Fluorescence spectroscopic analysis of coal-derived liquids: Determination of polycyclic aromatic hydrocarbon ring systems and identification of basic nitrogen heterocycles

Fluorescence spectroscopy was used to determine certain polycyclic aromatic ring systems in a flash pyrolysis tar, a hydrogenated flash pyrolysis tar and a coal hydrogenation oil after a simple Chromatographie separation. The method used led to semi-quantitative determination of aromatic ring systems rather than individual polycyclic aromatic hydrocarbons. The identification of basic nitrogen heterocycles in a coal pyrolysis tar and a coal hydrogenation oil is also reported. The basic fraction from the asphaltene and the oil of the flash pyrolysis tar did not require further separation prior to identification of the various bases.     

Characterization of coal liquids by 13C n.m.r. and FT-i.r. spectroscopy — fractions of oils of SRC-I and asphaltenes and preasphaltenes of SRC-I and SRC-II

Coal-derived products of SRC-I liquefaction of Blacksville coal and vacuum tower bottoms (VTB) of SRC-II liquefaction of Powhatan mine coal (both bituminous and from the Pittsburgh Seam) were separated into fractions by solvent extraction. The SRC-I was first extracted with ethylacetate, and solubles were subsequently separated into oils and a mixture of asphaltenes and preasphaltenes (APA). The VTB was Soxhlet extracted with pentane to remove any residual oils, followed by tetrahydrofuran to recover APA. The APA portions were then separated by sequential elution solvent chromatography (SESC) into fractions differing in chemical functionality, and then examined by ¹³C n.m.r. and FT-i.r. spectroscopic techniques. APA are intermediates and end products of coal liquefaction. SRC-II APA are of higher molecular weight than the APA of SRC-I. The lower numbered fractions of APA of SRC-I in SESC separation have the same functional groups as the corresponding fractions of middle and heavy distillates. However, the higher numbered fractions are rich in oxygen, which is mainly in carbonyl groups. Part of the carbonyl groups are in esters which cross-link aromatic clusters. Therefore, APA and the coal itself are ‘oligomeric’ in structure, with aromatic clusters linked by carbon bridges with different functional groups. The nature of carbonyl groups in APA has been analysed in detail.     

Application of the DEPT pulse sequence for the generation of 13CHn subspectra of coal-derived oils

The application of the recently developed DEPT pulse sequence for the generation of ¹³CH_n subspectra of coal-derived oils is determined. The technique is able to generate subspectra with accurate cancellation of signals of unwanted multiplicity for complex oil mixtures containing broad and overlapping resonances. However, the use of signal intensities in DEPT subspectra to determine quantitatively the amounts of CH_n groups present in oil mixtures suffers in accuracy due to variable polarization transfer and relaxation rates.     

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.     

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 upgraded SRC-11 and H-coal liquid products

Upgraded coal-derived liquids obtained from catalytic hydroprocessing of SRC-11 and H-coal syncrudes have been studied by i.r., p.m.r., g.c.-m.s., and silica gel chromatography. With increase in residence time, nitrogen, oxygen and aromatics decrease, while naphthenes increase substantially. All the upgraded liquids show low viscosity at 298 K (1.3–1.4 mN s m^?2), even though saturate and aromatic fractions varied with processing severity. In the aromatic-1 fraction, 1 -ring aromatics increase, and 3-ring aromatics decrease, with increase in severity of hydroprocessing. G.c.-m.s. analyses indicate a marked qualitative similarity for saturate and aromatic fractions irrespective of syncrude source. Only the heavier end of the aromatic-1 fraction is noticeably different. Tentative identifications based on m.s. and g.c. retention times are made for most of the significant components. 600 M Hz p.m.r. spectra of the upgraded SRC-11 and H-coal liquids appear identical, but the n.m.r. difference technique revealed slight differences between the two liquids in concentrations of certain species.     

化学沉淀法预处理高浓度氨氮废水的影响因素

在高浓度氨氮废水中投加一定质量的MgSO4.7H2O和Na2HPO4.12H2O,使氨氮生成沉淀物MgNH4PO4.6H2O得以除去。研究了化学沉淀法预处理高浓度氨氮废水的影响因素,通过正交实验得出废水pH值、反应物摩尔比和氨氮质量浓度对氨氮去除率的影响较大。     

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.     

离子交换色谱法分离硼同位素的研究进展

综述了离子交换色谱法分离硼同位素的进展。在目前的研究方法中,主要采用强碱性阴离子交换树脂、弱碱性阴离子交换树脂和硼特效树脂作为柱填充材料,本文对于这3种树脂的优缺点进行了比较,最后对影响单级分离因子的因素进行了讨论。表明离子交换色谱法是一种极具潜力的硼同位素分离方法,具有高效节能的特点。     

一步离子交换层析从Cohn组分V上清液中分离人血清白蛋白

传统的血浆低温乙醇沉淀工艺中Cohn组分V上清液由于其乙醇浓度高(体积浓度40％),进一步回收残余蛋白困难而被作为废弃组分.本研究探索了采用一步层析从Cohn组分V上清中回收入血清白蛋白的方法.首先以牛血清白蛋白(BSA)为模型蛋白,比较了三种不同类型介质在不同乙醇-水溶液中的吸附容量.疏水介质在乙醇-水溶液中对BSA...     

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.     

Characterization of extracts of coals and coal-derived products by liquid chromatography using optical activity detection

Extracts from various coals and coal-derived products were studied using liquid chromatography with optical activity detection. The chromatograms show that there are substantial numbers of optically active components in these samples. Since both dextrorotatory and laevorotatory components are present, some mutual cancellation would result if only the bulk optical rotation were measured. The chromatograms are generally rich in structure and contain distinct features which may be good fingerprints for establishing the origins of the coals and monitoring coal processing.     

Characterization of phenols and indanols in coal-derived liquids: Use of Curie-point vaporization gas chromato-graphy/mass spectrometry

A combination of liquid chromatography, gas chromatography and mass spectrometry techniques was used to characterize (alkyl)hydroxyaromatic compounds in several coal liquefaction process fractions, including Exxon Donor Solvent (EDS) atmospheric bottoms and hydrotreated atmospheric bottoms. Solvent extraction failed to provide representative subfractions independent of overall sample composition. Satisfactory subfractionation was achieved by liquid chromatography with increasingly polar solvents on a silica gel column. Subfractions as well as parent samples were analysed by g.c.-m.s. using a Curie-point flash vaporization technique for splitless injection onto glass SCOT columns. C₀-C₆ alkylphenols and C₀-C₃ alkylindanols were almost completely recovered in the benzene/ether subfractions and were found to be the dominant hydroxyaromatic series in both liquids. Whereas phenol distributions were virtually identical in both samples, indanol distributions differed markedly, indicating strong differences in reactivity towards hydrotreatment. The possible role and origin of indanols, the only major class of hydroxyhydroaromatic compounds in these coal-derived liquids, is discussed.     

Ageing of SRC II middle distillate from Illinois No. 6 coal: 1. In presence of copper and oxygen

The middle distillate from Illinois No. 6 solvent-refined coal (SRC II) is relatively stable to ageing by direct oxygenation at 335 K. Metallic copper accelerates oxygen ageing as is evident from an increase in viscosity and formation of pentane-insoluble components, I.r. spectra of aged samples show a significant reduction in the intensity of the free hydroxyl band. FT-i.r. spectra show that oxygen-containing compounds of the coal are concentrated in the pentane-insoluble fraction and that oxygen bubbled into the coal liquid is incorporated into the structure of this fraction. Gel permeation chromatograms also show the formation of aggregates of large molecular-size during ageing. 600-MHz n.m.r. spectra of the aged pentane-soluble fraction are similar to those of the unaged acid-free fraction. These results suggest that copper catalysis in the ageing reaction of the middle distillate involves the polymerization of acidic, phenolic compounds. The aged pentane-soluble fraction possesses the same viscosity as the original coal liquid, but contains less nitrogen and oxygen.     

Application of stimuli responsive polymers for sustainable ion exchange chromatography

Ion exchange processes are widely used in the food, bioprocessing and related industries for the isolation of proteins and other ionic species. Traditional ion exchange resins require salts, acids or bases for releasing adsorbed molecules creating a strong saline waste stream with negative environmental and economic impact. Stimuli responsive polymers (SRPs) with ion exchange functional groups can be used to selectively capture and release charged molecules from a complex mixture using physical stimuli to trigger conformational transitions in the polymer. The structural change of the polymers in response to a stimulus may lead to reduced ligand–target molecule interaction resulting in the release of the captured molecule without the use of chemical reagents, thereby reducing the environmental burden associated with ion exchange processes. The use of temperature responsive polymers has already been demonstrated for such applications at analytical scale. However, little progress has been made to extend these discoveries to the development of materials and methods amenable to industrial scale processing. So far, other SRPs such as, electric, magnetic and light responsive polymers remain largely unexplored for such application. This article discusses the potential of temperature responsive and other SRPs for developing sustainable ion exchange processes. It also highlights the material science and engineering challenges that need to be overcome to bring such processes to industrial application.     

Co-carbonization processes of a petroleum asphalt and coal-derived liquids: An approach to co-carbonization compatibility

Mixtures of three principal carbonizing materials (Kafji vacuum asphalt (KF-VR), solvent-refined coal (SRC) and solvent-treated coal (STC)) with five additives (three Ashland petroleum pitches (A240, A200 and A170), quinoline-soluble residue of steam-cracked crude oil (KP-QS) and coal-tar pitch (CTP-ASM)) were co-carbonized and development of optical texture in the resultant cokes was assessed to evaluate the compatibility of the mixtures. CTP-ASM showed the highest compatibility for KF-VR, but failed to modify STC. By contrast, A240 modified KF-VR and STC so that flow texture developed. FT-i.r. spectra of co-carbonization intermediates from STC had absorption bands between 1100–1300 cm^?1 attributable to phenoxyl groups. These were also present in co-carbonizations with CTP-ASM, but were only just apparent in co-carbonizations with A240. Measurement of naphthenic hydrogen, defined as R_nus, during co-carbonization, was consistent with deoxygenation via hydrogen transfer. Thus, the modifying activities of A240 and CTP are differentiated by the availability of transferrable hydrogen. Mechanisms of co-carbonization are discussed.     

液相色谱法快速分析煤基石脑油产品的烃族组成

为快速分析煤基石脑油产品的烃族组成,采用高效液相色谱正相色谱模式,以硅胶键合相氨基柱为固定相,正己烷为流动相,利用示差折光检测器对煤基石脑油组成进行分离,将油样分为饱和烃和芳烃。用标准物质对响应因子进行考察,并对实验数据的精密度和准确度进行分析。结果表明,实验建立的高效液相色谱法测试速度快,仅需6 min,各组分的标准偏差SD小于0.2,相对标准偏差RSD均在2%以下,相对误差最大为3.74%,与气相色谱法结果相比,饱和烃相对偏差低于5%,说明高效液相色谱法的精密度和准确度较高,用其测定煤基石脑油中饱和烃和芳烃含量的方法可行。     

Optimisation of nitrogen fertilisation

The optimisation of nitrogen fertilisation for cereals in Mediterranean regions is very difficult, because yields and leaching losses are depending on winter rainfall. In this article five years of nitrogen fertilisation trials are analysed in order to get a model which relates winter rainfall, nitrogen fertilisation and wheat yields. A highly significant model obtained, in which soil type and the cultivar were taken into account. In order to improve nitrogen use efficiency and to avoid unnecessary nitrogen fertilisation, information on the minimum amount of nitrogen at seeding time and for how long the first top dressing can be delayed without yield losses will be necessary.     

离子色谱法测定甘氨酸

本文建立了采用离子色谱快速测定酸化液中甘氨酸的含量的分析方法。选用metrosep C4-250阳离子色谱柱,保护柱为metrosep C4 Guard/4.0;淋洗液为3.0mmol.L-1HNO3＋1.0mmol.L-1吡啶二羧酸超纯水溶液,流速0.90mL.min-1;检测器：非抑制电导检测器。结果表明,该方法的相关性良好,相关系数为0.9998;样品的加标回收率范围为98.86%～100.83%;样品的测定的RSD平均值为0.80%;检出限为0.2mg.L-1;定量限为0.6mg.L-1。该方法线性范围广,精密度及准确度好,操作简便,用于实际样品测定结果准确。     

Size exclusion chromatography of H-coal liquids on silica,polyvinylacetate and polystyrene columns

The physico-chemical properties of liquids derived from Kentucky coals have been examined using size exclusion chromatography. Three major types of column packing for s.e.c. have been used in the H-coal liquid analysis: inorganic silica particles commonly known as controlled pore glass, soft polyvinylacetate gel and a rigid polystyrene-divinylbenzene gel. Of these, the PVA column appears to be a general and versatile choice for routine s.e.c. analysis of coal-derived liquids.