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AssigneeMitsubishi Rayon Co., Ltd.
InventorsHiroshi Sonobe, Masaaki Kato, Hideo Matsuzawa, Hiromichi Ishii, Masao Kobayashi
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The gas phase catalytic oxidation of an unsaturated aldehyde with molecular oxygen at 240.degree. to 390.degree. C to give the corresponding unsaturated carboxylic acid is conducted in the presence of a catalyst represented by the following formula: P.sub.a Mo.sub.b As.sub.c X.sub.d Y.sub.e Z.sub.f O.sub.g wherein a, b, c, d, e, f and g represent the atomic ratio of each component and a is 0.03 to 0.2, b is 1, c is 0.015 to 0.15, d is 0.003 to 1, e is 0.003 to 0.417, f is 0.003 to 1, and g is a value determined by the valencies of the elements present in the catalyst; and wherein X is copper, vanadium or mixtures thereof Y is at least one alkali metal selected from the group consisting of lithium, sodium, potassium, rubidium and cesium, and Z is at least one metal selected from the group consisting of magnesium, aluminum, calcium, titanium, zirconium, silver, antimony, tellurium, barium, tantalum and silicon. This catalyst is especially effective for the preparation of methacrylic acid from methacrolein, and has a very long lifetime.
A process for the preparation of unsaturated carboxylic acids, which comprises catalytically oxidizing acrolein, methacrolein or mixtures thereof in the gas phase at a temperature of 240.degree. to 390.degree. C with molecular oxygen to form the corresponding unsaturated carboxylic acid in the presence of a catalyst having the composition
Dependencies are inferred from the claim text.