title: Application of alkali metal-doped carbons for hydrogen recovery and isotope separation.
abstract: Hydrogen-sorption isotherms of alkali metal-doped carbons at 77 K were determined for promoting application of these materials as hydrogen-recovery and isotope-separation agent. The hydrogen-sorption behavior of rubidium-doped Grafoil, with composition of RbC24, showed high sorption ability against hydrogen at low pressure. Taking into account the fact that sorption-desorption was fast and reversible, and the equilibrium pressure at half coverage was very low, i.e., 40 Pa, RbC24 prepared from Grafoil is promising as a recovery agent for hydrogen gas at low pressure. The hydrogen (H2)/deuterium(D2)-sorption isotherms of potassium-doped carbons with composition of KC10, prepared from multi wall carbon nanotube (MWCNT) and carbons derived from petroleum cokes with heat-treatment temperatures of 1000 and 1500 degrees C, were also determined. Isotope separation coefficient was estimated from those isotherms. A very large isotope effect was found for KC10 prepared from MWCNT, comparable to those prepared from carbons with heat-treatment temperatures of 1000 or 1500 degrees C. However, a severe problem was found for KC10 (MWCNT) that repetition of the sorption-desorption cycles resulted in the decrease of the sorbed amount of H2 and D2.
authors.affiliation: Tokyo National College of Technology, 1220-2 Kunugida, Hachioji, Tokyo 193-0997, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Akuzawa
authors.forename: Y
authors.initials: Y
authors.lastname: Okano
authors.forename: T
authors.initials: T
authors.lastname: Iwashita
authors.forename: R
authors.initials: R
authors.lastname: Matsumoto
authors.forename: Y
authors.initials: Y
authors.lastname: Soneda