title: Postsynthetic Functionalization of Mg-MOF-74 with Tetraethylenepentamine: Structural Characterization and Enhanced CO2Adsorption.
abstract: Postsynthetic functionalization of magnesium 2,5-dihydroxyterephthalate (Mg-MOF-74) with tetraethylenepentamine (TEPA) resulted in improved CO2adsorption performance under dry and humid conditions. XPS, elemental analysis, and neutron powder diffraction studies indicated that TEPA was incorporated throughout the MOF particle, although it coordinated preferentially with the unsaturated metal sites located in the immediate proximity to the surface. Neutron and X-ray powder diffraction analyses showed that the MOF structure was preserved after amine incorporation, with slight changes in the lattice parameters. The adsorption capacity of the functionalized amino-Mg-MOF-74 (TEPA-MOF) for CO2was as high as 26.9 wt % versus 23.4 wt % for the original MOF due to the extra binding sites provided by the multiunit amines. The degree of functionalization with the amines was found to be important in enhancing CO2adsorption, as the optimal surface coverage improved performance and stability under both pure CO2and CO2/H2O coadsorption, and with partially saturated surface coverage, optimal CO2capacity could be achieved under both wet and dry conditions by a synergistic binding of CO2to the amines as well as metal centers.
authors.affiliation: Department of Chemical Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States.
authors.forename: Xiao
authors.initials: X
authors.lastname: Su
authors.affiliation: Department of Chemical Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States.
authors.forename: Lev
authors.initials: L
authors.lastname: Bromberg
authors.affiliation: Surface Measurements Systems , London HA0 4PE, United Kingdom.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Martis
authors.affiliation: Department of Chemical Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States.
authors.forename: Fritz
authors.initials: F
authors.lastname: Simeon
authors.affiliation: Chemical and Engineering Materials Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.
authors.forename: Ashfia
authors.initials: A
authors.lastname: Huq
authors.affiliation: Department of Chemical Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States.
authors.forename: T Alan
authors.initials: TA
authors.lastname: Hatton
keywords: amine functionalization; carbon dioxide adsorption; dynamic vapor sorption; magnesium 2,5-dihydroxyterephthalate; metal−organic framework