Insights into Cis-Amide-Modified Carbon Nanotubes for Selective Purification of CH4 and H2 from Gas Mixtures: A Comparative DFT Study

Download PDFsettingsOrder Article Reprints Open AccessArticle Insights into Cis-Amide-Modified Carbon Nanotubes for Selective Purification of CH4 and H2 from Gas Mixtures: A Comparative DFT Study by Atyeh Rahmanzadeh 1,Nasser AL-Hamdani 2ORCID,Evangelos P. Favvas 3ORCID andGiorgio De Luca 2,*ORCID 1 Dipartimento di Fisica, Università Della Calabria, 87036 Rende, Italy 2 Institute on Membrane Technology, ITM-CNR, Ponte P. Bucci, Cubo 17/c, 87036 Rende, Italy 3 Institute of Nanoscience and Nanotechnology, National Center for Scientific Research “Demokritos”, Aghia Paraskevi, 153 41 Athens, Greece * Author to whom correspondence should be addressed. Materials 2024, 17(14), 3588; https://doi.org/10.3390/ma17143588 Submission received: 24 May 2024 / Revised: 12 July 2024 / Accepted: 16 July 2024 / Published: 20 July 2024 (This article belongs to the Special Issue Advances in Carbon Nanotubes: Preparation, Properties and Applications) Downloadkeyboard_arrow_down Browse Figures Versions Notes Abstract Among a plethora of mixtures, the methane (CH4) and hydrogen (H2) 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 CH4/H2 mixture performs many critical tasks, the presence of other gases, such as carbon dioxide, sulfur compounds like H2S, 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 CH4 and H2 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 (H2O) was found to be more than six times higher than that of H2, 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 CH4/H2 gas mixtures.