Abstract: According to the method of manufacturing refined oil of the present invention, refined oil which has a viscosity of 20 cst or lower at 135° C., a pour point of 30° C. or lower, an alkali metal content of 1 wt ppm or less, a vanadium content of 10 wt ppm or less and a sulfur content of 0.3 wt % or lower can be prepared, by bringing feed oil into contact with hydrogen in the presence of the demetalizing/desulfurizing catalyst 3 and the hydrogenolysis catalyst 5. This method can decrease the viscosity, pour point and sulfur concentration of the refined oil to sufficiently low levels, and decreases the production cost.

Abstract: A refined oil is obtained by using a heavy oil having a hydrogen content of 12 wt % or less as a feed oil, and after carrying out a solvent extraction process such that the hydrogen content increases by 0.2 wt % over that of the feed oil, hydrorefining process is carried out such that the hydrogen content increases by 0.5 wt % over the extracted oil. Thereby, an inexpensive heavy oil can be used as a feedstock, and using a simple and reliable method, refined oil can be produced.

Abstract: According to the method of manufacturing refined oil of the present invention, refined oil which has a viscosity of 20 cst or lower at 135° C., a pour point of 30° C. or lower, an alkali metal content of 1 wt ppm or less, a vanadium content of 10 wt ppm or less and a sulfur content of 0.3 wt % or lower can be prepared, by bringing feed oil into contact with hydrogen in the presence of the demetalizing/desulfurizing catalyst 3 and the hydrogenolysis catalyst 5. This method can decrease the viscosity, pour point and sulfur concentration of the refined oil to sufficiently low levels, and decreases the production cost.