(728e) Evaluation of Oxygen Permeation Properties at Extremely Low Temperatures through Bridged-Type Organosilica Membranes with Different Pore Size

Industrial oxygen is purified by cryogenic distillation, in which cryogenic fluids of O₂, Ar, and N₂ flow inside the distillation column at a temperature of -180℃, which approximates the standard boiling point of liquid oxygen. The relative volatility of argon to oxygen is only 1.1, so that energy consumption is high due to the large number of shelf stages and large reflux ratio. Thus, the development of high O₂ selective permeation membranes for oxygen purification will enable a significant reduction in energy consumption via process intensification ^[1]. In the present study, bis(triethoxysilyl)methane (BTESM), which is known to have one of the most rigid and dense pore structures for bridged organosilica ^[2], was selected as the active separation layer, and its gas permeation properties were evaluated under temperatures ranging from 130 to 200℃. Binary separation (O₂/He, O₂/N₂) was also conducted to evaluate the effect of O₂ adsorption and its blockage of separation properties under extremely low temperatures. O₂ selectivity strongly depended on network pore size of BTESM membranes and O₂ selectivity for a membrane with small network pore size largely increased at -115℃.

References: [1] G. Maroukis et al., Chem. Eng. Res. Des. 184, 165-179, (2022) [2] M. Kanezashi et al., AIChE J. 63, 4491, (2017)