Rahmanzadeh Atyeh, Al-Hamdani Nasser, Favvas Evangelos P, De Luca Giorgio
Dipartimento di Fisica, Università Della Calabria, 87036 Rende, Italy.
Institute on Membrane Technology, ITM-CNR, Ponte P. Bucci, Cubo 17/c, 87036 Rende, Italy.
Materials (Basel). 2024 Jul 20;17(14):3588. doi: 10.3390/ma17143588.
Among a plethora of mixtures, the methane (CH) and hydrogen (H) mixture has garnered considerable attention for multiple reasons, especially in the framework of energy production and industrial processes as well as ecological considerations. Despite the fact that the CH/H mixture performs many critical tasks, the presence of other gases, such as carbon dioxide, sulfur compounds like HS, and water vapor, leads to many undesirable consequences. Thus purification of this mixture from these gases assumes considerable relevance. In the current research, first-principle calculations in the frame of density functional theory are carried out to propose a new functional group for vertically aligned carbon nanotubes (VA-CNTs) interacting preferentially with polar molecules rather than CH and H in order to obtain a more efficient methane and hydrogen separations The binding energies associated with the interactions between several chemical groups and target gases were calculated first, and then a functional group formed by a modified ethylene glycol and acetyl amide was selected. This functional group was attached to the CNT edge with an appropriate diameter, and hence the binding energies with the target gases and steric hindrance were evaluated. The binding energy of the most polar molecule (HO) was found to be more than six times higher than that of H, indicating a significant enhancement of the nanotube tip's affinity toward polar gases. Thus, this functionalization is beneficial for enhancing the capability of highly packed functionalized VA-CNT membranes to purify CH/H gas mixtures.
在众多混合物中，甲烷（CH）和氢气（H）的混合物因多种原因而备受关注，特别是在能源生产、工业过程以及生态考量的框架内。尽管CH/H混合物执行着许多关键任务，但其他气体的存在，如二氧化碳、硫化氢（HS）等含硫化合物以及水蒸气，会导致许多不良后果。因此，从这些气体中净化该混合物具有相当重要的意义。在当前的研究中，进行了密度泛函理论框架下的第一性原理计算，以提出一种新的官能团，用于垂直排列的碳纳米管（VA-CNTs），使其优先与极性分子而非CH和H相互作用，从而实现更高效的甲烷和氢气分离。首先计算了几个化学基团与目标气体之间相互作用的结合能，然后选择了由改性乙二醇和乙酰酰胺形成的官能团。将该官能团连接到具有合适直径的碳纳米管边缘，进而评估其与目标气体的结合能和空间位阻。发现最极性分子（HO）的结合能比H的结合能高出六倍多，这表明纳米管尖端对极性气体的亲和力显著增强。因此，这种功能化有利于提高高度填充的功能化VA-CNT膜净化CH/H气体混合物的能力。
