We are mainly conducting the following researches to explore and create novel functional materials based on confined nanospaces through mutual feedback between molecular modeling and experiments using various measurement and analysis techniques. We will update the outline of the researches and the obtained results as needed.
- High-Efficiency Adsorption Heat Pumps Using Flexible Nanoporous Materials
- High-Throughput CO2 Separation Using Flexible Metal–Organic Frameworks
- Development of Cryogenic Gas Adsorption and Recovery Technologies for Lunar Thermal Mining
- Development of Hydrogen Isotope Separation Technologies Using Ion Exchangers
High-Efficiency Adsorption Heat Pumps Using Flexible Nanoporous Materials
This is a collaborative study with Professor Hirotomo Nishihara at Tohoku University. We demonstrated that when water vapor or ethanol vapor is adsorbed in the liquid state into monolithic porous materials (nanosponge) composed of zeolite-templated carbon or graphene mesosponges, the application of mechanical pressure immediately induces desorption of the adsorbed molecules, and the accompanying liquid–gas phase transition generates cooling energy. In other words, when pressure is applied to compress the nanosponge, cooling energy is produced through the desorption of the adsorbed molecules. Conversely, when the applied pressure is released and the structure expands and recovers to its original state, heat is generated through the readsorption of vapor. By utilizing the latent heat associated with these processes, a heat pump can be realized. Nat. Commun. 10, 2599 (10 pp) (2019). doi.org/10.1038/s41467-019-10511-7
High-Throughput CO2 Separation Using Flexible Metal–Organic Frameworks
This is a collaborative study with Professor Shotaro Hiraide and Professor Minoru Miyahara at Kyoto University. We focused on a gate-type adsorbent, ELM-11, which can suppress heat generation during CO2 adsorption by undergoing endothermic structural transformation upon adsorption. We demonstrated that this material exhibits outstanding CO2 separation performance. Furthermore, by taking advantage of the unique properties of ELM-11, we proposed a high-throughput adsorption separation system and found that its CO2 separation efficiency is remarkably higher than that of conventional systems. This study was the first to demonstrate that gate-type adsorbents are highly effective for improving the efficiency and reducing the energy consumption of CO2 adsorption-based separation and recovery systems. In addition, the results are expected to strongly promote the exploration and development of even higher-performance gate-type adsorbents. Nat. Commun. 11, 3867 (15 pp) (2020). doi.org/10.1038/s41467-020-17625-3
Development of Cryogenic Gas Adsorption and Recovery Technologies for Lunar Thermal Mining
This research project was selected under the 12th Request for Proposal of JAXA Space Exploration, Innovation Hub Center and is being conducted in collaboration with Takasago Thermal Engineering Co., Ltd. We are developing fundamental technologies for a "Cryogenic Gas Adsorption and Recovery System" aimed at the separation and recovery of gases expected to be released together with water during lunar thermal mining, including helium isotopes (3He, 4He), hydrogen isotopes (H2，D2，DH), and CO. In this cryogenic gas adsorption and recovery system, highly gas-selective activated carbons are mounted on individual cryopanels operated at different temperatures in order to separate and recover each generated gas species. In this project, we are simultaneously exploring and developing novel activated carbons suitable for the separation and recovery of each gas, while also developing fabrication technologies for monolithic activated carbons optimized for integration into cryopanels. In particular, the primary focus of this research is the development of activated carbons capable of enabling the separation and recovery of 3He, which is expected to become important as a fuel for future fusion energy systems. 12th Request for Proposal of JAXA Space Exploration
Development of Hydrogen Isotope Separation Technologies Using Ion Exchangers
We are conducting research on the exploration of materials and the development of systems for the separation and enrichment of deuterium naturally present in freshwater (abundance relative to hydrogen: approximately 0.014%). Deuterium is a high-value material used in deuterated pharmaceuticals, NMR solvents, optical fibers, LSI devices, and organic electroluminescent devices, and is also expected to serve as a fuel for future fusion energy systems. In this research, we aim to identify deuteron exchangers that preferentially adsorb deuterium ions (deuterons) over hydrogen ions (protons) in water, while simultaneously developing deuterium enrichment systems utilizing these deuteron exchangers. To achieve this, we perform material screening using path integral Molecular Dynamics (PIMD) simulations based on machine-learning potentials. PIMD simulations incorporate the positional uncertainty (quantum effects) of light atomic nuclei such as protons and deuterons through Feynman’s path integral formulation and apply it within molecular dynamics simulations. The application of the path integral method is essential for quantitatively evaluating the selectivity of deuterons over protons.
