Generation of nitrogen by means of electrochemical oxygen depletion

Abstract

Ammonia in the form of fertilizer is essential for feeding the world's population. It consists of hydrogen and nitrogen, with the latter being sourced from atmospheric nitrogen via diverse methodologies. Commonly utilized processes are cryogenic or pressure swing adsorption. Due to the necessity of mitigating climate change, it is important to obtain ammonia and nitrogen in an environmentally friendly, energy and resource-efficient way. Electrochemical oxygen reduction by means of an oxygen depolarized cathode offers a promising green, carbon dioxide neutral nitrogen separation possibility with the supply of renewable energy. In this paper, electrochemical single cells based on proton conducting polymer electrolyte membranes are investigated with respect to different operating parameters, including cell and process ones. Depending on the air flow rate and maximum current provided, the oxygen content within the gas stream is reduced to <1%. This reduction in oxygen content is achieved while maintaining a commendably high Faraday efficiency of 90% across a wide potential range. These outcomes underscore the potential of electrochemical cells as environmentally-friendly and efficient technologies for enriching nitrogen.