Description:
OBJECTIVE: Develop and demonstrate new methods of ammonia synthesis capable of utilizing atmospheric nitrogen that do not require the sustained high pressures required for the Haber-Bosch process. DESCRIPTION: Ammonia is one of the most widely produced chemicals with a variety of uses including hydrogen storage for fuel cell applications, refrigeration, and fertilizer. In addition, it is also an intermediate in the production of explosives and gun propellants. In the early 1900"s Haber conducted groundbreaking research on the production of ammonia for which he received the Nobel Prize in 1918. His research was followed by that of Bosch who scaled up the process for industrial use. Using the Haber-Bosch process the production of ammonia is energy intensive due to the high pressures, 150-300 bar, and high temperatures, ~500 C, necessary to cleave the nitrogen-nitrogen triple bond with an iron catalyst. In addition the nitrogen and hydrogen reactants must be purified prior to use to minimize catalyst poisoning. Recent research indicates that solid-state electrochemical synthesis of ammonia using both proton and oxygen ion conducting electrolytes are a promising avenue to bypass the thermodynamic restrictions of the Haber-Bosch process, which limit the reaction equilibrium to 10 to 15% for a single reactor. In addition these electrochemical systems have achieved in excess of 70% hydrogen conversion to ammonia. PHASE I: Demonstrate feasibility for improved synthesis of ammonia in the absence of the sustained high pressures and temperatures required by the Haber-Bosch process. Process inputs should be limited to ambient air, hydrogen, water, and electricity. Show experimental results resulting in ammonia synthesis that exceed the Haber-Bosch reaction equilibrium of 10 to 15%. Determine the hydrogen utilization and optimize the reaction conditions to maximize ammonia production while minimizing ammonia decomposition. Quantify the required nitrogen and hydrogen purities necessary to allow sustained synthesis without poisoning any catalysts present. Process efficiency should exceed 50% of the Haber-Bosch process in terms of the energy use to produce a given mass. PHASE II: Based on the initial Phase I results develop a self-contained portable system capable of producing ammonia using only atmospheric nitrogen, water, and electricity. Scale and optimize the process to produce at least 5 kg/hr with an efficiency of at least 75% of the Haber-Bosch process in terms of the energy use to produce a given mass. The system should tolerate impurities of sulfur and carbon monoxide of up to 1%. PHASE III Dual Use Applications: The technology developed under this program will find dual-use in military and civilian applications. Military systems will enable production of ammonia at distributed locations using only water as an input with the potential to reduce supply chain logistics. Civilian applications will enable energy storage from renewable resources as well as the production of fertilizers and chemical precursors from non-petroleum sources. REFERENCES: 1. G. Marnellos and M. Stoukides,"Ammonia Synthesis at Atmospheric Pressure", Science, 282, 2 Oct 1998, pp. 98-100. 2. I. A. Amar, R. Lan, C. T. G. Petit and S Tao,"Solid-State Electrochemical Synthesis of Ammonia", J. Solid State Electrochem., 15, 2011, pp. 1845-1860. 3. A. Skodra and M. Stoukides,"Electrocatalytic Synthesis of Ammonia from Steam and Nitrogen at Atmospheric Pressure", Solid State Ionics, 180, 2009 pp. 1332-1336.
