PURPOSE: To carry out efficiently hydrogenation treatment by prolonging catalyst life, by a method wherein a powdered solid catalyst is mixed with hydrocarbon oil, the mixt. is subjected to the first hydrogenation treatment, and then the second hydrogenation treatment is carried out in the presence of a particulate solid catalyst.
CONSTITUTION: Hydrocarbon oil is mixed with a powdered solid catalyst having a particle diameter of not more than 0.3 mm in a mixer 4 to form a slurry which is then mixed with H2 supplied from a line 9. The mixture is introduced into the first hydrogenating reactor 1 where the first hydrogenation treatment is carried out to decompose S, N, and O components present in the feed oil and to adsorb metals present in the feed oil on the powdered solid catalyst, said metals being catalyst poison. Then products are introduced into the second hydrogenating reactor 2 where the second hydrogenation treatment is carried out in the presence of a particulate solid catalyst having an average pore diameter of 50-200 Angstrom and a particle diameter of not less than 0.5 mm. The resulting products is introduced into a gas separator 3. Gas in the products is separated through a line 13. Produced oil containing the catalyst powder is introduced into a solid-liquid separator 5. The produced oil is recovered through a line 15. The catalyst powder is recovered through a line 16