Synthesis of porous, nitrogen-doped adsorption/diffusion carbonaceous membranes for efficient CO₂ separation

A porous, nitrogen-doped carbonaceous free-standing membrane (TFMT-550) is prepared by a facile template-free method using letrozole as an intermediate to a triazole-functionalized-triazine framework, followed by carbonization. Such adsorption/diffusion membranes exhibit good separation performance of CO ₂ over N₂ and surpassing the most recent Robeson upper bound. An exceptional ideal CO₂/N₂ permselectivity of 47.5 was achieved with a good CO₂ permeability of 2.40 × 10 ^-13 mol m m^-2 s^-1 Pa^-1. The latter results arise from the presence of micropores, narrow distribution of small mesopores and from the strong dipole-quadrupole interactions between the large quadrupole moment of CO₂ molecules and the polar sites associated with N groups (e.g., triazine units) within the framework.