Nippon Steel Corporation

Nippon Steel Chemical Co., Ltd.

Masataka Kaneyasu

Akira Okamoto

Tadanori Hara

Yoshiaki Miura

A method for the manufacture of phthalic anhydride by the catalytic oxidation of naphthelene or ortho-xylene which comprises contacting a mixed gas consisting of naphthalene or ortho-xylene and a molecular oxygen-containing gas with a catalyst bed comprising a first catalyst packed on the upstream side of the flow of mixed gas and a second catalyst packed on the down-stream side of the flow, wherein the first catalyst has carried on a nonporous inactive carrier a catalytically active component composed of 67 to 90% by weight of titanium dioxide, 9 to 30% by weight of vanadium pentoxide and 0.7 to 3% by weight of a rubidium compound (calculated as Rb.sub.2 SO.sub.4), and the second catalyst has carried on the nonporous inactive carrier a catalytically active component composed of 67 to 94% by weight of titanium dioxide, 5 to 30% by weight of vanadium pentoxide and at least one member selected from the group consisting of 0.1 to 1% by weight of a tin compound (calculated as SnO.sub.2) and 0.5 to 3% by weight of a phosphorus compound (calculated as SnO.sub.2).

Method for manufacture of phthalic anhydride

In a wet process using a steel slag for waste gas desulfurization, the desulfurization is carried out according to the following formula:

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Kitakyushu, Japan

Masataka Kaneyasu