Patent ID: 7012039

Claim:
An oxide catalyst composition for use in producing methacrolein or a mixture of methacrolein and methacrylic acid by reacting at least one member selected from the group consisting of isobutylene and t-butanol with a molecular oxygen-containing gas, said oxide catalyst composition being represented by the following formula (I): (Mo+W) 12 Bi a A b B c Fe d X e Sb f O g (I) wherein: A is at least one member selected from the group consisting of lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium and |yttrium; B is at least one member selected from the group consisting of potassium, rubidium and cesium; X is cobalt solely, or a mixture of cobalt and at least one member selected from the group consisting of magnesium and nickel; wherein the number of molybdenum (Mo) atoms is in the range of from more than 9 to 12, and the number of tungsten (W) atoms is in the range of from 0 to less than 3, each relative to twelve atoms of the total of molybdenum (Mo) and tungsten (W); and a, b, c, d, e, f and g are, respectively, the atomic ratios of bismuth (Bi), A, B, iron (Fe), X, antimony (Sb) and oxygen (O), relative to twelve atoms of the total of molybdenum (Mo) and tungsten (W), wherein 0<a≦8, 0<b≦8, 0<c≦3, 0.2<d<5, 1≦e≦12, 0.1<f<3, and g is the number of oxygen atoms required to satisfy the valence requirements of the other elements present; and wherein a, b, c, d and f satisfy the requirements of the following formulae: 0.02 <b/ ( a+b+c )<0.6, 0 <c/ ( a+b+c )≦0.9, 0.01< d/ ( a+b+d )≦0.9, and 0.1 <d−f< 2.5.