| abstract |
The invention provides a process for the liquefaction of coal. The comminuted coal is slurried in a solvent or pasting oil and digested, normally under hydrogen pressure, e.g. of 50 to 250 atmospheres partial pressure, under catalytic conditions, at temperatures between about 380 DEG and 500 DEG C., preferably 400 DEG to 470 DEG C. and residence times between about 10 and 100 minutes. The solvent or pasting oil is obtained wholly or mostly by recycling from the distilled fractionation of the reaction products. The solvent system comprises a light fraction in the boiling range up to 200 DEG C. and a heavy residue fraction, boiling mainly above 450 DEG C., there being a more or less well-defined lack of solvent in a boiling range intermediate between 200 DEG and 450 DEG C. Preferably less than 20%, e.g. 5% or less of the solvent system boils between 200 DEG and 450 DEG C. The ratio of low boiling to high boiling solvent is preferably from about 3:1 to 1:3. The process can be controlled so that the coal is converted virtually completely into distillable products, more particularly predominantly in the crude diesel fuel range (200 DEG to 450 DEG C.). Optionally fractionating residue may be recovered as a further valuable product for making exceptionally high grade electrodes by delayed coking at 500 DEG C. followed by graphitization at 1400 DEG C. |