Reactor and process for producing alkyl methacrylates

A process for producing alkyl methacrylates, comprising:

• reacting methacrolein with an alkyl alcohol in the presence of an oxygen-containing gas and a particulate, pulverulent catalyst in a liquid phase, in a reaction mixture in a reactor, to obtain an alkyl methacrylate;
• wherein the reactor comprises a zone A, at least one zone B-1, at least one zone B-2, a zone B-3, and at least one zone C, and
• wherein
• zone A represents a primary reaction zone and is provided with at least one stirring means for intensive commixing of gaseous, liquid, and solid phases in zone A,
• the at least one zone B-1 is provided with internals for flow calming which very largely prevent entry of the gaseous phase into subsequent zones of the at least one zone B-2, zone B-3, and the at least one zone C,
• zone B-3 contains the reaction mixture which has been very largely freed of the gaseous phase and is connected to the at least one zone C,
• the at least one zone C comprises a continuously classifying sedimentation apparatus, wherein an average vertical flow in zone A and the at least one zone C is upwards, and an average vertical flow in the at least one zone B-1, the at least one zone B-2, and zone B-3 is downwards, and
• an energy input for suspension of the catalyst by the at least one stirring means is limited to not more than 3 kilowatts per cubic meter of the reaction mixture.