4 research outputs found
Selective adsorption of sulfur dioxide in a robust metal-organic framework material
Selective adsorption of SO2 is realized in a porous metal–organic framework material, and in-depth structural and spectroscopic investigations using X-rays, infrared, and neutrons define the underlying interactions that cause SO2 to bind more strongly than CO2 and N2
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Reversible coordinative binding and separation of sulfur dioxide in a robust metal-organic framework with open copper sites.
Emissions of SO2 from flue gas and marine transport have detrimental impacts on the environment and human health, but SO2 is also an important industrial feedstock if it can be recovered, stored and transported efficiently. Here we report the exceptional adsorption and separation of SO2 in a porous material, [Cu2(L)] (H4L = 4',4‴-(pyridine-3,5-diyl)bis([1,1'-biphenyl]-3,5-dicarboxylic acid)), MFM-170. MFM-170 exhibits fully reversible SO2 uptake of 17.5 mmol g-1 at 298 K and 1.0 bar, and the SO2 binding domains for trapped molecules within MFM-170 have been determined. We report the reversible coordination of SO2 to open Cu(II) sites, which contributes to excellent adsorption thermodynamics and selectivities for SO2 binding and facile regeneration of MFM-170 after desorption. MFM-170 is stable to water, acid and base and shows great promise for the dynamic separation of SO2 from simulated flue gas mixtures, as confirmed by breakthrough experiments
Reversible coordinative binding and separation of sulphur dioxide in a robust 3 metal-organic framework with open copper sites
Emissions of SO2 from flue gas and marine transport have detrimental impacts on the environment and human health, but SO2 is also an important industrial feedstock if it can be recovered, stored and transported efficiently. Here we report the exceptional adsorption and separation of SO2 in a porous material, [Cu2(L)] (H4L = 4′,4‴-(pyridine-3,5-diyl)bis([1,1′-biphenyl]-3,5-dicarboxylic acid)), MFM-170. MFM-170 exhibits fully reversible SO2 uptake of 17.5 mmol g−1 at 298 K and 1.0 bar, and the SO2 binding domains for trapped molecules within MFM-170 have been determined. We report the reversible coordination of SO2 to open Cu(ii) sites, which contributes to excellent adsorption thermodynamics and selectivities for SO2 binding and facile regeneration of MFM-170 after desorption. MFM-170 is stable to water, acid and base and shows great promise for the dynamic separation of SO2 from simulated flue gas mixtures, as confirmed by breakthrough experiments
Enhancement of CO<sub>2</sub> Adsorption and Catalytic Properties by Fe-Doping of [Ga<sub>2</sub>(OH)<sub>2</sub>(L)] (H<sub>4</sub>L = Biphenyl-3,3′,5,5′-tetracarboxylic Acid), MFM-300(Ga<sub>2</sub>)
Metal–organic
frameworks (MOFs) are usually synthesized
using a single type of metal ion, and MOFs containing mixtures of
different metal ions are of great interest and represent a methodology
to enhance and tune materials properties. We report the synthesis
of [Ga<sub>2</sub>(OH)<sub>2</sub>(L)] (H<sub>4</sub>L = biphenyl-3,3′,5,5′-tetracarboxylic
acid), designated as MFM-300(Ga<sub>2</sub>), (MFM = Manchester Framework
Material replacing NOTT designation), by solvothermal reaction of
Ga(NO<sub>3</sub>)<sub>3</sub> and H<sub>4</sub>L in a mixture of
DMF, THF, and water containing HCl for 3 days. MFM-300(Ga<sub>2</sub>) crystallizes in the tetragonal space group <i>I</i>4<sub>1</sub>22, <i>a</i> = <i>b</i> = 15.0174(7) Å
and <i>c</i> = 11.9111(11) Å and is isostructural with
the Al(III) analogue MFM-300(Al<sub>2</sub>) with pores decorated
with −OH groups bridging Ga(III) centers. The isostructural
Fe-doped material [Ga<sub>1.87</sub>Fe<sub>0.13</sub>(OH)<sub>2</sub>(L)], MFM-300(Ga<sub>1.87</sub>Fe<sub>0.13</sub>), can be prepared
under similar conditions to MFM-300(Ga<sub>2</sub>) via reaction of
a homogeneous mixture of Fe(NO<sub>3</sub>)<sub>3</sub> and Ga(NO<sub>3</sub>)<sub>3</sub> with biphenyl-3,3′,5,5′-tetracarboxylic
acid. An Fe(III)-based material [Fe<sub>3</sub>O<sub>1.5</sub>(OH)(HL)(L)<sub>0.5</sub>(H<sub>2</sub>O)<sub>3.5</sub>], MFM-310(Fe), was synthesized
with Fe(NO<sub>3</sub>)<sub>3</sub> and the same ligand via hydrothermal
methods. [MFM-310(Fe)] crystallizes in the orthorhombic space group <i>Pmn</i>2<sub>1</sub> with <i>a</i> = 10.560(4) Å, <i>b</i> = 19.451(8) Å, and <i>c</i> = 11.773(5)
Å and incorporates μ<sub>3</sub>-oxo-centered trinuclear
iron cluster nodes connected by ligands to give a 3D nonporous framework
that has a different structure to the MFM-300 series. Thus, Fe-doping
can be used to monitor the effects of the heteroatom center within
a parent Ga(III) framework without the requirement of synthesizing
the isostructural Fe(III) analogue [Fe<sub>2</sub>(OH)<sub>2</sub>(L)], MFM-300(Fe<sub>2</sub>), which we have thus far been unable
to prepare. Fe-doping of MFM-300(Ga<sub>2</sub>) affords positive
effects on gas adsorption capacities, particularly for CO<sub>2</sub> adsorption, whereby MFM-300(Ga<sub>1.87</sub>Fe<sub>0.13</sub>)
shows a 49% enhancement of CO<sub>2</sub> adsorption capacity in comparison
to the homometallic parent material. We thus report herein the highest
CO<sub>2</sub> uptake (2.86 mmol g<sup>–1</sup> at 273 K at
1 bar) for a Ga-based MOF. The single-crystal X-ray structures of
MFM-300(Ga<sub>2</sub>)-solv, MFM-300(Ga<sub>2</sub>), MFM-300(Ga<sub>2</sub>)·2.35CO<sub>2</sub>, MFM-300(Ga<sub>1.87</sub>Fe<sub>0.13</sub>)-solv, MFM-300(Ga<sub>1.87</sub>Fe<sub>0.13</sub>), and
MFM-300(Ga<sub>1.87</sub>Fe<sub>0.13</sub>)·2.0CO<sub>2</sub> have been determined. Most notably, <i>in situ</i> single-crystal
diffraction studies of gas-loaded materials have revealed that Fe-doping
has a significant impact on the molecular details for CO<sub>2</sub> binding in the pore, with the bridging M–OH hydroxyl groups
being preferred binding sites for CO<sub>2</sub> within these framework
materials. <i>In situ</i> synchrotron IR spectroscopic measurements
on CO<sub>2</sub> binding with respect to the −OH groups in
the pore are consistent with the above structural analyses. In addition,
we found that, compared to MFM-300(Ga<sub>2</sub>), Fe-doped MFM-300(Ga<sub>1.87</sub>Fe<sub>0.13</sub>) shows improved catalytic properties
for the ring-opening reaction of styrene oxide, but similar activity
for the room-temperature acetylation of benzaldehyde by methanol.
The role of Fe-doping in these systems is discussed as a mechanism
for enhancing porosity and the structural integrity of the parent
material