Abstract The isotherms of hydrogen isotope, absorbed or desorbed by palladium particles of various sizes were investigated at ∼100 kPa of various absorption-desorption cycles at room temperature (25 ℃). The maximum hydrogen (D) content of these samples, the hydrogen (D) absorption capactiy, was determined using the Langmuir monolayer coverage equation from the isotherms after several cycles. A ratio of the hydrogen absorption capactiy of palladium/kieselguhr (Pd/K) to that of pure palladium was calculated to determine the palladium content of Pd/K. The results showed that the particle size and cycle numbers affected the isotherms of the isotopes. Only 78 % of the maximum absorption capacity at 100 kPa was obtained at the first cycle of H absorption when the particle size was 10–30 mesh, and the absorption capacity approached 100 % after the first hydrogenation when the particle size was reduced to 100–150 mesh. At 10−100 kPa, where the Pd-H system existed in the hydride β-phase, the relationship between pressure and the content absorbed strictly followed the Langmuir equation (correlation coefficient was >0.9999), which confirmed that the hydrogen atoms in the octahedral interstices follow a monolayer coverage model. According to the linear plot, the monolayer absorption capacity of H or D in the hydride β-phase, Qm, was calculated from the slope of the curve. The calculated Qm (Pd-H) and Qm (Pd-D) were 3.31 and 3.16 mmol/g, respectively, while Qm (Pd/K-H) and Qm (Pd/K-D) were 1.231 and 1.182 mmol/g, respectively. The Pd content of Pd/K, investigated from the H and D isotherms, were 37.2 and 37.4 wt%, respectively, which correlated with the result from inductively coupled plasma atomic emission spectroscopy (ICP-AES) (37.7 wt%).

中文翻译：

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利用氢等温线定量测定硅藻土上沉积的钯含量

摘要 在室温（25 ℃）下，在〜100 kPa 的各种吸收-解吸循环下，研究了不同尺寸的钯颗粒吸收或解吸的氢同位素的等温线。这些样品的最大氢 (D) 含量，即氢 (D) 吸收能力，是使用朗缪尔单层覆盖方程从几个循环后的等温线确定的。计算钯/硅藻土的吸氢能力(Pd/K)与纯钯的吸氢能力之比，从而确定Pd/K的钯含量。结果表明，粒径和循环数影响同位素的等温线。当粒径为10~30目时，第一次吸氢仅获得100 kPa最大吸收容量的78%，而当粒径减小到100~30目时，第一次加氢后吸收容量接近100%。 150目。在10−100 kPa下，Pd-H体系以氢化物β相存在，压力与吸收含量之间的关系严格遵循Langmuir方程（相关系数>0.9999），这证实了八面体中的氢原子间隙遵循单层覆盖模型。根据线性图，氢化物β相中H或D的单层吸收容量Qm由曲线的斜率计算。计算出的Qm (Pd-H)和Qm (Pd-D)分别为3.31和3.16 mmol/g，而Qm (Pd/KH)和Qm (Pd/KD)分别为1.231和1.182 mmol/g。从 H 和 D 等温线研究，Pd/K 的 Pd 含量分别为 37.2 和 37.4 wt%，这与电感耦合等离子体原子发射光谱 (ICP-AES) 的结果 (37.7 wt%) 相关。