Ammonia Synthesis from Nitrogen and Water by Electricity Using an Electrochemical Cell with Ru Catalyst, Hydrogen-Permeable Pd-Ag Membrane, and Phosphate-Based Electrolyte

摘要

Conversion from renewable energy-based electricity to chemical fuels is a promising technology in the near future. NH3 is one of the candidates as chemical energy carriers, which can be synthesized from N2 and H2O using electricity. A new NH3 synthesis from N2 and H2O by electricity at 250℃ using an electrochemical cell that consists of a Ru/Cs~+/MgO catalyst, Pd-Ag membrane cathode, a CsH2PO4/SiP2O7 electrolyte, and Pt anode has been proposed in this work. An NH3 synthesis rate of 7.73~(10)10 mol s~(-1) cm~(-2) was obtained at 6.4 mA cm~(-2) and 1.2 V under a flow of N2 at 1 cm~3 min~(-1). The current efficiency for NH3 synthesis was 3.5%, and the other part was used for H2 formation. The examination depending on the flow rate of N2 was demonstrated and the small flow of N2 was found to be preferred for NH3 synthesis. The present cell is expected to open up new perspectives in the developments of the most suitable materials as NH3 catalysts, hydrogen membranes, and water electrolyzer for combination in a reactor at the intermediate temperature.