Improved Selectivity of Linear α-Olefins on Facilitated Transport Membranes— Experiment and Theory

Linear alpha olefins (LAOs) such as 1-hexene and 1-octene are experiencing a continuous increase in demand as value-added petrochemical feedstocks. Due to the high energy consumption associated with separating LAOs from their mixtures using distillation and extraction methods, there is a pressing need for more efficient separation approaches, such as membrane technology. Here, we develop facilitated transport membranes containing Ag nanoparticles for the separation of 1-hexene from n-hexane. These membranes exhibit high selectivity at ambient temperature and high downstream pressure due to specific interactions with TCNQ-activated Ag nanoparticles. We use density functional theory (DFT) to investigate the activation of Ag surfaces by TCNQ. We examine changes in the surface charge density of Ag depend on TCNQ coverage and calculate atomic charge differences through Bader charge analysis. Furthermore, we compute the adsorption energies of n-hexane, 1-hexene, 2-hexene, and 3-hexene on the Ag surface with various TCNQ coverages, and confirm the impact of carbon bonding on adsorption. These results demonstrate that the facilitated transport membrane has enhanced separation performance.