Ammonia borane-hydrogen cycle: Synthesis, dehydrogenation and regeneration
Herein, we report an optimal procedure for the preparative-scale synthesis of AB in high yields and purity from sodium borohydride and ammonium salts. The first systematic study of the transition metal-catalyzed methanolysis of AB, the isolation and characterization of the resulting borate salt, and recovery of AB has been described. A comparison of the transition metal-catalyzed methanolysis and hydrolysis of AB has been made. We have recognized and quantified the liberation of ammonia during the transition metal-catalyzed hydrolysis. It is known that, borazine, by-product of the pyrolysis reaction, is detrimental to the fuel cell membrane. We have reported an improved procedure for the preparation of borazine and shown that it can also be recycled to ammonia borane via trimethylborate. The solid residue, polyborazylene, formed after pyrolysis of ammonia borane has also been recycled to ammonia borane. Also reported is the direct synthesis of amine boranes form timethyl borate. ^
P. V. Ramachandran, Purdue University.
Chemistry, Inorganic|Chemistry, Organic