Process for electrochemical preparation of ammonia

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.

1 .- 20 . (canceled) 
     
     
         21 . 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; and   downstream of the electrolysis, at least partially separating a component from the ammonia.   
     
     
         22 . The process of  claim 21  wherein the component that is at least partially separated from the ammonia downstream of the electrolysis is at least one of nitrogen, water, argon, or hydrogen. 
     
     
         23 . The process of  claim 22  comprising recycling into the electrolysis at least one of the nitrogen or the water that is at least partially separated off from the ammonia. 
     
     
         24 . The process of  claim 22  comprising obtaining the nitrogen, which is the first reactant, from an air fractionation plant prior to feeding the nitrogen into the electrolysis cell. 
     
     
         25 . The process of  claim 24  comprising separating off argon prior to feeding the nitrogen in the electrolysis cell. 
     
     
         26 . The process of  claim 22  comprising removing from the electrolysis cell oxygen formed as a by-product in the electrolysis at an anode. 
     
     
         27 . The process of  claim 22  comprising purifying the ammonia obtained in the electrolysis in a refrigeration plant. 
     
     
         28 . The process of  claim 22  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. 
     
     
         29 . The process of  claim 22  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. 
 
     
     
         30 . The process of  claim 22  comprising effecting electrolytic conversion of the first and second reactants to the ammonia at a temperature of at least 150° C. 
     
     
         31 . The process of  claim 22  comprising effecting electrolytic conversion of the first and second reactants to the ammonia at a pressure of at least 15 bar. 
     
     
         32 . The process of  claim 22  comprising performing the electrolysis in batches via at least two electrolysis cells. 
     
     
         33 . The process of  claim 22  wherein for ammonia synthesis the process comprises using inert purge gases at least partly as fuels for producing the water vapor. 
     
     
         34 . A plant for preparing ammonia, 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; and   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.   
     
     
         35 . The plant of  claim 34  comprising at least one of a device for recycling water or water vapor to the electrolysis cell or a device for recycling nitrogen to the electrolysis cell. 
     
     
         36 . The plant of  claim 34  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. 
     
     
         37 . The plant of  claim 34  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. 
     
     
         38 . The plant of  claim 34  comprising a steam generator where the water vapor supplied to the electrolysis cell is generated. 
     
     
         39 . The plant of  claim 34  comprising a device for separating oxygen from a by-product stream removed from the electrolysis cell. 
     
     
         40 . The plant of  claim 34  wherein the electrolysis cell is a first electrolysis cell, the plant comprising a second electrolysis cell for producing the ammonia.