| CPC C07C 45/75 (2013.01) [B01D 3/145 (2013.01); B01D 5/006 (2013.01); B01D 17/0214 (2013.01); B01J 14/005 (2013.01); C07C 45/84 (2013.01)] | 17 Claims |
|
1. A process for preparing methacrolein from formaldehyde and propionaldehyde in the presence of water and in the presence of a homogeneous catalyst based at least on an acid and a base, the process comprising:
S1: introducing formaldehyde, propionaldehyde, water, and the homogeneous catalyst based at least on the acid and the base into a reactor,
S2: producing, in a liquid phase, a liquid reaction mixture in the reactor, wherein the reaction mixture comprises methacrolein and accompanying components, wherein the accompanying components comprise water, the catalyst, unconverted formaldehyde, and unconverted propionaldehyde,
S3: introducing the reaction mixture into a methacrolein workup plant and at least partly separating off the accompanying components present in the reaction mixture in the methacrolein workup plant, wherein the at least partly separating off comprises:
S3.i: introducing at least a fraction of the reaction mixture into a first distillation column that forms part of the methacrolein workup plant and separating the at least a fraction of the reaction mixture at least into a first distillation mixture and a second distillation mixture, wherein the first distillation mixture is in a form of a gas phase at the top of the first distillation column and comprises methacrolein, and the second distillation mixture is in a form of a liquid phase at the bottom of the first distillation column and comprises water and the catalyst,
S3.ii: introducing the first distillation mixture removed from the top of the first distillation column into a first condenser that forms part of the methacrolein workup plant and condensing the first distillation mixture,
S3.iii: removing condensate from the first condenser, introducing the condensate into a first phase separator that forms part of the methacrolein workup plant and separating the condensate into a first separation mixture and a second separation mixture in the first phase separator, wherein the first separation mixture is in a form of an organic phase comprising methacrolein, and the second separation mixture is in a form of an aqueous phase, and
S3.iv: removing the second distillation mixture from the bottom of the first distillation column,
S4: introducing at least a portion of the second distillation mixture removed in S3.iv into the reactor,
S5: introducing the second separation mixture into a second distillation column and separating the second separation mixture introduced at least into a third distillation mixture and a fourth distillation mixture, wherein the third distillation mixture is in a form of a gas phase at the top of the second distillation column and comprises methacrolein, and the fourth distillation mixture is in a form of a liquid phase at the bottom of the second distillation column and comprises water,
S6: removing the third distillation mixture from the top of the second distillation column and introducing the third distillation mixture into the methacrolein workup plant, and
S7: removing the fourth distillation mixture from the bottom of the second distillation column,
wherein a pressure in the reactor is higher than in the first distillation column.
|