Preparation of Methyl Methacrylate by Oxidative Esterification of Methacrolein

A new type catalyst was prepared and applied to the oxidative esterification reaction of methacrolein (MAL) to methyl methacrylate (MMA).Ionic liquid [bmim]PF_6(1-butyl-3-methylimidazolium fluorophosphate) was used in this reaction,and it was found that the ionic liquid not only increased the selectivity for methyl methacrylate but also inhibited its polymerization.With 0.84 mL MAL,1 mL [bmim]PF_6 and w(catalyst)=2.4%,at reaction temperature 50 ℃,pH=10.5,O_2 flowrate 6 mL/min and reaction time 6 h,the MAL conversion and MMA selectivity reached 96.2% and 98.7% respectively.