Societa' Italiana Resine S.i.r. S.p.a.

Luciano Cairati

Pierluigi Villa

Ferruccio Trifiro

Ferruccio Trifiro'

A catalyst active and selective in the oxidation of methanol to formaldehyde is prepared by mixing an aqueous molybdate solution with an aqueous solution of a ferric salt, while maintaining a Mo/Fe atomic ratio of from 1.6:1 to 2.2:1 in the mixture, heating the resulting suspension at 70.degree.-100.degree. C for at least 30 minutes, washing the resulting precipitate with water, drying said precipitate to reduce its water content to 2-8% by weight, reducing the dried precipitate to granules and drying the latter to completely remove water, impregnating the dried granules with an aqueous solution of a decomposable bismuth salt and drying and calcining the impregnated granules. The catalyst consists of granules of crystalline iron molybdate and molybdenum trioxide having on their surface an interaction product thereof with bismuth oxide, said molybdenum trioxide and said bismuth being present in an amount of 5-35 wt.% and 0.5-10 wt.%, respectively, with respect to the crystalline iron molybdate.

Catalyst for the oxidation of methanol to formaldehyde and process for

A catalyst active in the oxidation of methanol to formaldehyde is prepared by forming a suspension of an amorphous precipitate by mixing an aqueous molybdate solution with an aqueous solution of a ferric salt, while maintaining an atomic ratio Mo/Fe of at least 1.5:1 in the mixture, heating the suspension at 70.degree.-100.degree.C for at least 30 minutes, washing the resulting precipitate with water to remove the soluble salts and at least a part of the excess of soluble molybdate not transformed into iron molybdate, thereby to ensure in the washed solid an atomic ratio Mo/Fe of from 1.5:1 to 1.7:1, and drying the washed solid at a temperature not exceeding 120.degree.C for a period of at least 30 minutes. The catalyst consists of iron molybdate Fe.sub.2 (MoO.sub.4).sub.3 with an amount of free molybdenum trioxide ranging from zero to a value such that the atomic ratio Mo/Fe is from 1.5:1 to 1.7:1, and has a crystallinity degree of at least 90%.

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Cassano d'Adda (Milan), Italy

Luciano Cairati