Structural Analysis of Primary Coal Tar by FD-MS

Abstract

Understanding chemical structure of primary coal tar is substantially important to promote advanced application and utilization of coal where chemical reaction plays a key role. Mass spectrometry allows us to characterize complex mixture like coal tar pitch, coal extractions, and heavy oil. In the present study, two kinds of primary coal tar A and B were prepared from different types of coal A (bituminous coal) and B (subbituminous coal). The main components such as Hexane Soluble (HS) and Hexane Insoluble-Toluene Soluble (HI-TS) fractions obtained by extraction of each tar were measured by Field Desorption Mass Spectrometry (FD-MS) to determine their constituent chemical structures. The ¹H NMR spectra of HS and HI-TS were measured to confirm the reliability of proportion of hydrogen types that have been determined by FD-MS. As a result, both of the proportions in HS fractions were found to be almost consistent, while those in HI-TS fractions show a difference because of their more complex chemical components than HS fractions. Based on the combined analysis of FD-MS and NMR, we concluded that the HS in primary coal tar A mainly consists of polycyclic aromatic hydrocarbons (PAHs) and aliphatic structures including aromatic carbons, while the HS in primary coal tar B mainly consists of aliphatic structures. These results suggest that determining chemical structures and their ratios only from FD-MS spectra is useful to concretely clarify difference between some types of primary coal tar.

Classification of chemical structures contained HS fractions for primary coal tar A and B.