System and method for ammonia synthesis

Abstract

Systems and methods are disclosed herein for synthesizing ammonia using nano-size metal or metal alloy catalyst particles. Hydrogen and nitrogen gases are passed through a system comprising, for example, a bed of magnetite supporting nano-size iron or iron alloy catalyst particles having an optional oxide layer that forms the catalyst.

1 . (canceled) 
     
     
         2 . A method for producing ammonia comprising:
 mixing a first catalyst including a millimeter-sized, granular, ferrous material, with a second catalyst, distinct from the first catalyst, including discrete nano-sized ferrous catalyst particles that comprise a metallic core with an oxide shell, such that the discrete nano-sized ferrous catalyst particles are dispersed onto the millimeter-sized, granular, ferrous material, and at least some of the nano-sized ferrous catalyst particles adjacent to other of the nano-sized ferrous catalyst particles on a grain of the millimeter-sized, granular, ferrous material are discrete and separated from each other; and   reacting hydrogen gas (H 2 ) and nitrogen gas (N 2 ) in a reactor comprising the mixture of the first catalyst and the second catalyst, the dispersion further configured such that the adjacent nano-sized ferrous catalyst particles remain discrete and separated from each other on the grain of the millimeter-sized, granular, ferrous material after the production of ammonia from the hydrogen gas and the nitrogen gas.   
     
     
         3 . The method of  claim 2 , the first catalyst further comprising a promoter. 
     
     
         4 . The method of  claim 2 , the oxide shell having a shell thickness within a range of about 0.5 nm and 25 nm. 
     
     
         5 . The method of  claim 4 , the oxide shell having a shell thickness within a range of about 0.5 nm and 10 nm. 
     
     
         6 . The method of  claim 5 , the oxide shell having a shell thickness within a range of about 0.5 and 1.5 nm. 
     
     
         7 . The method of  claim 2 , the second catalyst having an average diameter within a range of about 15 nm and 30 nm. 
     
     
         8 . The method of  claim 2 , wherein the reacting the H 2  and the N 2  comprises doing so at a temperature within a range of about 200° C. and 600° C. 
     
     
         9 . The method of  claim 8 , wherein the reacting the H 2  and the N 2  comprises doing so at a temperature within a range of about 350° C. and 450° C. 
     
     
         10 . The method of  claim 2 , wherein the reacting the H 2  and the N 2  comprises doing so at a pressure of less than about 100 atm. 
     
     
         11 . A material for use in catalyzing ammonia production, the material comprising:
 a first catalyst including a millimeter-sized, granular, ferrous material, and   a second catalyst, distinct from the first catalyst, including discrete nano-sized ferrous catalyst particles that comprise a metallic core with an oxide shell,   wherein
 the discrete nano-sized ferrous catalyst particles are dispersed onto the millimeter-sized, granular, ferrous material, and 
 at least some of the nano-sized ferrous catalyst particles adjacent to other of the nano-sized ferrous catalyst particles on a grain of the millimeter-sized, granular, ferrous material are discrete and separated from each other, and are configured to remain discrete and separated from each other on the grain of the millimeter-sized, granular, ferrous material after the first catalyst and the second catalyst are exposed to hydrogen gas (H 2 ) and nitrogen gas (N 2 ) for ammonia production. 
   
     
     
         12 . The material of  claim 11 , the first catalyst further comprising a promoter. 
     
     
         13 . The material of  claim 11 , the oxide shell having a shell thickness within a range of about 0.5 nm and 25 nm. 
     
     
         14 . The material of  claim 13 , the oxide shell having a shell thickness within a range of about 0.5 nm and 10 nm. 
     
     
         15 . The material of  claim 14 , the oxide shell having a shell thickness within a range of about 0.5 and 1.5 nm. 
     
     
         16 . The material of  claim 11 , the second catalyst having an average diameter within a range of about 15 nm and 30 nm.