| abstract |
In the hydrogenation of coal slurried in recycle oil in the presence of a suspended hydrogenation catalyst, a substantial proportion of the catalyst can be recovered for recycle to the process by using a catalyst which is significantly more finely divided than the ash particles from the coal, subjecting the hydrogenated slurry to a gravity concentration process whereby the coarser, ash particles are selectively concentrated in a lower layer and a relatively larger proportion of the finer catalyst particles remain suspended in the supernatant oil, and recycling at least a part of the supernatant oil containing suspended catalyst to the coal hydrogenation process. |