Sulfur- and Nitrogen-Incorporated Phenothiazine-Based Porous Organic Polymer: Selective and Efficient CO<sub>2</sub> Capture and Evaluation for Vacuum Swing Adsorption
Mosim Ansari, Aasif Helal, Abuzar Khan, Ismail Abdulazeez, Mohd Yusuf Khan
Abstract
Carbon capture and storage (CCS) is considered an effective strategy for reducing CO 2 emissions and addressing climate change. We report the synthesis of rigid, robust phenothiazine and 3D triptycene-containing microporous polymer (NS-TMP) possessing nitrogen and sulfur heteroatoms via a one-pot facile Friedel–Crafts reaction as an efficient microporous adsorbent for selective CO 2 capture. The incorporation of triptycene units in the NS-TMP polymer structure imparts several advantageous characteristics, including inherent microporosity, increased surface area, and enhanced thermal stability. NS-TMP exhibits significant micropore volume, a BET-specific surface area (SA BET ) of 863 m 2 /g, and promising thermal stability ( T d = 321 °C). Additionally, the presence of phenothiazine units containing N and S heteroatoms enhances its ability for selective CO 2 capture. NS-TMP demonstrates a strong affinity for CO 2, with a heat of adsorption ( Q st ) of 35 kJ/mol, indicating an excellent CO 2 adsorption capacity, significantly influenced by the micropore volume. The selectivity for CO 2 /N 2 and CO 2 over CH 4 for NS-TMP was estimated to be reasonably high, reaching values of 72 and 11, respectively, showcasing its potential for effective CO 2 separation in various applications. Furthermore, Grand Canonical Monte Carlo (GCMC) simulation was conducted to study the adsorption of CO 2 in NS-TMP. Using the isotherm data, performance indicators for a cyclic vacuum swing adsorption (VSA) process were measured to estimate the practical suitability of NS-TMP.