Formation and stability of mesophase during coal hydrogenation. 1. Formation of mesophase

Abstract

Vitrinite samples from Australian bituminous coals were hydrogenated in autoclaves without vehicle solvent, and the solid products were examined microscopically. When a vitrinite sample was stirred during hydrogenation, the yields of liquid and gaseous products were high. However, when the samples were not stirred, the yields were low, and the solid products contained a high proportion of mesophase. In a vertical section of a vitrinite sample which was unstirred during hydrogenation, the surface in contact with hydrogen was covered by isotropic material, underlaid by a zone of mixed isotropic and mosaic-textured material. Away from the surface, the proportion of isotropic material decreased. The authors conclude that mesophase is formed from material previously liquefied, more readily under hydrogen-deficient conditions than under conditions in which hydrogen is freely available. Application of this conclusion may increase the efficiency of hydrogenation processes by reducing the deleterious effects of mesophase formation.