Porous vermiculite membrane with high permeance for carbon capture

Abstract

Two-dimensional (2D) membranes with interlayer nanochannels hold great promise for CO2 capture. However, the permeance is often limited by the high transmembrane resistance primarily caused by the tortuous interlayer diffusion pathway. Here, a facile method for preparing 2D porous vermiculite (PVMT) membranes is presented to boost CO2 transport by increasing the number of additional through-plane channels. The pristine vermiculite (VMT) nanosheets were treated with acid etching to generate nanopores by dissolving metal cations thereon. The resulting porous nanosheets were co-assembled with polyethyleneimine (PEI) molecules by vacuum-assisted self-assembly to fabricate PVMT-PEI membranes. The PEI molecules regulate the channel size to elevate the diffusion of CO2 and their amino groups afford affinity toward CO2 to increase its dissolution, thus intensifying the facilitated transport mechanism. The optimized PVMT-PEI membrane shows high performance with CO2 permeance of 568 GPU and CO2/CH4 selectivity of 27.6, which is 165% and 94% higher than pristine VMT membrane. In addition, the PVMT-PEI membranes exhibit good long-term operation stability.