Fast hydrogen generation from solid NH3BH3 under moderate heating and supplying a limited quantity of CoCl2 or NiCl2 solution

Abstract New results of an investigation of NH 3 BH 3 dehydrogenation with supplying a limited quantity of aqueous solution of a catalyst precursor to a solid-state bed of the hydride particles with subsequent external heating at 40–90 °C are presented. Measurements of the reaction layer temperature and the amount of the evolved hydrogen have shown that at external heating temperature higher than 85°С there was acceleration of the first stage of the process, the highly exothermic catalytic hydrolysis of a portion of ammonia borane, which resulted in a stronger heating of the reaction layer and the start of NH 3 BH 3 thermolysis. This type of process is referred to as hydrothermolysis. A TEM, ATR FTIR, and XRD investigation has shown that in the reaction medium the metal chlorides become reduced to an amorphous catalytically active phase. During this process, ammonia reacts with chlorides to form NH 4 Cl. All of this leads to increased rate of hydrogen generation and hydrogen yield. Gravimetric hydrogen capacity of 7.6 wt% and the average rate of H 2 evolution of 39 ml·g comp. −1 min −1 have been achieved at molar ratios of NH 3 BH 3 /MCl 2  = 50 (M = Co, Ni) and H 2 O/NH 3 BH 3  = 2 and at external heating of 85°С.