PNNL

Abstract

The proposed pathways for Xe/Kr removal and capture can essentially be divided in two categories: selective absorption by dissolution in solvents and physisorption on porous materials. Physisorption-based separation and adsorption on highly functional porous materials are promising alternatives for energy intensive cryogenic distillation process, where the adsorbents are characterized by high surface areas for removal capacities and often can be chemically fine-tuned to enhance the adsorbate–adsorbent interactions for optimum selectivity. Several traditional porous adsorbents such as zeolites and activated carbon have been tested for noble gas capture, but have shown low capacity, selectivity, and lack of modularity. Metal-organic frameworks (MOFs) or porous coordination polymers (PCPs) are an emerging class of solid-state adsorbents, tailor-made for applications ranging from gas-adsorption and separation to catalysis and sensing. Herein, we give a concise summary on the background and development of Xe/Kr separation technologies with focus to UNF reprocessing and the prospect of MOF-based adsorbents for that particular application.