Method for producing methyl methacrylate

Patent metadata

Field	Value
Publication number	US-11414371-B2
Application number	US-202017043975-A
Country	US
Kind code	B2
Filing date	Apr 15, 2020
Priority date	Jun 28, 2019
Publication date	Aug 16, 2022
Grant date	Aug 16, 2022

Abstract

A method for producing methyl methacrylate including:a distillation step including:supplying a reaction solution, which is obtained by subjecting methacrolein, methanol, and molecular oxygen to oxidative esterification in an oxidative esterification reactor and which contains the methyl methacrylate as a reaction product, to a first distillation column located at downstream of the oxidative esterification reactor,extracting a fraction containing the methacrolein and the methanol from a medium section of the first distillation column, andextracting a column bottom liquid containing the methyl methacrylate from a column bottom of the first distillation column,wherein a concentration of the methanol in the column bottom liquid is 1% by mass or more and 30% by mass or less.

First claim

The invention claimed is:

1. A method for producing methyl methacrylate, comprising:
a distillation step comprising
supplying a reaction solution, which is obtained by subjecting methacrolein, methanol, and molecular oxygen to oxidative esterification in an oxidative esterification reactor and which comprises the methyl methacrylate as a reaction product, to a first distillation column located at downstream of the oxidative esterification reactor,
extracting a fraction comprising the methacrolein and the methanol from a medium section of the first distillation column, and
extracting a column bottom liquid comprising the methyl methacrylate from a column bottom of the first distillation column,

wherein a concentration of the methanol in the column bottom liquid is 1% by mass or more and 30% by mass or less.

2. The method for producing methyl methacrylate according to claim 1 , further comprising a step of phase-separating the column bottom liquid into a light phase and a heavy phase.

3. The method for producing methyl methacrylate according to claim 2 , further comprising a step of distilling the heavy phase in a second distillation column to obtain a fraction comprising the methanol.

4. The method for producing methyl methacrylate according to claim 3 , wherein the fraction comprising the methanol obtained from the second distillation column is recycled to the oxidative esterification reaction.

5. The method for producing methyl methacrylate according to claim 2 , further comprising
a step of subjecting the light phase to purification, and
a step of adding a polymerization inhibitor to the light phase after the purification.

6. The method for producing methyl methacrylate according to claim 1 , further comprising a step of subjecting the methacrolein, the methanol, and the molecular oxygen to oxidative esterification in the oxidative esterification reactor, to obtain the reaction solution.

7. The method for producing methyl methacrylate according to claim 1 , wherein the fraction, which comprises the methacrolein and the methanol and which has been extracted from the medium section of the first distillation column, is recycled to the oxidative esterification reaction.

8. The method for producing methyl methacrylate according to claim 1 , wherein a methanol is further added to the first distillation column in the distillation step to adjust the concentration of the methanol in the column bottom liquid.

9. The method for producing methyl methacrylate according to claim 8 , wherein a ratio of the number of moles of the methanol to be further added, to the number of moles of the methacrolein contained in the reaction solution is 0.1 or more and 3.0 or less.

10. The method for producing methyl methacrylate according to claim 1 , wherein, in the distillation step, a temperature of the column bottom of the first distillation column is 45° C. or higher and 80° C. or lower, and a pressure of the column bottom of the first distillation column is −50 kPaG or more and 0 kPaG or less.

11. The method for producing methyl methacrylate according to claim 1 , wherein a residence time of the column bottom liquid of the first distillation column calculated by the following formula is 1.5 hours or less:
residence time (hour)=amount (kg) of column bottom liquid present in first distillation column/extraction amount (kg/hour) of column bottom liquid per unit time.

12. The method for producing methyl methacrylate according to claim 1 , wherein a concentration of an intermediate boiling point material in the column bottom liquid in the first distillation column is 0.1% by mass or more.

13. The method for producing methyl methacrylate according to claim 12 , wherein the intermediate boiling point material comprises methyl acrylate.

14. The method for producing methyl methacrylate according to claim 1 , wherein at least a part of the column bottom liquid is extracted, then heated by a heat-exchange with a vent gas generated from the oxidative esterification reactor, and thereafter returned to the column bottom of the first distillation column.

15. The method for producing methyl methacrylate according to claim 1 ,
wherein:
an amount of the methacrolein extracted from the medium section of the first distillation column is 95% by mass or more of an amount of the methacrolein contained in the reaction solution; and
an amount of the methanol extracted from the medium section of the first distillation column is 70% by mass or more of an amount of the methanol contained in the reaction solution.

16. The method for producing methyl methacrylate according to claim 1 , further comprising a step of cooling a column top gas out of the first distillation column to obtain a condensate,
wherein a concentration of the methanol in the condensate is 30% by mass or less.

Assignees

• Asahi Chemical Ind

Inventors

• Saito Hideyuki
• Ito Takamasa
• Idemoto Masahiko

Classifications

• C07C69/54

  Acrylic acid esters; Methacrylic acid esters · CPC title

• B01D3/34

  with one or more auxiliary substances · CPC title

• C07C67/54

  by distillation · CPC title

• C07C67/42 Primary

  by oxidation of secondary alcohols or ketones · CPC title

• B01D3/007

  Energy recuperation; Heat pumps · CPC title