Abstract
Helium (He) is one of the indispensable and rare strategic materials for national defense and high-tech industries. However, daunting challenges have to be overcome for the supply shortage of He resources. Benefitted from the wide pore size distribution, sufficient intrinsic porosity, and high specific surface area, metal–organic framework (MOF) materials are prospective candidates for He purification in the membrane-based separation technology. In this work, through first-principles calculations and molecular dynamics (MD) simulations, we studied the permeability and filtration performance of He by the newly synthesized two-dimensional Fe-PTC MOF and its analogue Ni-PTC MOF. We found that both Fe-PTC and Ni-PTC have superior high performance for He separation. The selectivity of He over N2 was calculated to be ~1017 for Fe-PTC and ~1015 for Ni-PTC, respectively, both higher than most of the previously proposed 2D porous membranes. Meanwhile, high He permeance (10−4~10−3 mol s−1 m−2 Pa−1) can be obtained for the Fe/Ni-PTC MOF for temperatures ranging from 200 to 500 K. Therefore, the present study offers a highly prospective membrane for He separation, which has great potential in industrial application.
Highlights
As a rare strategic material, helium (He) is urgently needed in the medical, scientific research, and aerospace industries [1,2,3]
Searching for a membrane with properly-sized pores for He separation is of great importance to achieve the goal of optimized balance of high permeance with sufficiently high selectivity
In this work, using combined first-principles calculations and molecular dynamics (MD) simulations, we theoretically demonstrated that the 2D Fe-PTC metal–organic framework (MOF) and its analogues Ni-PTC MOF can efficiently separate He from natural gas and inert gases
Summary
As a rare strategic material, helium (He) is urgently needed in the medical, scientific research, and aerospace industries [1,2,3]. The main source of He is the by-product in the exploitation of natural gas [4,5] Purification of He with membranebased separation technology has become a promising method, because of its low energy consumption, eco-friendly nature, simple operation, and other advantages [6,7,8,9,10]. In 2015, the experimentally available g-C3N4 membrane has been demonstrated to possess high selectivity (107~1065 at 300 K) for separating He from impure gas molecules (H2, N2, CO, CH4, Ne, and Ar) in natural gas [13]. Liu et al has shown that the nano-porous g-C2O membrane is a promising membrane for He separation with high selectivity (30~1028 at 300 K) and permeance (1.03 × 107 GPU) [15]. Searching for a membrane with properly-sized pores for He separation is of great importance to achieve the goal of optimized balance of high permeance with sufficiently high selectivity
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