Electrochemical synthesis of ammonia: A low pressure, low temperature approach

A successful electrolytic ammonia process can enable a new nitrogen fertilizer industry based on networks of distributed-scale, near-point-of-use production plants. the Proton, NIST and CSM team has proven the feasibility of an alkaline membrane electrolyzer as an ammonia generator, conducted successful nanoparticle synthesis, and has shown improved catalyst efficiency for Fe, FeNi and Ni nanoparticles over Pt black. To enable the screening of promising cathode catalyst materials, and prove the AEM-based ammonia generation concept, Proton designed and built an AEM system based on a lab-scale, 25 cm2 test cell. The screening efforts have revealed Fe only materials to be highly active, but unstable. Conservative estimates of initial efficiency are as high as 41%. However this efficiency is short lived, and decreases to single digit efficiency in a matter of hours. Ni only materials behave oppositely. They have demonstrated single digit efficiencies initially, with good relative stabilities with time. Interestingly, the Fe-Ni materials appear to have a combination of both Fe and Ni properties, and differences in performance may be attributable to differences in composition. This indicates that a good approach to catalyst optimization would include tuning the morphology to get the benefits of the Fe efficiency, while protecting it with Ni to gain stability.