Hydrophobic Block-Structured PDMS/Pt-mesoporous Silica Catalysts for Sustainable Water-Hydrogen Isotope Exchange

Abstract

Efficient separation of hydrogen isotopes is essential for sustainable hydrogen management and environmental protection in nuclear and other industrial systems. Conventional hydrogen isotope separation technologies, including cryogenic distillation, Girdler sulfide process and ammonia–hydrogen exchange, consume massive energy and involve corrosive or toxic reagents, leading to significant environmental and operational challenges. In contrast, the liquid phase catalytic exchange (LPCE) process, based on water–hydrogen gas isotope exchange, provides an efficient and energy-conserving alternative consistent with sustainable catalytic processes. In this study, a platinum decorated mesoporous silica-polydimethylsiloxane composite (Pt@SiO₂-PDMS) was developed and applied as a catalyst for LPCE process. Physico-chemical characterizations verified the decoration of Pt into the mesoporous silica without destruction of mesoporous structure. The Pt@SiO₂ particles were homogeneously distributed in the PDMS matrix and the resulting composite maintained an intrinsic hydrophobic surface with a water contact angle above 108°. The catalyst composite exhibited effective hydrogen isotope exchange performance up to column efficiency of 67.7% at 80 °C when Pt@SiO₂-PDMS randomly packed with Dixon rings in a volume ratio of 2:1 in the LPCE process. Furthermore, stable operation was maintained continuously for 14 days at 80 °C, demonstrating the durability of catalyst composite and application on actual process conditions. The selective hydrogen isotope exchange between liquid water and hydrogen gas with Pt@SiO₂-PDMS catalyst is attributed to the effective porous structure of SiO₂, Pt loading of Pt@SiO₂ and hydrophobic nature of the PDMS matrix.