A PROCESS FOR OBTAINING METHACROLEIN AND METHACRYLIC ACID FROM A REACTION PRODUCT GAS OBTAINED BY KNOWN CATALYTICAL OXIDATION OF ISOBUTYLENE,TERTIARY BUTANOL,METHACROLEIN OR ISOBUTYL ALDEHYDE

摘要

To recover methacrolein and/or methacrylic acid by quenching a reaction product gas obtained by catalytic oxidation of isobutylene or the like, the reaction product gas is charged into a quench column through a double-wall pipe and is then brought into contact with a condensate as a cooling medium. Deposition of terephthalic acid and the like inside the column is prevented by controlling the temperature of a bottom in the quench column and that of an overhead gas of a quench column unit. An aromatic carboxylic acid, aromatic aldehyde and/or metal powder such as stainless steel powder is added to an aqueous solution of methacrylic acid, which contains terephthalic acid and the like, so that the terephthalic acid and the like are caused to precipitate for their removal.