 °C. The decarboxylation of acids and decomposition of esters at 350–450 °C decreased the content of these compounds. Meanwhile, the intense cracking reactions of aliphatic compounds and alkyl chains at 400–450 °C decreased the carbon chain lengths and molecular weights of these compounds. From the analytical results obtained for the BB fractions, we suggest that some carboxylic acids or carboxyl group-containing compounds may be trapped on carbonate particles by the formation of Ca₂₊COO_? bonds, whereas other oxygenated compounds (e.g., esters and phenols) can be adsorbed preferentially by clay minerals through Lewis acid-base interactions.     

Zur Pyrolyse von 3-Ethylpent-2-en – Ein weiterer Hinweis auf eine Homoallyl-Umlagerung

Pyrolysis of 3-Ethylpent-2-ene — a Further Evidence for a Homoallylic-Rearrangement The pyrolysis of 3-ethylpent-2-ene has been studied under conditions of steam cracking in the temperature range 600—700°C in a laboratory scale tubular reactor. The main products of decomposition were methane, 2-ethylbutadiene and isoprene. The majority of products obviously arose from H abstraction and radical addition, typical for radical chain reactions in olefins decomposition including phenomena resulting from allylic resonance. The formation of isoprene, however, could only be explained by a reaction network including a homoallylic rearrangement.     

微波功率对油页岩热解的影响

对甘肃油页岩进行了微波热解实验研究,考察了油页岩在微波场中的升温特性及功率对页岩油、半焦、干馏气产率和组成的影响。结果表明：在微波场中油页岩干馏终温可达800℃以上;不同功率下干馏气组成不同,在480 W时干馏气中有效组分（H2＋CH4＋CO）达55%以上;随着功率的增大,半焦产率逐渐减小;页岩油产率随功率先增加后减小,在480 W时达到最大值13.5%;而干馏气产率随功率逐渐增大,在480 W时可达10%。     

Rapid and catalytic pyrolysis of corn stalks

Non-catalytic and catalytic rapid pyrolysis of corn stalks was studied in a tubular fixed-bed reactor. The optimum operating conditions giving the highest liquid yield was determined as pyrolysis temperature of 500 °C, sweeping gas flow rate of 400 cm³ min^− 1 and heating rate of 500 °C min^− 1. In the catalytic process, rapid pyrolysis of stalks was performed at the optimum conditions with catalysts such as ZSM-5, HY and USY. The highest liquid yield from the catalytic pyrolysis was 27.55% with ZSM-5, while the oil from non-catalytic pyrolysis was 33.30%. In the last part, various spectroscopic and chromatographic methods were applied for characterization of bio-oils. Although catalytic pyrolysis converts the long chains of alkanes and alkenes of the oils into lower weight hydrocarbons, the obtained oil yields were lower than those of non-catalytic pyrolysis. USY catalyst gives the highest amount of aromatics among the catalysts used. Moreover, TG–DTA analyses were applied on raw materials to investigate thermal degradation of corn stalks and calculate the kinetic parameters.     

The pyrolysis of scrap automotive tyres: The influence of temperature and heating rate on product composition

Shredded automotive tyre waste was pyrolysed in a 200 cm³ static batch reactor in a N₂ atmosphere. The compositions and properties of the derived gases, pyrolytic oils and solid char were determined in relation to pyrolysis temperatures up to 720 °C and at heating rates between 5 and 80 °C min⁻¹. As the pyrolysis temperature was increased the percentage mass of solid char decreased, while gas and oil products increased until 600 °C after which there was a minimal change to product yield, the scrap tyres producing approximately 55% oil, 10% gas and 35% char. There was a small effect of heating rate on the product yield. The gases were identified as H₂, CO, CO₂, C₄H₆, CH₄ and C₂H₆, with lower concentrations of other hydrocarbon gases. Chemical class composition analysis by liquid chromatography showed that an increase in temperature produced a decrease in the proportion of aliphatic fractions and an increase in aromatic fractions for each heating rate. The molecular mass range of the oils, as determined by size exclusion chromatography, was up to 1600 mass units with a peak in the 300–400 range. There was an increase in molecular mass range as the pyrolysis temperature was increased. FT-i.r. analysis of the oils indicated the presence of alkanes, alkenes, ketones or aldehydes, aromatic, polyaromatic and substituted aromatic groups. Surface area determination of the solid chars showed a significant increase with increasing pyrolysis temperature and heating rate.     

不同碱金属乌桕油皂微波极化脱羧成烃类燃料的工艺

不饱和脂肪酸盐微波极化条件下更容易脱羧成烃,本研究分别以氢氧化锂、氢氧化钠、氢氧化钾皂化乌桕油,以不同碱金属乌桕油皂化物和乌桕油为研究对象,在恒定的微波功率下裂解脱羧成烃,通过GC-MS等分析裂解产物,微波能选择性地加热乌桕油皂羧基端,不饱和键在微波极化过程中与碳负离子中间体形成P-?共轭体系,使裂解反应（脱羧、端烯化、异构化和芳构化等）顺利进行。皂化物极性越大,升温速率越快,液体烃类产率越高,脱羧效果越明显,裂解液体的密度为0.825～0.865 g/cm3,黏度为2.10～2.55 mm2/s,与柴油的性质非常相似,从而证明微波极化乌桕油皂脱羧制烃类燃料的可行性。     

煤系共伴生油页岩热解残渣利用技术

油页岩残渣是油页岩热解过程中排放的固体废物,约占油页岩的80%~90%。中国油页岩残渣利用率较低,残渣堆积量日益增多,后续问题十分突出。煤系油页岩残渣的资源化利用成为油页岩热解提油产业发展的瓶颈。介绍了油页岩热解加工利用现状及其残渣在废水处理和废气吸附方面的应用,分析了当前页岩热解残渣利用过程中存在利用方式单一的问题,并结合油页岩热解残渣结构和组成的特殊性,提出了油页岩残渣用作环保材料如吸附剂的发展方向。     

神木烟煤与桦甸油页岩的共热解特性

采用热重分析仪和固定床反应器研究了神木烟煤和桦甸油页岩的混合共热解特性及协同作用机制. 结果表明,神木煤与桦甸油页岩混合共热解的失重率高于计算值,表明二者在热解和挥发分逸出过程中存在相互作用,促进了挥发分释放,减少了半焦生成. 煤与油页岩的协同作用可增加热解油收率、降低半焦和水收率. 油页岩与煤质量比为1:1时,所得油收率最高,为9.84%,比计算值提高8.8%. 共热解有助于提高轻质油含量和收率,油页岩与煤质量比为1:4时,轻质油含量超过80%,收率约为7.5%,比计算值分别提高了8%和11.2%,表明添加少量油页岩可明显提高热解油品质. 共热解过程中油页岩产生的富氢组分及自由基能抑制煤热解产生的芳香族化合物的聚合反应,促进芳烃向产物油转化,提高热解油的收率和品质.     

Effect of the concentration of organic matter on the yield of thermal bitumen from the baltic oil shale kukersite

The low-temperature (360°C) autoclave pyrolysis of the oil shale kukersite, which has carbonatetype mineral matter, with various organic matter (OM) concentrations of 31.8–90.1% and the separation of the pyrolyzate from the mineral matter at the stage of thermal bitumen formation by extraction with various solvents such as benzene, ethanol, and their mixtures were considered. The OM distribution between a gas, an extract, and a residue insoluble in a given solvent was characterized. It was found that, in the pyrolysis of oil shale in an autoclave, the extract yield on an OM basis somewhat increased as the OM content of oil shale increased because the concentration of OM adsorbed on the mineral matter of oil shale remained constant.     

Monitoring oil shale retorts by off-gas alkenealkane ratios

Data from 125 kg and 6000 kg oil shale pilot retorts indicate that off-gas ethene/ethane and $\text{propene}\text{propane}$ ratios are useful for monitoring retort performance. Information supplied by these ratios may be particularly valuable for in situ retorts. Since response time is short, the ratios may be useful for control as well as diagnosis of retort operation. The pilot retort data show that, for a smoothly operating combustion retort, the ratios provide an estimate of the effective shale heating rate. Rough operation, indicated by wide fluctuations in peak temperature, is reflected by fluctuations in the ratios. Particularly high ratios indicate exposure of oil to excessive temperature and/or oxygen with resultant loss of oil yield. A relation between elevated ratios and oil loss via conversion to gaseous hydrocarbons is demonstrated for retorting of shale blocks immersed in a bed of smaller shale particles. Chemical interpretation of the data is made by comparison with the thermal cracking of straight-chain hexadecane and pyrolysis of polyethylene. A free radical, chain reaction scheme is proposed. The dependence of $\text{alkene}\text{alkane}$ values on heating rate is attributed to competition between carboncarbon bond cleavage versus hydrogen atom-transfer processes. The contribution of oxidation reactions to elevated $\text{alkene}\text{alkane}$ values is also discussed.