THE EFFECTS OF SOLVENT QUALITY ON THE LIQUEFACTION OF 2 DIFFERENT TYPES OF COAL

Thermal and catalytic liquefaction runs were performed at 400 and 430 degrees C for 30 min in hydrogen with different hydroaromatic:aromatic , hydroaromatic:naphthenic or naphthenic:aromatic solvent blend ratios for Australian bituminous and Indonesian subbituminous coals. The res ults indicate that the subbituminous coal needs more efficient externa l hydrogen transfer to maintain high conversion than does the bitumino us coal, implying that both hydrogen transfer from donor solvent and c atalytic transfer from molecular hydrogen are important in improving s ubbituminous coal liquefaction yields. In bituminous coal liquefaction , it appears that the form of hydrogen, whether molecular or donatable from hydroaromatic solvent, is not critical as long as the internal h ydrogen is present in sufficient amount and in a form usable by the co al and a minimum hydroaromaticity of the solvent system (tetralin:naph thalene ratio 1:3) is maintained. A temperature increase from 400 to 4 30 degrees C significantly affects the bituminous coal liquefaction yi eld, but little improvement is observed for the subbituminous coal. To optimize liquefaction, the solvent quality, temperature and catalyst must be properly chosen, depending on coal rank.