PROCESS FOR PRODUCING METHACRYLIC ACID

摘要

A process for producing methacrylic acid through vapor-phase catalytic oxidation of methacrolein by molecular oxygen, in which the catalyst can be used for a prolonged period of time. In the production of methacrylic acid through vapor-phase catalytic oxidation of methacrolein as a raw material by molecular oxygen in the presence of a catalyst consisting of a composite oxide containing molybdenum and phosphorus, not only is a pressure control involving stepwise or continuous changing of reaction pressure carried out so that the reactivity of the raw material is constant at reaction temperatures ranging from 285° to 305°C, but also a molar ratio control involving stepwise or continuous changing of the molecular oxygen/raw material molar ratio in a reaction gas is carried out simultaneously with or independently from the pressure control.