Development of hydrophobic platinum catalyst for oxidation of tritium in JAEA

Iwai, Yasunori; Edao, Yuki; Asahara, Hiroo*; Hayashi, Takumi

Tritium oxidation over noble catalyst is a fundamental reaction in the fusion fields since the system of catalytic reactor for the oxidation of tritium in combination with following tritiated vapor absorber has been applied in tritium handling facilities to control the tritium release into the environment as low as achievable. To enhance tritium safety as much as possible with taking severe accidents such as complete loss of power supply into account, technology of hydrophobic catalyst has been drawing intense interest recently because of its potential application in passive recombiner for tritium oxidation at room temperature. To design a passive recombiner packed with hydrophobic catalyst for tritium oxidation, the development of manufacturing technology for hydrophobic platinum catalyst and the following data on reaction rate are essential. This presentation deals with the reaction rate for tritium oxidation over hydrophobic platinum catalyst at temperatures from room temperature to 343 K. Two kinds of hydrophobic platinum catalysts; supported with styrene-divinylbenzene and with silica were used for this test. The results indicate that (1) the reaction rate is effected by the particle size of platinum, (2) the order of reaction is 0.5 of hydrogen concentration at room temperature. The rate-determining step approximation method is applied for the discussion on the reaction mechanism of tritium oxidation over platinum catalyst.