A remarkable two-dimensional membrane for multifunctional gas separation: halogenated metal-free fused-ring polyphthalocyanine

Abstract

We theoretically explore the structural and mechanical properties of metal-free fused-ring polyphthalocyanine (H₂PPc) and halogenated H₂PPc (F-H₂PPc and Cl-H₂PPc) membranes, and the energy profiles for gaseous H₂, CO, CH₄, CO₂ and N₂ molecules adsorbing on and passing through these monolayers. Importantly, we reconsider in depth the values of the parameters in the definition of permeance, and corroborate the validity of the model from first-principles theory with the results of H₂ diffusion from classic molecular dynamics simulations. With well-defined nanosized pores, halogenated H₂PPc monolayers turn out to be multifunctional gas separation membranes, i.e. F-H₂PPc for H₂/CO, H₂/CH₄, CO₂/N₂, CO₂/CH₄, CO/CH₄ and N₂/CH₄ separation as well as Cl-H₂PPc for H₂/CO, H₂/CH₄ and H₂/CO₂ separation, which should be of great potential in energy and environmental fields.