Investigation of Organic Structural Characteristics of Low-Rank Coal Lithotypes

摘要

The structural characteristics of low-rank coals and separated lithotypes were examined by several techniques. The bulk of the work was accomplished with pressure differential scanning calorimetry (PDSC). Supplemental information regarding functional groups was generated by electron spectroscopy for chemical analysis (ESCA) and infrared spectroscopy (IR). Aromaticities were calculated from the PDSC thermogram by a peak height ratio method which has been used in the past on whole coals, organic compounds, and polymers. Aromaticities were determined for whole coals and separated lithotypes (fusain, durain, and vitrain). The fusain is the most aromatic of the lithotypes, with aromaticities ranging from 0.67 to 0.80. Calculations made using the proportions of each lithotype present in the coal determined a weighted aromaticity which correspnds very closely to aromaticity on the whole coal. ESCA was used to examine the carbon ls peak for whole coal and lithotypes. Correlations were made between the relative abundances of C-C, C=O, and C-O bond types and coal lithotype. In nearly all cases, fusain had the largest ratio of C-C bonds. The spectral modes in the infrared which showed significant differences with lithotype include C=O and C-H stretching. 3 references, 4 figures, 4 tables. (ERA citation 09:015818)