Ammonia (NH3) is a top 10 energy consuming chemical in the United States (U.S.) and one of the most energy intensive chemicals to manufacture in the world. In addition to consuming 1-2% of world-wide energy, the production of NH3 also generates 350 million metric tons of carbon dioxide emissions yearly, which is ~1% of total greenhouse gas (GHG) emissions world-wide. As such, novel NH3 manufacturing techniques have the potential to have an extremely large impact on total energy consumption and emissions. However, promising new processes for efficient and emission-free NH3 generation, such as electrochemical ammonia synthesis, require novel catalyst design and synthesis approaches, which do not exist today. Current electro-catalysts suffer from a tendency to adsorb protons instead of nitrogen at the surface, and result in low device efficiencies due to competition with hydrogen generation. Objective and approach for Phase 1 project: To enable a more efficient and green electrochemical ammonia generation process, Proton OnSite and their partners propose to develop a catalyst manufacturing approach which will utilize bi-functional peptides to 1) control nanoparticle (NP) synthesis, and 2) functionalize the NP catalyst surface to facilitate a more organized and favorable reactant environment for NH3 production. Peptide sequences will be chosen from the enzyme nitrogenase, and will mimic the natural function of the enzyme to achieve a highly efficient and specific catalyst material. They will flex their already existing electrochemical ammonia test bed, which features an alkaline-based design. This design has the potential for low-cost materials of construction, and models suggest the potential to consume less energy than the incumbent ammonia generation processes used today, if an efficient catalyst is developed. The alkaline-based design also allows for the use of a greater variety of potentially more active and selective materials, including peptides. In Phase I, the key technology advancement will be to demonstrate production of ammonia from nitrogen and water in an electrochemical system utilizing the proposed peptide-functionalized nanocatalyst approach. The main goal will be show that the developed material has higher performance than other catalysts found in literature at low temperatures, which typically have not had greater than 1% Faradic efficiency. Commercial Applications and Other
Benefits: The successful development of an easily manufactured active and selective peptide-functionalized nanocatalyst for electrochemical ammonia generation would enable Proton OnSite to flex their electrolyzer stack design for ammonia generation use. The technical objectives laid out in Phase I will set the stage for a practical demonstration in Phase II. If this demonstration is achieved, future products can be envisioned and developed. Since electrolyzer technology is highly scalable, products could support a range of distributed applications, and could be designed on scale to distribute ammonia locally to farms or industrially. In addition, the catalyst developed in this project will enable a transformative approach to manufacturing ammonia using less energy and allowing the use of renewable energy sources. In contrast to the incumbent process, this electrically driven process eliminates the need for high temperature and pressure as well as hydrogen gas, using water as the source of protons instead of fossil fuels. Therefore, the process is able to achieve optimal efficiency soon after start-up, and is compatible with intermittent operation. This feature enables utilization (and monetization) of renewable electricity without the need for transmission capacity expansion. This approach has the potential to provide frequency regulation services to grid operators by providing a fast response load. To the extent that renewable electricity is utilized to drive the process, CO2 emissions will be eliminated from the production step, and further reduction of emissions will be realized through the reduced need for ammonia transport. In the Plains and Upper Midwest, excess wind production capacity, transmission limitations, and high regional demand for N-fertilizers combine to create excellent economic drivers for this technology. Key Words: Electrochemical ammonia generation, alkaline exchange membranes, electrolysis, protein engineering, nitrogenase, nanocatalysts
