The use of ionic liquids in the sodium tetrahydroborate based hydrogen storage system.

摘要

The transportation industry of the future may rely on hydrogen powered fuel cell vehicles. These vehicles need to store a sufficient amount of hydrogen for them to be viable. NaBH4 based hydrogen storage would make this possible. The leading NaBH4 based hydrogen storage technology is insufficient in satisfying the hydrogen storage requirement of a fuel cell vehicle. The key challenges of this hydrogen storage technology are that a high pH environment is required, expensive metal catalyst is required, and the hydrogen storage density is relatively low. In this research the viability of using a new approach to NaBH4 based hydrogen storage was explored. This new approach consisted of using a novel solvent called an ionic liquid for the purpose of dissolving NaBH4 (so higher hydrogen storage density can be achieved), and to avoid operating in a high pH environment. Other conditions in which this technology would have to operate (such as operating in the limited-water condition) were also explored. The ionic liquids 3-butyl-1,2-dimethylimidazolium chloride ([Bmmim]Cl) and 3-butyl-1,2-dimethylimidazolium tetrafluoroborate ([Bmmim]BF4-) were used in this study.; Low solubility for NaBH4 and NaB(OH)4 was found within these ionic liquids. However conducting NaBH4 hydrolysis in the presence of these ionic liquid showed performance that was better than that observed for the purely water system. The limited-water condition does have an impact on the performance of NaBH4 hydrolysis, in which poor NaBH4 hydrolysis performance was observed. Taking these findings into consideration, a NaBH4 based hydrogen storage device that could be constructed based on these results would have a chance of attaining commercial success.