FT-IR Investigation of the Structural Changes of Sulcis and South Africa Coals under Progressive Heating in Vacuum: Correlation with Volatile Matter

Table 3

Infrared absorptions range and analytical IR bands for considered vapors and gases.

Sample	Formula	Range (cm^−1)	Assignment	Range (cm^−1)	Assignment	Analytical bands; (cm^−1)
Methane	CH4	3200–2900	𝜈C--H	1350–1250	𝛿C--H	3015, 1307
Hydrocarbons	HC	3200–2800	𝜈C--H	1450–1370	𝛿C--H	2950
Hydrocarbons uns.	C=C	3200–3000	𝜈=C--H	1100–800	𝛾C--H	1663, 913, 890*
Ethylene	C2H4	3200–3000	𝜈=C--H	1100–900	𝛾C--H	1890, 950
Acetylene	C2H2	3300–3250	𝜈C--H	700–610	𝛾C--H	730
Carbon dioxide	CO2	2500–2200	𝜈asC=O	700–600	𝛿C=O	2350
Carbon monoxide	CO	2250–2050	𝜈CO	—	—	2120
Carbon disulpfhide	CS2	1550–1450	𝜈C=S	—	—	1537
sulphur Dioxide	SO2	1400–1300	𝜈S=O	1250–1100	𝛿S=O	1133
Carbonyl Sulphide	COS	2100–1970	𝜈C=O	900–800	𝛿S=C=O	2070
Benzene	C6H6	1500–1400	𝜈C=C	1100–1000	r-ring	3030, 674
Toluene	C6H5-CH3	1665–1430	𝜈C=C	800–650	r-ring	729, 694
MAH	C6H5-X	1665–1430	𝜈C=C	910–665	r-ring	741, 769, 796, 910, 776**
Methanol	CH3-OH	3700–2400	𝜈OH	1050–950	𝜈C--OH	1054
Acetone	CH3-CO-CH3	2000–1500	𝜈C=O	1200–1050	𝛿C=O	1220
Ammonia	NH3	1800–1400	𝑠H--N--H	1250–680	wN–H	968
Hydrocyanic acid	HCN	3400–3200	𝜈CH, 𝜈CN	750–650	𝛿C--H	3312, 712
Nitrous oxide	N2O	2300–2000	𝜈NN	—	—	2240
Nitrogen oxide	NO	2000–1800	𝜈N=O	—	—	1875
Nitrogen dioxide	NO2	1700–1550	𝜈N--O	—	—	1625

MAH: mononuclear aromatic hydrocarbons; X: ethyl, isopropyl groups 𝜈: stretching vibration; deformations: 𝛿: in plane 𝛾: out-of-plane r: rocking, s: scissoring, and w: wagging.
∗For propylene, isobutene; **For o-Xylene, m-Xylene, p-Xylene, isopropyl-benzene, and ethyl-benzene.