Computational Insights on the Role of NanochannelEnvironment in the CO 2 /CH 4 and H 2 /CH 4 Separation Using Restacked Covalent Organic FrameworkMembranes

To fabricate high performing ultrathin membranes, the interlayer nanochannel environment, which is hard to be observed and characterized in experiments, plays a key role in membrane performance. In this work, a series of restacked ultrathin 2D-COF membranes are computationally constructed to explore the influence of nanochannel microenvironment on the separation of CO2/CH4 and H2/CH4. The results show that the molecular sieving property can be achieved for both CO2/CH4 and H2/CH4 mixtures through the size control by tuning the nanochannels with different size. However, when fixing the size of the nanochannel, the energy control through changing the stacking modes of the few more layer restacked nanosheets is only effective in improving the membrane selectivity for CO2/CH4 but not for H2/CH4. Under energy control, CH4 permeance plays the key role in the CO2/CH4 separation performance, and heterogeneous energetic microenvironment with interlayer diffusion inlets and outlets in high potential energy is benef...