PURPOSE: To obtain the titled catalyst capable of preparing an unsaturated acid such as (meth)acrylic acid in high yield, by a method wherein compounds containing P and Mo being catalyst componential elements are mixed in the presence of water to form a solution mixture or a slurry and, after drying, the obtained solid substance is ground in the presence of aromatic hydrocarbon before molding.
CONSTITUTION: In preparing an unsaturated acid such as (meth)acrylic acid from (meth)acrolein by using a hetero-polyacid system containing P and Mo as catalyst components, the aforementioned catalyst is prepared according to the following method. That is a compound containing prescribed amounts of catalyst componential elements (e.g., MoO3, H3PO4 or the like) are mixed in the presence of water to prepare a solution mixture or a slurry. In mixing, a temp. is generally 20W80°C and ageing is desirably performed at 50W90°C for 1W20hr after mixing. In the next step, the aforementioned solution mixture or slurry is dried to obtain a solid substance which is, in turn, ground in the presence of an aromatic compound represented by formula (wherein R is a lower alkyl group and n is 0, 1, 2 or 3) (e.g., benzene) to form particles with a particle size of 15μm or less and the aromatic compound is pref. removed to mold said particles. The obtained molded substance is dried at 50W150°C if necessary to be used as the aforementioned catalyst.
FUJINAGA MASATAKA
FURUTA KEIICHI
