(610e) Computational Investigation of Mxene Family for Different CO2/H2 Mixture Adsorption Processes: VSA, PSA, TSA, Ptsa, and Vtsa

Separation of CO₂ from H₂ is a very important process to produce pure H₂ which is an efficient and clean energy source. In addition, CO₂ is a greenhouse gas and the rapid increase in its amount in the atmosphere causes global warming and threatens all over the world. Adsorption has been an effective application for CO₂ capture and H₂ purification. Depending on the adsorption and desorption conditions which affect the performance of adsorbents, several type of adsorption processes are defined such as pressure swing adsorption (PSA), vacuum swing adsorption (VSA), temperature swing adsorption (TSA), pressure−temperature swing adsorption (PTSA), and vacuum−temperature swing adsorption (VTSA). MXenes, a new family of two-dimensional (2D) materials, appear to be promising materials for adsorption-based CO₂ capture with their high thermal conductivity, tunable pore structure and functionalization capabilities. Molecular simulation approaches are accepted as promising tools to gain mechanistic understanding related to adsorption-based separation performance of adsorbents and screen the extensive pool of adsorbent materials for specific application. Therefore, it is aimed in this study to investigate all possible MXene types either provided in experimental studies or suggested by theoretical studies for adsorption-based separation of CO₂/H₂ mixture. We reported MXene database for the first time in the literature, which covers simulated adsorbent metrics of 730 MXene structures for binary CO₂/H₂ separation. For CO₂/H₂:25/75 mixture adsorption, top MXene structures at PSA and VSA conditions were determined according to specific adsorbent metrics. For PSA and VSA conditions, promising ten MXene structures dominantly consist of 6B group transition metals (Cr, Mo, and W) from the elements in the d-block of periodic table. However, for TSA, PTSA and VTSA conditions, we realized that the use of high temperature for desorption leads MXenes functionalized with bulky –(NCS)₂ group and in-plane ordered vacancy MXenes such as Nb_1.33C and W_1.33C become prominent. Finally, binary gas adsorption performances of MXene family were compared with the well-known COF and MOF families. Considering %R and CO₂/H₂ adsorption selectivities, MXene family performs better performance than COF family. Although MOF family is better than MXene family in terms of APS and CO₂/H₂ adsorption selectivities, greater portion of MXene structures from the family exceeds %R≥85% criteria compared to MOF family under both PSA and VSA conditions.

(Financial support by the Scientific and Technological Research Council of Turkey (TUBITAK) is acknowledged (Grant No. 120M180).)