Process for producing ethanol

Patent metadata

Field	Value
Publication number	US-9975828-B2
Application number	US-201515315192-A
Country	US
Kind code	B2
Filing date	Jun 18, 2015
Priority date	Jun 19, 2014
Publication date	May 22, 2018
Grant date	May 22, 2018

Abstract

Hydrogenation of methyl acetate to methanol and ethanol by feeding a hydrogenation feed of methyl acetate, water, hydrogen and a carbon oxide into a hydrogenation unit containing a copper-zinc oxide hydrogenation catalyst to produce a hydrogenation product stream of ethanol, methanol, unreacted methyl acetate, water, unreacted hydrogen, carbon monoxide, carbon dioxide, and ethyl acetate. The hydrogenation unit is operated in the vapor phase at elevated temperature and pressure. The total molar ratio of hydrogen to methyl acetate fed to the hydrogenation unit is 5:1 to 20:1. The total molar ratio of methyl acetate to carbon oxide(s) fed to the hydrogenation unit is 1:2 to 100:1. The hydrogenation product stream is separated into a liquid stream containing ethanol, methanol, unreacted methyl acetate, water and ethyl acetate, and a gaseous stream containing unreacted hydrogen, carbon monoxide and carbon dioxide, and a portion of the gaseous stream is recycled to the hydrogenation unit.

First claim

The invention claimed is:

1. A process for the hydrogenation of methyl acetate to methanol and ethanol comprising feeding a hydrogenation feed composition comprising methyl acetate and water, together with hydrogen and at least one carbon oxide selected from carbon monoxide and carbon dioxide, into a hydrogenation unit containing a copper-zinc oxide hydrogenation catalyst and hydrogenating the methyl acetate to produce a hydrogenation product stream comprising ethanol, methanol, unreacted methyl acetate, water, unreacted hydrogen, carbon monoxide, carbon dioxide, and ethyl acetate, wherein said hydrogenation unit is operated in the vapour phase at elevated temperature and elevated pressure, and wherein the total molar ratio of hydrogen to methyl acetate fed to the hydrogenation unit is in the range of from 5:1 to 20:1, and the total molar ratio of methyl acetate to carbon oxide(s) fed to the hydrogenation unit is in the range of from 1:2 to 100:1, and wherein the hydrogenation product stream is separated into a first liquid product stream comprising the majority of the ethanol, methanol, unreacted methyl acetate, water, and ethyl acetate, and a first gaseous product stream comprising the majority of the unreacted hydrogen, carbon monoxide, and carbon dioxide, and wherein at least a portion of the first gaseous product stream is recycled to the hydrogenation unit.

2. A process according to claim 1 , wherein the total molar ratio of hydrogen to methyl acetate fed to the hydrogenation unit is in the range of from 5:1 to 18:1.

3. A process according to claim 1 , wherein the carbon oxide is carbon monoxide.

4. A process according to claim 1 , wherein the carbon oxide is carbon dioxide.

5. A process according to claim 1 , wherein the carbon oxide is a combination of carbon monoxide and carbon dioxide.

6. A process according to claim 1 , wherein the copper-zinc oxide hydrogenation catalyst is an unsupported copper-zinc oxide catalyst.

7. A process according to claim 1 , wherein the copper-zinc oxide hydrogenation catalyst is supported on a suitable catalyst support material.

8. A process according to claim 1 , wherein the hydrogenation feed composition comprises from 0.5 to 5 mol % water.

9. A process according to claim 1 , wherein the hydrogenation feed composition additionally comprises methanol.

10. A process according to claim 9 , wherein at least 80 wt. % of the hydrogenation feed composition consists of methyl acetate, methanol and water.

11. A process according to claim 1 , wherein the hydrogenation product stream is separated into the first liquid product stream and the first gaseous product stream by first cooling the hydrogenation product stream to a temperature such that the majority of the methanol, ethanol, methyl acetate, ethyl acetate and water present in the hydrogenation product stream condense and subsequently separating the cooled hydrogenation product stream into the first liquid product stream and the first gaseous product stream.

12. A process according to claim 1 , wherein at least 80 vol. % of the first gaseous product stream is recycled to the hydrogenation unit.

13. A process for the manufacture of ethanol from acetic acid and hydrogen, wherein said process comprises the following steps:
(A) reacting acetic acid together with methanol in an esterification reaction vessel to produce a hydrogenation feed composition comprising methyl acetate and water;
(B) feeding the hydrogenation feed composition from step (A), together with hydrogen and at least one carbon oxide selected from carbon monoxide and carbon dioxide, into a hydrogenation unit and hydrogenating the methyl acetate to methanol and ethanol in accordance with the process of claim 1 ;
(C) separating a lower boiling product stream comprising methanol, methyl acetate and ethyl acetate, and a higher boiling product stream comprising ethanol and water from the first liquid product stream produced in the process of step (B); and, optionally
(D) removing water from the higher boiling product stream of step (C).

14. A process for the production of ethanol from acetic acid and hydrogen, said process comprising the following steps:
(1) in an esterification reaction vessel, reacting methanol with acetic acid at elevated temperature in the presence of an esterification catalyst and an entrainer, said entrainer being sparingly soluble in water and forms a minimum boiling point azeotrope therewith, to form an esterification product composition comprising entrainer, unreacted methanol, methyl acetate and water, and, in a distillation column, recovering from the esterification product composition an overhead product fraction comprising methyl acetate, methanol and water, and, from an intermediate point in the distillation column, removing a liquid sidestream fraction comprising water, methanol, entrainer and methyl acetate; wherein the molar ratio of acetic acid to methanol in the esterification reaction vessel is in the range of from 1:1.1 to 1:1.8 and the distillation column is operated at a head pressure of at most 5 bara, and wherein the amount of water present in the overhead product fraction comprising methyl acetate, methanol and water is in the range of from 0.5 to 5 mol %;
(2) feeding a hydrogenation feed composition consisting of at least part of the overhead product fraction from step (1), together with hydrogen and at least one carbon oxide selected from carbon monoxide and carbon dioxide, into a hydrogenation unit and hydrogenating the methyl acetate to methanol and ethanol in accordance with the process of claim 1 ;
(3) separating a lower boiling product stream comprising methanol, methyl acetate and ethyl acetate, and a higher boiling product stream comprising ethanol, water, from the first liquid product stream from step (2) in a distillation column operated at a head pressure of at most 5 bara;
(4) recycling at least part of the lower boiling product stream from step (3) to the esterification reaction vessel of step (1); and, optionally
(5) removing water from the higher boiling product stream of step (3).

Assignees

• Bp Plc

Inventors

• Bailey Craig
• Bolton Leslie William
• Deeley Jon Michael Stewart

Classifications

• C07C67/08

  by reacting carboxylic acids or symmetrical anhydrides with the hydroxy or O-metal group of organic compounds · CPC title

• C07C29/149 Primary

  with hydrogen or hydrogen-containing gases · CPC title

• Y02P20/582

  Recycling of unreacted starting or intermediate materials · CPC title