Showing papers by "Taner Yildirim published in 2014"

Computation-Ready, Experimental Metal–Organic Frameworks: A Tool To Enable High-Throughput Screening of Nanoporous Crystals

Abstract: Experimentally refined crystal structures for metal–organic frameworks (MOFs) often include solvent molecules and partially occupied or disordered atoms. This creates a major impediment to applying high-throughput computational screening to MOFs. To address this problem, we have constructed a database of MOF structures that are derived from experimental data but are immediately suitable for molecular simulations. The computation-ready, experimental (CoRE) MOF database contains over 4700 porous structures with publically available atomic coordinates. Important physical and chemical properties including the surface area and pore dimensions are reported for these structures. To demonstrate the utility of the database, we performed grand canonical Monte Carlo simulations of methane adsorption on all structures in the CoRE MOF database. We investigated the structural properties of the CoRE MOFs that govern methane storage capacity and found that these relationships agree well with those derived recently from a...

Exceptional CO2 capture in a hierarchically porous carbon with simultaneous high surface area and pore volume

Abstract: A new type of hierarchically porous carbon (HPC) structures of simultaneously high surface area and high pore volume has been synthesised from carefully controlled carbonization of in-house optimised metal–organic frameworks (MOFs) Changes in synthesis conditions lead to millimetre-sized MOF-5 crystals in a high yield Subsequent carbonization of the MOFs yield HPCs with simultaneously high surface area, up to 2734 m2 g−1, and exceptionally high total pore volume, up to 553 cm3 g−1 In the HPCs, micropores are mostly retained and meso- and macro- pores are generated from defects in the individual crystals, which is made possible by structural inheritance from the MOF precursor The resulting HPCs show a significant amount of CO2 adsorption, over 27 mmol g−1 (119 wt%) at 30 bar and 27 °C, which is one of the highest values reported in the literature for porous carbons The findings are comparatively analysed with the literature The results show great potential for the development of high capacity carbon-based sorbents for effective pre-combustion CO2 capture and other gas and energy storage applications

A Porous Metal–Organic Framework with Dynamic Pyrimidine Groups Exhibiting Record High Methane Storage Working Capacity

Abstract: We have realized a new porous metal–organic framework UTSA-76a with pyrimidine groups on the linker, exhibiting high volumetric methane uptake of ∼260 cm3 (STP) cm–3 at 298 K and 65 bar, and record high working capacity of ∼200 cm3 (STP) cm–3 (between 5 and 65 bar). Such exceptionally high working capacity is attributed to the central “dynamic” pyrimidine groups within UTSA-76a, which are capable of adjusting their orientations to optimize the methane packing at high pressure, as revealed by computational studies and neutron scattering experiments.

Computational Design of Metal–Organic Frameworks Based on Stable Zirconium Building Units for Storage and Delivery of Methane

Abstract: A metal–organic framework (MOF) with high volumetric deliverable capacity for methane was synthesized after being identified by computational screening of 204 hypothetical MOF structures featuring (Zr6O4)(OH)4(CO2)n inorganic building blocks. The predicted MOF (NU-800) has an fcu topology in which zirconium nodes are connected via ditopic 1,4-benzenedipropynoic acid linkers. Based on our computer simulations, alkyne groups adjacent to the inorganic zirconium nodes provide more efficient methane packing around the nodes at high pressures. The high predicted gas uptake properties of this new MOF were confirmed by high-pressure isotherm measurements over a large temperature and pressure range. The measured methane deliverable capacity of NU-800 between 65 and 5.8 bar is 167 cc(STP)/cc (0.215 g/g), the highest among zirconium-based MOFs. High-pressure uptake values of H2 and CO2 are also among the highest reported. These high gas uptake characteristics, along with the expected highly stable structure of NU-80...

Water‐Stable Zirconium‐Based Metal–Organic Framework Material with High‐Surface Area and Gas‐Storage Capacities

Abstract: We designed, synthesized, and characterized a new Zr-based metal-organic framework material, NU- 1100, with a pore volume of 1.53 ccg 1 and Brunauer- Emmett-Teller (BET) surface area of 4020 m 2 g 1 ; to our knowledge, currently the highest published for Zr-based MOFs. CH4/CO2/H2 adsorption isotherms were obtained over a broad range of pressures and temperatures and are in excellent agreement with the computational predic- tions. The total hydrogen adsorption at 65 bar and 77 K is 0.092 g g 1 , which corresponds to 43 g L 1 . The volumetric and gravimetric methane-storage capacities at 65 bar and 298 K are approximately 180 vSTP/v and 0.27 g g 1 , respec- tively.

Defect creation by linker fragmentation in metal-organic frameworks and its effects on gas uptake properties.

Abstract: We successfully demonstrate an approach based on linker fragmentation to create defects and tune the pore volumes and surface areas of two metal-organic frameworks, NU-125 and HKUST-1, both of which feature copper paddlewheel nodes. Depending on the linker fragment composition, the defect can be either a vacant site or a functional group that the original linker does not have. In the first case, we show that both surface area and pore volume increase, while in the second case they decrease. The effect of defects on the high-pressure gas uptake is also studied over a large temperature and pressure range for different gases. We found that despite an increase in pore volume and surface area in structures with vacant sites, the absolute adsorption for methane decreases for HKUST-1 and slightly increases for NU-125. However, the working capacity (deliverable amount between 65 and 5 bar) in both cases remains similar to parent frameworks due to lower uptakes at low pressures. In the case of NU-125, the effect of defects became more pronounced at lower temperatures, reflecting the greater surface areas and pore volumes of the altered forms.

Isoreticular series of (3,24)-connected metal-organic frameworks: Facile synthesis and high methane uptake properties

Abstract: We have successfully used a highly efficient copper-catalyzed "click" reaction for the synthesis of a new series of hexacarboxylic acid linkers with varying sizes for the construction of isoreticular (3,24)-connected metal-organic frameworks (MOFs)-namely, NU-138, NU-139, and NU-140. One of these MOFs, NU-140, exhibits a gravimetric methane uptake of 0.34 g/g at 65 bar and 298 K, corresponding to almost 70% of the DOE target (0.5 g/g), and has a working capacity (deliverable amount between 65 and 5 bar) of 0.29 g/g, which translates into a volumetric working capacity of 170 cc(STP)/cc. These values demonstrate that NU-140 performs well for methane storage purposes, from both a gravimetric and a volumetric point of view. Adsorption of CO2 and H-2 along with simulated isotherms are also reported.

A porous metal–organic framework with an elongated anthracene derivative exhibiting a high working capacity for the storage of methane

Abstract: We have developed a new porous metal–organic framework (MOF) (UTSA-80) with an elongated anthracene derivative as a linker. The activated UTSA-80a has a pore volume of 1.03 cm3 g−1 and a gravimetric Brunauer–Emmett–Teller surface area of ca. 2280 m2 g−1, higher than those of PCN-14. The volumetric methane storage capacity of UTSA-80a at 35 bar and 298 K is 192 cm3 (STP) cm−3, which makes it one of the few porous MOFs with a storage capacity >190 cm3 (STP) cm−3 at 35 bar. The volumetric uptake of methane by UTSA-80a reaches 233 cm3 (STP) cm−3 at room temperature and 65 bar; this is 88.6% of the new volumetric target of the US Department of Energy if the packing density loss is ignored. This capacity is comparable with that of PCN-14. However, as a result of the lower methane uptake of UTSA-80a at 5 bar, it has a much higher methane storage working capacity (deliverable amount of methane between 65 and 5 bar) of 174 cm3 (STP) cm−3 compared with PCN-14 [157–160 cm3 (STP) cm−3]. This value is slightly lower than the 190 cm3 (STP) cm−3 achieved by HKUST-1, suggesting that it is a promising material for methane storage in transport applications. Such an exceptionally high working capacity can probably be attributed to the elongated anthracene derivative used as a linker within UTSA-80a, which adjusts the pore sizes/cages and interactions with the methane molecules to optimize the methane working capacity.