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Production of sodium borohydride by using dynamic behaviors of protide at the extreme surface of magnesium particlesS. Suda, N. Morigasaki, Y. Iwase & Z.P. Li
J. Alloys & Cmpds
Vol.404-406 (2005) pp.643-647
http://dx.doi.org/10.1016/j.jallcom.2005.02.101AbstractAn advanced process for the production of sodium borohydride (NaBH4) as a hydrogen storage material was developed, which applied the dynamic hydriding and dehydriding behaviors of protide (H-) in Mg–H system under transitional temperature conditions.
An abundant natural resource named borax (Na2B4O7·10H2O) and the anhydrous sodium metaborate (NaBO2) recovered from the “spent fuel” as NaBO2·4H2O were used as the starting material in the present process. Powder-state Mg played an important role in the transitional hydriding and dehydriding process where the gaseous hydrogen was converted to protide at the extreme surface of Mg to form NaBH4 in exchange with the simultaneous transition of oxygen in NaBO2 to form MgO.
In the present process, the protide as the most reactive state among the four states of hydrogen is applied for the synthesis of NaBH4, which can exist in metal–hydrogen complexes, such as NaAlH4 and NaBH4.
The NaBH4 yield was reached higher than 90% by a single batch process but was found to be largely dependent on the rate of temperature change and the particle size, i.e., the specific surface area of Mg particles.
Sodium borohydride formation when Mg reacts with hydrous sodium borates under hydrogenBin Hong Liu, Zhou Peng Li & Jing Ke Zhu
J. Alloys & Cmpds
Vol.476(1-2) 2009 pp.L16-L20
http://dx.doi.org/10.1016/j.jallcom.2008.09.057AbstractIn this work, we explored the possibility of NaBH4 synthesis when Mg reacted with hydrous sodium borates under hydrogen. It was found that Mg could react with the water in molten hydrous borates to form MgO and release hydrogen, which can be used for NaBH4 synthesis. Then remained Mg would react with formed anhydrous borate to form NaBH4. NaBO2 conversion rate was decreased with increase of the crystalline water content in the hydrous sodium borates. Based on experimental results, a mechanism of NaBH4 formation when Mg reacted with hydrous sodium borates was suggested.
NaBH4 formation mechanism by reaction of sodium borate with Mg and H2Z.P. Li, B.H. Liu, J.K. Zhu, N. Morigasaki & S. Suda
J. Alloys & Cmpds
Vol.437(1-2) 2007 pp.311-316
http://dx.doi.org/10.1016/j.jallcom.2006.07.119AbstractIt has been reported that sodium (potassium) borohydride can be formed by reaction of sodium (potassium) borate with Mg and hydrogen or magnesium hydride. However, few investigations on reaction mechanism have been reported. Here, we studied the NaBH4 formation mechanism of Mg + NaBO2 + 2H2 = NaBH4 + MgO through morphology observations, structure and micro composition analyses. It was found that when heating the reactor to 400 °C, NaBO2 particles were agglomerated with Mg particles and a NaBO2 network was formed due to the sintering effect. With further heating the reactor, a porous product layer (composed of NaBH4 and MgO) was formed on Mg particles. It was found that no matter whether Mg was hydrogenated or not, Mg could react with sodium borate and hydrogen to form sodium borohydride. Elevating the reaction temperature was of benefit to NaBH4 formation. Higher NaBH4 yield can be obtained by using partially hydrogenated then dehydrogenated Mg.
Protective effect of green tea polyphenol EGCG against neuronal damage and brain edema after unilateral cerebral ischemia in gerbils.pdf
2009 pp.1704-1706