(699d) Performance and Behavior of Na+-Gated Nanochannel Membranes for Ammonia Gas Separation

Ammonia (NH₃) is currently the second most highly produced chemical in the world and 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. It is proposed to use the Na⁺-gated nanochannel membranes to selectively permeate NH₃ at lower operating conditions than the HB process. The NH₃ was found to be concentrated in the permeate side with high NH₃/H₂ and NH₃/N₂ selectivity (>250) at 300 °C and ~21 bar. The Na⁺-gated nanochannel membrane was stable for >120h in continuous separation of NH₃/H₂/N₂ gas mixture at 300 °C and 12 bar. The membrane performance suggests that the Na⁺-gated nanochannels selectively permeates NH₃ and potentially can be used in both membrane reactor and purification of NH₃.