| abstract |
The invention presents catalysts for producing phthalic anhydride by vapor phase catalytic oxidation of orthoxylene and/or naphthalene with molecular oxygen or gas containing molecular oxygen. The catalyst is prepared by supporting a catalytic active substance comprising 1 to 20 parts by weight (hereinafter abbreviated "parts") of vanadium oxide as V₂O₃, 99 to 80 parts of anatase type titanium dioxide with specific surface area of 10 to 60 m²/g as TiO₂ and per 100 parts of the sum of these two ingredients, 0.05 to 1.2 parts of at least one element selected from potassium, cesium, rubidium and thallium as oxide, and 0.05 to 2 parts of silver as Ag₂O on a heat resistant inorganic carrier. The catalyst may also contain, per 100 parts in total of vanadium oxide and titanium dioxide, 0 to 1 part of niobium as Nb₂O₅, 0 to 1.2 parts of phosphorus as P₂O₃, and 0 to 5 parts of antimony as Sb₂O₃ (however, contents of niobium, phosphorus and antimony will not be zero at the same time). |