Self-Organization of Hexane-Insoluble Asphaltenes of Coal Pitch

Abstract

Recently, there has been growing interest in asphaltenes, which are byproducts of petroleum processing and coal liquefaction. However, most data on the macromolecular structure and morphological characteristics of asphaltene aggregates relate to the petrochemical industry. We know that the concentration of asphaltene in solution affects the structure of their associates, which is also modified by the presence of various additives. The formation of planar associates of asphaltenes and condensed graphite-like structures are of particular interest. In order to optimize the graphitization of the anode mass, coal pitch (the β fraction) is investigated. In the heat treatment of the anode mass, the best binder is pitch with a high content of β fraction. The structuring of the asphaltene macromolecules in solution has not been studied for coal pitch. In the present work, in order to investigate the self-assembly of molecular aggregates of coal-pitch asphaltenes, the morphology and structure of powder particles for coal-pitch asphaltenes are investigated by various methods. The β fraction of pitch containing asphaltenes is separated by means of selectively soluble groups. Toluene and hexane are used as the selective solvents. On the basis of X-ray phase analysis, the coke residue of coal-pitch asphaltenes contains crystallites of naphthene–aromatic layers. The crystalline properties of the deposited asphaltene particles hardly depend on the deposition conditions. The powder mainly consists of turbostratic carbon structures.