Regeneration of Supported Ammonia Borane to Achieve Higher Yield

Ammonia borane is considered as a potential hydrogen storage material due to its high hydrogen content, ease of handling, and moderate dehydrogenation temperature. The regeneration of ammonia borane (AB) is essential for its use as a sustainable hydrogen storage material. In the current work, we attempted to regenerate AB from the post heated product (spent fuel, i. e., products obtained after hydrogen release) through a digestion mediated B−O−C route. We have also demonstrated the dehydrogenation and regeneration compatibility with the use of a cost-effective layered aluminosilicate support material, bentonite (gBen), and this facilitated both the dehydrogenation and regeneration processes. The isothermal dehydrogenation study suggested that the support material helped to improve the hydrogen release kinetics from AB at lower temperatures. During the regeneration process, gBen supported AB is observed to provide a higher yield (71 %) of the digested compound ammonium tetramethylborate (ATMB) as against post heated AB (with 35 % in case of pure AB to post AB to ATMB), which finally resulted in increasing the overall regeneration yield of AB. The regeneration of AB with high yield and purity is confirmed by ¹¹B NMR and XRD analysis.