(309a) Carbon Nanostructure-Mediated Ultra-Rapid Separation

Highly rapid separation has been requested for energy saving technologies. If the separation rate is quite small regardless of the high selectivity, the separation is energy intensive. We must challenge the highly rapid separation with a high selectivity using adsorption or membrane separation. This presentation will show the very rapid adsorption separation of isotopic O₂ and ultrafast membrane separation of air and H₂ with carbon nanostructured materials. Dynamic adsorption of mixed ¹⁸O₂ and ¹⁶O₂ around 112 K on nanoporous carbons having in-pore narrow sites gives high adsorption selectivity of > 5 within 30 min [1], being more than 100 times larger than the current separation technology. ¹⁸O₂ is indispensable to advanced medical imaging for cancer detection. This adsorption separation is possible around the boiling temperature of methane, which is accessable through cryogenic liquified-natural-gas technology. Ultrafast separation of H₂ from CH₄ is requisite for construction of the steady hydrogen energy society. we developed a graphene-wrapped MFI zeolite molecular-sieving membrane for the ultrafast separation of H₂ from CH₄ at a permeability reaching 5.8 × 10⁶ barrers at a single gas selectivity of 245, whose permeability is 100 times larger than the previously developed ones. The subnanoscale interface space between the graphene and zeolite surface enables such an ultrafast separation [2]. Highly efficient air separation is key to construct an energy saving technologies. MD study on nanowindows with concerted rim motions in graphene showed the promising direction for ultrafast air separation[3].

[1] S. Kumar, A. Bagusetty, Y. Gogotsi, J. K. Johnson, K. Kaneko et al , Nature Comm. 2021,12, 546- 556.[2] R. Kukobat, M. Sakai, H. Tanaka, C. Lastoskie, M. Matsukata, T. Hayashi, K. Kaneko et al. Sci. Adv. In press. [3] F. Vallejos-Burgos, F.-X. Coudert, K. Kaneko, Nature Comm. 2018, 9,1812-1821.