Isotopic effects on the permeation of all hydrogen isotopologues through MFI-ZSM-5 zeolite membranes. (13th January 2020)

• Record Type: Journal Article
• Authors: Antunes, R.; Böhmländer, A.; Cruz, M.M.; Frances, L.; Hillesheimer, D.; Krasch, B.; Welte, S.
• Is Part Of: International journal of hydrogen energy. Volume 45:Number 3(2020)
• Page Start: 2009
• Page End: 2016
• Publication Date: 2020-01-13
• Subjects: Isotopic effects -- Hydrogen isotopologues -- Zeolite membrane -- MFI -- Tritium; Hydrogen as fuel -- Periodicals; Hydrogène (Combustible) -- Périodiques; Hydrogen as fuel; Periodicals; 665.81
• DOI: 10.1016/j.ijhydene.2019.11.099
• Languages: English
• ISSNs: 0360-3199

Abstract

Abstract: In a fusion reactor, tritium will be continuously produced in the breeding blanket and a dedicated tritium extraction and removal system (TERS) is used to recover the newly bred tritium. In the TERS for the solid blanket, zeolite membranes are proposed to be used to pre-concentrate HT/H2 in He before Pd/Ag membranes. Therefore, permeation experiments were carried out using two experimental facilities to determine the permeances of all hydrogen isotopologues (Q2 = H2, HD, D2, HT, DT, T2 ) through MFI-ZSM-5 membranes. This study aimed at investigating the existence of isotopic effects on the Q2 permeation and hence on the separation of Q2 from He. The results exhibit a strong dependency of the permeance with the mass of the isotopologue: the selectivity decreases from around 1.8 for H2 /He to 1.3 for D2 /He down to 1.1 for T2 /He. This phenomenon is attributed to the existence of defects in the zeolite structure through which the molecules permeate according to Knudsen diffusion. These results were observed for inactive and active Q2 mixtures and no other effects related to the dipole moment of the asymmetric isotopologues (HD, HT, DT) or tritium decay were observed. Moreover, these results were obtained for three MFI-ZSM-5 membranes, showing a high reproducibility. Our results demonstrate that the pre-concentration of Q2 in He with MFI-ZSM-5 membranes appears to be challenging in the scope of the TERS. Graphical abstract: Image 1 Highlights: Permeation of hydrogen through MFI membranes is dependent on the isotopologues mass. Isotopic effect due to the existence of defects in the zeolite layer. Separation of Q2/He is highest for H2 and lowest for T2. MFI membranes exhibit low separation performances for the tritium extraction system.