Method of producing ethylene oxide and ethylene glycol

Patent metadata

Field	Value
Publication number	US-11618739-B2
Application number	US-201917266564-A
Country	US
Kind code	B2
Filing date	Aug 9, 2019
Priority date	Aug 10, 2018
Publication date	Apr 4, 2023
Grant date	Apr 4, 2023

Abstract

There is provided a method of producing ethylene oxide and ethylene glycol capable of reducing a concentration in discharged water of 1,4-dioxane contained generated in a step of producing ethylene oxide and ethylene glycol.
A method of producing ethylene oxide and ethylene glycol includes a predetermined step of producing ethylene oxide, and a step of extracting a part of a column bottom liquid of an ethylene oxide stripping column in the step of producing ethylene oxide and supplying the extracted column bottom liquid to a by-produced ethylene glycol concentration column, concentrating ethylene glycol produced as a by-product in the step of producing ethylene oxide, and distilling and separating 1,4-dioxane produced as a by-product in the step of producing ethylene oxide, wherein the by-produced ethylene glycol concentration column is a divided wall distillation column.

First claim

The invention claimed is:

1. A method of producing ethylene oxide and ethylene glycol, the method comprising:
a step of producing ethylene oxide, including
supplying, to an ethylene oxide absorption column, a reaction product gas containing ethylene oxide and generated in an ethylene oxidation reaction step in which ethylene is subjected to catalytic gas phase oxidation using a molecular oxygen-containing gas in the presence of a silver catalyst,
bringing the reaction product gas into contact with an absorption liquid supplied to the ethylene oxide absorption column,
supplying a column bottom liquid of the ethylene oxide absorption column, which contains ethylene oxide, to an ethylene oxide stripping column, and
obtaining steam containing ethylene oxide from a column top portion of the ethylene oxide stripping column by heating a column bottom portion of the ethylene oxide stripping column;
a step of extracting a part of a column bottom liquid of the ethylene oxide stripping column and supplying the extracted column bottom liquid to a by-produced ethylene glycol concentration column as a first ethylene oxide (EO) discharged water;
a step of supplying, to a dehydrating column, an aqueous solution obtained by condensing the steam containing ethylene oxide obtained from the column top portion of the ethylene oxide stripping column, introducing, into a light fraction separation column, a fraction obtained by condensing steam having a high concentration of ethylene oxide obtained from a column top portion of the dehydrating column, and heating a column bottom liquid of the light fraction separation column to separate a light fraction, wherein a part of discharged water discharged from a column bottom portion of the dehydrating column is subjected to an ethylene glycolation (EG) treatment and supplied to the by-produced ethylene glycol concentration column as a second EO discharged water;
a carbon dioxide gas recovering step of supplying at least a part of a carbon dioxide-containing gas discharged from a column top portion of the ethylene oxide absorption column to a carbon dioxide gas absorption column, extracting a carbon dioxide gas-rich absorption liquid obtained by bringing the carbon dioxide-containing gas into contact with an absorption liquid as a column bottom liquid of the carbon dioxide gas absorption column and supplying the extracted carbon dioxide gas-rich absorption liquid to an upper portion of a carbon dioxide gas stripping column, and stripping a carbon dioxide gas from the carbon dioxide gas-rich absorption liquid and discharging the carbon dioxide gas from a column top portion of the carbon dioxide gas stripping column as an exhaust gas, wherein discharged water discharged from the carbon dioxide gas recovering step is supplied to the by-produced ethylene glycol concentration column as a CO 2 discharged water;
an ethylene glycol purification step of purifying concentrated ethylene glycol, wherein a part of discharged water generated in the ethylene glycol purification step is supplied to the by-produced ethylene glycol concentration column as an EG discharged water; and
a step of concentrating ethylene glycol produced as a by-product in the step of producing ethylene oxide, and distilling and separating 1,4-dioxane produced as a by-product in the step of producing ethylene oxide,
wherein the by-produced ethylene glycol concentration column is a divided wall distillation column, and
wherein a supply position of a feed liquid containing the first EO discharged water and the second EO discharged water and a supply position of a feed liquid containing the CO 2 discharged water and EG discharged water supplied to the by-produced ethylene glycol concentration column are different depending on a concentration of ethylene glycol in the feed liquids.

2. The method according to claim 1 , wherein a concentration of 1,4-dioxane in discharged water discharged from the by-produced ethylene glycol concentration column is 0.5 mg/L or less.

3. The method according to claim 1 , wherein in the by-produced ethylene glycol concentration column, a low-boiling component containing 1,4-dioxane is concentrated at a column top portion, and a concentrated liquid is treated in a waste liquid combustion facility.

Assignees

• Nippon Catalytic Chem Ind

Inventors

• Sato Shota
• Suzuki Hideto
• Higashioka Daisuke

Classifications

• C07D301/10 Primary

  with catalysts containing silver or gold · CPC title

• C07C29/106

  of oxiranes · CPC title

• B01D3/141

  where at least one distillation column contains at least one dividing wall · CPC title

• C07C29/84

  by extractive distillation · CPC title

• B01D3/28

  Fractionating columns with surface contact and vertical guides, e.g. film action · CPC title