An investigation was carried out to determine the viability of electrowinning lithium from LiOH in molten chloride, with a view to developing a system for the storage and transportation of hydrogen using LiH as the storage medium. It was predicted from the chemical potential diagram for the Li-O-H system that Li metal cannot be electrowon from a LiOH-containing salt, as any Li generated by electrolysis will readily react with LiOH to form Li 2 O. Electrolysis in molten LiCl-42 mol% KCl or molten LiCl-17 mol% KCl-26 mol% CsCl was therefore utilized, in which LiOH was fed into an anode compartment separated from the Li metal deposited at the cathode by a porous magnesia diaphragm, thereby preventing the transportation of LiOH into a cathode compartment. Using this arrangement, Li metal was successfully obtained with a cathode current efficiency of 84-86%. The generation of CO 2 at the graphite anode was also found to decrease with decreasing electrolysis temperature when using a chloride melt with a lower eutectic temperature. Hydrogen storage materials.-Hydrogen energy is expected to offer a number of advantages in terms of providing high energy efficiency through the use of fuel cells and a reduction in the environmental impact of CO 2 and NO x emissions; however, there has as yet been no effective, large-scale supply system established for hydrogen. The most promising methods for the storage and transportation of hydrogen that are currently under development have been briefly reviewed in a previous article by the authors, 1 in which it was revealed that the large hydrogen-storage capacity of LiH can provide a compact medium ideally suited to transportation. In light of this, we herein present a novel system for the storage and transportation of hydrogen that is based on using LiH as the storage medium.
ZrO 2 -supported Ru catalysts were prepared by an impregnation method and by NaBH 4 reduction from RuCl 3 •3H 2 O and a commercial ZrO 2 support. The catalyst prepared by NaBH 4 reduction showed high activity (around 60%) at 673 K for NH 3 decomposition, whereas the catalyst prepared by the impregnation method exhibited low activity (10%) under the same reaction conditions. X-ray fluorescence spectrometry indicated that the catalyst prepared by NaBH 4 reduction was free of Cl, whereas the catalyst prepared by the impregnation method contained more than 5 wt % Cl from the Ru precursor. This was main factor that caused the differences in catalytic activity. In addition, the Ru/ZrO 2 catalyst prepared by NaBH 4 reduction was active for NH 3 decomposition without H 2 pretreatment, and its activity was slightly higher than that of the catalyst pretreated with H 2 . The transmission electron microscopy and H 2 pulse chemical adsorption results demonstrated that the Ru metal particle size also affected the activity.
The Ru/CeO 2 (JRC-CEO-3) catalyst prepared by NaBH 4 reduction showed a high activity for NH 3 decomposition compared with the other catalysts prepared in this work; however, this catalyst gradually lost its activity due to the accumulation of adsorbed species produced during the reaction. Cs signi cantly improved the catalytic performance of the Ru/CeO 2 catalyst, and the optimum Cs/Ru molar ratio was 0.4 because excess Cs species gradually covered the exposed Ru metal active sites. Cs-Ru/CeO 2 -0.4 catalyzed the NH 3 decomposition reaction without H 2 pretreatment because the catalyst was activated by NH 3 or H 2 produced by NH 3 decomposition. Moreover, Cs not only increased the N-H bond dissociation rate but also decreased the e ect of the H 2 partial pressure on the catalytic performance. Consequently, the Cs-Ru/CeO 2 -0.4 catalyst exhibited a high, stable activity (NH 3 conversion: 92% at 623 K and 60% at 573 K) with a gas hourly space velocity of 2000 mL-NH 3 g-cat 1 h 1 .
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