金属-有机骨架材料用于去除天然气中H2S的计算研究

众所周知, 天然气作为一种利用效率高的清洁能源, 其需求量正与日俱增. 但天然气中包含的H₂S等有害气体会危害人类健康、腐蚀设备、污染生态环境等. 为解决这一问题, 寻找良好的H₂S吸附剂, 本文采用巨正则系综蒙特卡罗(GCMC)模拟方法, 针对天然气中H₂S/CH₄混合气分离, 对33种具有代表性的稳定金属-有机骨架(MOF)材料进行H₂S选择性和工作容量(变压吸附(PSA)及真空变压吸附(VSA)过程)的筛选. 结果表明,ZIF-80, Zn₂-bpydtc, CAU-1-(OH)₂, CH₃O-MOFa最适用于本体系VSA过程的气体分离; 而后两者最适用于PSA过程的气体分离.通过分析高选择性和高工作容量材料的结构特征, 发现改性官能基团以及小孔作用的出现是影响选择性的关键因素, 其中―Cl、―OH、―OCH₃基团对H₂S气体的吸附作用力最强. 具有高的工作容量材料的特点是选择性高, 对气体吸附作用力大, 吸附位置多. 基于筛选出的高选择性、高工作容量的稳定MOF材料总结出的强化H₂S选择性及工作容量的一般性规律, 为MOF材料应用于天然气脱硫提供了理论基础.

Computational Study of Metal-Organic Frameworks for Removing H2S from Natural Gas

Natural gas is a highly efficient energy source subject to growing demand. Natural gas contains H₂S, which can harmhuman health and cause equipment corrosion and environmental pollution. Effective H₂S adsorbents are necessary to overcome these problems. Grand canonical Monte Carlo (GCMS) simulations were performed to study the selectivity and working capacity (pressure swing adsorption (PSA) and vacuumpressure swing adsorption (VSA) processes) of H₂S in 33 kinds of stable metal-organic frameworks (MOFs), with the aim of separating H₂S from H₂S/CH₄ gas mixture. ZIF-80, Zn₂-bpydtc, CAU-1-(OH)₂, and CH₃O-MOFa were suitable materials for the VSAprocess. CAU-1-(OH)₂ and CH₃O-MOFa were suitable for the PSA process. The structures of materials exhibiting high selectivity and working capacity suggested that appropriate functionality and small pore sizes were important for high selectivity. MOFs with ―Cl, ―OH, and ―OCH₃ functionality exhibited the strongest adsorption. Materials exhibiting high selectivity, strong interaction with H₂S, and large numbers of adsorption sites may have high working capacities. High selectivity and high working capacity stable MOFs were screened and analyzed, to enhance the selectivity and working capacity toward H₂S. This provides a theoretical basis for separating H₂S fromnatural gas using MOFs.