Highly selective separation of CO2/N2 using [Emim][Tf2N] supported ionic liquid membranes prepared by supercritical fluid deposition

Supported ionic liquid membrane (SILM) using low surface tension ionic liquid [Emim] [Tf2N] and gamma-Al2O3 is prepared with the supercritical fluid deposition (SCFD) method, and supercritical carbon dioxide (scCO(2)) shuttles and diffuses into the interior of the support to render the deposition of ionic liquid (IL) in its nano-micro pores. In this study, the influence of preparation parameters includes deposition pressure (9-18MPa), deposition time (0-24 h), ethanol amount (0-18.75 vol%) and IL amount (1.0-5 mg/g) were investigated. Besides, the performance of SILMs were evaluated by analyzing IL load, N-2 and CO2 permeability, and ideal CO2/N-2 selectivity. Under the optimum condition, the [Emim] [Tf2N]-SILMs exhibited separation performance with CO2 permeance of 22.6 GPU and CO2/N-2 selectivity of 27.1. Furthermore, [Emim] [Tf2N]-SILM maintains proper pressure resistance and long-term stability, which is more suitable for CO2 separation, capture and storage in large-scale applications.