New Hydrogen Storage Material Can Take The Heat

Hydrogen gas is touted as a possible clean alternative energy source. But without a way to store the gas safely, hydrogen-fuel cells won’t be practical. And for some applications, the stored gas must be stable for long periods of time, sometimes under extreme temperatures. Now, researchers have created an H₂ storage molecule that does not decompose even at temperatures up to 150 °C (J. Am. Chem. Soc. 2014, DOI: 10.1021/ja511766p).

Shih-Yuan Liu, an organometallic chemist at Boston College, and his colleagues work on synthesizing amine borane compounds that can store and release H₂. Amine boranes have relatively high H₂-storage capacities and can release the gas quickly, but generally the compounds aren’t stable at high temperatures.

The researchers synthesized the new compound, a bis-BN cyclohexane in three steps. When dissolved in tetrahydrofuran along with a ruthenium catalyst at room temperature, the compound releases hydrogen in as little as 15 minutes.

The molecule’s storage capacity is 4.7% hydrogen by weight. For use in vehicle fuel cells, the researchers would have to reengineer the compound to increase capacity, Liu says, seeing as the Department of Energy has set a 5.5 wt % target for hydrogen storage systems for 2020. But the compound may be appropriate for other applications, such as in backup generators that would store energy long term in case of a natural disaster, he says.