GB1422694A - Process for recovering methacrylic acid and methanol - Google Patents

Abstract

1422694 Recovery of methacrylic acid and of methanol MITSUBISHI RAYON CO Ltd 2 April 1973 15649/73 Heading C2C Methacrylic acid is separated from an aqueous solution (A) containing 3-50% by weight of methacrylic acid and 0À1-14% acetic acid; and simultaneously methanol is separated from a mixture (B) containing at least 40% methylmethacrylate, 3-4% methanol and 22% or less water, by feeding mixture (B), either as a single mixture or as separate compositions which together make up (B), close to one end of a columntype extractor, further water (C) close to the other end and (A) at an intermediate point, thereby effecting countercurrent contact of an aqueous phase with an organic phase, and withdrawing an organic phase consisting mainly of methacrylic acid and methylmethacrylate from the end of the reactor at which (C) is fed, and an aqueous phase consisting mainly of methanol, water and acetic acid from the other end; the weight ratio of (B) to (A) is between 0À2 : 1 and 3À0 : 1, and that between (C) and (A) is between 0À1 : 1 and 3À0 : 1. (A) may be an aqueous product from the oxidation of isobutene and/or methacrolein, and all or part of (B) may be crude ester obtained by esterifying methacrylic acid with methanol; further methylmethacrylate may be mixed with the crude ester to form (B), either externally or by supplying the two streams to the extractor by separate inlets which are close together. The organic phase from the column may be distilled to separate acid from ester, and the aqueous phase from the column may be distilled to recover methanol for recycle to the esterification.