SOLID STATE 13 C NMR STUDY OF CHINESE COALS

ABSTRACT

Ten coals of different metamorphic degree have been investigated by the use of ¹³ C CP/MAS NMR technique, of which the spin-lattice relaxation, variable contact time and dipolar dephasing experiments were performed on each coal. The data from above experiments, together with normal CP/MAS integration over selected chemical shift ranges, were used to derive 12 parameters of carbon skeletal structure including the aromaticity. These parameters are correlated with carbon content (weight per cent) in coal and we find that there are close relations between the NMR parameters and metamorphic degree of coals- From the ratio of aromatic bridgehead to aromatic peripheral carbons as measured by NMR, the aromatic cluster size may be estimated for each coal.     

STUDY OF STRUCTURAL FEATURE OF PEAT, LIGNITE AND HUMIC ACID BY SOLID STATEl3C NMR SPECTROSCOPY

Four low rank coals (peat and lignite) and their derived humic acids have been investigated by the^l3C CP/MAS/TOSS NMR technique. The NMR analysis indicates that the peat contains a significant amount of unaltered plant components including cellulose, hemicellulose, lignin, waxes, and resins.

Variable contact time and dipolar dephasing experiments were performed on each sample. The data from above experiments, together with normal CP/MAS integration over selected chemical shift range, were used to derive 12 parameters of carbon skeletal structure including the aromaticity.From the ratio of aromatic bridgehead carbons, f_a^cp, to the aromatic peripheral carbons, f^cpxBp as measured by NMR, the aromatic cluster size may be estimated for each coal.     

STUDY OF STRUCTURAL FEATURE OF PEAT,LIGNITE AND HUMIC ACID BY SOLID STATEl3C NMR SPECTROSCOPY

Abstract

Four low rank coals (peat and lignite) and their derived humic acids have been investigated by the^l3C CP/MAS/TOSS NMR technique. The NMR analysis indicates that the peat contains a significant amount of unaltered plant components including cellulose, hemicellulose, lignin, waxes, and resins.

Variable contact time and dipolar dephasing experiments were performed on each sample. The data from above experiments, together with normal CP/MAS integration over selected chemical shift range, were used to derive 12 parameters of carbon skeletal structure including the aromaticity.From the ratio of aromatic bridgehead carbons, f_a ^cp, to the aromatic peripheral carbons, f^cpxBp as measured by NMR, the aromatic cluster size may be estimated for each coal.     

华北晚古生代煤的交叉极化/魔角自旋碳-13核磁共振研究

用固体高分辨¹³C核磁共振技术,研究不同变质程度的天然煤样和人工模拟煤样的化学结构演化规律,揭示了煤化过程中煤的结构演变控制着烃类生成的机理。     

应用固体13C NMR 技术研究碳酸盐烃源岩的生烃潜力和热演化程度

应用固体¹³CNMR技术对不同类型、不同演化程度碳酸盐岩干酪根的化学组成和结构特征进行了研究,结果表明干酪根结构中的脂碳是油气的主要贡献者;剖析了油、气潜力碳在不同演化阶段的变化特征.对芳碳率、芳氢率、芳核平均结构尺寸等参数的分析表明,后者是最有效的热演化衡量标尺,并建立了芳核平均结构尺寸与镜质体反射率的关系.     

华北晚古生代煤的交叉极化/魔角自旋碳-13核磁共振研究

用固体高分辨¹³C核磁共振技术,研究不同变质程度的天然煤样和人工模拟煤样的化学结构演化规律,揭示了煤化过程中煤的结构演变控制着烃类生成的机理。     

CHARACTERIZATION OF COAL CHARS FROM A FLASH PYROLYSIS PROCESS BY CROSS POLARIZATION/MAGIC ANGLE SPINNING 13C NMR

Chars from the Illinois Springfield (No. 5) Coal are prepared by flash pyrolysis at progressively higher charring temperatures. The results of a study of these chars by ¹³C NMR with CP/MAS indicate that the initial stage of heating (300^°C) produces a char with aromatic carbon fraction (f_ar) of 68%, and successive heating gives chars with f_ar of 70% (400^°C), 73% (500^°C), 89% (600^°C), 95% (700^°C), and 96% (800^°C). However, the actual amount of aromatic and aliphatic carbon in the char can be calculated by using the NMR measurements, the organic carbon content of the char, and the weight of the char. The calculated values show that the amount of aromatic carbon in char remains relatively constant at each temperature, but the amount of aliphatic carbon in char is reduced during higher temperature charring. At 600^°C, both a large reduction of the aliphatic carbon content and a maximum weight loss occur. Evidently, the aliphatic-bond carbon in coal is the principal source of volatiles derived from coal. The apparent increase in aromaticity (f_ar) of the char heated to progressively higher temperatures is due to the loss of aliphatic-bond moieties and reduction in volume of materials.     

CHARACTERIZATION OF COAL CHARS FROM A FLASH PYROLYSIS PROCESS BY CROSS POLARIZATION/MAGIC ANGLE SPINNING 13C NMR

ABSTRACT

Chars from the Illinois Springfield (No. 5) Coal are prepared by flash pyrolysis at progressively higher charring temperatures. The results of a study of these chars by ¹³C NMR with CP/MAS indicate that the initial stage of heating (300^°C) produces a char with aromatic carbon fraction (f_ar) of 68%, and successive heating gives chars with f_ar of 70% (400^°C), 73% (500^°C), 89% (600^°C), 95% (700^°C), and 96% (800^°C). However, the actual amount of aromatic and aliphatic carbon in the char can be calculated by using the NMR measurements, the organic carbon content of the char, and the weight of the char. The calculated values show that the amount of aromatic carbon in char remains relatively constant at each temperature, but the amount of aliphatic carbon in char is reduced during higher temperature charring. At 600^°C, both a large reduction of the aliphatic carbon content and a maximum weight loss occur. Evidently, the aliphatic-bond carbon in coal is the principal source of volatiles derived from coal. The apparent increase in aromaticity (f_ar) of the char heated to progressively higher temperatures is due to the loss of aliphatic-bond moieties and reduction in volume of materials.     

用13CNMR CP/MAS波谱表征干酪根的性质

用固体¹³C核磁共振(NMR)交叉极化(CP)魔角旋转(MAS)波谱技术,研究大庆地区不同类型与成熟度的20个干酪根样品的性质;根据7种化学结构与干酪根有关的模型物质的化学位移数据,总结干酪根NMR谱中脂碳与芳碳谱带峰型的变化规律,提出除视芳碳率f_a外,脂碳和芳碳峰的峰高与半峰宽之比h₁/B₁与h₂/B₂,与干酪根的结构密切相关,是表征干酪根类型与成熟度的良好参数。实验表明,干酪根的芳碳率、环缩合指数,以及h₁/B₁,h₂/B₂与H/C之间有很好的线性关系。据此提出了用f_a划分干酪根类型的具体指标,并用h₁/B₁与h₂/B₂作图以表征干酪根的类型及其演化途径。     

煤变质程度对煤储层物性的控制作用

通过对大量煤岩样品的压汞实验和低温氮吸附实验测试结果的系统分析，讨论了煤变质程度对煤储层物性的控制作用。结果发现：煤样的压汞孔隙度随煤级的升高呈现出高-低-高的变化趋势；孔喉平均直径小于1 μm的孔隙结构在各种不同煤级的样品中均大量分布，而孔喉平均直径大于1 μm的孔隙结构则仅在中低煤级样品中大量分布，在无烟煤中更是很少见到；在中低煤级阶段，随着煤变质程度的增高，低温氮测试的煤比表面积逐渐降低，到无烟煤阶段，煤的比表面积又开始增加。结论认为：煤的孔隙度、孔隙结构和比表面积均受煤变质程度的控制，且在烟煤与无烟煤的交界处发生突变。     

煤液化油模型分子结构的研究

对神华煤在连续液化装置的加氢液化油(试样1#)和实验室获得的液化油(试样2#)进行了模型分子结构的研究。通过元素分析、平均相对分子质量的测定、核磁共振谱图和傅里叶变换红外光谱的分析,得到了两种液化油的平均分子结构式和相关的结构参数,并利用这些参数推测了模型分子的结构。实验结果表明,试样1#和试样2#的平均相对分子质量分别为228,299;平均分子式分别为C17H23N0.1S0.006O0.02和C23H21N0.02S0.002O0.1;试样1#的模型分子结构以含一个芳香环的部分氢化芳烃为主体;试样2#主要以含3~4个芳香环的缩合芳烃为结构单元;两种试样芳香环上均存在取代基,但取代基的碳数不一样,且存在少量氮和氧形成杂环。     

STRUCTURAL CHARACTERIZATION OF PETROLEUM BASED FEEDSTOCKS FOR CARBON BLACK PRODUCTION

Some selected petroleum based feedstocks have been characterized by ¹H and ¹³C NMR spectroscopy for their possible use as carbon black feedstock (CBFS). Feedstocks studied are pyrolysis tars, clarified oils, aromatic extracts and vacuum residue. Analysis of average structural NMR parameters show that pyrolysis tars because of their being highly aromatic in character (high BMCI) are the most suitable feedstock for carbon black. Aromatic extracts rank the next. Clarified oils of Indian refinery origin needs further processing due to middle distillate mode refining severity.     

VARIATION IN THE CHEMICAL NATURE OF ASPHALTENES WITH THE PROCESS, THE COAL AND THE REACTION CONDITIONS

Average structure data for twelve asphaltenes are reported, based on ¹³C- and H- n.m.r. spectroscopy combined with elemental, molecular weight and functional group analyses. The asphaltenes were from supercritical gas extraction, flash pyrolysis and hydrogenation of a brown and a bituminous coal. The effect of the reaction temperature and, for hydrogenation, the catalyst and solvent on the nature of the asphaltene produced was studied. The asphaltene obtained from supercritical gas extraction of the brown coal at 350°C was the least aromatic (f_a = 0.44) with the highest H/C atomic ratio (1.16) and probably consists mainly of single ring aromatlcs with about half of the aromatic sites substituted. A significant proportion of the carbon in this asphaltene is in long alkyl chains and the hydroxyl content is high. Whereas, the asphaltenes produced by hydrogenatlon of the bituminous coal at 450°C were far more aromatic with more highly condensed but less substituted aromatic ring systems and few, if any, long alkyl chains, together with a lower hydroxyl content. The asphaltenes obtained from the brown coal are less aromatic with less condensed aromatic ring systems but a higher degree of aromatic substitution than those produced from the bituminous coal under the same conditions. The asphaltenes formed at 450°C had lower H/C atomic ratios, molecular weights and degree of aromatic substitution, but higher aromaticities Ohan those produced at 35O°C or 400°C under like processing conditions. The asphaltene produced in the presence of both stannous chloride catalyst and tetralin was less aromatic than when either of these species was absent.     

Structural Aspects of Crude Oil Derived Asphaltenes by NMR and XRD and Spectroscopic Techniques

Asphaltene samples obtained from crude processed at two Indian refineries were characterized for chemical composition and structure by nuclear magnetic resonance (NMR), X-ray diffractometry (XRD), fluorescence spectroscopic techniques, and chromatographic (column and GPC) techniques. Estimation of NMR average structural parameters were obtained by combined ¹H, NMR ¹³C, NMR DEPT-45, and QUAT pulse sequence spectral editing techniques. The macrostructure and crystalline parameters of these samples were obtained by XRD. The nature of the functional groups have been obtained by IR technique. A combined NMR and XRD parameters were used to estimate the size of average aromatic structural units. Asphaltenes from one of the crudes (ASP-A) was found to be highly pericondensed, highly substituted, and higher molecular size compared to ASP-B asphaltene molecules. The number of aromatic sheets per unit sheets are 3.7 and 2.5 in the sample ASP-A and ASP-B, respectively. Both the asphaltene molecules in the samples have periodically and systematic arrangement of aromatic sheets in the unit sheet. The number of aromatic rings per unit sheet in ASP-A and ASP-B are 6.0 and 5.0, respectively. The fluorescence spectral studies has also exhibited λ_max (the wavelength of maximum intensity) at 505 and 509 nm confirming to pericondensed higher polycondensed aromatic ring system in both the samples. The analysis of liquid chromatographic fractions of these samples show that each sample is composed of several polycondensed aromatic systems where unit sheet of ring sizes vary from 1.8 to 6.3 with varying molecular sizes. These structural parameters allowed a model structure of the asphaltenes to be constructed.     

VARIATION IN THE CHEMICAL NATURE OF ASPHALTENES WITH THE PROCESS,THE COAL AND THE REACTION CONDITIONS

ABSTRACT

Average structure data for twelve asphaltenes are reported, based on ¹³C- and H- n.m.r. spectroscopy combined with elemental, molecular weight and functional group analyses. The asphaltenes were from supercritical gas extraction, flash pyrolysis and hydrogenation of a brown and a bituminous coal. The effect of the reaction temperature and, for hydrogenation, the catalyst and solvent on the nature of the asphaltene produced was studied. The asphaltene obtained from supercritical gas extraction of the brown coal at 350°C was the least aromatic (f_a = 0.44) with the highest H/C atomic ratio (1.16) and probably consists mainly of single ring aromatlcs with about half of the aromatic sites substituted. A significant proportion of the carbon in this asphaltene is in long alkyl chains and the hydroxyl content is high. Whereas, the asphaltenes produced by hydrogenatlon of the bituminous coal at 450°C were far more aromatic with more highly condensed but less substituted aromatic ring systems and few, if any, long alkyl chains, together with a lower hydroxyl content. The asphaltenes obtained from the brown coal are less aromatic with less condensed aromatic ring systems but a higher degree of aromatic substitution than those produced from the bituminous coal under the same conditions. The asphaltenes formed at 450°C had lower H/C atomic ratios, molecular weights and degree of aromatic substitution, but higher aromaticities Ohan those produced at 35O°C or 400°C under like processing conditions. The asphaltene produced in the presence of both stannous chloride catalyst and tetralin was less aromatic than when either of these species was absent.     

柴达木盆地团鱼山地区石门沟组煤与油页岩沉积环境

柴达木盆地北缘团鱼山地区中侏罗统煤与油页岩广泛发育,但勘探程度较低,煤与油页岩沉积环境及成因研究较薄弱。利用团鱼山地区QD-2全取心井,通过岩石热解、有机碳、工业分析、GC和GC-MS等分析,开展研究区煤与油页岩有机地球化学特征及沉积环境分析。研究发现,研究区油页岩属于高灰分含量、低总有机碳含量、低—中含油率油页岩;而煤属于低灰分含量、高总有机碳含量、低变质的褐煤。煤与油页岩样品中均检测出正构烷烃、类异戊二烯烃、萜类、甾类及芳烃类化合物。在气相色谱图上,煤与油页岩正构烷烃呈前低后高单峰式分布;煤样品Pr/Ph高于油页岩,规则甾烷相对含量为C29>>C28>C27,芳烃类中,倍半萜类和二萜类化合物丰富。综合分析表明,研究区煤与油页岩均处于未成熟演化阶段,有机质来源以陆生裸子植物为主。油页岩形成于弱氧化的淡水浅湖环境,而煤则形成于氧化的沼泽环境,因此研究区煤与油页岩在有机质来源上无较大区别,而在沉积环境上差异较大。对比分析发现,有机质类型、来源及沉积环境的差异导致柴达木盆地团鱼山地区石门沟组含煤段与页岩段油页岩存在不同的赋存特征。     

STRUCTURAL CHARACTERIZATION OF AROMATIC FRACTIONS OF SOME TYPICAL SOLVENT REFINED COALS USING MASS SPECTROMETRIC TECHNIQUES

Three aromatic fractions from two typical Chinese solvent-refined coals (one, FS2, derived from bituminous-sapropelitic cannel coal, and the other two, DT2A and DT2B, derived from a bituminous, weakly caking coal) were characterized for their chemical composition and molecular weight distribution using field ionization (FI) and field desorption (FD) mass spectrometric techniques. Some characteristic components derived from the chemical ionization technique were subjected to further fragmentation analyses using tandem mass spectrometry.

The FS2 fraction is composed of 3-5 ring condensed aromatics of cata configuration with abundant naphthenic groups fused with an aromatic cluster. The most abundant component -- cyclopentachrysene -- is resolved at M/Z 268, which may possibly be the product of aroir.atization of hopanes existing in the source material during dia- and catagenesis. Sample DT2A contains polycyclic aromatic hydrocarbons with a higher degree of aromatic condensation and 3-5 ring clusters. The concentration of C-4 substituted phenanthrene was especially high, indicating the probable presence of retene derived from triterpanic acid in the land plantresins during geological conversion of coal. The second aromatic fraction, DT2B, is differentiated from DT2A mainly by the aromatic ring number (6-9 rings for DT2B) and degree of aromatic condensation (mainly cata configuration). The suitability for producing advanced carbon materials of the three samples studied is discussed.     

DIMETHYL SULPHOXIDE-A SOLVENT FOR THE STUDY OF COALS

Dimethyl sulphoxide (DMSO) has been found to be a very good solvent for the study of Tow rank coals. Chemical studies of a Texas lignite, its DMSO soluble fraction obtained under ambient conditions, the DMSO insoluble residue and its humic acids have been carried out. Physico-chemical techniques such as Fourier transform infrared spectrometry (FTIR), and ¹³C cross-polarization/magic angle spin (¹³C CP/MAS) NMR spectrometry and chemical methods such as pertri fluoroacetic acid oxidation and the determination of acidic group concentrations have shown that the DMSO-soluble portion possesses a chemical structure which is similar to both that of the neat lignite and of the DMSO-insoluble residue. The humic acids are highly aromatic and acidic in nature. Preliminary data obtained through the use of ²⁵²Cf plasma desorption mass spectrometry (²⁵²Cf PDMS) suggests the existence of a common species in both the DMSO extract and the humic acids.     

等变质煤中镜质组有机地球化学研究——核磁共振特征

本文应用核磁共振法CP/MAS-13C-NMR和1H-NMR技术,研究高挥发份烟煤阶段(R°_max≈0.64～0.74%)两种煤相的镜质组和镜质组氯仿可溶物的核磁共振特征,并结合元素分析、抽提物分离分析以及煤岩学特征等,对这两种煤相镜质组的结构进行研究。      

������ú�����������γɵ�������

民和盆地构造位置处于祁连山褶皱系东部，是一个中新生代发展起来的断、坳山间盆地。盆地中西部中侏罗统窑街组蕴藏着丰富的煤炭资源，煤层气局部富集于窑街、炭山岭煤田。煤岩有机地球化学及煤层甲烷碳同位素研究表明，该区煤层气具有油型与煤型混合气特征。煤层气分布具有明显的分带现象，由浅到深分别为ＣＯ２—Ｎ２带、Ｎ２带、Ｎ２—ＣＨ４带、ＣＨ４带。煤层气富集主要受煤的变质程度，顶、底板岩性，出露程度，埋藏深度及构造等因素的控制，且多分布于背斜、断块等构造的高部位。