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首页> 外文期刊>The journal of physical chemistry, C. Nanomaterials and interfaces >Equilibrium Isotope Effect for Hydrogen Absorption in Palladium
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Equilibrium Isotope Effect for Hydrogen Absorption in Palladium

机译：钯中氢的平衡同位素效应

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Absorption isotherms at 323 K for the H-D-Pd system were measured by introducing H2 and D2 into Pd in sequence. The method using addition of isotopes to the system in sequence to investigate isotope exchange effects has not been previously reported. The equilibrium absorption pressure in the plateau region of the mixed-isotope system varies with the ratio of H/D in the solid phase. It lies between those of the single-isotope systems of H-Pd and D-Pd. Higher equilibrium pressures are associated with high D/H ratios in the solid phase. A model proposed previously (Luo, W.; Cowgill, D.; Causey, R.; Stewart, K. J. Phys. Chem., B 2008,112, 8099) for mixed isotope hydride desorption, which correlates the equilibrium plateau pressure of the mixed H-D system with the fractions of D and H in the solid and the equilibrium plateau pressures of the single-isotope systems, is also successfully applied to absorption. When D2 is introduced into the H-Pd system in the plateau region, both the H-D exchange processes in the gas phase and net H (D) absorption take place. The former does not result in a total pressure change, but the latter creates a total pressure decrease. These reactions produce a D concentration increase in both the bulk Pd and the gaseous phase, as expected. Curiously, however, they also result in a counterintuitive small H concentration increase in bulk Pd and a decrease in gaseous H. Analogous results are obtained when the order of D2-H2 introduction is reversed. In the plateau region, isotope displacement does not take place. Once in the β-phase, isotope displacement does take place. The equilibrium isotope H-D partitions in the gas phase, H2, HD, and D2, are controlled by the equilibrium constant, K_(HD), and their equilibrium partitions among H and D between gas and bulk Pd are controlled by the separation factor, α.
机译：通过将H2和D2依次引入Pd中，测量H-D-Pd系统在323 K处的吸收等温线。以前尚未报道过使用向系统中依次添加同位素来研究同位素交换作用的方法。混合同位素系统的平稳区域中的平衡吸收压力随固相中H / D的比率而变化。它介于H-Pd和D-Pd的单同位素系统之间。较高的平衡压力与固相中较高的D / H比有关。先前提出的混合同位素氢化物解吸模型（Luo，W .; Cowgill，D .; Causey，R .; Stewart，KJ Phys。Chem。，B 2008,112，8099），该模型与混合同位素氢化物解吸有关具有固体中D和H的分数以及单同位素系统的平衡平稳压力的HD系统也成功地应用于吸收。当将D2引入高原区域的H-Pd系统时，会同时发生气相中的H-D交换过程和净H（D）吸收。前者不会导致总压力变化，但后者会导致总压力下降。如所期望的，这些反应在本体Pd和气相中均产生D浓度增加。然而，令人奇怪的是，它们还导致体积Pd中H浓度的反常增加很小，而气态H的含量却减少了。当D2-H2的引入顺序相反时，可获得类似的结果。在高原地区，不会发生同位素置换。一旦进入β相，同位素就会发生位移。气相中的平衡同位素HD分区H2，HD和D2受平衡常数K_（HD）的控制，气相与本体Pd之间的H和D之间的平衡同位素HD的分离因子α受到控制。

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