Patent ID: 9617199
Date: 2017-04-11
CPC Classifications: B01J,C07C,Y02P

Claim:
1. A process for preparing methyl methacrylate, comprising: reacting methacrolein in a continuous oxidative esterification with oxygen and methanol which is conducted in a liquid phase in a reactor at a pressure of 2 to 100 bar in the presence of a heterogeneous catalyst comprising gold-containing nanoparticles having a particle size less than 20 nm; withdrawing continuously the liquid phase from the reactor and adjusting the pH after the withdrawal to a pH between 5 and 9 by addition of a basic solution outside of the reactor; and conducting at least 50% of the withdrawn liquid phase having a pH between 5 and 9back into the reactor, wherein the methacrolein is dewatered by distillation in the presence of methanol before being fed into the reactor.