Metal Oxides (such as Al2O3 and TiO2) as Catalyst Supports for Hydrogen Release by Hydrolysis of Sodium Borohydride NaBH4
Hydrolysis of NaBH4 to release molecular hydrogen is today an intensely investigated reaction and most of the studies focus on the material used as catalyst. Among the various metals tested up to now, cobalt has soon showed to be the most attractive in terms of reactivity and cost. Nevertheless, in order to further decrease its cost by decreasing its amount as well as to increase its reactivity, cobalt has been dispersed over supports. The as-formed supported catalysts have showed to be more efficient. This is the topic of the present study. Herein it is showed that CoCl2 supported over an Al2O3 support with a specific surface area of 180 m2 g-1 is more reactive than CoCl2 supported over a high-surface-area activated carbon (780 m2 g-1), CoCl2 being in-situ reduced into the Co-based active phase. CoCl2-Al2O3 is besides as reactive as another CoCl2-Al2O3 catalyst, the latter support having a higher specific surface area (i.e. 250 m2 g-1). In fact, CoCl2-Al2O3 is more performing than neat CoCl2 whereas the latter has been often showed as being one of the best catalytic systems. To further gain in reactivity, a new, alternative strategy has been envisaged. The Al2O3 was mixed together with a controlled amount of another oxide, namely TiO2. The CoCl2- Al2O3-TiO2(20 wt%) was found to be more reactive than CoCl2-Al2O3. All of these reactivity data are reported and briefly discussed hereafter. Further studies are in progress to highlight the reasons of such improved reactivity.
Pietro VINCENZINI, Sheldon WIEDERHORN and Paolo COLOMBO
O. Akdim et al., "Metal Oxides (such as Al2O3 and TiO2) as Catalyst Supports for Hydrogen Release by Hydrolysis of Sodium Borohydride NaBH4", Advances in Science and Technology, Vol. 65, pp. 209-214, 2010