Hydrotreating coal-derived liquid distillation fractions. 1. Study of single-stage treated products for transport fuel use

A coal-derived liquid distillate obtained from catalytic hydrogenation of Wandoan coal at Australian Coal Industry Research Laboratories has been fractionated into three main distillation fractions: naphtha, kerosine, and diesel. Compositional properties of each fraction are reported, particularly elemental, ¹H and ¹³C n.m.r. and h.p.l.c. results. Hydrorefining of each fraction was undertaken in a trickle-bed reactor at various conditions using commercial nickel-molybdenum hydrotreating catalysts. The hydrotreated liquid products were assessed for transport fuel use or as feedstocks for further processing.     

Structural characterization of Saudi Arabian heavy crude oil by n.m.r. spectroscopy

Saudi Arabian heavy crude oil was separated into six fractions, including five distillate fractions (<93, 93–204, 204–260, 260–343 and 343–454 °C) and a >454 °C distillation residue. Each fraction was analysed by ¹H and ¹³C n.m.r. spectroscopy, and combined gained information from these analyses provided reliable average structural parameters. These included estimation of aliphatic and aromatic content, average paraffinic chain length, and estimation of hydrogen, methyl and alkyl bearing aromatic carbons for each of the six fractions. The extent of branching in paraffinic chains and amount of aromatic bridgehead carbons were also calculated.     

Analysis of a coal-derived liquid obtained by mild hydrogenation: 3. Acid,base and polar fractions

Polar fractions of a coal-derived liquid obtained by mild hydrogenation of Japanese Taiheiyo coal were investigated. The acid fraction was mainly composed of dimethyl or trimethyl phenols with a minor content of indanols. Z = − 7 N (tetrahydroquinoline) and − 9 N (octahydro-phenanthridine/acridine) series were dominant in the base fraction. Neutral oil was separated into six fractions (DS01–06) by vacuum distillation and each fraction was further separated into saturate, aromatic and polar fractions by liquid chromatography. The polar sub-fractions of DS01 (b.p. 186–281 °C) and DS02 (b.p. 281–305 °C) were analysed by f.i.m.s. and g.c.-m.s. Phenols and tetralinols (or indanols) both with long alkyl chains were major components of these fractions. Those of DS03–DS06, which were too complex to analyse by g.c. only, were repeatedly hydrogenated to eliminate the functional groups and then dehydrogenated to simplify the subsequent analysis. The components in the hydrogenated/dehydrogenated products were identified by g.c. and g.c.-m.s. and compared with the type analysis data obtained from f.i.m.s. of each polar subfraction assuming that those aromatic nuclei having hydroxyl functional groups are partially hydrogenated, if at all. Thus a quantitative analysis of the neutral polar fractions was calculated, which shows them to be composed of only seven kinds of aromatic nuclei.     

Correlation of chemical constitution and boiling point with separation behaviour during distillation of coal liquid

The separation behaviour of coal hydrogenation liquids during distillation was clarified using correlations between chemical structural factors (R_a, R_n and C_al) and boiling points of narrow cut distillation fractions. The separation order according to chemical structure at given distillation temperatures was represented on a three-dimensional R_aR_nC_al diagram. In this diagram, one axis represents the number of aromatic rings in the structure of a compound (R_a), one represents the number of naphthenic rings (R_n), and the third axis represents the number of alkyl carbons (C_al). This diagram is believed to be an appropriate way to handle the analysis of molecules in coal liquids, which are extremely complicated mixtures. Kerosene, light oil and heavy oil from coal liquid were also characterized on this diagram. The distribution ranges of components during separation in distillation agree fairly well with their corresponding distillation temperature range on the R_a R_nC_al diagram proposed. The distillation curve was predicted from the structural analyses with h.p.l.c./g.c.-m.s. and constitution-boiling point correlation as shown in the R_aR_nC_al diagram.     

Composition of an SRC-II coal-derived liquid: Changes in composition resulting from hydrotreatment at different levels of severity

An SRC-II coal-derived liquid fuel and eight upgraded coal liquids derived from it were separated into chemical class-type fractions by preparative liquid chromatography. Mass and infrared spectroscopy, gas chromatography and non-aqueous titration were used, together with the mass balance data from the l.c. separations, to describe changes in composition of the liquids as a function of severity of hydrotreating conditions. The relative abundance of the following classes of compounds was determined in each of the liquids : saturates, monoaromatics, diaromatics, polyaromatics, total acids, total bases, hydroxyarenes, strong acids, pyrrolic benzologs, carbonyl compounds (amides), basic diarylamines, basic monoarylamines, azaarenes, and strong bases. The results are discussed in the light of known reaction pathways for aromatic ring saturation and heteroatom removal.     

Compositions of distillate recycle solvents derived from direct coal liquefaction in the SRC-I process: 1. Hydrocarbons

The qualitative and quantitative compositions of 260–427 °C distillate recycle solvents derived from direct liquefaction of subbituminous Wyodak coal and bituminous Kentucky $\text{9}\text{14}$ coal in the SRC-I process are discussed. A liquid chromatography method which involves a column switching technique was used to provide solubility characteristics and compound-class compositions. The hydrocarbon compounds, which accountfor> 60 wt% of the distillate recycle solvents, were further analysed using a unique combination of high-performance liquid chromatography (h.p.l.c.) and field ionization mass spectrometry (f.i.m.s.). Thirty homologous series were identified. Carbon number and distribution and concentration of the homologous series were determined. The h.p.l.c./f.i.m.s. method unravelled various hydroaromatic types which otherwise would be very difficult or impossible to determine.     

Determination of functional groups of coal-derived liquids by n.m.r. and elemental analysis

A new method of structural analysis was applied to a group of hydroliquefied coal samples. The method uses elemental analysis and n.m.r. data to estimate the concentrations of functional groups in the samples. The samples included oil and asphaltene fractions obtained in a series of hydroliquefaction experiments, and a set of nine fractions separated from a coal-derived oil. The structural characterization of these samples demonstrates that estimates of functional group concentrations can be used to provide detailed structural profiles of complex mixtures and to obtain limited information about reaction pathways.     

Application of short path distillation for recovery of polyphenols from deodorizer distillate

During physical refining of oil derived from ‘high temperature short time’ (HTST) pretreated rapeseeds, polyphenols are separated from the oil during deodorization and accumulate together with other high‐value minor compounds in the so‐called deodorizer distillate. For recovery of these compounds single‐stage and multistage short path distillations were carried out in a laboratory scale apparatus at evaporation temperatures between 110 and 170°C and pressures between 0.006 and 0.01 mbar. In addition, the removal of traces of pesticides from rapeseed deodorizer distillate was investigated. It was observed that these compounds can be separated from deodorizer distillate by means of short path distillation very effectively. On the basis of these experiments, a recovery process for polyphenols was proposed involving short path distillation, acid catalyzed esterification with methanol, solvent crystallization and solvent extraction processes. The final product was a polyphenol enriched extract containing about 14% of polyphenols. A polyphenol recovery of 50% is considered to be reachable and fractions rich in tocopherols and sterols may be obtained as by‐products.     

Characterization of coal-derived liquids by C n.m.r. and FT-i.r. spectroscopy: Fractions of middle and heavy distillates of SRC-II

Coal-derived products of the SRC-II liquefaction of Powhatan Mine (Pittsburgh Seam) bituminous coal were separated into various fractions either by solvent extraction or by distillation. Subsequently, the middle and heavy distillates were separated by sequential elution solvent chromatography into fractions differing in chemical functionality. These fractions were examined by ¹³C n.m.r. and FT-i.r. spectroscopic techniques. In addition to developing the techniques, the work was undertaken to relate the product composition to the possible reactions occurring during the solvent-induced pyrolytic fragmentation of coal. The bulk of the SRC-II generated middle distillate is composed of two-ring nonpolar aromatic compounds, tetralins, one-ring phenols, indoles, and some alkanes. The heavy distillate contains three-and four-ring systems.     

Analysis of a coal-derived liquid using highpressure liquid chromatography and synchronous fluorescence spectrometry

Synchronous fluorescence spectra of model polycondensed aromatic hydrocarbon molecules were recorded and used to identify the number of condensed rings in the aromatic molecules. A coal-derived liquid from Yubarishinko coal was initially separated into fractions having different number of condensed aromatic rings, and each fraction was further divided into narrow fractions having different numbers of carbon atoms. These fractions were studied using synchronous fluorescence spectroscopy. Results indicate the potential usefulness of synchronous fluorescence spectroscopy as a method of analysis of complex mixtures as coal-derived liquids despite the limitation of the method that some molecules give only weak peaks. Several components in some fractions were identified by a combination of synchronous fluorescence spectra and conventional excitation and emission fluorescence spectra.     

Characterization of high-boiling petroleum distillate fractions by proton and 13C nuclear magnetic resonance spectrometry

High-boiling (535–675 °C) distillate fractions of Wilmington (Calif. USA) and Gach Saran (Iran) crude oils were separated into saturate, monoaromatic, diaromatic and polyaromatic-polar fractions by passage through a silica-gel—alumina dual packed chromatography column. These fractions were further separated on the basis of molecular volume by gel-permeation chromatography (g.p.c.). Select g.p.c. fractions were then analyzed by ¹H and ¹³C n.m.r. spectroscopy. The fraction of aromatic carbons (Ar-C) of the total carbon content of a given series of g.p.c. fractions, obtained directly from the ¹³C n.m.r. spectra, showed a significant range of values (e.g. 13.2% to 29.2%) within each series. Furthermore, the values of %Ar-C within a series of g.p.c. fractions showed a maximum in each case. No such maximum was observed in the ¹H n.m.r. spectra for the fraction of aromatic proton (%Ar-H) content compared to the total proton content of any of the g.p.c. fraction series. Signals observed in the ¹³C n.m.r. spectra confirmed the presence of aliphatic chains attached to aromatic structures in the monoaromatic, diaromatic and polyaromatic-polar g.p.c. series of each distillate fraction. Well-defined signals, not attributable to straight-chain aliphatic material, were also observed in the ¹³C n.m.r. spectra. Comparison of the chemical shifts of these ¹³C n.m.r. signals with those spectra of model compounds obtained experimentally, and with appropriate systems in the literature, strongly suggested the presence of saturated terpenoid-like structures as well as the presence of methyl groups in sterically hindered positions on an aromatic ring system. Gated decoupling techniques and the use of a relaxation agent were used to overcome the deleterious effects of slow relaxation times and Nuclear Overhauser Enhancement (NOE) on the analytical quality of the ¹³C n.m.r. spectra.     

Analysis of polar compound classes in SRC-II liquids: Comparison of non-aqueous titrametric,i.r. spectrometric and h.p.l.c. methods

Results for various types of polar compounds in SRC-11 coal-derived liquids and other fuels were obtained by one or more of the three analytical methods: non-aqueous titration, i.r. spectroscopy and h.p.l.c. Practical aspects as well as precision, accuracy and assumptions necessary for effective application of each of the methods are discussed. H.p.l.c. is applicable to the widest variety of compound types, is the most rapid, most sensitive and shows the best promise for increased development and improvement. Application and development of these techniques is a logical step toward improving process monitoring, catalyst development, toxicological screening and general fuel analysis.     

Relationship between solvent-derived and compound-class fractions in coal-derived distillates and vacuum still bottoms

High-boiling SRC-1 process-derived distillable liquids and nondistillable vacuum still bottoms (VSB) from Wyodak and Kentucky 9/14 coals were separated into solvent-derived and compound-class fractions using Chromatographic techniques. The fractions were characterized using infrared spectrometry, proton nuclear magnetic resonance spectrometry, field ionization mass spectrometry, and elemental analysis. Emphasis was placed on the determination of the composition of oils and asphaltenes. Results showed that oils and asphaltenes consist of the same compound classes: hydrocarbons, nitrogen compounds, and hydroxyl aromatics. The main differences between the oil and asphaltene fractions are in concentrations of compound classes. It was found that oils are rich in hydrocarbons while asphaltenes are rich in hydroxyl aromatics. Also, oils and asphaltenes contain compounds of the same homologous series, and molecular weight is not a factor which differentiates oils and asphaltenes. Components in VSB oils have higher molecular weights than components in distillate asphaltenes. Molecular structure rather than molecular weight is a major parameter that determines solubility of coal-derived liquids.     

Analysis of coal-derived liquid obtained by mild hydrogenation: 1. Neutral oil distilling at 186–343 °C

Taiheiyo coal (77% C) was hydrogenated under mild conditions to preserve the unit structure of the parent coal as far as possible. The n-hexane-solubles (yield, 49.8 wt% daf coal) were washed with acid and base and the neutral material separated into 7 fractions by vacuum distillation. The three lower boiling fractions, DS01 (7.3 wt% neutral oil), DS02 (3.6 wt%) and DS03 (4.8 wt%), were further separated by liquid chromatography into hydrocarbon subfractions which were analysed by g.c. and g.c.-m.s. Saturates are most abundant, especially the n-alkanes which comprise ≈9–13 wt% of each fraction. The saturates also contain isoprenoids (C₁₅, C₁₆, C₁₈, C₁₉ and C₂₀), branched alkanes, n-alkyl cyclohexanes, terpanes and others. With increasing boiling point, smaller amounts of monoaromatic ring hydrocarbons and more di- or triaromatic ring hydrocarbons are found. The alkyl side-chains of aromatic nuclei have a large carbon number, especially in the smaller rings. The existence of phenyltetralin or phenylnaphthalene shows a feature of bonding between aromatic nuclei.     

分子蒸馏新技术在天然香料分离中的应用

利用分子蒸馏新技术从天然香料肉桂油和山苍子油中分离提纯肉桂醛和柠檬醛,用GC–MS联用仪对分离物中肉桂醛和柠檬醛的质量分数进行分析,重点研究了压力和温度等主要影响因素。结果表明：在其他条件一定时,从山苍子油中分离柠檬醛较优的蒸馏压力和蒸馏温度分别为0.15 kPa和45 ℃,此条件下可获得柠檬醛含量为98.2%的馏余物产品;从肉桂油分离提纯肉桂醛较理想的蒸馏压力和蒸馏温度分别为0.2 kPa和60 ℃,此条件下可获得肉桂醛含量为98.7%的馏出物产品。     

Structures of the distillates obtained from hydrogenation and pyrolysis of Liddell coal

The structures of the distillable fractions (oils, b.p. >200 °C and volatile fractions, b.p. <200 °C) of the products from hydrogenation and pyrolysis of an Australian bituminous coal (Liddell) were investigated by gas chromatography-mass spectrometry (g.c.-m.s.) and nuclear magnetic resonance spectroscopy (n.m.r.). The distillable oil generated from hydrogenation of Liddell coal at 400 °C, using nickel molybdenum ortin (II) chloride as catalyst and tetralin or recycle oil as vehicle, consisted of a wide range of compounds. Long straight-chain alkanes were important components together with alkyl-substituted benzenes and tetralins, phenols and polycyclic material. When yields were low, as in the case of catalytic experiments with nickel molybdenum catalysts and no vehicle, isoprenoids could be identified. When a substantial proportion of the coal was converted to oil, branched-chain alkanes were not important components of the product. The replacement of tetralin and nickel molybdenum catalyst with stannous chloride reduced the amounts of methyl tetralins in the product. When tetralin was replaced by recycle oil, alkanes were more important components of the liquid products. Although alkenes were absent in oils generated by hydrogenation, they were important components of oils generated by pyrolysis. The highly volatile fractions (b.p. <200 °C) produced during hydrogenation consisted of alkyl-substituted benzenes, decalins, methylindan and straight-chain alkanes. Straight-chain alkanes were more abundant in those volatile fractions generated by hydrogenation with recycle vehicle than with tetralin. The Brown-Ladner method of estimating the fraction of aromatic carbon in distillable oils was adequate for less volatile fractions but was inadequate for the highly volatile fractions because of the large amounts of α-CH₃ and β-CH₃ alkyl groups present.     

Characterisation of separated melamine—formaldehyde adducts (methylolmelamines) and adduct mixtures by h.p.l.c. and by n.m.r. and u.v. spectroscopy

Most of the individual methylolmelamines that occur in melamine–formaldehyde adduct mixtures have been separated by preparative high-performance liquid chromatography (h.p.l.c.) and recovered in amounts sufficient to allow their characterisation by high-field ¹H- and ¹³C-n.m.r. Particular attention has been paid to the chemical shifts of the aromatic azine carbons of the melamine nuclei. These carbon shifts are shown broadly to be in agreement with some values previously published, but additional assignments have been made. It is shown that a satisfactory quantitative analysis of the methylolmelamines in a melamine–formaldehyde adduct mixture can be carried out either by h.p.l.c. or by ¹³C-n.m.r.     

Purification of steryl esters from soybean oil deodorizer distillate

Soybean oil deodorizer distillate (SODD) contains steryl esters in addition to tocopherols and sterols. Tocopherols and sterols have been industrially purified from SODD but no purification process for steryl esters has been developed. SODD was efficiently separated to low b.p. substances (including tocopherols and sterols) and high b.p. substances (including 11.2 wt% DAG, 32.1 wt% TAG, and 45.4 wt% steryl esters) by molecular distillation. The high b.p. fraction is referred to as soybean oil deodorizer distillate steryl ester concentrate (SODDSEC). We attempted to purify steryl esters after a lipase-catalyzed hydrolysis of acylglycerols in SODDSEC. Screening of industrially available lipases indicated that Candida rugosa lipase was most effective. Based on the study of several factors affecting hydrolysis, the reaction conditions were determined as follows: ratio of SODDSEC/water, 1∶1 (w/w); lipase amount, 15 U/g reaction mixture; temperature, 30°C. When SODDSEC was agitated for 24 h under these conditions, acylglycerols were almost completely hydrolyzed and the content of steryl esters did not change. However, study with a mixture of steryl oleate/trilinolein (1∶1, w/w) indicated that about 20% of constituent FA in steryl esters were exchanged with constituent FA in acylglycerols. Steryl esters in the oil layer obtained by the SODDSEC treatment with lipase were successfully purified by molecular distillation (purity, 97.3%; recovery, 87.7%).     

1H- and 13C-n.m.r. studies on naphtha and light distillate saturate hydrocarbon fractions obtained from in-situ shale oil

Shale oil, obtained from an in-situ oil shale experiment, from the Green River formation in Southwestern Wyoming was thermally fractionated into naphtha, light distillate, heavy distillate and residue fractions. The naphtha and light distillate fractions were further separated into saturates, olefins and aromatic subfractions. ¹H- and ¹³C-n.m.r. spectra and mass spectral data were obtained for the saturated hydrocarbons of the naphtha and light distillate fractions. Resonances in the n.m.r. spectra were assigned to normal alkanes and to methyl- and dimethyl-branched alkanes. The composition as determined by n.m.r. of the naphtha saturates was found to be ≈82% straight-chain alkanes with an average carbon-chain-length of ≈C₁₁ and ≈18% branched/cyclo-alkanes. The composition of the light distillate saturates was found to be ≈ 69% straight-chain alkanes with an average carbon-chain-length of ≈C₁₅and ≈31% branched/cyclo-alkanes. The dimethyl-branched alkanes in both saturate fractions were proposed to have the molecular substructure of saturated isoprenoids. In the naphtha saturates the isoprenoid substructure

is evident. However, in the light distillate saturates, both isoprenoid substructures,

and

, are evident. ¹³C spin-lattice re-laxation times also were determined for the dominant resonances observed in the spectra of the naphtha and light distillate saturates. Relaxation times for the molecular species in the naphtha saturate fraction were observed to be longer than those observed for the light distillate saturate fraction. It was found that the ratio of the overall average relaxation times for the naphtha and light distillate saturate fractions corresponded to the inverse ratio of the average molecular weights of each fraction as determined from average alkane carbon-chain-length determination. Intermolecular (segmental) motion of the carbon chain of the straight-chain alkanes in both saturate fractions is also evident from the relaxation time measurements.     

Studies on the composition of some distillate waxes

Structural composition of two distillate waxes obtained from Ankleshwar crude oil tank bottoms have been determined using physical properties correlations, high temperature g.l.c., ¹H-n.m.r. and ¹³C-Fourier transform n.m.r. spectroscopy. Both waxes seem to contain predominantly n-paraffins.