Ammonia (NH3) is a kind of widely produced chemical that plays a critical role in manufacturing fertilizers as well as other chemicals, such as refrigerants and plastics. Furthermore, the potential of NH3 is considered as a promising energy carrier for H2 due to the volumetric storage density, as well as easier and lower cost for storage and transportation. Currently, NH3 is commonly synthesized by the Haber-Bosch (HB) process where nitrogen (N2) and hydrogen (H2) gases are reacted at high temperature (400-500 °C) and pressure (150-350 bar). The challenge for NH3 synthesis is that the reaction is thermodynamically limited and the efficient separation with the unreacted gases, which results in the low N2 conversion, NH3 yield and severe energy consumption. Consequently, NH3 synthesis results in the 2% of global energy consumption and 1–2% of CO2 emissions based on traditional HB process due to its large use of fossil fuels. It is proposed to use the Na+-gated nanochannel membranes loading with NH3 synthesis catalyst/Ru (ruthenium) to selectively permeate NH3 timely at lower operating conditions than traditional HB process, which can result in the NH3 synthesis process forward to facilitate the increase of N2 conversion and NH3 yield tremendously. The NH3 was found to be concentrated in the permeate side with high NH3/H2 and NH3/N2 selectivity at 350 °C and 35 bar. Furthermore, the Na+-gated nanochannel membrane reactor can maintain stable in a continuous NH3 synthesis process. The higher NH3 yield with Na+-gated membrane reactor at moderate operating condition suggests that it has a great application potential in industrial NH3 synthesis process.
