Ruthenium immobilized on Al2O3 pellets as a catalyst for hydrogen generation from hydrolysis and methanolysis of sodium borohydride

Ru immobilized Al2O3 pellets were synthesized as a catalyst for hydrogen generation in NaBH4 solutions. Under the Ru/Al2O3 catalysis, the hydrogen generation rate from the hydrolysis and methanolysis of NaBH4 in alkaline solution was explored as a function of NaBH4 concentration and temperature. Meanwhile, the borate byproducts derived from the NaBH4 hydrolysis were characterized by XRD and NMR. The results showed that the hydrogen generation rate depended on NaBH4 concentration for the hydrolysis, but did not for the methanolysis. 10 wt% NaBH4 hydrolysis containing 1 wt% NaOH catalyzed with 0.5 g Ru/Al2O3 could generate hydrogen with a rate of about 65.5 ml min(-1) g(-1). The productivity and activation energy of hydrogen generation from the NaBH4 hydrolysis were 93% and 41.8 kJ mol(-1), and from the NaBH4 methanolysis were 97% and 51.0 kJ mol(-1), respectively. The XRD and NMR analyses showed that the species from the hydrolysis byproducts varied with the NaBH4 concentration could be the borax (Na2B4O7 center dot H2O) and sodium borate hydrate (NaBO2 center dot H2O).