Integrated Ammonia Capture and Exchange on Ion-Exchanged 4A Zeolites

Ammonia poses a challenge in effluent gas streams due to its corrosive nature. However, in fusion settings tritiated ammonia can be formed, leading to both tritium loss in inventory and the generation of reactive species. Therefore, identifying pathways in which both tritium can be recovered, and the ammonia can be easily handled would be beneficial. One such way to do so would be to combine two useful techniques: ammonia sequestration and hydrogen exchange (ND₃→NH₃). However, materials that can both adsorb ammonia and subsequently perform reactions on ammonia have not been well explored. In this work, we present the development of ion-exchanged A-type zeolites to be utilized as a support material for platinum catalysts. In this way, the zeolite can adsorb ammonia and the platinum catalyst can facilitate hydrogen exchange allowing for bifunctional reactivity of the material to be achieved. A variety of elements were explored for their effect on A-type zeolites and resulted in an isotopic difference in the adsorption of ND₃ and NH₃, noting the use of deuterium as a surrogate for tritium. Several platinum-impregnated zeolites were able to remove ND₃ from the gas stream, indicating that utilizing these materials in isotope recovery processes would improve accountability of these valuable hydrogen isotopes.