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

Xiaoyu Hu,Bin Yu,Junhong Luo,Jiangfeng Song,Yong Liu,Zhi Zhang,Chao Lv,Peilong Li,Ning Zeng,Xin Zhang

doi:10.3390/nano9121688

Abstract

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.

Highlights

Tritium plays a pivotal role in nuclear power plants, nuclear fuel reprocessing, as well as future fusion reactors [1,2]
We report the effective in-situ growth of NiAl layered double oxides (LDO) derived from the layered double hydroxide (LDH) precursor which are firstly applied for the vapor phase catalytic exchange (VPCE) process
The high dispersed Ni-based catalyst derived from LDH is proposed and verified with better catalytic performance than traditional impregnated Ni/Al2O3 catalysts

Summary

Introduction

Tritium plays a pivotal role in nuclear power plants, nuclear fuel reprocessing, as well as future fusion reactors [1,2]. Some active metal (Ni, Cr, Pd, Pt etc.) for hydrogen isotope exchange processes could be introduced into the LDH by using a hydrothermal method and co-precipitation, ion-exchange, precipitation-reduction method [23]. These advantages of LDH inspire us to fabricate an efficient VPCE catalyst from LDH. The layered structure, high specific surface area, porous structure, homogeneous metallic phase as well as stronger metal-support interactions of in-situ Ni catalysts contribute to the much higher VPCE activity in comparison with the impregnated NiO/γ-Al2O3 catalysts at a reaction temperature of below 400 ◦C. The used ultrapure water throughout the experimental processes was obtained from a Milli-Q ultrapure system (10.5 MΩ cm)

Synthesis of Petal-Like NiAl-LDH

Characterization

Catalytic Activity Evaluation

Results and Discussion

Conclusions