CATALYTIC BEHAVIOR OF SULFATE AND SULFIDE IN S-PROMOTED IRON-OXIDE CATALYSTS FOR LIQUEFACTION OF BITUMINOUS COAL AND LIGNITE

Catalytic activities of sulphate (S-6+) and sulphide (S-2-) for liquefaction of bituminous coal and lignite were studied. In addition, their catalytic activities in the presence of tetralin during liquefaction of both coals were also investigated. The specific catalysts used were FeS2 as a sulphide, and Fe2O3(SO4)2- and ammonium sulphate as sulphates. The liquefaction for different types of coals was carried out in the presence of these catalysts and tetralin as donor solvent under either 10 MPa of H-2 or N-2 initial pressure by using a 70 ml autoclave. The intrinsic activities of these catalysts were evaluated by the distribution of products obtained from tetralin during coal liquefaction. Catalyst Fe2O3(SO4)2- showed the highest activities for hydrogenation and hydrocracking of tetralin. FeS2 showed slightly lower activities. Ammonium sulphate showed activity only for dehydrogenation of tetralin. Also, both catalyst Fe2O3(SO4)2- and FeS2 showed significantly high activity for hydroliquefaction of coals and the ammonium sulphate was found to be inactive. Our results also indicated that the hydroliquefaction activity of catalysts occurs preferentially via reaction with molecular hydrogen rather than through participation of donor solvent.