Brown-Ladner Method Research Articles

Mesophase formation in coal liquid solvent fractions

The single greatest influence on the mesophase microstructure is the chemical composition of the organic precursor. The effects of oxygen content and structural parameters of precursors from solvent fractions of coal liquefaction products on the microstructure and pyrolysis yields were determined. The fractions were analysed using the Brown-Ladner method to obtain average molecular structural parameters. It was found that pyrolysis yield increases with increased aromaticity and oxygen content and that mesophase microstructure is determined primarily by the oxygen content of the precursors.

Improved method to alkylate Yūbari coal of Japan using molten potassium under refluxing THF

A modification to Sternberg's procedures of reductive alkylation of coals is proposed. The ‘coal anion’ formation reaction is conducted under refluxing THF without any electron transfer agent and with molten potassium metal. The method was applied to Yūbari coal (86 wt % C) whereby varying reaction times (0.5–6 h) altered the lengths of alkyl groups (CH 3C 4H 9) added. In a typical experiment, a butylated Yubari coal, prepared by the 2 h reaction, contained 7 butyl groups per 100 original carbon atoms and solubility in hot benzene was 75 wt %. The numbers of alkyl groups introduced and the solubilities of coals increased with reaction time. Values obtained were comparable to those reported using conventional procedures which required longer reaction times and an electron transfer agent l.r. spectra of butylated coals showed strong adsorption peaks attributed to aliphatic groups. Benzene-soluble—pentane-insoluble material of the alkylated coal had less condensed aromatic components with more alkyl side-chains compared with Yūbari SRC, which were estimated by the Brown—Ladner method. Contamination of the alkylated coal by THF fragments seems to be negligible, since hydrogenated naphthalene, obtained after treatment with molten potassium, contains no alkylated products. The reaction proceeded also in HMPA, but not in straight-chain hexane.

Supported molten zinc chloride catalysts. 2. Hydrocracking of coal extract.

With a supported molten zinc chloride catalyst as well as with molten zinc chloride alone, coal extract could be efficiently hydrocracked into low boiling liquid fractions under relatively mild reaction conditions. The effect of the carrier on catalytic activity and the reaction conditions for hydrocracking of coal extract were investigated using a batch autoclave. The liquid products were separated by GPC. They composed of five groups of compounds and their structual parameters were estimated by a modified Brown-Ladner's method. The reaction mechanism was also discussed.

The Nature of Athabasca Tar Sand (Canada) and Tar Sand Derivatives. A Comparison with Coal-hydrogenolysis Products

Abstract Solvent extracts of Athabasca tar sand were analyzed by the Brown-Ladner method, the Takeya et al. method, and the Speight method on the basis of the 1H-NMR data and by 13C-NMR spectroscopy. The structural characteristics of Athabasca tar sand derivatives were also compared with those of coal-hydrogenolysis products. The results show that the structural characteristics of hexane solubles, monomers consisting of one aromatic ring substituted highly with C6 aliphatic chains, resemble those of the oil fraction produced during the initial stage of the hydrogenolysis of Taiheiyo coal. However, the structural characteristics of the hexane insoluble-benzene solubles, oligomers consisting of 2 aromatic rings substituted highly with C4–5 aliphatic chains, are different from those of any coal-hydrogenolysis products. In addition, the close agreement between the fa value obtained by the Brown-Ladner method and 13C-NMR may indicate that, for solvent extracts of Athabasca tar sand, the assumption in the Brown-Ladner method that the atomic H/C ratio of aliphatic structures is 2 is proper.

Structural Investigation of Column Chromatographed Asphalts by Proton and Carbon-13 NMR Spectroscop

Proton and carbon-13 nuclear magnetic resonance spectroscopies of various asphalts and their fractionated samples were carried out to investigate average molecular structures.Aromaticity calculated from relative intensities of aromatic and aliphatic region of 13C NMR spectra was in fair agreement with that of calculated from proton distribution of 1H NMR using Brown-Ladner method. The structural parameters derived from carbon distribution-number of unsubstituted aromatic carbon, that of substituted aromatic carbon, number of condensed aromatic carbon, etc.-agreed with those derived from 1H NMR within experimental errors. In the aliphatic region of 13C NMR spectra, characteristic peaks assignable to; 29. 7ppm: -(CH2) n-n>7, 14. 1ppm: CH3-CH2-CH2-, etc, can be observed. The relative intensities of these peaks suggest that the methylene chain included in asphalt is much longer (-(CH2) n) n>12 than that has been considered hitherto.Among the five asphalts of differrent crudes, the aromaticities of Taching asphalts are the lowest on all fractions. Mubarras asphalt contains large amount of saturate fraction. The aromaticities of the fractionated samples were, however, not significantly different from the other asphalts fractions. Among the other three, Arabian Light, Iranian Heavy, and Kuwait, no essential differences were observed.