Development of carbon alloy for selective recovery of hydrogen gas under low pressure and for hydrogen-isotope separation

测定了碱金属掺杂炭在77 K下的吸氢等温线，为碱金属掺杂炭作为氢回收剂和同位素分离剂的应用提供了依据。掺铷石墨箔（RbC 24）在低压下表现出较强的吸氢能力。考虑到吸附-脱附过程快速可逆，且半覆盖度平衡压力很低的特点，提出了一种新的吸附-脱附方法。e. 40 Pa时，由石墨箔制备的RbC_（24）有望作为低压氢气回收剂。测定了由多壁碳纳米管（MWCNT）和石油焦碳制备的KC 10掺钾碳在1000和1500°C热处理温度下的氢（H2）/氘（D2）吸附等温线。同位素分离系数估计从这些等温线。与由热处理温度为1000或1500°C的碳制备的KC 10相比，发现由MWCNT制备的KC 10具有非常大的同位素效应。然而，对于KCl 10（MWCNT），发现了一个严重的问题，即吸附-解吸循环的重复导致H2和D2的吸附量减少。

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°C, were also determined. Isotope separation coefficient was estimated from those isotherms. A very large isotope effect was found for KC10 prepared from MWCNT, compared with those prepared from carbons with heat-treatment temperatures of 1000 or 1500°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.