Coal cluster analysis

The expected thermal decomposition of the proposed structure is in agreement with the distribution of thermal decomposition products from the coal. The products include minimally disturbed ring cluster fragments from the molecular structure which comprise the coal "tar". Analysis of the tar gives information on the ring cluster size in the coal and on the structure of the aliphatic bridges. 

Click, D.C. and Davis, A. Variability in the inorganic element content of U.S. coals, including results of cluster analysis. Organic Geochemistry, 1987, 11, 331. 

In an investigation that sought to clarify the effects of coal rank on liquefaction yields (106), a computer cluster analysis of some 100 U.S. coals... 

It is necessary to notify, that the critical analysis of the Flory theory application for the determination of molecular mass and the crossing density of the coal structure has been done in the Painter s works [16], Authors assert, that the possible formation of hydrogen bonds between the hydroxy groups of low-metamorphized coal has an important role here that is why, even a lot of empirical amendments introduction into calculations leads to obtaining the understated values of molecular masses of clusters. 

NMR Analysis. NMR analysis was performed on the residue from HC 1401-350. The results are compared to the analysis of the parent coal in Table 4. The data confirm the lower ahphatic content and higher aromatic content in the preliquefaction samples determined by FT-IR. The increase in the aromatic content is in protonated carbon (0.28 for the residue compared to 0.17 for the coal). The major decrease in the aliphatics is in the CH2 groups (0.27 in the coal vs. 0.16 in the residue). The cluster size in the preliquefaction coal (12.3 carbons) appears to be higher than for the raw coal (9.7). The carboxyl carbon (f J in the preliquefaction product (0.05) is also lower than in the raw coal (0.08), consistent with the FT-IR and TG-FTIR results. 

The objective of this communication is to report structural information on a bituminous coal from a thorough characterization of its extracts. The characterization was carried out according to a scheme devised on the basis of our current understanding of coal chemistry. The scheme consists of considerations in preparation, fractionation, and analysis of coal-derived liquids (CDL) to obtain molecular-level information on the CDL per se as well as on the parent coal. The information obtained relates mostly to the structure of component clusters. 

Using refined X-ray dilfraction techniques and the extraction of the radial distribution function from molecular X-ray scattering it has been possible to develop a model for a graphene layer [31]. This model is free of the difficulties mentioned above and predicts cluster sizes of between n = 3 and n — 5 for pericondensed rings (coronene, hexaperibenzo coronene) in full agreement with electron microscopic [25] and NMR [131] data which led to construction of Fig. 19. The model material [31] was a coal sample before carbonization containing, as well as the main fraction of sp2 centres, about 20% carbon atoms in aliphatic connectivity. This one-dimensional structure analysis represents a real example of the scheme displayed in Fig. 9(C). 

In the final analysis for the methane production increase from the coal seam by CO2 injection, a simple model cluster of coal surface adopted is depicted in... 

In recent decades, there has been a strong tendency to characterize coals by structural analysis. Thus, coal can be characterized in terms of aromaticity (percentage of total carbon atoms existing in aromatic structures), number of aromatic atoms (or rings per cluster), number and types of functional groups, locations of oxygen atoms, location and types of heteroatoms. This has led to the postulation of speculative structure for coal which may (questionably) lead to a better understanding of utilization processes such as combustion. 

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