Process for hydrotreating heavy hydrocarbons in liquid phase in the presence of a dispersed catalyst

A process for hydrotreating an asphaltene-containing hydrocarbon oil charge stock, comprising the steps of:

• (a) admixing said hydrocarbon oil charge stock with hydrogen and fresh catalyst, said catalyst comprising at least one metal compound whose metal component is selected from groups Vb, VIb, VIIb and the iron group of group VIII, the amount of said metal compound, expressed as metal, relative to said hydrocarbon oil charge stock being from 20 to 500 ppm by weight;
• (b) passing the resultant mixture from step (a) through a heating zone comprising a heated surface, said mixture being maintained in said heating zone at a temperature of from 350.degree. to 470.degree. C. for from 15 to 180 seconds;
• (c) introducing the heated mixture from step (b) into a hydrotreating reaction zone, introducing a recycle catalyst suspension as hereinafter defined into said reaction zone, and maintaining the resultant hydrotreatment reaction mixture in said reaction zone at a temperature of from 350.degree. to 470.degree. C. and a pressure of from 50 to 200 bars for from 0.1 to 4 hours, the introduction of said recycle catalyst suspension providing said hydrotreatment reaction mixture with from 1,000 to 20,000 ppm by weight of said metal catalyst component, expressed as metal, relative to the weight of said hydrocarbon oil charge stock used in step (a);
• (d) fractionating the hydrotreated reaction mixture from step (c) into at least one gas phase and at least one phase comprising a slurry of said catalyst in hydrotreated hydrocarbon oil;
• (e) fractionating said slurry from step (d), and separately recovering a hydrotreated hydrocarbon oil product fraction and a catalyst fraction, at least a portion of the recovered catalyst fraction being suspended in a hydrocarbon oil recycle carrier and the suspension being supplied at a temperature lower than 350.degree. C. to step (c) as said recycle catalyst suspension.