Ion-Exchanged SAPO-34 Membranes for Krypton–Xenon Separation: Control of Permeation Properties and Fabrication of Hollow Fiber Membranes

• Published in: ACS applied materials & interfaces Vol. 10; no. 7; pp. 6361 - 6368
• Main Authors: Kwon, Yeon Hye, Min, Byunghyun, Yang, Shaowei, Koh, Dong-Yeun, Bhave, Ramesh R., Nair, Sankar
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 21-02-2018; American Chemical Society (ACS)
• Subjects: fuel cycle; krypton; membrane; NUCLEAR FUEL CYCLE AND FUEL MATERIALS; off-gas; separation; zeolite; zeolite; membrane; fuel cycle; krypton; separation; off-gas
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/acsami.7b18244

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.