【摘要】 氦气在科学和工业等领域中都具有不可替代的作用,其主要存在于天然气中。如何高效地从天然气中分离氦气显得至关重要。本文基于密度泛函理论（DFT）方法系统地探究了菱形石墨炔（rhombic-graphyne,R-GY）分离膜对He和其他天然气组分（Ne、Ar、CO₂、N₂和CH₄）的吸附、选择和渗透性能。结果表明,R-GY作为He分离膜可同时满足高选择性和高渗透率的要求。常温下,R-GY薄膜对He/Ne、He/CO₂、He/N₂、He/Ar和He/CH₄的选择性可分别达到2?10⁷、3?10²⁰、9?10²⁶、7?10³⁷和5?10⁵¹,即使在600 K时仍可保持较高水平。此外,由于较低的扩散能垒,He穿透R-GY薄膜的渗透率在常温下可达到10^-6 mol·m^-2·s^-1·Pa^-1,高出工业标准近3个数量级;而其他气体组分在常温下的渗透率仅为10^-58-10^-14 mol·m^-2·s^-1·Pa^-1,气体无法渗透R-GY薄膜。更多还原

【Abstract】 Helium,which primarily occurs as a component of natural gas,has an irreplaceable role in both scientific and industrial fields.Therefore,it is crucial to separate helium from natural gas efficiently.Using density functional theory（DFT）,we systematically investigate the adsorption,selectivity,and permeability characteristics of the rhombic-graphyne（R-GY）monolayer membrane for He and other components of natural gas（Ne,Ar,CO₂,N₂,and CH₄）.These results demonstrate that the R-GY monolayer can fulfill the requirements of both high selectivity and high permeance as a membrane for He separation.At 300 K,the He selectivities of the R-GY membrane can be up to 2?10⁷,3?10²⁰,9?10²⁶,7?10³⁷,and 5?10⁵¹ over Ne,CO₂,N₂,Ar,and CH₄,respectively.The membrane can maintain high selectivity even at 600 K.In addition,the He permeance of R-GY at room temperature can reach 10^-6 mol·m^-2·s^-1·Pa^-1,which is higher than the industrial standard by about three orders of magnitude,because of its low diffusion energy barrier.In contrast,the permeance of the other gas components is only 10^-58–10^-14 mol·m^-2·s^-1·Pa^-1 at room temperature,indicating the impermeability of the R-GY to these components.更多还原