Patent ID: 7012156

Claim:
A method for producing methacrylic acid by gas phase oxidation of methacrolein, comprising: injecting a feed gas comprising methacrolein, oxygen and CO 2 in the presence of a catalyst of a general formula of P a Mo 11 V b X c Y d O e , wherein X is one or more elements selected from the group of alkaline metal and Tl element, and wherein Y is one or more elements selected from the group consisting of Cu, Pb, Sb, Cr and Ce, and wherein a is 0.8–1.6; b is 0.6–2; c is 0.8–2.2; d is 0.1–0.8; and e is a necessary value of valency in line with the general formula; and wherein CO 2 comprises about 4 to about 20 mol % of the feed gas.