RELATION BETWEEN RELEASE OF CONVERSION PRODUCTS IN COAL-LIQUEFACTION AND CROSS-LINKING

A study was made of the relation between the release of coal conversio n products and cross-linking, using catalytic solvent-free hydrogenati on in order to avoid problems in data interpretation caused by the pre sence of solvent. Twenty-five subbituminous and bituminous coals were hydrogenated in the absence of solvent at 5 and 10 MPa H-2 (cold), tem peratures of 300,350 and 400-degrees-C and reaction time 30 min, with molybdenum sulfide as catalyst supported on the coal. The low-rank coa ls selected were more reactive than the bituminous ones. The subbitumi nous coals gave a maximum liquids production at 350-degrees-C. At 400- degrees-C the liquids yield decreased but the oil yield increased. Liq uids from the hydrogenation of subbituminous coals were less asphalten ic than those from the bituminous ones. The residual chars were charac terized by the extent of swelling in pyridine. For the subbituminous c oals the swelling decreased with increasing conversion, reaching maxim um cross-linking at the most severe conditions in most instances. The bituminous coals showed a different behaviour at low conversion, but a t higher conversion the relation between conversion and swelling appea red to be similar to that for the subbituminous coals.