Adsorption rate of hydrogen isotopes on Ca-mordenite

カルシウム交換型モルナイトにおける水素同位体の吸着速度

河村 繕範; 枝尾 祐希; 山西 敏彦

Kawamura, Yoshinori; Edao, Yuki; Yamanishi, Toshihiko

水素同位体分離分析用のガスクロマトグラフの分離カラムに適した吸着材を開発する目的で、合成ゼオライトであるモルデナイト型ゼオライトの交換カチオン(Na)を別のイオンで交換した試料を作成し、水素同位体吸着挙動を調べている。Caで交換したモルデナイト型ゼオライトが大きな吸着容量を示したことを受け、Ca交換型モルデナイトにおけるH及びDの吸着破過曲線を194K及び175Kの温度で採取解析し、物質移動係数を推定することで吸着速度を定量した。水素同位体吸着の律速過程は多孔質粒子内の拡散であり、有効拡散係数の同位体差も原料物質より大きくなった。よって、Ca交換型モルデナイトは原料物質よりも同位体分離の性能向上が期待できる。

To develop an adsorbent that is suitable for a separation column of gas chromatograph for hydrogen isotope analysis, the mordenite-type zeolite of which cations (Na) were exchanged with other cations have been prepared and their hydrogen isotope adsorption behavior is being investigated. Then, it has been shown experimentally that mordenite-type zeolite of which cation has been exchanged with Ca (Ca-MOR) has fairly large adsorption capacity. So, breakthrough curves of H (or D) adsorption on Ca-MOR at 194 K and 175 K have been observed and mass transfer coefficients have been estimated from them. The rate-controlling step of hydrogen adsorption is hydrogen diffusion in porous adsorbent. And, isotopic difference of effective diffusivity in Ca-MOR is larger than that in Na-MOR. Therefore, in comparison with Na-MOR, use of Ca-MOR is expected to enhance the hydrogen isotope separation capability.