Development of Al2O3 carrier-Ru composite catalyst for hydrogen generation from alkaline NaBH4 hydrolysis

A recyclable and reusable Ru/Al2O3 catalyst is prepared for hydrogen generation from the hydrolysis process of alkaline sodium borohydride (NaBH4) solution. The hydrogen generation rate by the hydrolysis and methanolysis of alkaline NaBH4 was explored as a function of NaOH concentration. Meantime, the byproducts derived from the spent alkaline NaBH4 solution were characterized by X-ray diffraction (XRD), scanning electro microscope/energy dispersive spectrometer (SEM/EDS) and NMR (Nuclear Magnetic Resonance). The effect of NaOH concentration on the hydrogen generation from the hydrolysis of NaBH4 significantly depends on the type of catalysts. With increasing NaOH concentration, the hydrogen generation rates decrease when using ruthenium (Ru) composite as a catalyst. The hydrogen generation rate of the methanolysis of NaBH4 is significantly inhibited in the presence of NaOH as compared with the hydrolysis of NaBH4. The durability test of the Ru/Al2O3 catalyst shows that the hydrogen generation rate decreases with recycling and reuse. The XRD and NMR analysis results show that the borate hydrate (NaBO2 H2O) was derived from the hydrolysis of 20 wt% and 30 wt% NaBH4. -- Highlights: ► A recyclable Ru/Al2O3 catalyst was synthesized for hydrogen generation. ► Ru/Al2O3 significantly promotes the hydrogen generation rate from alkaline NaBH4 solution. ► The prepared Ru/Al2O3 catalyst can easily collect from the spent alkaline NaBH4 solution.