TEXTURAL CHANGES IN COALS DURING HYDROGENATION

Two coals lone subbituminous and one bituminous) have been hydrogenate d without solvent under different experimental conditions. Tests witho ut a catalyst were performed at 300, 350, and 400 degrees C with a hyd rogen pressure of 5 or 10 MPa. Two Fe-catalyst precursors (FeSO4 and r ed mud) were tested at 10 MPa of H-2 and increasing the temperature ra nge up to 500 degrees C in the case of the bituminous coal. The result s indicate that mainly at 400 degrees C and 5 MPa of H-2 important rep olymerization reactions take place in the subbituminous coal, generati ng a large macropore volume in the solid residues. In Fe-catalyzed pro cesses, and independently of the catalytic precursor, 425 degrees C se ems to be a critical temperature. At lower temperatures, the hydrogena tion reaction is predominant and the residues show increasing open por osity, at higher temperatures and mainly at 500 degrees C, the repolym erization processes are predominant, obtaining lower conversion and le ss porous residues. The repolymerization reactions bring about a block age of porosity in all pore ranges.