Structural Characterization of Large Polycyclic Aromatic Hydrocarbons. Part 2: Solvent Separated Fractions of Coal Tar Pitch and Naphthalene Derived Pitch
Complex polycyclic aromatic hydrocarbon (PAH) mixtures separated from a coal tar pitch (CP) and naphthalene pitch (NP) by sequential extraction with heptane and toluene were characterized in detail by applying a multiarray analytical approach. Gas chromatography mass spectrometry (GC MS) size exclusion chromatography (SEC) laser desorption ionization time of flight mass spectrometry (LDI TOFMS) and thermogravimetry (TG) were used to relate the volatility and coking yield of pitch components to their solubility and molecular weight distribution. Spectroscopic analysis, including infrared (IR) ultraviolet visible (UV vis) and fluorescence spectroscopy, proved to be useful for measuring specific features of aromatic systems, such as the aromatic content, degree of aliphatic substitution, and size distribution of PAHs of different molecular weights. In particular, it has been shown that the spectroscopic analysis is an essential tool for characterizing very large PAH systems concentrated in the pitch tol.