Preparation method of methacrylic acid

Abstract

The present invention relates to a preparation method of methacrylic acid which improves reaction selectivity of methacrylic acid. The method may include while producing methacrylic acid by gas phase of oxidation of oxidizing methachrolane in the presence of catalyst. Particularly, the present invention relates to the preparation method of methacrylic acid comprising the step of introducing CO2 up to 3˜80 mole % of the feed gas in the presence off catalyst having the general formula of PaMo11VbXcYdOe, wherein X is may be one or more elements selected from the group of alkaline metal and Tl element, Y is may be one or more elements selected from the group of Cu, Pb, Sb, Cr and Ce, and In addition, a, b, c, d and e is are the molar ratio of each necessary element when molybdenum is 11, where 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 suitable value for elemental valency in the composition of said formula respectively.

Dependencies are inferred from the claim text.