Synthesis of Porous Carbon Structures by Thermal Treatment of Solid Products of Plasmochemical Pyrolysis of Hydrocarbons and Heavy Petroleum Products

Abstract—Carbon structures formed after plasma-induced liquid phase pyrolysis of hydrocarbons were studied. We studied pyrolysis of the products of petroleum refining: fuel oil, heavy catalytic cracking residue, and individual organic substances: furfural, cyclohexane, hexane, isooctane, benzene. The plasma unit generated direct current discharge through graphite electrodes. The elemental composition of the source materials and resulting solid residues was evaluated. Additional heat treatment of solid products was carried out at 900, 1500, and 2800°C in an argon atmosphere. The specific surface area and porous structure parameters of the samples were estimated from nitrogen adsorption data. High-resolution transmission electron microscopy was used to study the microstructure of benzene and fuel oil pyrolysis residues. The relationship between porous structure parameters and relative content of hydrogen (C/H) in the solid residues is discussed. The existence of a positive correlation between the C/H parameter and specific surface area was established. It was also found that, with increasing heat treatment temperature, the specific surface area decreased for all studied samples. It is established that the volume of mesopores increases, and their average diameter decreases with increase in C/H of solid residues of the feedstock. The volume of micropores increases with increasing C/H, whereas their sizes change only slightly. As the heat treatment temperature increases, the overall relative porosity decreases. The prospects of plasma pyrolysis combined with subsequent high temperature heat treatment to obtain carbon materials with controlled porous structure are discussed.