Hexagonal Boron Nitride with Designed Nanopores as a High-Efficiency Membrane for Separating Gaseous Hydrogen from Methane

Using first-principles calculations and molecular dynamics simulations, we theoretically explored the potential applications of hexagonal boron nitride (h-BN) for H-2/CH4 separation. The h-BN with appropriate pores possesses excellent H-2/CH4 selectivity (>10(5) at room temperature). Furthermore, the adsorption energies (0.1 eV more or less) of both H-2 and CH4 on the designed monolayer membranes are sufficiently low to prevent the blocking of the nanopores in a realistic separating process. Particularly, we demonstrate a highly promising membrane (h-BN with a triangular pore and a N9H9 rim) with a calculated diffusion barrier of 0.01 eV for H-2 diffusion, and the simulated flux of H-2 across the single layer is as large as 4.0 x 10(7) GPU at 300 K. Additionally, the estimated permeability of H-2 significantly exceeds the industrially accepted standard for gas separation over a broad temperature range. Therefore, our results suggest that porous boron nitride nanosheets will be applicable as new membranes for gas separation.