Characterization of Volatiles in Coal Tar Pitch by Gas Chromatography/Mass Spectrometry and Atmospheric Pressure Solid Analysis Probe/Time of Flight-Mass Spectrometry

Volatiles obtained by heating carbon disulfide-extractable portions from coal tar pitch were characterized by gas chromatography/mass spectrometry (GC/MS) and atmospheric pressure solid analysis probe/time of flight-mass spectrometry (ASAP/TOF-MS). The results show that the maximum yield of volatiles was obtained at temperatures from 200 to 300 degrees C. In total, ninety-one compounds were identified by GC/MS, including fifty-eight condensed arenes, nineteen oxygen-containing compounds, thirteen nitrogen-containing compounds, and a sulfur-containing compound. The total relative content of the heteroatom-containing compounds decreased with rising temperature, whereas the content of the condensed arenes increased. According to ASAP/TOF-MS analysis, the molecular masses of the volatiles released at temperatures of 30 to 200 degrees C, 200 to 300 degrees C, and 300 to 410 degrees C are between 110 and 260, 150 and 350, and 280 and 420 u, respectively. ASAP/TOF-MS was shown to be an effective tool for characterizing high-molecular weight species that are difficult to be determined by GC/MS analysis.