Yield and Composition of Semicoking Tars from Low-Quality Coal

Analytical methods are used to derive data regarding the yield and composition of liquid semicoking products from coal of limited metamorphic development (D, DG, and G coal). With greater metamorphic development of the coal, the yield of liquid semicoking tar increases, and the content of tar-asphaltene components in the tar rises. Chromatography combined with mass spectrometry shows that, in low-temperature pyrolysis, the liquid product formed consist of a complex mixture of saturated and aromatic hydrocarbons and heteroorganic compounds. In all the tars, normal and branched n-alkanes and n-alkenes are identified. The aromatic hydrocarbons include mono-, di-, and trisubstituted n-alkylbenzenes and alkylated naphthalenes. The heteroorganic compounds consist predominantly of oxygen-bearing compounds in the form of phenols with alkyl substituents. The different quantities of these components in the liquid products may be attributed to differences in the chemical structure of the coal's organic mass.