Abstract: Production processes are provided which can produce, at a relatively low temperature and in a reduced number of steps, anatase titanium oxide powder having high photocatalytic activity and large specific surface area and anatase titanium oxide slurry having high storage stability and dispersibility. The slurry thus obtained can also be coated, as a coating material having photocatalytic activity, on materials having low heat resistance. In the production process of anatase titanium oxide powder according to the present invention, a titania sol solution, a titania gel, or a titania sol-gel mixture is heat treated in a closed vessel under pressure, and the treated product is then dried to produce anatase titanium oxide powder.

Abstract: A method for producing an anatase type titanium dioxide powder which comprises subjecting a titania sol, a titania gel or a titania sol-gel mixture to a heat treatment and simultaneously to a pressure treatment in a closed vessel, and subsequently drying the resulting product; and a method for producing an anatase type titanium dioxide slurry which comprises subjecting a titania sol, a titania gel or a titania sol-gel mixture to a heat treatment and simultaneously to a pressure treatment in a closed vessel, and subsequently agitating the resulting product to provide a dispersion. This method can be used for producing an anatase type titanium dioxide powder which exhibits high photocatalytic activity and has a large specific surface area, and an anatase type titanium dioxide slurry which has high storage stability and high dispersibility in a process operated at a relatively low temperature and having a small number of steps.

Abstract: An extraction residue obtained by solvent deasphalting of a residual oil is mixed with a carrier gas and thermally cracked at a temperature of 400.degree. C. to 600.degree. C. in a tube-type cracking apparatus to obtain cracked oil and pitch. The use of the carrier gas, which may be either an inert gas such as nitrogen or a reactive gas such as hydrogen, permits a flow velocity through the cracking apparatus sufficient to substantially prevent coking. Preferably, the cracking conditions are controlled so that the yield of cracked oil is not more than about 30 to 35%.