Search

Anthropogenic greenhouse gas emissions pose a serious threat to our environment. Therefore, the development of efficient systems to mitigate these issues is of utmost importance. In recent years, Sulphur hexafluoride (SF ) has garnered increasing attention due to its global warming potential, which greatly exceeds that of CO2 on a 100-year scale. These studies were undertaken to investigate SF6 sorption in novel metal-organic framework materials (MOFs)and how their components affect their function. First, the influence of secondary building units on coordination and sorption properties (SBUs) of SF6 on Ytterbium, Thulium, Cerium and Hafnium 1,3,6,8-tetrakis(4-carboxyphenyl) pyrene-based (TBAPy4−) MOFs was investigated. Secondly, the possibility of altering surface-chemical properties by pre-synthesis fluorination/amination of UIO-67/68 isostructures was studied. In the first case, the SF6 sorption properties of four novel, highly porous 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene-based (TBAPy4−) MOFs containing either Ytterbium, Thulium or Cerium all in the +3-oxidation state, orHafnium (+4) was studied. Pore size effects, coordination-effects on structure, and gas sportive propertieswere investigated and found to change and in some cases improve in the case of SF6 adsorbate. In the second case, the structures remain the same throughout these different changes, maintaining the Fmmcrystallographic space group characteristic for UIO-MOFs, enabling investigation of the effect of fluorination in isolation from other possible changes. While adding one more novel material. These changes in turn cause changes in SF6 working capacity, uptake, selectivity in simulated binary mixtures and isothermal enthalpy of adsorption. The influence of specific surface area on the isosteric enthalpy of adsorption revealed differences between functionalities. There is a multi-faceted purpose in these studies. The creation of novel structures contributes to the basic science and understanding o

Sulfur hexafluoride (SF6) is a highly potent greenhouse gas (GHG) that is mainly emitted from high-voltage electrical applications. The global warming potential (GWP) of the gas is almost 23 000 times that of CO2 and therefore, controlling its emission and recovery is of great importance from both an environmental and economic perspective. Solid adsorbents and adsorption-based technology is a cost-effective and energy-efficient pathway to recapture SF6 from its sources, which usually consist of dilute SF6 in N2. Here, we present a group of four highly porous and robust gallium- or vanadium-based metal–organic frameworks (MOFs) with exceptional SF6 uptake and selectivity. In particular, the novel gallium 1,2,4,5-tetrakis(4-carboxlatephenyl)benzene (TCPB4−) MOF (Ga-TBAPy) possesses 1-dimensional channels of suitable size (5.2 × 8.4 Å and 5.3 × 10 Å) to adsorb up to 2.25 mmol g−1 of SF6 at 10 kPa with an excellent SF6-over-N2 selectivity of 418. Ga-TCPB also exhibits high chemical stability in aqueous and acidic media as well as in organic solvents. 3D electron diffraction (3D ED) patterns combined with high-resolution electron microscopy images were employed to investigate the structure of these water-stable and cyclable MOF SF6 adsorbents. Furthermore, this study demonstrates the possibility of using these highly stable MOFs to capture SF6 from a gas mixture as well as how MOFs can offer an alternative and efficient way to mitigate the global warming contributions from the emission of SF6.

Bismuth-based metal-organic frameworks (Bi-MOFs) such as bismuth subgallate are important for applications ranging from medicine to gas separation and catalysis. Due to the porous nature of such Bi-MOFs, it would be valuable to understand their gas sorption and separation properties. Here, we present the gas sorption properties of three microporous Bi-MOFs, namely, CAU-17, CAU-33, and SU-101, along with a new trimesate-based structure, UU-200. We perform a detailed analysis of the sorption properties and kinetics of these Bi-MOFs. UU-200 shows good uptake capacities for CO2 (45.81 cm3 g−1 STP) and SF6 (24.69 cm3 g−1 STP) with CO2/N2 and SF6/N2 selectivities over 35 and 44, respectively at 293 K, 100 kPa. The structure of UU-200 is investigated using continuous rotation electron diffraction and is found to be a 3D porous framework containing pores with a diameter of 3.4–3.5 Å. Bi-MOFs as a group of relatively under-investigated types of MOFs have interesting sorption properties that render them promising for greenhouse gas adsorbents with good gas uptake capacities and high selectivities.

Four novel metal-organic frameworks (MOFs) composed of 4,4’,4’’,4’’’-(pyrene-1,3,6,8-tetrayl)tetrabenzoate (TBAPy4-) (UU-201, UU-203) or 1,2,4,5-tetrakis(4-carboxlatephenyl)benzene (TCPB4-) linkers (UU-202, UU-204) and vanadium (UU-201, UU-203) or gallium (UU-202, UU-204) were synthesized in this work. 3D electron diffraction was employed to investigate the structure of these MOFs. All four MOFs were highly porous with specific surface areas (Langmuir) ranging from ~900 to over ~1800 m2g-1. The MOFs also showed high levels of greenhouse gas uptake especially towards SF6 (UU-201, 4.0 mmol g-1, 293 K 1 bar) and selective adsorption towards SF6 and CO2 over N2 and CH4. Sorption kinetics were investigated in detail and the structures were found to contain 1-dimensional channels with diameters of approx. 9.1 x 13.6 Å and 6.5 x 13.7 Å. These novel MOFs have shown interesting sorption properties for potential gas capture and separation applications, especially for the separation of SF6 from N2, which is relevant in the electronics industry.

Four novel metal-organic frameworks (MOFs) composed of 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene (TBAPy4-) or 1,2,4,5-tetrakis(4-carboxlatephenyl)benzene (TCPB4-) linkers with gallium (Ga) or vanadium (V) were synthesized in this work. 3D electron diffraction patterns combined with high-resolution electron microscopy images were employed to investigate the structure of these MOFs. All four MOFs were highly porous with specific Langmuir surface area ranging from ~900 to over ~1800 m2 g-1. The MOFs also showed high uptake of greenhouse gas and especially selective towards SF6 (110 cm3 cm-3, 293 K 1 bar) and CO2 over N2 (or CH4). Sorption kinetics were investigated in detail and the MOF with the highest gas uptake had pore channels with diameters of approx. 9.1 13.6 and 6.5 13.7 in dimension. These Ga- and V-MOFs are potentially interesting candidate sorbents for greenhouse gas capture and separation applications, especially for the separation of SF6 and CO2 from N2, which are relevant in the electronics and chemical industry, respectively.