1,152,766. Liquid-phase catalysis. MELLEBEZONS. 16 Feb., 1967 [10 March, 1966], No. 7555/67. Heading B1F. [Also in Division C2] Compounds to be hydrogenated and an excess of hydrogen from 3 to 6 times as large as the hydrogen consumption during the same time or, otherwise expressed, from 4 to 10 cubic metres/hour/sq. decimetre of horizontal cross section of the bath are introduced into a reactor 1 containing a bath of liquid medium of dispersed hydrogenation catalyst. The bath has a fixed level 3 surmounted by a free space for separated hydrogen and comprises an inert solvent for compound(s) to be hydrogenated and the product(s) of hydrogenation which solvent has a boiling temperature above the reaction temperature and may be the compounds in or products of the hydrogenation. The bath is of great height compared with its other dimensions and the compounds to be hydrogenated are introduced at 7 in the lower part of the bath. The hydrogen stream introduced at 4 emulsifies in the liquid medium and is removed at 13 for recycle. An amount of liquid is continuously withdrawn at 9, decanted in 10, the catalyst slurry is returned at 11, the products of the reaction are separated and the solvent recovered is returned to the bath at 11. The fixed level is maintained by returning and adding liquid to compensate for that withdrawn.