Process for preparing methacrolein

Patent metadata

Field	Value
Publication number	US-11401229-B2
Application number	US-201816613942-A
Country	US
Kind code	B2
Filing date	May 24, 2018
Priority date	May 25, 2017
Publication date	Aug 2, 2022
Grant date	Aug 2, 2022

Abstract

Provided is a process for preparing dry methacrolein which maximizes capture of methanol. Also provided is a process for producing methyl methacrylate.

First claim

What is claimed is:

1. A process for preparing methacrolein comprising:
(a) mixing water and an amine-acid catalyst to provide a catalyst stream;
(b) sending the catalyst stream and a reaction stream comprising propionaldehyde, formaldehyde, and methanol to a reactor to produce a first intermediate stream comprising methacrolein, methanol, and at least 8 weight % water;
(c) providing the first intermediate stream to a phase separator to produce (i) an organic phase comprising water and at least 70 weight % methacrolein, and (ii) an aqueous phase comprising methacrolein, methanol, amine-acid catalyst, and at least 70 weight % water;
(d) distilling the organic phase in a first distillation column to produce (i) a second intermediate stream comprising methacrolein and less than 2 weight % water, and (ii) an overhead stream;
(e) distilling the second intermediate stream in a second distillation column to produce (i) a first product stream comprising methacrolein and methanol in a combined amount of at least 97 weight %, less than 2 weight % water, and less than 1 weight % of impurities comprising one or more of acetic acid, propionic acid, methacrolein dimer, and 2-methyl-2-pentenal, and (ii) a waste stream;
(f) recycling at least part of the overhead stream to the phase separator;
(g) distilling the aqueous phase in a third distillation column to produce (i) a second product stream comprising methacrolein, methanol, and less than 5 weight % water, (ii) a bottoms stream comprising amine-acid catalyst, and (iii) a side draw stream comprising water and less than 2 weight % methanol; and
(h) recycling at least part of the bottoms stream to the catalyst stream.

2. The process of claim 1 , wherein the propionaldehyde is produced by contacting ethylene with CO and H 2 in the presence of a hydroformylation catalyst.

3. The process of claim 1 , further comprising providing at least part of the first product stream to a process comprising contacting the methacrolein with methanol and an oxygen-containing gas in the presence of an oxidative esterification catalyst to produce methyl methacrylate.

4. The process of claim 1 , further comprising providing at least part of the second product stream to a process comprising contacting the methacrolein with methanol and an oxygen-containing gas in the presence of an oxidative esterification catalyst to produce methyl methacrylate.

5. The process of claim 1 , further comprising providing at least part of the first product stream and at least part of the second product stream to a process comprising contacting the methacrolein with methanol and an oxygen-containing gas in the presence of an oxidative esterification catalyst to produce methyl methacrylate.

6. The process of claim 2 , further comprising providing at least part of the first product stream and at least part of the second product stream to a process comprising contacting the methacrolein with methanol and an oxygen-containing gas in the presence of an oxidative esterification catalyst to produce methyl methacrylate.

7. The process of claim 1 , wherein the first distillation column is operated as a stripping column.

8. The process of claim 1 , wherein the organic phase comprises less than 10 weight % methanol.

9. The process of claim 1 , wherein the phase separator is operated at a temperature of less than 15° C.

10. The process of claim 1 , wherein the ratio of the second intermediate stream exiting the first distillation column to the organic phase entering the first distillation column is from 1:10 to 8:10.

Assignees

• Rohm & Haas

Inventors

• Chakrabarti Reetam
• Hruby Sarah L
• Krapchetov Dmitri A
• Ngo Minh N
• Sathiosatham Muhunthan
• Silvano Mark A

Classifications

• C07C45/78

  Separation; Purification; Stabilisation; Use of additives · CPC title

• C07C51/252

  of propene, butenes, acrolein or methacrolein · CPC title

• C07C45/82

  by distillation · CPC title

• C07C2531/04

  containing carboxylic acids or their salts · CPC title

• C07C45/75 Primary

  Reactions with formaldehyde · CPC title