Xe is only produced by cryogenic distillation of air, and its availability is limited by the extremely low abundance. Therefore, Xe recovery after usage is the only way to guarantee sufficient supply and broad application. Herein we demonstrate DD3R zeolite as a benchmark membrane material for CO2 /Xe separation. The CO2 permeance after an optimized membrane synthesis is one order magnitude higher than for conventional membranes and is less susceptible to water vapour. The overall membrane performance is dominated by diffusivity selectivity of CO2 over Xe in DD3R zeolite membranes, whereby rigidity of the zeolite structure plays a key role. For relevant anaesthetic composition (<5 % CO2 ) and condition (humid), CO2 permeance and CO2 /Xe selectivity stabilized at 2.0×10-8 mol m-2 s-1 Pa-1 and 67, respectively, during long-term operation (>320 h). This endows DD3R zeolite membranes great potential for on-stream CO2 removal from the Xe-based closed-circuit anesthesia system. The large cost reduction of up to 4 orders of magnitude by membrane Xe-recycling (>99+%) allows the use of the precious Xe as anaesthetics gas a viable general option in surgery.
Keywords: carbon dioxide; gas separation; membranes; noble gases; zeolites.
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