High-Flux Electrochemical Synthesis of Ammonia in Ionic Liquid

Project Overview

Ammonia (NH₃) is the most widely manufactured chemical in the world, widely used as a fertilizer and traditionally synthesized using the Haber-Bosch method. Alternative electrochemical NH₃ synthesis technologies are limited by low coulombic efficiency (<10 %) and low turnover frequency of nitrogen reduction electrocatalysts at T <100 ^oC. The goal of this project is to demonstrate the feasibility of nitrogen reduction reaction (NRR) to nitride ions (N^3-) for high throughput electrochemical synthesis of ammonia using an ionic liquid (IL) as the electrolyte. To perform the electrochemical synthesis of ammonia, we synthesized and characterized fluorinated ionic liquids that have been reported to exhibit high solubility for N₂ gas. We have also set up a two-electrode system to conduct control experiments to ensure that the ammonia formation is not a false-positive caused by contamination within the cell, gases, or the ionic liquid itself, a well-known issue in the field.

Mission Impact

Modular, distributed, carbon-neutral NH₃ production addresses the transportation and storage bottleneck of carbon neutral liquid fuels with a potential of ~1.5 Gton/yr of CO₂ emission reduction in the US, displacing ~25 quads/yr of fossil energy and leveraging intermittent renewable energy instead of fossil-generated electricity. In the short-term, modular NH₃ production from renewables in the Midwest could decrease CO₂ emissions by ~20 Mton/yr (equivalent to energy savings of ~0.2 quads/yr), by avoiding both transport of NH₃ from overseas and steam reforming as the hydrogen source. Thus, the proposed electrochemical NH₃ synthesis technology supports the mission focus area of "negative emissions" by decarbonizing one of the major industrial sources of carbon.

Publications, Presentations, and Patents

Ceron, M. R.; Wood, M.; Eshelman, H. High-Flux Electrochemical Synthesis of Ammonia in Ionic Liquid. IM: LLNL-PROP-820207. ROI submitted.