Isotope exchange reaction of tritium on precious metal catalyst based on cation-exchanged mordenite for blanket tritium recovery

摘要

It is known that the chemical forms of tritium released from a ceramic breeder blanket are hydrogen form and water form. To recover tritiated water vapor, adoption of dryer that is packed column of synthetic zeolite has been proposed. On the other hand, synthetic zeolite is often used as a support of precious metal catalyst. Such catalysts usually have a capability of hydrogen isotope exchange between gas and water vapor. If this catalyst is used to dryer, the dryer may obtain a preferable function for tritium recovery by isotopic exchange reaction. To assess such functions, reaction rate should be estimated. The results of water adsorption experiment on cation-exchanged mordenite-type zeolite suggested the possibility that state of adsorbed water varied by exchanged cation. So, in this work, precious metal catalyst based on cation-exchanged mordenite was prepared, and the reaction rate of chemical exchange between hydrogen and tritiated water was investigated under temperature range between 30 degrees C and 80 C by the steady-state approximation. In the case of platinum on Na-mordenite, the reaction between gaseous hydrogen and tritiated water vapor was almost expressed as first-order reaction concerning tritiated water vapor concentration. (C) 2015 Elsevier B.V. All rights reserved.