13C NMR spectroscopy has been shown to be an important tool in the characterization of coal structure. Important quantitative information about the carbon skeletal structure is obtained through 13C NMR spectral analysis of coal. Solid-state 13C NMR analysis techniques have progressed beyond the mere determination of aromaticity and can now describe features such as the number of aromatic carbons per cluster and the number of attachments per aromatic cluster. These 13C 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 the expense of the process, extensive 13C NMR data are not available for most coals. A non linear correlation has been developed that predicts the chemical structure parameters of both U.S. and non-U.S. coals generally measured by 13C NMR and often required for advanced devolatilization models. The chemical structure parameters correlated include (i) the average molecular weight per side chain (M δ ); (ii) the average molecular weight per aromatic cluster (M cl); (iii) the ratio of bridges to total attachments (p 0); and (iv) the total attachments per cluster (σ + 1). The correlation is based on ultimate and proximate analysis, which are generally known for most coals. 13C NMR data from 30 coals were used to develop this correlation. The correlation has been used to estimate the chemical structure parameters generally obtained from 13C NMR measurements, and then applied to coal devolatilization predictions using the CPD model and compared with measured total volatiles and tar yields. The predicted yields compare well with measured yields for most coals.

A model that predicts the amount and distribution between tar and light gas of nitrogen released during devolatilization has been developed and incorporated into the chemical percolation devolatilization (CPD) model. This work represents the first volatile nitrogen release model developed on the basis of 13C NMR measurements of coal structure. This work also represents the first volatile nitrogen release model evaluated by comparing model predictions with chemical structural features of the char (determined by 13C NMR spectral analyses). The model is limited to nitrogen release during primary pyrolysis, and assumes that all light-gas nitrogen is HCN. Model predictions of nitrogen release compare well with measured values for most coals and devolatilization conditions tested.