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Abstract: The separation of a hydrogen isotope mixture on porous materials was studied using equilibrium and breakthrough experiments. The adsorption equilibria of H2 and D2 on SBA-15 with mesopores and molecular sieves 5A, Y, and 10X with micropores were measured at 77 K using the volumetric method. The breakthrough experiments of a H2 and D2 mixture in each adsorbent bed were carried out at various conditions of flow rate and pressure. The equilibrium ratio of D2 to H2 on mesoporous molecular sieves was larger than the ratio on microporous molecular sieves (SBA-15 > 10X > Y > 5A), but the difference among the adsorbents decreased with increases in pressure. On the other hand, the order of breakthrough separation factor showed the opposite result (SBA-15 < 10X < Y < 5A). The breakthrough separation factors for zeolite 10X was approximately equal to the equilibrium ratio of D2 to H2 at the corresponding partial pressures, whereas zeolites 5A and Y showed higher breakthrough separation factors than their equilibrium ratios. In SBA-15, the separation factors from breakthrough results were even smaller than the corresponding equilibrium ratio. In the microporous adsorbent with a limited pore size (zeolite 5A in the study), the diffusion mechanism contributed to the separation of hydrogen isotope gases as one of key factors. [Copyright &y& Elsevier]

Abstract: The equilibrium and kinetic adsorption data of H2 and D2 on the micropore molecular sieve Y were collected at 77K with the volumetric setup, and adsorption rate constants of deuterium evaluated from kinetic adsorption isotherms are larger than that of hydrogen at low pressure. In order to further study the influence factor of hydrogen isotope separation, the breakthrough curves of H2 and D2 mixture on this adsorbent were measured with the single column adsorption apparatus. Effects of different flow rate and pressure on separation efficiency were investigated, and up to 1.52 of the separation factor is obtained at the total gas pressure of 0.4MPa and flow rate of 129.79cm3/min with the adsorption bed length of 1.0m. However, the ratios of the adsorbed amount of deuterium over hydrogen are only 1.18 and 1.17 at 0.0139 and 0.0175MPa, respectively. Based on the difference between equilibrium adsorption and dynamic adsorption in the column, the key factor of separating H2 and D2 mixture depends on their dynamic difference. Lastly, a model for the fixed adsorption bed was built to simulate the concentration distribution of H2 and D2, and the simulation results agree well with experimental results. [Copyright &y& Elsevier]