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

Abstract

Although the development and application of a BNH_x -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 BNH_x -waste, catalytic hydrodehalogenation of the generated boron halide, and base-exchange between Et₃ NBH₃ and ammonia. Catalytic hydrodehalogenation provides a convenient means to generate B-H bonds using molecular hydrogen, avoiding potentially energetically expensive reduction reagents.

Keywords: BNH waste; ammonia borane; boron compounds; hydrodehalogenation; nickel boride.