Hybrid Postsynthetic Functionalization of Tetraethylenepentamine onto MIL-101(Cr) for Separation of CO₂from CH₄

Abstract

To remove CO2 from CH4, tetraethylenepentamine was grafted onto coordinatively unsaturated centers of MIL-101­(Cr) by postsynthetic functionalization: wet impregnation at 298 K, followed by grafting, drying, and washing. Compared to MIL-101­(Cr), TEPA–MIL-101­(Cr) showed 54% higher CO2 adsorption at 1 bar and 98% reduction of CH4 adsorption at 60 bar. The ideal adsorption solution theory (IAST) selectivity of CO2/CH4 for a binary gas mixture of 2% CO2 + 98% CH4 at 298 K and 60 bar predicted by the Toth equation was found to be 11 and 598 for ungrafted and grafted MIL-101­(Cr), respectively. Single column breakthrough tests were performed for upgrading the 2% CO2 + 98% CH4 mixture to liquefied quality of natural gas (CO2 < 50 ppm) under various operating conditions including different temperatures and total amount of purge gas at the fixed pressure of 60 bar and temperature of 298 K. At the feed flow rate of 1000 sccm, the TEPA–MIL-101­(Cr) extrudates obtained 0.89 mmol/g CO2 adsorption capacity and nearly 83% of adsorbed CO2 can be removed by regenerating extrudates at 393 K with 79 cm3/gadsorbent of total amount of purge gas.

Strong Influence of Amine Grafting on MIL-101 (Cr) Metal–Organic Framework with Exceptional CO2/N2 Selectivity

“…During the grafting process, TEPA forms the dative bond with CUS of MIL-101 through the primary amine site and therefore the remaining amines would contribute in CO 2 adsorption. This will provide strong affinity between CO 2 molecules and CO 2 -philic sites (amine groups) that results in the formation of carbamate . The chemical reaction that occurs between CO 2 and amine functional groups can be expressed as follows Unlike CO 2 that adsorbs through the chemisorption mechanism, N 2 is a nonreactive gas molecule with lower quadrupole moment and polarizability than CO 2 that adsorbs only through the physisorption mechanism .…”

“…This will provide strong affinity between CO 2 molecules and CO 2philic sites (amine groups) that results in the formation of carbamate. 47 The chemical reaction that occurs between CO 2 and amine functional groups can be expressed as follows 48 ∫…”

Amine-Functionalized MIL-101 Monoliths for CO2 Removal from Enclosed Environments

“…To enable an efficient capture process for enclosed environments, it is crucial to select an adsorbent that exhibits sharp adsorption uptake at ultralow pressures. − Recently, through structure modification and subsequent amine functionalization, Darunte et al demonstrated the applicability of polyethylenimine (PEI)-impregnated MIL-101 for dilute CO 2 capture. It was shown that 85 wt % PEI impregnation yields 1.0 mmol/g CO 2 adsorption capacity at 400 ppm .…”

Elimination of 4‐chlorophenol in aqueous solution by the Novel Pd/MIL‐101(Cr)‐Hydrogen‐Accelerated catalytic fenton system

“…In recent years, the metal–organic frameworks (MOFs) material, with high specific surface area, tunable and large pore size, and diversity open metal sites, are showing great application potential of gas separation, sensing, energy storage and catalysis . Especially in the field of hydrogen storage, these properties facilitate the adsorption of H 2 on the surface of it.…”