Metal-organic framework MIL-101 loaded with polymethacrylamide with or without further reduction: Effective and selective CO2 adsorption with amino or amide functionality

Abstract

In order to improve the performances of a typical/highly porous metal-organic framework (MOF, MIL-101 structure) in CO2 adsorption/capture, methacrylamide was polymerized (to polymethacrylamide or PM) inside of MIL-101 (to get PM@MOF) and further reduced with lithium aluminum hydride. The obtained adsorbents (R-PM24@MOF or PM24@MOF) had highly enhanced performances, compared with the pristine MOF, in CO2 capture both in the adsorption capacity (especially at low pressure of 0.15 atm) and adsorption selectivity (against N2), suggesting the polyamides loading (and subsequent reduction) on MOFs is an effective mean to derive competitive adsorbent for CO2 adsorption/capture. For example, the developed adsorbent (R-PM24@MOF) showed 1.4 mmol/g of adsorbed CO2 (at 0.15 atm and 298 K) and adsorption selectivity (CO2/N2) of 143 at 298 K (CO2/N2 = 0.75/0.15, at 1 atm); which are ~3 and ~10 times to that of pristine MIL-101, respectively. The remarkably enhanced performances could be explained with the introduced functional groups and reduced porosity (for decreased N2 adsorption). Moreover, the adsorbent could be easily recycled, suggesting the potential application in selective adsorption of CO2 from off gas of post-combustions.