Development of Hydrogen Isotope Separation Process Using Advanced Catalyst Synthesized with Nano-structure in Supercritical Carbon Dioxide

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As a method of enriching low isotopic concentrations of deuterium and tritium, chemical exchange between water and hydrogen molecules is most promising, but platinum catalyst is indispensable to exchange hydrogen atoms between water and hydrogen diatomic molecules. The currently available catalyst is made of platinum nanoparticles on the plastic polymer support, which is easily burnable, and then the safety concern should be paid for using with radioactive hydrogen isotopes. The plastic support has a drawback of causing large pressure drop when it is packed in a isotope exchange column. In This study, in order to solve these technical problems, unburnable stainless steel gauze of very small pressure drop was employed. With a super hydrophobic suite layer, which was funned on the surface of the gauze by chemical vapor deposition of a silicon compound Since the superhydrophobic layer has a nano structure of uneven and rough surface, we introduced chemical reagent of platinum precursor by … More using reversed micelle formed with a surfactant in super critical carbon dioxide, which shows a large molecular diffusivity in to a tiny pores. In this study, in the first place, we found a commercially available surfactant of low cost works successfully for this purpose, and platinum precursor was introduced in the hydrophobic structure, then funned platinum nanoparticles as planned. Additionally we found an another new method of introducing platinum precursor in nanopores on the hydrophobic surface structure : the method is based on the capillary condensation of a solute, which was in this case, a platinum precursor in supercritical carbon dioxide, platinum nanoparticles of which diameter was 2 nm were formed and deposited in the superhydrophobic layer, which was confirmed by a transmittance microscope imaging Concerning with performance of the newly prowled catalyst, we performed an isotopic exchange experiment using deuterium gas and deutriated water, and then qualitative data were obtained showing the newly prepared catalyst works as a catalyst packed in a column for hydrogen isotope separation by the chemical exchange reaction between water and hydrogen gas. The scientific and technical results gained in this study were described in a paper published in an academic periodical journal and four papers in the proceedings of the international conferences. A patent application was submitted for u utilization of capillary condensation of a solute in supercritical carbon dioxide. Less