Process for preparing isocyanates

Patent metadata

Field	Value
Publication number	US-11225546-B2
Application number	US-201816491922-A
Country	US
Kind code	B2
Filing date	Feb 28, 2018
Priority date	Mar 6, 2017
Publication date	Jan 18, 2022
Grant date	Jan 18, 2022

Abstract

A process for preparing an isocyanate product includes providing a phosgene inlet stream and an amine in solvent inlet stream to a phosgenation mixer, the amine in-solvent inlet stream including one or more amines and one or more inert solvents, and during steady state operation compensating for a fouling pressure drop increase by decreasing a pressure drop in the phosgenation mixer over a time period divided into at least a first period of time T1 and a second period of time T2 that is subsequent to the first period of time T1. During the second period of time T2 an amine concentration of the one or more amines in the amine-in-solvent stream is higher than during the first period of time T1, and during the second period of time T2 a phosgene-to-amine ratio value in the phosgenation mixer is higher than during the first period of time T1.

First claim

The invention claimed is:

1. A process for preparing an isocyanate product, the process comprising:
providing a phosgene inlet stream and an amine-in-solvent inlet stream to a phosgenation mixer, the amine-in-solvent inlet stream including one or more amines and one or more inert solvents; and
during steady state operation compensating for a fouling pressure drop increase by decreasing a pressure drop in the phosgenation mixer over a time period divided into at least a first period of time T 1 and a second period of time T 2 that is subsequent to the first period of time T 1 , during the second period of time T 2 an amine concentration of the one or more amines in the amine-in-solvent stream is higher than during the first period of time T 1 , and during the second period of time T 2 a phosgene-to-amine ratio value in the phosgenation mixer is higher than during the first period of time T 1 .

2. The process as claimed in claim 1 , wherein the amine concentration is increased for the second period of time T 2 by decreasing a solvent flow rate for the amine-in-solvent inlet stream.

3. The process as claimed in claim 1 , wherein the phosgene-to-amine ratio value is increased by for the second period of time T 2 by increasing a flow rate of the phosgene inlet stream.

4. The process as claimed in claim 1 , wherein an amine concentration for the second period of time T 2 is greater by an amount from 0.2% to 3.0% relative to an amine concentration for the first period of time T 1 .

5. The process as claimed in claim 1 , wherein a phosgene-to-amine ratio value for the second period of time T 2 is greater by an amount from 0.05 to 1.00 relative to a phosgene-to-amine ratio value for the first period of time T 1 .

6. The process as claimed in claim 1 , wherein the phosgenation mixer includes one or more jet openings having a diameter from 1 mm to 10 mm for the amine-in-solvent inlet stream.

7. The process as claimed in claim 1 , wherein the fouling pressure drop is correlated with at least frictional pressure drop in a piping that connects the phosgenation mixer to a downstream separator.

8. The process as claimed in claim 1 , wherein the pressure drop in the phosgenation mixer is correlated with at least adjustments in the composition of the amine-in-solvent inlet stream.

9. The process as claimed in claim 1 , wherein the isocyanate product is polymeric methylene diphenyl diisocyanate.

10. The process as claimed in claim 1 , wherein during the time period a relatively constant isocyanate product production rate and a relatively constant quality value are maintained, the quality value being a measure of the loss of isocyanate groups by the formation of specific by-products.

Assignees

• Dow Global Technologies Llc

Inventors

• Klinger Artur
• Gillis Paul A
• Khan Irfan

Classifications

• B01F25/31423

  with a plurality of perforations in the circumferential direction only and covering the whole circumference · CPC title

• C07C263/10 Primary

  by reaction of amines with carbonyl halides, e.g. with phosgene · CPC title

• C08G18/7664 Primary

  containing alkylene polyphenyl groups · CPC title

• C07C265/14

  containing at least two isocyanate groups bound to the same carbon skeleton · CPC title

• B01F5/048

  Operations & Transport · mapped topic