NETWORK SWELLING OF COALS

In this paper the solvent swelling technique is applied to coal residues obtained by catalytic hydrogenation, to monitor the changes produced in crosslinking density during the hydrogenation process. An attempt is made to correlate the volumetric swelling ratio with coal rank, temperature and residence time as well as with gas evolution (CO2 and H2S). The results indicate that for the two coals studied, the crosslinking is strongly dependent on temperature and residence time. Even though the crosslinking density is lower for the raw subbituminous coal than for the bituminous one, the former crosslinks more readily and at a lower temperature. This temperature is more suitable for monitoring the changes produced in the subbituminous coal network. The main changes in crosslinking density are produced at short residence times for both coals. The same percentage of CO2 is evolved in both cases, but it is less influential on crosslinking in the bituminous coal than in the subbituminous one. However, the opposite is true for the evolution of H2S. © 1990.