Computational understanding of Na-LTA for ethanol-water separation

There is a growing demand for high purity ethanol as an electronic chemical. The conventional distillation process is effective for separating ethanol from water but consumes a significant amount of energy. Selective membrane separation using the LTA-type molecular sieve has been introduced as an alternative. The density functional theory simulation indicates that aluminum (Al) sites are evenly distributed throughout the framework, while sodium (Na⁺) ions are preferentially located in the six-membered ring. The movement of ethanol molecules can cause Na⁺ ions to be transported towards the eight-membered ring, hindering the passage of ethanol through the channel. In contrast, the energy barrier for water molecules passing through the channel occupied by Na⁺ ions is significantly lower, leading to a high level of selectivity for ethanol-water separation.