SYSTEM AND METHOD FOR AMMONIA SYNTHESIS
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.