The Recycling of Spent Ammonia Borane with HBr/AlBr₃ and Other HX/AlX₃‐Based Schemes

Abstract

Although the development and application of a BNHx‐waste recycling process is one of the major prerequisites for the use of ammonia borane as hydrogen source material, most research groups in the field have focused on AB hydrogen release and only few groups have worked on the development of energetically viable recycling schemes. In our work we target the development of a closed recycling process containing three desired steps: superacid break‐up of the BNHx‐waste, catalytic hydrodehalogenation of the generated boron halide, and base‐exchange between Et3NBH3 and ammonia. Catalytic hydrodehalogenation provides a convenient means to generate B−H bonds using molecular hydrogen, avoiding potentially energetically expensive reduction reagents.

How to Design Hydrogen Storage Materials? Fundamentals, Synthesis, and Storage Tanks

“…More recently these authors proposed a more effective superacid digestion system based on the trio AlBr 3 /HBr/CS 2 . [413] Linear polyaminoborane was digested at room temperature within 4 h and polyborazylene required a temperature of 80°C (for >12 h). All of these important achievements demonstrate that B-N-H based hydrogen compounds can potentially be used as one-shoot hydrogen generation systems and that a new chemical industry could be built to support their commercialisation and regeneration.…”

A ligand-free in situ-generated cobalt nanoparticle catalyst for (Z)-selective transfer semihydrogenation of alkynes

“…NH 3 ÁBH 3 , as a new type of energy material, has high hydrogen storage mass fraction (19.6 wt%) and bulk hydrogen storage density (0.145 kg H 2 L À1 ). [31][32][33][34][35][36] Recently, some researchers used NH 3 ÁBH 3 as the hydrogen source for the reduction of alkynes due to its remarkable advantages in hydrogen release performance and the recoverability of the dehydrogenation products. [37][38][39][40][41][42] Early noble metal catalysts, such as gold, 43-47 ruthenium 48-51 and iridium [52][53][54] were utilized for the semihydrogenation of alkynes, but the high cost and limited reserves of noble metal Scheme 1 Examples of the hydrogenation of alkynes to alkenes.…”

“…NH 3 ·BH 3 , as a new type of energy material, has high hydrogen storage mass fraction (19.6 wt%) and bulk hydrogen storage density (0.145 kg H 2 L −1 ). 31–36 Recently, some researchers used NH 3 ·BH 3 as the hydrogen source for the reduction of alkynes due to its remarkable advantages in hydrogen release performance and the recoverability of the dehydrogenation products. 37–42…”

Surface-Controlled Conversion of Ammonia Borane from Boron Nitride

“…While some reports of AB regeneration [19][20][21] and lithium amidoborane (LiNH 2 BH 3 ) [22] have been published, there is still a great challenge remaining which is full-regeneration of AB from hexagonal boron nitride (h-BN). Based upon simple thermodynamic argument, h-BN is too far downhill to be considered as a precursor for AB (endothermic reaction, ∆H = 215.4 kJ/mol) due to full-dehydrogenated state of AB [23,24].…”