Amine tethered pore-expanded MCM-41: A promising adsorbent for CO 2 capture

Abstract

The current work investigates the influence of pore size as well as pore volume of MCM-41 supports on amine tethering. Initially, monoamine tethering on MCM-41-3 as well as MCM-41-30 is carried out under dry conditions to screen the best support. The CO2 adsorption capacity and amine efficiency results revealed the beneficial effect of utilizing MCM-41-30, which is a pore-expanded support fabricated by our research group in a cost-effective manner for amino silane tethering. In order to increase the amine loading and further enhance the CO2 uptake in the important low pressure regime (0.1–0.2 bar), wet grafting process is followed for amino silane tethering on MCM-41-30 support. The present work also elucidates the performance of amine tethered MCM-41-30 in terms of post combustion CO2 capture metrics such as (i) CO2 adsorption capacity (ii) amine efficiency (iii) operating window (iv) CO2 adsorption kinetics (v) selectivity (vi) cyclic adsorption-desorption studies and (vii) cost. Comparative analysis of the same with other adsorbents such as activated carbon, zeolites, metal organic frameworks, amine impregnated and amine tethered mesoporous silica is highlighted to rank the performance for post combustion CO2 capture application. The mono and triamine tethered MCM-41 adsorbents developed in the current work, exhibited a maximum adsorption capacity of ∼1.2 and ∼2.1 mmol/g (75 °C, 0.2 bar) respectively. This in turn, indicated that MCM-41-30 support developed herein serves as a promising support for amine tethering application and demonstrates effective CO2 capture characteristics.