Volume 24 Issue 5 - July 19, 2013 PDF
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Novel fabrication of solid-state NaBH4/Ru-based catalyst composites for hydrogen evolution using a high-energy ball-milling process
Cheng-Hong Liu1, Bing-Hung Chen1,∗, Chan-Li Hsueh2, Jie-Ren Ku2, Fanghei Tsau2
1 Department of Chemical Engineering, National Cheng Kung University, Tainan, 70101 Taiwan
2 New Energy Technology Division, Energy and Environment Research Laboratories, Industrial Technology Research Institute (ITRI), Hsinchu 31040, Taiwan
Corresponding author (BH Chen): bkchen@mail.ncku.edu.tw
 
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Solid-state NaBH4/Ru-based catalyst composites have been synthesized for hydrogen production through a high-energy ball-milling process, providing uniform dispersion of Ru3+/ion exchange resin catalysts among pulverized NaBH4 (SBH) particles, increasing the contacts of SBH with active catalytic sites. As a result, the gravimetric hydrogen storage capacity as high as 7.3 wt% could be reached by using water as a limiting reagent to overcome the issue of deactivated catalysts whose active sites are blocked by precipitates caused by limited NaBO2 solubility occurring in conventional aqueous SBH systems for hydrogen evolution. In this study, conversion, hydrogen storage capacity, and temperature variation during SBH hydrolysis reaction were compared under different addition amount of water as shown in Figure 1.
Figure 1. (a) Time-dependent H2 conversion and gravimetric H2 capacity of NaBH4 (SBH) with loading weight ratios of SBH/H2O as 1/2 and 1/10; (b) Variation of reaction temperature during the hydrolysis reaction of NaBH4 with SBH/H2O = 1/2 and 1/10.

It is found that the reaction rate and hydrogen storage capacity obviously increase with the decrease of addition amount of water, to make the whole system be solid phase. In addition, the major product obtained from hydrolysis reaction is characterized to be NaBO2•2H2O while SBH/H2O = 1/2 with TGA (Figure 2) and XRD analyses, which is consistent with the phase diagram in previous literature. High hydrogen storage capacity as 7.3 wt% we obtained in this study has a high potential to reach the goal of 6 wt %, set by DoE by 2010.
Figure 2. TGA curves of (a) the hydrolyzed product from a reacting system with SBH/H2O = 1/2; (b) pure NaBO2• 4H2O; (c) the hydrolyzed product from a reacting system with SBH/H2O = 1/10.
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