Optimization of {sup 1}H and {sup 13}C NMR methods for structural characterization of acetone and pyridine soluble/insoluble fractions of a coal tar pitch
- Imperial College London, London (United Kingdom). Department of Chemical Engineering and Chemical Technology
{sup 1}H and {sup 13}C high-resolution liquid-state NMR methods were used for the quantitative characterization of different molecular weight fractions of a coal tar pitch (CTP). Three fractions were studied: pitch acetone solubles (PAS), pitch pyridine soluble-acetone insolubles (PPS), and pitch pyridine insolubles (PPI). Standard liquid-state NMR methods were modified and calibrated for use with undeuterated quinoline or undeuterated 1-methyl-2-pyrrolidinone (NMP) as the solvent. This made it possible to calculate the average structural parameters for the higher molecular weight (MW) fractions of the coal tar pitch. Quantitative comparisons of structural differences between the solubility-separated fractions of the pitch are reported. The aromaticity and the average number of aromatic rings per polynuclear aromatic structure were both found to decrease with increasing solubility. Similarly, pericondensed and all other quaternary carbon species were found to decrease with increasing solubility. This suggests that 'continental' type structures become more dominant as the solvent solubility of these coal derived fractions diminishes. The estimated average number of aromatic rings ranged from 1 to 2 rings in the PAS fraction, 4 to 21 rings in the PPS fraction, and 11 to 210 rings in the PPI fraction. These ring-numbers were directly related to the number average molecular mass (M{sub n}) assigned to the particular fraction in the average structural parameter (ASP) calculations. The lower-limit of the M{sub n} values was derived from the ASP calculations as 200, 450, and 6200 u for the PAS, PPS, and PPI fractions, respectively. 66 refs., 7 figs., 15 tabs.
- OSTI ID:
- 21073535
- Journal Information:
- Energy and Fuels, Vol. 22, Issue 3; Other Information: t.j.morgan@imperial.ac.uk; ISSN 0887-0624
- Country of Publication:
- United States
- Language:
- English
Similar Records
Improved coal conversion in CO/water systems: Final report for the period September 4, 1984 through September 1, 1986
Analytical study on mesocarbon microbeads derived from coal tar pitch