Development and application of a correlation of C-13 NMR chemical structural analyses of coal based on elemental composition and volatile matter content

C-13 NMR spectroscopy has been shown to be an important tool in the charact erization of coal structure. Important quantitative information about the c arbon skeletal structure is obtained through C-13 NMR spectral analysis of coal. Solid-state C-13 NMR analysis techniques have progressed beyond the m ere determination of aromaticity and can now describe features such as the number of aromatic carbons per cluster and the number of attachments per ar omatic cluster. These C-13 NMR data have been used to better understand the complicated structure of coal, to compare structural differences in coal, tar, and char, and to model coal devolatilization. Unfortunately, due to th e expense of the process, extensive C-13 NMR data are not available for mos t coals. A nonlinear correlation has been developed that predicts the chemi cal structure parameters of both U.S. and non-U.S. coals generally measured by C-13 NMR and often required for advanced devolatilization models. The c hemical structure parameters correlated include (i) the average molecular w eight per side chain (Md); (ii) the average molecular weight per aromatic c luster (M-cl); (iii) the ratio of bridges to total attachments (p(0)); and (iv) the total attachments per cluster (sigma + 1). The correlation is base d on ultimate and proximate analysis, which are generally known for most co als. C-13 NMR data from 30 coals were used to develop this correlation. The correlation has been used to estimate the chemical structure parameters ge nerally obtained from C-13 NMR measurements, and then applied to coal devol atilization predictions using the CPD model and compared with measured tota l volatiles and tar yields. The predicted yields compare well with measured yields for most coals.