Comparison of Huolinhe lignite structural features by using ¹³C NMR & FTIR techniques

The chemical structures of Huolinhe lignite (HLHM) were characterized with ¹³C NMR & FTIR techniques. According to ¹³C NMR analysis, HLHM consisted of 34.32% aliphatic carbons, 61.25% aromatic carbons and 4.43% carbonyl carbons. Each aromatic cluster contained 1-2 rings on average and the number of substituents on each aromatic ring was 3-4. The length of average methylene chain was 1.4 and the branched degree of aliphatic chain was 25.47%, showing the aliphatic carbons mainly consisted in the form of short chain. Several structural parameters were obtained by calculation based on FTIR data and curve-resolved band. Structural parameters (average methylene chain length, substituted degree of aromatic ring, aliphatic chain branched degree) obtained by FTIR analysis were consistent with the results of ¹³C NMR analysis. Although aromatic carbon rate existed certain deviation between FTIR and ¹³C NMR results, FTIR analysis can still reflect the carbon skeleton structure characteristics of coal in some ways.