New Form of Ammonia Borane Offers Up to 30 wt% Hydrogen Storage
11 May 2009
Researchers have discovered a new high-pressure form of ammonia borane (AB) that can store up to around 30 wt% hydrogen in total. A paper on their work was published in the 5 May issue of the Proceedings of the National Academy of Sciences (PNAS).
The researchers, graduate student Yu Lin and Assistant Professor Wendy Mao at Stanford University and Ho-kwang Mao, senior staff scientist at the Geophysical Laboratory at the Carnegie Institution of Washington, worked with ammonia borane (NH3BH3), which already has a relatively high hydrogen content (19.6 wt%) (earlier post), at high pressure in a atmosphere artificially enriched with hydrogen.
The new AB–H2 compound can store an estimated 8–12 wt% molecular H2 in addition to the chemically bonded H2 in AB. This phase formed slowly at 6.2 GPa [899,234 psi], but the reaction rate could be enhanced by crushing the AB sample to increase its contact area with H2... Storage of significant amounts of additional molecular H2 in AB increases the already high hydrogen content of AB, and may provide guidance for developing improved hydrogen storage materials.
—Lin et al. (2009)
There are potentially several ways to help stabilize the compound under normal temperature and pressure conditions. One idea is that there might be some “alternative chemical paths, like adding some catalyst to try to stabilize the system,” Lin said.
Resources
Yu Lin, Wendy L. Mao, and Ho-kwang Mao (2009) Storage of molecular hydrogen in an ammonia borane compound at high pressure. PNAS doi: 10.1073/pnas.0903511106
Comments