Air separation by facilitated transport of oxygen through a Pebax membrane incorporated with a cobalt complex

Abstract

Separation of air to produce enriched oxygen (O₂) and nitrogen (N₂) has been of great importance in the chemical industry. In the present investigation, thin film composite (TFC) membranes were prepared by coating a thin layer of poly(ether-block-amide) (Pebax-1657) incorporated with a cobalt(II) phthalocyanine (CoPc) compound onto a polyethersulfone (PES) ultraporous substrate. The surface and cross-sectional morphologies, intermolecular interactions and crystalline nature of the membranes were investigated by SEM, FTIR and XRD spectroscopy, respectively. Effect of CoPc loading and feed pressure on the permeance of pure O₂ and N₂ gases was evaluated and ideal selectivity was determined using indigenously fabricated high-pressure gas permeability equipment. O₂/N₂ ideal selectivity was enhanced from 2.9 to 8.5 with an increase in CoPc loading from 0 to 1 wt%, at a constant feed pressure of 2 kg cm⁻². A molecular dynamics simulation based on a COMPASS force field was performed to understand the diffusion behavior of O₂ and N₂ through the CoPc loaded Pebax-1657 membrane. This study confirmed that the CoPc complex present in the Pebax-1657 membrane facilitates preferential O₂ transport to produce enriched N₂ and O₂ from air for both inert gas and medical applications.