Ali Kemal Sekizkardes

A 2D Mesoporous Imine‐Linked Covalent Organic Framework for High Pressure Gas Storage Applications

Hole-some mixture: A 2D mesoporous covalent organic framework (see figure) featuring expanded pyrene cores and linked by imine linkages has a high surface area (SA(BET) = 2723 m(2)  g(-1)) and exhibits significant gas storage capacities under high pressure, which make this class of material very promising for gas storage applications.

Pyrene-directed growth of nanoporous benzimidazole-linked nanofibers and their application to selective CO2 capture and separation

A pyrene-based benzimidazole-linked polymer (BILP-10) has been synthesized by the co-condensation of 1,3,6,8-tetrakis(4-formylphenyl)pyrene and 1,2,4,5-benzenetetramine tetrahydrochloride in dimethylformamide. The use of pyrene as a molecular building unit leads to the formation of self-assembled nanofibers that have moderate surface area (SABET = 787 m2 g−1) and very high CO2/N2 (128) and CO2/CH4 (18) selectivities at 273 K. Furthermore, results from gas uptake measurements indicate that BILP-10 can store significant amounts of CO2 (4.0 mmol at 273 K/1.0 bar) and H2 (1.6 wt% at 77 K/1.0 bar) with respective isosteric heats of adsorption of 38.2 and 9.3 kJ mol−1 which exceed all of the previously reported values for BILPs and are among the highest values reported to date for unmodified porous organic polymers. Under high pressure settings, BILP-10 displays moderate uptakes of H2 (27.3 g L−1, 77 K/40 bar), CH4 (72 L L−1, 298 K/40 bar), and CO2 (13.3 mmol g−1, 298 K/40 bar). The unusually high CO2 and H2 binding affinities of BILP-10 are presumably facilitated by the amphoteric pore walls of the polymer that contain imidazole moieties and the predominant microporous nature.

Application of pyrene-derived benzimidazole-linked polymers to CO2 separation under pressure and vacuum swing adsorption settings

Pyrene-derived benzimidazole-linked polymers (BILPs) have been prepared and evaluated for selective CO2 uptake and separation under pressure and vacuum swing conditions. Condensation of 1,3,6,8-tetrakis(4-formylphenyl)pyrene (TFPPy) with 2,3,6,7,10,11-hexaaminotriphenylene, 2,3,6,7,14,15 hexaaminotriptycene, and 3,3′-diaminobenzidine afforded BILP-11, BILP-12 and BILP-13, respectively, in good yields. BILP-12 exhibits the highest specific surface area (SABET = 1497 m2 g−1) among all known BILPs and it also has very high CO2 uptake 5.06 mmol g−1 at 273 K and 1.0 bar. Initial slope selectivity calculations indicate that BILP-11 has high selectivity for CO2/N2 (103) and CO2/CH4 (11) at 273 K. IAST selectivity calculations of BILPs at 298 K also showed high CO2/N2 (31–56) and CO2/CH4 (6.6–7.6) selectivity levels. The isosteric heats of adsorption for CO2 fall in the range of 32 to 36 kJ mol−1 and were considerably higher than those of CH4 (16.1–21.7 kJ mol−1). More importantly, the performance of pyrene-based BILPs in CO2 removal from flue gas and methane-rich gases (natural gas and landfill gas) under different industrial conditions was investigated according to evaluation criteria suggested recently by Bae and Snurr. The outcome of this study revealed that BILPs are among the best known porous materials in the field; they exhibit high working capacity, regenerability, and sorbent selection parameters. Collectively, these properties coupled with the remarkable physicochemical stability of BILPs make this class of polymers very promising for CO2 separation applications.

Continuous Flow Processing of ZIF-8 Membranes on Polymeric Porous Hollow Fiber Supports for CO2 Capture

We have utilized an environmentally friendly synthesis approach for the accelerated growth of a selective inorganic membrane on a polymeric hollow fiber support for postcombustion carbon capture. Specifically, continuous defect-free ZIF-8 thin films were grown and anchored using continuous flow synthesis on the outer surface of porous supports using water as solvent. These membranes demonstrated CO2 permeance of 22 GPU and the highest reported CO2/N2 selectivity of 52 for a continuous flow synthesized ZIF-8 membrane.

Separation of carbon dioxide from flue gas by mixed matrix membranes using dual phase microporous polymeric constituents

This study presents the fabrication of a new mixed matrix membrane using two microporous polymers: a polymer of intrinsic microporosity PIM-1 and a benzimidazole linked polymer, BILP-101, and their CO2 separation properties from post-combustion flue gas. 17, 30 and 40 wt% loadings of BILP-101 into PIM-1 were tested, resulting in mechanically stable films showing very good interfacial interaction due to the inherent H-bonding capability of the constituent materials. Gas transport studies showed that BILP-101/PIM-1 membranes exhibit high CO2 permeability (7200 Barrer) and selectivity over N2 (15). The selected hybrid membrane was further tested for CO2 separation using actual flue gas from a coal-fired power plant.

Highly porous photoluminescent diazaborole-linked polymers: synthesis, characterization, and application to selective gas adsorption

The formation of boron–nitrogen (B–N) bonds has been widely explored for the synthesis of small molecules, oligomers, or linear polymers; however, its use in constructing porous organic frameworks remains very scarce. In this study, three highly porous diazaborole-linked polymers (DBLPs) have been synthesized by condensation reactions using 2,3,6,7,14,15-hexaaminotriptycene and aryl boronic acids. DBLPs are microporous and exhibit high Brunauer–Emmett–Teller surface area (730–986 m2 g−1) which enable their use in small gas storage and separation. At ambient pressure, the amorphous polymers show high CO2 (DBLP-4: 4.5 mmol g−1 at 273 K) and H2 (DBLP-3: 2.13 wt% at 77 K) uptake while their physicochemical nature leads to high CO2/N2 (35–42) and moderate CO2/CH4 (4.9–6.2) selectivity. The electronic impact of integrating diazaborole moieties into the backbone of these polymers was investigated for DBLP-4 which exhibits green emission with a broad peak ranging from 350 to 680 nm upon excitation with 340 nm in DMF without photobleaching. This study demonstrates the effectiveness of B–N formation in targeting highly porous frameworks with promising optical properties.