## 3 Results and Discussions
### Characterization of Narrow Distillate Fractions by \({}^{1}h\) Nmr  
The main virtue of NMR analysis is its ability to associate resonances in specific chemical shift ranges with particular structural features. Based on this, the chemical shifts of hydrogen in the MLCT-Z and MLCT-S and their narrow fractions were measured by \({}^{1}\)H NMR. The division of the H\({}_{Ar}\), (Aromatic ring protons and aromatic ring hydroxyl, polynuclear aromatic hydrogen, \(\delta\) = 6.0-9.0), H\({}_{\alpha}\) (\(\alpha\)-CH\({}_{2}\), \(\alpha\)-CH\({}_{3}\) alkyl protons in aromatic rings, alcohols and mercaptan hydroge, \(\delta\) = 2.0-4.0), H\({}_{\mathrm{N}}\) (-CH/CH\({}_{2}\) in cycloalkanes, normal alkanes and iso-alkanes, \(\delta\) = 1.4-2.0), H\({}_{\mathrm{\beta}}\) (\(\beta\)-CH\({}_{2}\), \(\beta\)-CH\({}_{3}\) alkyl protons in aromatic ring, \(\beta\)-CH\({}_{2}\) groups in longer alkyl chain, \(\delta\) = 1.0-1.4), H\({}_{\mathrm{Y}}\) (\(\gamma\)-CH\({}_{3}\) in aromatic cyclic alkyl protons, cycloalkanes, and alkanes, \(\delta\) = 0.5-1.0) regions of the \({}^{1}\)H NMR spectrum, as shown in Table 3, provided qualitative and quantitative information about different types of hydrogen. Data were expressed as the mean of three separate calculations. From the data in Table 3, it can be seen that the distribution of hydrogen in the MLCT-Z and its narrow fraction was approximately the same as that in the MLCT-S and its narrow fraction, and the components of the two kinds of coal tar were quite similar. With the increase of the distillation temperature, the variation of the hydrogen content in the MLCT-Z and MLCT-S distillates was  
Figure 4: Gas chromatography-mass spectrometer (GC-MS) chromatograms of narrow distillate fractions. (**a**) The main components of narrow fractions from MLCT-Z; (**b**) The main components of narrow fractions from MLCT-S.  
inconsistent. Overall, the naphthenic hydrogen peak areas of the narrow fractions of the two coal tars were the lowest, indicating that the naphthenic structure components in the coal tar samples were relatively small. The fractions with the highest H\({}_{\rm N}\) content of MLCT-Z and MLCT-S were greater than 360 \({}^{\circ}\)C and 340-360 \({}^{\circ}\)C, respectively, indicating that H\({}_{\rm N}\) had different distillation ranges in different coal tars. In contrast, the H\({}_{\rm\alpha}\) content was the most in the fractions within the range of 210-250 \({}^{\circ}\)C, manifesting that there were more methyl ethyl benzenes in this segment in the form of \(\alpha\)-CH\({}_{2}\) alkyl protons and\(\alpha\)-CH\({}_{3}\) alkyl protons. Compared to the peak areas of different hydrogen in the narrow fraction of each coal tar, it was found that the fractions with IBP-170 \({}^{\circ}\)C and above 300 \({}^{\circ}\)C in the distillation range contain more H\({}_{\rm\beta}\), showing that a high amount of hydrogen in the \(\beta\) or further positions of the aromatic ring were in the form of CH\({}_{2}\) and -CH-, or in the form of -CH- attached to methyl groups. The data showed that the H\({}_{\rm\beta}\) content of the MLCT-Z was much higher than that of the MLCT-S when the distillation range was 340-360 \({}^{\circ}\)C. Combined with the results of GC-MS analysis, the contents of long-chain alkanes and methyl phenols of this narrow fraction in MLCT-Z were higher than those of MLCT-S. The fraction of 170-210 \({}^{\circ}\)C in the distillation range was mainly composed of H\({}_{\rm Ar}\), indicating that there were more components with an aromatic ring structure. Combined with the results of element analysis, it was found that the O content in this segment was relatively high, which proved that this narrow fraction was mainly composed of phenolic compounds such as methyl phenol and dimethyl phenol. It was reported that the boiling range of phenol oil was 170-210 \({}^{\circ}\)C, which proved the reliability of the \({}^{1}\)HNMR analysis of coal tar.