Search

Establishing new energy-saving systems for gas separation using porous materials is indispensable for ensuring a sustainable future. Herein, we show that ELM-11 ([Cu(BF4)2(4, 4′-bipyridine)2]n), a member of flexible metal–organic frameworks (MOFs), exhibits rapid responsiveness to a gas feed and an ‘intrinsic thermal management’ capability originating from a structural deformation upon gas adsorption (gate-opening). These two characteristics are suitable for developing a pressure vacuum swing adsorption (PVSA) system with rapid operations. A combined experimental and theoretical study reveals that ELM-11 enables the high-throughput separation of CO2 from a CO2/CH4 gas mixture through adiabatic operations, which are extreme conditions in rapid pressure vacuum swing adsorption. We also propose an operational solution to the ‘slipping-off’ problem, which is that the flexible MOFs cannot adsorb target molecules when the partial pressure of the target gas decreases below the gate-opening pressure. Furthermore, the superiority of our proposed system over conventional systems is demonstrated., ゲート型吸着剤を活用した二酸化炭素の高効率分離システムを提案 --二酸化炭素の分離回収技術の開発に貢献--. 京都大学プレスリリース. 2020-08-04.

Coordination polymers (CPs) or metal-organic frameworks (MOFs) have attracted considerable attention because of the tunable diversity of structures and functions. A 4,4'-bipyridine molecule, which is a simple, linear, exobidentate, and rigid ligand molecule, can construct two-dimensional (2D) square grid type CPs. Only the 2D-CPs with appropriate metal cations and counter anions exhibit flexibility and adsorb gas with a gate mechanism and these 2D-CPs are called elastic layer-structured metal-organic frameworks (ELMs). Such a unique property can make it possible to overcome the dilemma of strong adsorption and easy desorption, which is one of the ideal properties for practical adsorbents.

Elastic layer-structured metal organic frameworks (ELMs) having flexible two-dimensional structure show a gate phenomenon in sorption/desorption of simple gas molecules. The gate phenomenon is accompanied by expansion/shrinkage of the layers. The gas sorption/desorption is not based on a physical adsorption, but on a chemical reaction, which includes high cooperativity. The cooperative reaction could be analyzed thermodynamically. The gate phenomenon showed advantages in separation of CO2 from mixed gases and in storage of CH4 owing to easy release of absorbed molecules.

N2 adsorption on Cu–organic crystals [Cu(bpy)2(BF4)2] (bpy = bipyridine) at 77 K begins suddenly at P/P 0 = 0.1. This unique adsorption is named gate adsorption. Gate adsorption is associated with the change of crystal structure from GCMC and dynamic GCMC simulations. An expansion of 10% opens internal pore spaces in the crystal, giving rise to gate adsorption. The complete filling of the internal spaces with N2 molecules induces an expansion of 30%.

The development of “LAMINELIGHT®” laminated stainless steel foil for the packaging of lithium-ion batteries is now complete. As a result of simulation, the degree of the deformation of battery packaging made from laminated stainless steel foil caused by rising inner pressure is less than that made from laminated aluminum foil. The simulation also shows that stainless steel foil packaging has a high level of stability and can withstand stress as the laminated resin film is smaller than that of laminated aluminum foil. In addition, the result of laminated stainless steel foil’s critical piercing load is about four times higher than that of laminated aluminum foil. These results show that laminated stainless steel foil can make packaging tougher and more durable than laminated aluminum foil.

Reduction of several α,β-unsaturated ketones with dimethylphenylsilane and 10–100 mol% of CuF(PPh3)3·2EtOH or CuCl/PPh3/Bu4NF proceeds in a 1,4-selective manner to give the corresponding saturated ketones in up to >99% yield.

One-dimensional metal-organic compounds with cis, trans symmetry-controlled counter anions were synthesized (cis compound {[Cu(azpy)(H2O)2(OTs)2]*2H2O*(acetone)} (1) and trans compound {[Cu(H2O)4Cu(azpy)2(OTs)2(H2O)2]*2(OTs)*2H2O*2EtOH} (2)). Only 2, having trans conformation, exhibited a complete structure-restoration effect with a mechanism involving layering of molecular "bricks" of water and solvent molecules.

Accurate particle densities of the Cu-based metal organic framework [Cu(4,4'-bipyridine) 2 (BF 4 ) 2 ] for He, N 2 and CH 4 molecules using the high-pressure buoyancy method have been determined. A smaller probe molecule gave a larger particle density (1.70 g/ml from He, 1.66 g/ml from N 2 , 1.60 g/ml from CH 4 ). The effect of particle density on the evaluation of the surface excess mass for supercritical gas adsorption was examined; the above particle density difference gave rise to a 2–4% difference in the surface excess mass.

We measured adsorption and desorption isotherms of methane on [Cu(4, 4'-bipyridine)2(BF4)2] (LPC) at 258, 273, and 303 K. Adsorption proceeds almost vertically at a definite pressure, which is named gate pressure. The lower the measurement temperature, the smaller the gate pressure. The temperature dependence of the gate pressure is expressed by the Clapeyron-Clausius equation, giving a thermodynamic evidence on the clathrate formation between the Cu complex and methane.

Hydrosilylation of 1-alkynes catalyzed by RhI(PPh3)3 gives (E)- and (Z)-alkenylsilanes in a stereodivergent manner by switching the reaction conditions and the order of the addition of the reagents. The reaction is also applied to the synthesis of silicon-containing polymers with (E) and (Z) main-chain structures via polyaddition.