Method for production of methyl methacrylate by oxidative esterification using a heterogeneous catalyst

A method for preparing methyl methacrylate from methacrolein and methanol;

• said method comprising contacting in a reactor a mixture comprising methacrolein, methanol and oxygen with a heterogeneous catalyst comprising a support and a noble metal, wherein the noble metal comprises gold, wherein the catalyst has an average diameter of at least 300 microns, wherein oxygen concentration at a reactor outlet is from 1 to 7.5 mol % and wherein pH at a reactor outlet is no greater than 7.5.