Combined GC/MS and FD-MS Analysis of Tar Components Obtained by Lignite Gasification under Wide Temperature Conditions

A laboratory-scale fluidized bed gasifier was used to pyrolyze lignite under a wide range of gasification temperatures (873-1123 K). The obtained tar components were clarified using an analytical method combining gas chromatograph mass spectroscopy (GC/MS) and field desorption mass spectrometry (FD-MS). As a result, the main tar components obtained at the maximum temperature of 1123 K were polycyclic aromatic hydrocarbons (PAHs) without substituents and peaks in molecular weight intervals of 24 and 26 were observed. Tar components increased as the gasification temperature decreased, including PAHs without substituents and PAHs with substituents such as methyl groups. These tar components were observed to have peaks in the molecular weight intervals such as 14, 50, 76, in addition to 24 and 26. Furthermore, pyrolysis at a freeboard temperature of 873 K produced a significant number of tar components, some of which were oxygen-containing compounds. These included oxygen-containing PAHs with hydroxyl groups as substituents as well as methyl groups. Regularity with molecular weight intervals such as 14, 16, 50, and 76 was also observed. However, when the freeboard temperature increased to 1123 K, the main components were substantially reduced, such that the unsubstituted PAHs were prominent.