Mechanism of hydrogenation of coal-derived asphaltene

Abstract

Use of asphaltene instead of the parent coal as the starting material for hydrogenolysis makes it easier to discuss the reaction mechanism, because the mean chemical structures of both reactant and products can be deduced from structural analysis. In this study asphaltene from Japanese Akabira coal was hydrogenated at 400 or 370 °C under initial pressures of 9.8 or 10.4 MPa using red-mud and sulphur catalyst. The structures of the products (oil and remaining asphaltene) and of the original asphaltene were analysed statistically by n.m.r. data. Most of the conversion of asphaltene to oil was caused by saturation of aromatic rings, decomposition of naphthenic rings, dehydroxylation and the decrease of inert ( O + N + S) elements resulting from the opening of hetero-rings; the splitting of linkages between unit structures did not contribute to the conversion.