Abstract
To investigate the feasibility of nondistillable bottom recycle for the enhancement of liquid yields, two stage liquefaction of Yallourn and Taiheiyo coals were conducted using NiMo/Al2O3 with red mud at the first stage.
Over successive passes, high coal conversion (>96wt%) at the first stage was maintained, and yields of gas and THFI were not increased. It was also indicated that 60wt% of both coals were converted to cyclohexane solubles at the initial stage accompanied with the promoted conversion of coal and/or cyclohexane insolubles. The improvement of conversion and product selectivity seems to be related with the changes in quality of recycle solvent in terms of the efficiency of hydrogen transfer reaction, and with the removal of hetero compounds causing the regressive reaction.
The above results suggest the possibility of highly efficient conversion of organics inherent in both brown and subbituminous coals to liquid products.
