*2.3. 13C NMR Results Analysis*

Figure 2 shows 13C NMR spectra of HLH lignite. It is including 2 main peaks. The lipid-carbon peak area with chemical shift of 0–90 <sup>×</sup> <sup>10</sup>−<sup>6</sup> and the aromatic-carbon peak area with chemical shift of 90–165 <sup>×</sup> 10<sup>−</sup>6. The sample also contains a small amount of carbonyl carbon, with a chemical shift of 165–220 <sup>×</sup> 10−<sup>6</sup> in the peak area [16,17]. The carbon spectra obtained before and after modification were fitted by peak-splitting method, and 9 carbon skeleton structural parameters were obtained. The results are shown in Table 7.

**Figure 2.** Peak fit of 13C NMR of HLH before and after modification.

**Table 7.** Structure attribution and relative content of chemical shifts in 13C NMR spectra of HLH before and after modification.


XBP <sup>=</sup> fa<sup>B</sup> /(fa<sup>H</sup> <sup>+</sup> fa<sup>O</sup> <sup>+</sup> fa<sup>S</sup> <sup>+</sup> fa<sup>B</sup> ), the ratio of aromatic bridge carbon to peripheral carbon of HLH before and after modification is an important parameter to construct macromolecular structure model of lignite, which represent condensation degree of polycyclic aromatic hydrocarbons as well as reflecting the size of aromatic cluster. According the parameters shown above, the XBP of 3 samples could be calculated, and the value of HLH is 0.26, 0.29 for sample with microwave modification, and 0.28 for sample with ultrasonic modification.
