Abstract: A mixed oxide solid composition of the formulas (I): (a) Mo12Co4.7Bi1Ni2.6Fe3.7W0.5Sn0.5Si1K0.08Ox; (b) Mo12Co3.5Bi1.1Fe0.8W0.5Si1.4K0.05Ox; and (c) Mo12Co3.8Bi1.2Fe0.9W1.1Si1.5K0.05Ox, wherein x is the quantity of oxygen bonded to the other elements and depends on their oxidation states, is suitable for the manufacture of acrolein by oxidizing propylene. The solid composition reacts with propylene according to the redox reaction (1): solidoxidized+propylene→solidreduced+acrolein  (1) To manufacture acrolein, gaseous propylene is passed over the solid composition. Redox reaction (1) is conducted at a temperature of 200 to 600° C., at a pressure of 1.01×104 to 1.01 to 106 Pa (0.1 to 10 atmospheres) and with a residence time of 0.01 second to 90 seconds, in the absence of molecular oxygen.

Abstract: A mixed oxide solid composition of formula (I):Mo.sub.12 W.sub.a Bi.sub.b Fe.sub.c Co.sub.d Ni.sub.e Si.sub.f K.sub.g Sn.sub.h O.sub.x (I)where O.ltoreq.a.ltoreq.5, 0.5.ltoreq.b.ltoreq.5, 0.1.ltoreq.c.ltoreq.10, 0.5.ltoreq.d.ltoreq.10, 0.ltoreq.e.ltoreq.10, 0.ltoreq.f.ltoreq.15, 0.ltoreq.g.ltoreq.1, 0.ltoreq.h.ltoreq.2 and x is the quantity of oxygen bonded to the other elements and depends on their oxidation states, is used in the manufacture of acrolein by oxidizing propylene, the solid composition reacting with propylene according to the redox reaction (1):solid.sub.oxidized +propylene.fwdarw.solid.sub.reduced +acrolein(I)To manufacture acrolein, gaseous propylene is passed over a solid composition of formula (I), to conduct the redox reaction (1) by operating at a temperature of 200 to 600.degree. C., at a pressure of 1.01.times.10.sup.4 to 1.01 to 10.sup.6 Pa (0.1 to 10 atmospheres) and with a residence time of 0.01 second to 90 seconds, in the absence of molecular oxygen.