ИСТИНА

The chemical isotope exchange (ChIE) process in the water-hydrogen system is used to heavy water recycling and to detritiation of water waste. Industrial progress of this system became possible due to development of heterogeneous hydrophobic catalysts. However, the low heat resistance of these catalysts limits their operational temperatures. In this work, the ChIE mechanism in the water–hydrogen system was studied in the temperature range from 285 to 368 K on the new hydrophobic catalyst RCTU-4 (Pt/CDVB). It was shown that at 323 K the maximum value of the mass transfer coefficient is observed, which decreases with a further increase in temperature. This dependence is explained from the point of view of hydrogen and water vapor competitive adsorption at the catalyst active sites. This is confirmed by direct measurement of temperature dependence of the catalytic reaction between water vapors and hydrogen. At a relative humidity of RH = 100%, the reaction rate decreases at temperatures above 343 K. If the ratio PH2O/PH2 in the mixture is kept constant, the catalyst activity increases in the all studied temperature range (Ea = 15 kJ/mol).