Infrared Characterization of Coal-Derived Asphaltenes and Their Acidic and Basic Components

Abstract

The centrifuged liquid product from the SYNTHOIL coal liquefaction process of the Energy Research and Development Administration can be solvent separated to give oils and asphaltenes. SYNTHOIL asphaltenes, operationally defined as the benzene soluble-hexane insoluble components, have recently been the subject of an investigation by Sternberg et al. It was demonstrated that such materials can be separated into acid-neutral and base fractions that can hydrogen bond. Nuclear magnetic resonance (NMR) studies of the asphaltene fractions and of the individual fractions in the presence of selected electron donors or electron acceptors provided strong evidence for the existence of intermolecular hydrogen bonding. The tremendous utility of infrared spectrometry as a means of studying hydrogen bonding and, in particular, the unique capability of infrared spectrometry to differentiate between inter- and intramolecular hydrogen bonding even when they occur simultaneously, prompted the present investigation.