Publications by authors named "Yun-Ho Ahn"

Article Synopsis
  • Filler morphology control significantly improves gas separation in mixed matrix membranes (MMMs) through the design of a vertical transport channel utilizing crystal twinning in ZIF nanoplate.
  • Twinned ZIF-8 (TZIF-8) enhances propylene/propane separation when added to 6FDA-DAM polymer, achieving a propylene permeability of 40 Barrer and selectivity of 82.
  • The study indicates that the structure of the TZIF-8 provides effective pathways for desired gas molecules while creating barriers for undesired ones, outperforming previous MMMs and matching polycrystalline ZIF-8 membranes.
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This study presents a novel approach for fabricating ZIF-8 membranes supported on α-alumina hollow fibers through the introduction of a graphene oxide (GO) gutter layer and the application of zinc oxide (ZnO) Atomic Layer Deposition (ALD). The method successfully addressed key challenges, including excessive precursor penetration and membrane thickness. The introduction of the GO layer and subsequent ZnO ALD treatment significantly reduced membrane thickness to approximately 300 nm and eliminated delamination issues between the GO layer and the alumina support.

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Gas hydrates, a type of inclusion compound capable of trapping gas molecules within a lattice structure composed of water molecules, are gaining attention as an environmentally benign gas storage or separation platform. In general, the formation of gas hydrates from water requires high-pressure and low-temperature conditions, resulting in significant energy consumption. In this study, tetrabutylammonium fluoride (TBAF) was utilized as a thermodynamic promoter forming a semi-clathrate-type hydrate, enabling gas capture or separation at room temperature.

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The thermal distillation of crude oil mixtures is an energy-intensive process, accounting for nearly 1% of global energy consumption. Membrane-based separations are an appealing alternative or tandem process to distillation due to intrinsic energy efficiency advantages. We developed a family of spirocyclic polytriazoles from structurally diverse monomers for membrane applications.

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Most pharmaceuticals are stereoisomers that each enantiomer shows dramatically different biological activity. Therefore, the production of optically pure chemicals through sustainable and energy-efficient technology is one of the main objectives in the pharmaceutical industry. Membrane-based separation is a continuous process performed on a large scale that uses far less energy than the conventional thermal separation process.

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We discover new structure II (sII) hydrate forming agents of two C H O molecules (2-methyl-2-propen-1-ol and 2-butanone) and report the abnormal structural transition of binary C H O+CH hydrates between structure I (sI) and sII with varying temperature and pressure conditions. In both (2-methyl-2-propen-1-ol+CH ) and (2-butanone+CH ) systems, the phase boundary of the two different hydrate phases (sI and sII) exists at the slope change of the phase-equilibrium curve in the semi-logarithmic plots. We confirm the crystal structures of two hydrates synthesized at low (278 K and 6 MPa) and high (286 K and 15 MPa) temperature and pressure conditions by using high-resolution powder diffraction and Raman spectroscopy.

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Clathrate hydrates have received massive attention because of their potential application as energy storage materials. Host water frameworks of clathrate hydrates provide empty cavities that can capture not only small molecular guests but also radical species induced by γ-irradiation. In this work, we investigated structure II methyl vinyl ketone (MVK) binary clathrate hydrates with CH, O, and N and the effects of secondary guest species on MVK conformation in the cavity of hydrate and on the thermodynamic stability of unirradiated and γ-irradiated hydrate phases.

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