Catalyst for production of unsaturated aldehydes

A catalyst for the production of unsaturated aldehydes, said catalyst being represented by the general formula

• Bi.sub.a W.sub.b Fe.sub.c Mo.sub.d A.sub.e B.sub.f C.sub.g D.sub.h O.sub.x
• wherein Bi represents bismuth, W represents tungsten, Fe represents iron, Mo represents molybdenum, O represents oxygen, A represents nickel (Ni) and/or cobalt (Co), B represents at least one element selected from the group consisting of alkali metals, alkaline earth metals and thallium, C represents at least one element selected from the group consisting of phosphorus (P), arsenic (As), boron (B), antimony (Sb), tin (Sn), cerium (Ce), lead (Pb) and niobium (Nb), D represents at least one element selected from the group consisting of silicon (Si), aluminum (Al), zirconium (Zr) and titanium (Ti), a, b, c, d, e, f, g, h and x represent the atomic ratios of the individual elements, and when d is taken as 12, a=0.1-10.0, b=0.5-10.0 (provided that a/b=0.01-6.0), c=0.1-10.0, e=2.0-20.0, f=0.001-10.0, g=0-10.0, and h=0-30, and x takes a number determined by the atomic valences of the individual elements;
• said catalyst having been calcined in air at a temperature of from 400.degree. C.-600.degree. C.
• the Bi component being introduced thereinto in the form of a bismuth tungstate obtained beforehand by calcining a mixture of a bismuth compound and a tungsten compound at a temperature of 600.degree. to 900.degree. C.