Acid Initiation of Ammonia–Borane Dehydrogenation for Hydrogen Storage

Abstract

Liberating hydrogen: Strong Lewis or Brønsted acids react with ammonia–borane (H3NBH3) to form an in situ boronium cation, resulting in the formation of a mixture of cyclic and acyclic BNHx oligomers and the liberation of H2 (see scheme). A proposed mechanism is supported by an examination of the reaction thermodynamics using density functional theory.

Accelerating the Understanding and Development of Hydrogen Storage Materials: A Review of the Five-Year Efforts of the Three DOE Hydrogen Storage Materials Centers of Excellence

“…This of course suggested catalytic approaches that offer the opportunity to increase the rate and decrease the temperature of onset of hydrogen release. R&D performed by the CHSCoE (Baker, Sneddon, Heinekey, Goldberg, Burrell, and their colleagues [74][75][76][77][78][79][80][81][82][83][84][85][86][87] ) and by researchers outside of the Center resulted in the description of many different catalytic processes and catalysts for the dehydrogenation of ammonia borane (Figure 14). In order to perform the catalytic dehydrogenation of ammonia borane, it is necessary to make intimate contact of ammonia borane with the catalyst.…”

Improved hydrogen desorption properties of ammonia borane by Ni-modified metal-organic frameworks

“…The elimination of poisonous byproducts and decrease of decomposition temperature, therefore, play a very important role for AB used in PEMFC. To overcome these barriers, a number of approaches have been developed, including activation by transition metal catalysts [11e15], ionic liquids [16] and acid catalysts [17]. Despite considerable effort, these have not met the requirement of PEMFC.…”

Amineborane Based Chemical Hydrogen Storage - Final Report

“…of H 2 can be achieved, rather than the 3 equiv. predicted by Equation 3.1, even with prolonged heating at 85 o C. 1,7 As a result, a number of approaches are now being explored to induce efficient AB H 2 -release, including, for example, activation by transition metal catalysts, [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] acid catalysts, 28 base catalysts, 29 and nano and meso-porous scaffolds. [30][31][32] Most of these additives use organic solvents either as the reaction medium or as the AB transport and loading method.…”

“…of HCl gave less than 1.0 H 2 -equivalents after 350 min. Previous computational studies 28,73 of the acid-induced dehydrogenation of ammonia borane and ammonia triborane both support a mechanism involving the initial elimination of one equivalent of H 2 via the reaction of the acid proton with a hydridic B-H hydrogen of the amine boranes. In aqueous solutions, subsequent electrophilic association of the resulting cationic species (i.e.…”