Nippon Shokubai Kagaku Kogyo Co., Ltd.

Chisako Nishio

Masaaki Okuno

Kenji Ueda

Tatsuya Kawabata

Shinya Tanaka

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 V.sub.2 O.sub.3, 99 to 80 parts of anatase type titanium dioxide with specific surface area of 10 to 60 m.sup.2 /g as TiO.sub.2 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 Ag.sub.2 O 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 Nb.sub.2 O.sub.5, 0 to 1.2 parts of phosphorus as P.sub.2 O.sub.3, and 0 to 5 parts of antimony as Sb.sub.2 O.sub.3 (however, contents of niobium, phosphorus and antimony will not be zero at the same time).

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Kanagawa, Japan

Chisako Nishio