Hydrogen Isotope Separation by Catalyzed Exchange Between Hydrogen and Liquid Water
ABSTRACT The discovery, at Chalk River Nuclear Laboratories, of a simple method of wetproofing platinum catalysts so that they retain their activity in liquid water stimulated a concentrated research program for the development of catalysts for the hydrogen-water isotopic exchange reaction. This paper reviews 10 years of study which have resulted in the development of highly active platinum catalysts which remain effective in water for periods greater than a year.The most efficient way to use these catalysts for the separation of hydrogen isotopes is in a trickle bed reactor which effects a continuous separation. The catalyst is packed in a column with hydrogen and water flowing countercurrently through the bed. The overall isotope transfer rate measured for the exchange reaction is influenced by various parameters, such as hydrogen and water flow rates, temperature, hydrogen pressure, and platinum metal loading. The effect of these parameters as well as the improved performance obtained by diluting the hydrophobic catalyst with inert hydrophilic packing are discussed.The hydrophobic catalysts can be effectively used in a variety of applications of particular interest in the nuclear industry. A Combined Electrolysis Catalytic Exchange - Heavy Water Process (CECE-HWP) is being developed at Chalk River with the ultimate aim of producing parasitic heavy water from electrolytic hydrogen streams. Other more immediate applications include the final enrichment of heavy water and the extraction of tritium from light and heavy water. Pilot plant studies on these latter processes are currently in progress.
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ABSTRACT: The styrene divinylbenzene copolymer (SDBC) supported platinum catalyst and the liquid phase catalytic exchange (LPCE) column have been developed to be applicable to the Wolsong tritium removal facility (WTRF) in Korea. The catalyst deactivation subject to both reversible uniform poisoning and permanent loss by impurity poisoning was investigated using a time-on-stream theory and a simplified shell progressive poisoning scenario in special case of higher internal diffusion resistance. Experimental data from fixed bed reactors with the Pt/SDBC catalysts have been used to establish the deactivation model and to estimate key parameters to be used in the WTRF LPCE column design. It was found that an impurity control in the streams would be critical to the WTRF LPCE column operation since the impurity poisoning played a very important role in the overall catalytic exchange reaction. Except for the case of the severe impurity poisoning of the whole catalysts, the LPCE column can be in operation over 10 years without any regeneration of the catalysts.Journal of Nuclear Science and Technology - J NUCL SCI TECHNOL. 01/2006; 43(8):874-883.
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ABSTRACT: A procedure for wet-proofing Pt/silicalite catalysts with polytetrafluoroethylene fibres is described. The procedure yielded catalysts with stable and high activities for the exchange of hydrogen isotopes between liquid water and hydrogen gas. Characterization of the catalysts by hydrogen chemisorption and scanning electron microscopy showed that the wet-proofing procedure can produce catalysts in which most of the Pt surface in the Pt/silicalite before wet-proofing can remain accessible. Hydrogen chemisorption was found to be a valuable tool for prescreening of wet-proofed catalysts.On décrit une méthode d'imperméabilisation de catalyseurs de Pt/Silicalite avec des fibres de polytétrafluoroéthyléne. On a obtenu par cette méthode des catalyseurs d'une activité stable et élevée pour l'échange d'isotopes d'hydrogène entre l'eau liquide et le gaz hydrogène. La caractérisation des catalyseurs par la chimisorption et la microscopie À balayage électronique montre que cette méthode d'imperméabilisation est capable de produire des catalyseurs dans lesquels une grande partie de la surface de Pt dans le Pt/silicalite avant l'imperméabilisation peut rester accessible. La chimisorption à l'hydrogène s'avère un outil intéressant pour la présélection des catalyseurs imperméables.The Canadian Journal of Chemical Engineering 01/1994; 72(2):296-303. · 1.00 Impact Factor
- Atomic Energy 01/1998; 85(1):462-467. · 0.03 Impact Factor