Table 3. Relative Content of Different Carbon Structure of Raw Coal and HTD Samples.

samples	Fal1	Fal2	Fal1+ Fal2	Far1	Far2	Far1+ Far2	FCOO	FC=O
chemical shift (ppm)	0–65	65–100	0–100	100–150	150–170	100–170	170–190	190–220
raw coal	32.12	2.78	34.90	49.97	9.19	59.16	4.55	1.39
HTD150	31.27	3.12	34.39	50.78	9.50	60.28	4.23	1.10
HTD200	30.89	2.04	32.93	52.27	9.91	62.18	3.98	0.91
HTD250	26.83	1.85	28.68	56.48	10.37	66.85	3.67	0.80
HTD310	25.95	1.37	27.32	59.79	8.99	68.78	2.91	0.99