Amine tethered pore-expanded MCM-41 for CO2 capture: Experimental, isotherm and kinetic modeling studies

• Pore-expanded MCM-41 (PE-MCM-41) serves as promising support for mono and tri amine tethering.
• A maximum amine loading of 6.39 mmol(N)/g is achieved for tri amine tethered PE-MCM-41.
• Mono amine tethered PE-MCM-41 exhibited an excellent amine efficiency of ∼0.5.
• The highest CO2 adsorption capacity of ∼2.1 mmol/g is achieved for tri amine tethered PE-MCM-41 under flue gas conditions.
• Isotherm and kinetic modeling studies are carried out for both the amine tethered PE-MCM-41 adsorbents.

At present, research activities based on different separation technologies are vigorously carried out with the aim to capture carbon dioxide (CO2), which remains as the major contributor for global warming problem. As a part of such research activity, mono and tri amine tethered pore-expanded MCM-41 (AP-PE-MCM-41 and TP-PE-MCM-41) mesoporous silica adsorbents are developed in the present work. The TP-PE-MCM-41 adsorbent exhibited an excellent CO2 adsorption capacity of ∼2.1 mmol/g under flue gas conditions (Pressure = 0.2 bar, Temperature = 75 °C), which is the highest reported CO2 adsorption capacity for a tri-amine tethered mesoporous silica adsorbent so far to the best of our knowledge. The experimental CO2 uptake data are fitted to Langmuir and Langmuir dual-site models. Langmuir-dual site model elucidated that chemisorption controls the initial stages of adsorption followed by physisorption during the latter stages of adsorption process. Kinetic uptake measurements are performed for both the adsorbents and the uptake profile is further analyzed by pseudo-first order, pseudo-second order and double-exponential models. Double-exponential model provided an excellent fit to the kinetic data indicating that CO2 adsorption on amine tethered PE-MCM-41 samples is governed by both chemisorption and physisorption.

Figure optionsDownload as PowerPoint slide