1996 Volume 75 Issue 5 Pages 343-350
Effects of the amount of iron/sulfur catalyst on yields and hydrogen transfer of Victorian brown coal were investigated using two kinds of process solvents derived from the two-stage brown coal liquefaction (BCL) process; one is a solvent recycled in primary hydrogenation (PY-S, non-hydrogen donor solvent), and the other is a solvent recovered from secondary hydrogenation over Ni-Mo catalyst (SD-S, hydrogen donor solvent). In addition, the influence of hydrogen pressure and reaction time were also investigated using these solvents in the presence of the catalyst.
SD-S was effective under non-catalytic and lower hydrogen pressure conditions compared with PY-S, but distillate yield was low under these conditions. On the other hand, PY-S provided higher distillate yield and hydrogen efficiency (defined by ratio of distillate yield to amount of hydrogen transferred to all liquefaction products) than SD-S under the condition of high hydrogen pressure and high catalyst concentration. These results indicate that the effects of the catalyst on liquefaction reaction is small in hydrogen donor solvent, and non-donor solvent is effective under severe conditions. The hydrogen efficiency increased with increases in pressure and catalyst concentration, and showed a peak at the optimum reaction time, which depended on the conditions and solvent properties.