Reactivity of Al-rich Alloys with Water Promoted by Liquid Al Grain Boundary Phases

Al–Ga–Sn, Al–Ga–In and Al–Ga–In–Sn alloys were prepared using arc melting technique. Their microstructures were investigated by X-ray diffraction and scanning electron microscopy with energy dispersed X-ray. Based on microstructure analysis, the phase constituents of alloys at Al grain boundaries were identified. The melting points of Al grain boundary phases were measured using differential scanning calorimeter.The reactivities of Al–water at different water temperatures indicate that liquid Al grain boundary phases promote Al–water reactions of alloys. The melting points of Al grain boundary phases affect the reaction temperatures of Al–water, leading to different reaction temperatures of alloys. The measured H2 generation rate and yields of alloys are related to the compositions of alloys. The theory of microgalvanic cell is used to explain the observed different H2 generation rates of alloys.

Synthesis of a Novel Co-B/CTAB Catalyst via Solid-state-reaction at Room Temperature for Hydrolysis of Ammonia-borane

Cobalt-boride(Co-B)is emerging as one of the promising materials in the base-hydrolytic dehydrogena-tion of ammonia-borane(AB).In order to avoid the low specific area and poor catalytic capacity of Co-B catalyst caused by aggregation arising from the strong reducing property and rapid reaction condensation of sodium borohy-dride(NaBHa),novel cobalt boride/cetyltrimethylammonium bromide(Co-B/CTAB)catalyst was obtained via solid-state grinding at room temperature,and the catalyst was further characterized by XRD,SEM,XPS and BET.The hydrogen generation rate(HGR)was then determined by the hydrolysis reaction of AB.The SEM images indicate that a lot of irregular folds and curled edges are formed on the sample with a maximum surface area of 145.57 m2/g,thus possibly resulting in the high hydrogen production(HGR was 10.68 L.minlg),which may be attributed to CTAB that provide favorable large specific surface area and abundant porous structure.Additionally,catalyst will not be affected by solvants during solid-state reaction.As a diluent,the surfactant CTAB hindered the reaction rate of sodium borohydride reduction to cobalt boride and obtained the novel catalyst with a large specific surface area.