Hydrolytic dehydrogenation of NH 3 BH 3 catalyzed by ruthenium nanoparticles supported on magnesium-aluminum layered double-hydroxides.

Ammonia borane (AB, NH 3 BH 3 ) with extremely high hydrogen content (19.6 wt%) is considered to be one of the most promising chemical hydrides for storing hydrogen. According to the starting materials of AB and H 2 O, a hydrogen capacity of 7.8 wt% is achieved for the AB hydrolytic dehydrogenation system with the presence of a highly efficient catalyst. In this work, ruthenium nanoparticles supported on magnesium-aluminum layered double hydroxides (Ru/MgAl-LDHs) were successfully synthesized via a simple method, i.e. , chemical reduction. The effect of Mg/Al molar ratios in MgAl-LDHs on the catalytic performance for AB hydrolytic dehydrogenation was systematically investigated. Catalyzed by the as-synthesized Ru/Mg 1 Al 1 -LDHs catalyst, it took about 130 s at room temperature to complete the hydrolysis reaction of AB, which achieved a rate of hydrogen production of about 740 ml s -1 g -1 . Furthermore, a relatively high activity (TOF = 137.1 mol H 2 mol Ru -1 min -1 ), low activation energy ( E a = 30.8 kJ mol -1 ) and fairly good recyclability of the Ru/Mg 1 Al 1 -LDHs catalyst in ten cycles were achieved toward AB hydrolysis for hydrogen generation. More importantly, the mechanism of AB hydrolysis catalyzed by Ru/MgAl-LDHs was simulated via density functional theory. The facile preparation and high catalytic performance of Ru/MgAl-LDHs make it an efficient catalyst for hydrolytic dehydrogenation of AB.