Development of Al_2O_3 carrier-Ru composite catalyst for hydrogen generation from alkaline NaBH_4 hydrolysis

摘要

A recyclable and reusable Ru/Al_2O_3 catalyst is prepared for hydrogen generation from the hydrolysis process of alkaline sodium borohydride (NaBH_4) solution. The hydrogen generation rate by the hydrolysis and methanolysis of alkaline NaBh_4 was explored as a function of NaOH concentration. Meantime, the byproducts derived from the spent alkaline NaBH_4 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 NaBH_4 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 NaBH_4 is significantly inhibited in the presence of NaOH as compared with the hydrolysis of NaBH_4. The durability test of the RU/Al_2O_3 catalyst shows that the hydrogen generation rate decreases with recycling and reuse. The XRD and NMR analysis results show that the borate hydrate (NaBO_2 H_2O) was derived from the hydrolysis of 20 wt% and 30 wt% NaBH_4.