Molecular structure of a brown coal

A model for the structural unit of a typical Rheinische Braunkohle has been developed from the results of elemental analyses, pyrolysis experiments and titration studies and from extrapolation of literature data for similar coals. The model presented here has been successfully applied to explain the pyrolysis and hydropyrolysis behaviour of Rheinische Braunkohle.     

Molecular modeling of the structure and properties of coal organic matter

The algorithms and results of molecular modeling of the structure and (physicochemical and processing) properties of coal organic matter (COM) and its components (macerals) based on two approaches, (1) a generalized model of the COM structure and (2) the concept of a self-associated multimer in the COM structure of have been presented. A set of structural parameters characterizing the molecules of organic and hetero-organic compounds that simulate the structure of coals is used in the first approach, and the structure of the organic substance of coal in the second approach is treated as a mixture of superimposed individual components with known values of the properties of interest reflecting the structural features of the organic matter and elemental composition of coal.     

Molecular structure of bituminous coal studied with pulse nuclear magnetic resonance

High-volatile bituminous coal and coal saturated with fully deuterated solvents, were studied using the ¹H n.m.r. pulse technique. Free-induction decay (FID) signals were separated into Gaussian and Lorentzian components and contents of immobile and mobile phases of coal matter were calculated. Spin-spin relaxation times, T₂, for both phases were determined. Some solvents caused a significant decrease in the content of the coal immobile phase. It is concluded that the immobile phase of coal consists of macromolecules and molecules. The latter are attached to macromolecules by electrondonor-acceptor interactions which can be destroyed by some solvents. The contents of macromolecules (60 wt%) and molecules (40 wt%) in the coal were determined.     

Ore components in coal

The dependence of the mineral content in coal and concentrates on the degree of metamorphism is analyzed.     

Classification of the mineral components of coal

The influence of mineral components of coal on their extraction and processing is studied. A classification of the mineral components for regular and commercial coal is proposed on the basis of the mineralogical composition.     

Micropore structure of coal

The adsorption of carbon dioxide at 298 K, 273 K and 253 K by the vitrains of twelve Japanese coals and five foreign coals has been studied. The Dubinin-Polanyi equation was used in order to interpret the isotherms. Equilibrium points at different temperatures fell satisfactorily on a single straight line of the Dubinin-Polanyi equation. It was shown that it is possible to estimate the differential heat of adsorption of these coals from an isotherm obtained at a single temperature if the isotherm follows the Dubinin-Polanyi equation. The heats of adsorption of carbon dioxide on coals amounted to 6–7.5 kcal/mol regardless of rank. The rate of adsorption of carbon dioxide on coals was measured at a constant pressure of 260 mmHg at 298 K. The micropore volume, the gradient of the Dubinin plot and the rate of adsorption are discussed in relation to characteristics of their infra-red adsorption spectra. It is concluded that the micropore structure of coal is closely related to the number of hydrogen atoms bound directly to carbon atoms. A possible explanation of this is suggested.     

不同来源木质素磺酸钠的结构特征及用作水煤浆分散剂

引言 木质素磺酸盐分子中含有苯丙烷基(C6-C3)疏水骨架和磺酸基为主要亲水基团,是具有阴离子表面活性剂结构特征的高分子化合物,来源于亚硫酸法生产纸浆或纤维浆的副产物,具有吸附分散性,广泛应用于染料、涂料、石油、煤炭工业和建筑业等领域[1-2].     

Molecular probe chromatography of bituminous coal

The properties of some bituminous coals and an anthracite have been studied by “Molecular Probe Chromatography” using selected probes. Irrespective of the rank of coal, some behaviour common to all has been found. Following the sorption of air components and carbon dioxide at ambient temperature, interesting flow-disturbed peaks have been observed. Unlike the behaviour observed on a freshly packed column, both the retention and peak asymmetry of carbon dioxide increase upon column conditioning. The probe molecules, irrespective of their chemical identity, are sorbed on the surface by adsorption alone, up to 175°C. The probes are retained in the column both by specific and non-specific interaction forces and the contribution of the former to retention predominates in low rank coal. The selectivity of carbon dioxide at ambient temperature, and the retention of water and methanol at 175°C are dependent on the rank of coal. This dependence is similar to the porosity—rank relationship of coal. The permeability of bituminous coal decreases progressively with rank.     

Molecular electronics. Synthesis and testing of components

Molecular electronics involves the use of single or small packets of molecules as the fundamental units for computing. While initial targets are the substitution of solid-state wires and devices with molecules, long-range goals involve the development of novel addressable electronic properties from molecules. A comparison of traditional solid-state devices to molecular systems is described. Issues of cost and ease of manufacture are outlined, along with the syntheses and testing of molecular wires and devices.     

枣泉煤分子模型构建及热解的分子模拟

以宁东枣泉煤为研究对象，使用工业分析、元素分析、X射线光电子能谱、¹³C固体核磁等表征手段和计算机辅助，构建获得枣泉煤大分子结构模型。经过分子动力学退火动力学模拟和几何结构全优化，与初始结构相比键长、键角发生明显改变，立体构型显著，芳香层片之间近似平行的排列方式明显。获得的傅里叶变换红外和¹³C固体核磁的实验与计算谱图总体吻合较好，进一步证明了构建模型的合理性。使用反应分子动力学方法模拟枣泉煤的热解过程，考察不同热解终温和升温速率对热解行为的影响。结果发现，随着温度的升高，反应速率逐渐加快。不同升温速率对枣泉煤热解过程中气体的产生有显著影响。在动力学模拟中大多产生C₁₅以下的碎片，大分子的种类则并不多。随着升温速率的增加，气、液、固三相产物整体上都呈现下降的趋势。此外，还根据反应分子动力学模拟结果追踪了热解过程中CO₂的形成机理，获得了三种不同的CO₂形成路径。     

Regular coal structure and conversion severity

In two separate coal conversion studies, one dealing with CO-water conversions of Illinois No. 6 coal, and the other with H₂S addition to conventional tetralin conversions of the lower-rank Wyodak 2, data have been collected over a range of conversion levels. For both studies the degrees of conversion were increased by increasing the reducing power of the medium, while the conversion temperature was kept constant at 400 °C for all runs. The conversion levels for the CO-water runs ranged from 29 to 60%, while the tetralin-H₂S runs yielded conversions from 44 to 67%. Sequential elution solvent chromatography and field ionization mass spectrometry were used for analyses of toluene-soluble fractions from the CO-water runs and THF-soluble fractions from the H₂S-tetralin runs, respectively. The analyses showed that the fraction compositions remained constant with increasing degrees of conversion. This finding suggests that there may be some gross regularity in the structure of coal. Moreover, the results here are in contrast to work reported earlier, in which increased conversion levels, reached through greater conversion temperatures, yielded products with successively increased condensation and aromatization. It is thus suggested that severity be considered in terms of two components. Thermal severity reflects the temperature/time component of conversion chemistry, and derives from simple Arrhenius behaviour of competing reactions, while reduction severity reflects only on the reducing power of the system.     

Interaction of low-metamorphic coal components in coking batch

The interaction of low-metamorphic coal components in coking batch during pyrolysis is studied. The characteristics of the resulting coke are presented, and the partial hydrogenation is discussed.     

Hydro-treatment of a direct coal liquefaction residue and its components

Direct coal liquefaction residue (DCLR) contains a significant fraction of heavy liquids. Better use of DCLR is an important task to overall economy of direct coal liquefaction. This paper studies hydro-treatment of a DCLR and its solvent-extraction components under typical direct coal liquefaction conditions. The DCLR is found hydro-treatable, resulting in more light products and less heavy products. In one case, 40 wt% heavy fractions in the DCLR are converted into light fractions. Hexane soluble fraction (HS) is the most stable while pre-asphaltene fraction (PA) is the most active during the hydro-treatment. Some synergetic effect can be observed when DCLR is treated as whole. The fractions of DCLR, before and after the hydro-treatment, are subjected to FTIR and NMR analyses, which show increase in hydrogen content and decrease in oxygen content in HS fractions after the hydro-treatment. GPC analysis reveals that the hydro-treatment results in slight decreases in molecular weight of HS fraction. The data seem to suggest that separation and hydro-treatment of liquid fractions from a DCLR is a viable option for high oil yield.     

Polyene model of coal structure and metamorphism

Eight coal ranks (G, GZhO, GZh, K, KO, KS, and T) are investigated by IR spectroscopy in the range between 1800 and 650 cm–1, with polynomial decomposition of the spectra obtained. The similarities and differences in the IR spectra for two series of coal are noted: specifically, fat coal (Zh, GZh, GZhO, and G) and coking coal (K, KO, KS, and T). For both series, we consider the regions of the spectra containing narrow absorption bands. On passing from Zh and G coal in the fat set and from K to T coal in the coking set, the intensity of the IR absorption bands at 1450 and 1370 cm^–1 declines, on account of deformation C?H vibrations of the CH₂ and CH₃ groups, while the absorption of oxygen-bearing groups appears. These experimental data are inconsistent with accepted concepts regarding the metamorphism on passing from gas coal (rank G) to lean coal (rank T).     

Chemical structure of Wyodak coal

The chemical structure of a sub-bituminous coal from the Wyodak seam, Wyoming, has been investigated using the technique of per TFA oxidative degradation. The relative amounts of products differ markedly from those from a typical bituminous coal (Illinois No. 6 seam, Monterey mine).     

溶胀处理煤对煤结构与煤基聚苯胺导电性影响

首次选用苯胺为溶剂对神府煤(SFC)进行溶胀处理,以研究其对煤结构与煤基聚苯胺导电性的影响,对其结构进行TG/DSC、FTIR和SEM分析,并通过溶胀SFC处理煤为聚合基体,在苯胺和引发剂条件下聚合为煤基聚苯胺,测定了其导电率。结果表明:苯胺溶胀处理破坏了煤中非共价键,降低了煤的交联缔合度,疏松了煤的孔结构,在此条件下的煤基聚苯胺的导电率均小于溶胀处理前原煤为聚合基体的煤基聚苯胺导电率,这与煤大分子网络结构受到一定程度破坏有关,这可为煤基聚苯胺的扩大化生产提供重要参考。     

Mechanism of swelling and extraction and coal structure

An attempt is made to develop a comprehensive model of coal structure based on results of various experiments involving extraction and swelling of a coal by solvents. These are described in terms of electron-donor and electron-acceptor characteristics, of mass spectrometric analysis of coal extracts, of pulse ¹H n.m.r. measurements of mobilities of coal components, porosity measurements. The theory of coal swelling cannot be adapted from the theory of polymer swelling.