Abstract
Separation of radioisotope 85Kr from 136Xe is of importance in used nuclear fuel reprocessing. Membrane separation based on zeolite molecular sieves such as chabazite SAPO-34 is an attractive alternative to energy-intensive cryogenic distillation. We report the synthesis of SAPO-34 membranes with considerably enhanced performance via thickness reduction based upon control of a steam-assisted vapor-solid conversion technique followed by ion exchange with alkali metal cations. The reduction of membrane thickness leads to a large increase in Kr permeance from 7.5 to 26.3 gas permeation units (GPU) with ideal Kr/Xe selectivities >20 at 298 K. Cation-exchanged membranes show large (>50%) increases in selectivity at ambient or slight subambient conditions. The adsorption, diffusion, and permeation characteristics of ion-exchanged SAPO-34 materials and membranes are investigated in detail, with potassium-exchanged SAPO-34 membranes showing particularly attractive performance. We then demonstrate the fabrication of selective SAPO-34 membranes on α-alumina hollow fibers.
Original language | English |
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Pages (from-to) | 6361-6368 |
Number of pages | 8 |
Journal | ACS Applied Materials and Interfaces |
Volume | 10 |
Issue number | 7 |
DOIs | |
State | Published - Feb 21 2018 |
Funding
This work was supported by the Department of Energy - Office of Nuclear Energy (DE-NE 0008298). We thank Prof. R. Lively (Georgia Tech) for discussions on hollow fiber spinning and facility use. We also thank Dr. R. Jubin, Dr. G. Del Cul, and Dr. E. Collins (all ORNL) for discussions on off-gas separation.
Keywords
- fuel cycle
- krypton
- membrane
- off-gas
- separation
- zeolite