Process for electrochemical preparation of ammonia

Patent metadata

Field	Value
Publication number	US-2021388511-A1
Application number	US-202117458981-A
Country	US
Kind code	A1
Filing date	Aug 27, 2021
Priority date	Jul 21, 2016
Publication date	Dec 16, 2021
Grant date	—

Abstract

A process for preparing ammonia via an electrolysis cell may involve feeding nitrogen as a first reactant into the electrolysis cell and using water or water vapor as a second reactant for electrolysis. In at least one step downstream of the electrolysis, there is a separation of other components from the ammonia, such as an at-least-partial separation of nitrogen, water, argon and/or hydrogen. Recovery of the reactants is connected upstream of the ammonia electrolysis. The nitrogen used as the first reactant may be procured beforehand in an air fractionation plant. The process may further involve removing from the electrolysis cell oxygen formed as a by-product in the electrolysis at an anode.

First claim

What is claimed is:

1 . A process for preparing ammonia by electrolysis using an electrolysis cell, the process comprising:
feeding nitrogen as a first reactant into the electrolysis cell; using water or water vapor as a second reactant for the electrolysis; downstream of the electrolysis, in a first device, separating nitrogen from an ammonia-containing product stream removed from the electrolysis cell; and separating water from the ammonia-containing product stream in a second device downstream of the first device.

2 . The process of claim 1 comprising separating argon from the ammonia-containing product stream in the first device.

3 . The process of claim 1 comprising recycling into the electrolysis at least one of the nitrogen or the water that is separated off from the ammonia-containing product stream.

4 . The process of claim 1 comprising obtaining the nitrogen, which is the first reactant, from an air fractionation plant prior to feeding the nitrogen into the electrolysis cell.

5 . The process of claim 4 comprising separating off argon prior to feeding the nitrogen into the electrolysis cell.

6 . The process of claim 1 comprising removing from the electrolysis cell oxygen formed as a by-product in the electrolysis at an anode.

7 . The process of claim 1 comprising purifying ammonia obtained in the electrolysis in a refrigeration plant.

8 . The process of claim 1 comprising generating the water vapor used as the second reactant in a steam boiler and feeding the water vapor into the electrolysis cell as water vapor.

9 . The process of claim 1 comprising:
feeding liquid water into the electrolysis cell; and
generating the water vapor used as the second reactant by supplying energy and by evaporation of the liquid water that has been fed into the electrolysis cell.

10 . The process of claim 1 comprising effecting electrolytic conversion of the first and second reactants to ammonia at a temperature of at least 150° C.

11 . The process of claim 1 comprising effecting electrolytic conversion of the first and second reactants to ammonia at a pressure of at least 15 bar.

12 . The process of claim 1 comprising performing the electrolysis in batches via at least two electrolysis cells.

13 . The process of claim 1 wherein for ammonia synthesis the process comprises using inert purge gasses at least partly as fuels for producing the water vapor.

14 . A plant for preparing ammonia by electrolysis, the plant comprising:
an electrolysis cell for producing the ammonia; a device for supplying gaseous nitrogen to the electrolysis cell; a device for supplying water vapor or liquid water to the electrolysis cell; a device for removing a product stream from the electrolysis cell; a device for separating at least nitrogen from the product stream; a device for separating water from the product stream, which device for separating water is disposed downstream of the device for separating at least nitrogen; and a device for recycling water or water vapor to the electrolysis cell.

15 . The plant of claim 14 comprising a device for recycling nitrogen to the electrolysis cell.

16 . The plant of claim 14 comprising a refrigeration plant for purifying the ammonia, wherein the refrigeration plant is disposed downstream of the device for separating at least nitrogen from the product stream.

17 . The plant of claim 14 comprising an air fractionation plant where the nitrogen supplied to the electrolysis cell is generated, wherein the air fractionation plant is disposed upstream of the electrolysis cell.

18 . The plant of claim 14 comprising a steam generator where the water vapor supplied to the electrolysis cell is generated.

19 . The plant of claim 14 comprising a device for separating oxygen from a by-product stream removed from the electrolysis cell.

20 . The plant of claim 14 wherein the electrolysis cell is a first electrolysis cell, the plant comprising a second electrolysis cell for producing the ammonia.

Assignees

• Thyssenkrupp Ind Solutions Ag
• Thyssenkrupp Ag

Inventors

• Johanning Joachim
• Dostal Daniela

Classifications

• C25B15/083

  Separating products · CPC title

• C25B1/00 Primary

  Electrolytic production of inorganic compounds or non-metals · CPC title

• C25B1/27

  Ammonia · CPC title

• Y02P20/129

  Energy recovery, e.g. by cogeneration, H2recovery or pressure recovery turbines · CPC title

• C25B15/087

  Recycling of electrolyte to electrochemical cell · CPC title