Thermodynamics Study on Liquid Phase Catalytic Exchange for Water Detritiation

Liquid phase catalytic exchange (LPCE) is one of the key technologies for tritium removal of tritiated water, such as effluents from Fukushima nuclear power plant. Although former researchers have widely studied this process theoretically, the reported results differ from each other due to different assumptions and parameters adopted. In this work, the principle of Gibbs free energy minimization is applied, with only basic physical properties and no more other assumptions involved. The predictions of isotope exchange are more accurate, and the average error between calculation results and experimental data reduces from 4.45%~6.65% to 2.17%. Then the catalytic exchange behaviors are systematically investigated in the protium-deuterium (H-D) system, and the influence of the cascade processes are emphatically analyzed. The method established in this paper could be applied to catalytic exchange systems for tritium separation, which is essential for the development of water detritiation.

Catalytic exchange of hydrogen isotopes intensified by two-phase stratified flow in wettability designable microchannels

Liquid phase catalytic exchange of hydrogen isotopes is intensified by stratified flow in a microchannel reactor coated with hydrophobic Pt/AC/PDMS.

Ni-Based Catalyst Derived from NiAl Layered Double Hydroxide for Vapor Phase Catalytic Exchange between Hydrogen and Water

A high-efficient and low-cost catalyst on hydrogen isotope separation between hydrogen and water is an essential factor in industrial application for heavy water production and water detritiation. In past studies, Pt-based catalysts were developed but not practical for commercial use due to their high cost for vapor phase catalytic exchange (VPCE), while for impregnated nickel catalysts with a lower cost the problems of agglomeration and low Ni utilization existed. Therefore, to solve these problems, in-situ grown Ni-based catalysts (NiAl-LDO) derived from a layered double hydroxide (LDH) precursor were fabricated and first applied in VPCE in this work. Compared with traditional impregnated Ni-based catalysts, NiAl-LDO catalysts own a unique layered structure, homogeneous dispersed metallic phase, higher specific surface area as well as stronger metal-support interactions to prevent active metal from agglomerating. These advantages are beneficial for exposing more active sites to improve dynamic contacts between H2 and HDO in a catalyst surface and can bring excellent catalytic activity under a reaction temperature of lower than 400 °C. Additionally, we found that the dissociative chemisorption of HDO and H2 occurs not only in Ni (111) but also in NiO species where chemisorbed H(ads), D(ads), OH(ads) and OD(ads) are formed. The results highlight that both of the Ni2+ species and Ni0 species possess catalytic activities for VPCE process.