초록 ▼

In an oxidation process for converting methacrolein to methacrylic acid, methacrylic acid is recovered by cooling and condensing the effluent from the oxidation, followed by azeotropic distillation of the condensate with a suitable solvent, such as methyl n-propyl ketone. The condensed effluent cont

In an oxidation process for converting methacrolein to methacrylic acid, methacrylic acid is recovered by cooling and condensing the effluent from the oxidation, followed by azeotropic distillation of the condensate with a suitable solvent, such as methyl n-propyl ketone. The condensed effluent contains methacrylic acid and water as the major components along with by-product acetic acid, a minor amount of unreacted methacrolein and impurities. Substantially dry crude methacrylic acid is separated as a bottom product from the azeotropic distillation and an azeotrope of water and the solvent is taken overhead and condensed. After condensation, solvent-rich and water-rich phases form and are separated. The solvent-rich phase is returned to the distillation column as a reflux, while the water-rich phase is sent to a stripping column for recovery of residual solvent. Water is withdrawn from the bottom of the stripping column and recycled or discarded, as desired. Optionally, an additional distillation column may be used in order to remove unreacted methacrolein from the solvent used in the azeotropic distillation.

대표청구항 ▼

In a process for the preparation of methacrylic acid by the vapor phase catalytic oxidation of methacrolein in the presence of molecular oxygen, water vapor, and inert gases, the recovery of methacrylic acid from the effluent vapors from said oxidation by: (a) cooling and condensing said effluent to

In a process for the preparation of methacrylic acid by the vapor phase catalytic oxidation of methacrolein in the presence of molecular oxygen, water vapor, and inert gases, the recovery of methacrylic acid from the effluent vapors from said oxidation by: (a) cooling and condensing said effluent to a pre-determined temperature and thereby forming a vapor portion comprising substantially unreacted methacrolein and inert gases and a liquid portion comprising substantially methacrylic acid, acetic acid, water, a minor amount of unreacted methacrolein, and impurities; (b) separating said liquid portion of (a) from said vapor portion of (a) and azeotropically distilling at a sub-atmospheric pressure said liquid portion in the presence of a solvent selected from the group consisting of methyl n-propyl ketone, methyl ethyl ketone, methyl isobutyl ketone, methyl isopropyl ketone, diethyl ketone, ethyl isopropyl ketone, ethyl tertiary amyl ether, methyl tertiary amyl ether, n-propyl ether, and mixtures thereof, the overhead product from said distillation comprising substantially an azeotrope of said solvent and water and a minor amount of unreacted methacrolein and the bottom product therefrom being substantially free of water and comprising said methacrylic acid, acetic acid, and impurities.