Mitigation of Pervasive Haber Process Carbon Pollution: Ammonia synthesis from air and water in suspensions of nanoscale Fe/Fe2O3

George Washington University, Washington DC

Investigators

Abstract

With this award, the Environmental Chemical Sciences Program of the Division of Chemistry is funding Professor Stuart Licht of George Washington University to develop the fundamental science of a process to produce ammonia, a critical feedstock for the production of fertilizer. This process utilizes air, water and sunlight, without creating carbon-containing byproducts. Currently, the Haber process to produce ammonia effectively feeds the world population through fertilizer production; however, this process is energy intensive, releasing over 200 million tons of carbon dioxide to the atmosphere each year. Introduction of Haber synthetic ammonia has paralleled the explosive increase in world population from 2 billion in 1930 to 7 billion today. In this research program, an alternative chemical process is being developed for the production of ammonia from N2, water and thermal energy. Also needed are common materials (molten hydroxide, Ni electrodes) and an inexpensive, nanoscale Fe/Fe2O3 catalyst. The broader impacts include the training of graduate students in the field of renewable energy, specifically in the domain of solar synthesis. This proposal is an effort to explore electrolytic and solar synthetic pathways to produce critically needed ammonia for fertilizer. The recent discovery in the Licht research group of this alternative chemistry for the production of ammonia from atmospheric nitrogen produces ammonia without carbon dioxide and at up to 70% coulombic efficiency by electrolysis in molten hydroxide using suspensions of nanoscale Fe2O3. The process requires little energy at high temperature. With STEP (Solar Thermal Electrochemical Process), when the thermal energy is provided by sunlight, ammonia is produced without emission of any carbon dioxide. The project seeks to improve understanding of the fundamental basis of this new synthetic pathway to produce ammonia by exploring the mechanism and seeking to increasing the activity of the process and optimize the solar energy coupling. The interfacial electrochemistry of the water plus air conversion to ammonia is being probed, the architecture of nanoscale catalyst is being varied and a solar (STEP) ammonia prototype is to be explored, including a new solar pressurized route, to further increase solar energy efficiency.