Electrochemical Synthesis Of α-AlH₃ And Research Of Alane Adduct

It is estimated that the world energy consumption will double over the next half century.Meeting this demand will be challenging and meeting this demand while maintaining or reducing our current environmental footprint will require significant changes in the way we produce,distribute,store and use energy.A crucial step in this process will be reducing our dependence on carbon-based fossil fuel.On this background,Aluminum hydride（AlH₃）and its associated compounds make up a fascinating class of materials that have motivated considerable scientific and technological research over the past 50 years.Due to its high energy density,AlH₃ has become a promising hydrogen and energy storage material that has been used（or proposed for use）as a rocket fuel,explosive,reducing agent and as a hydrogen source for portable fuel cells.However,application has been hindered by its trivial,dangerous synthesis process and low storage stability.i.e.decomposition to Al metal at room temperature..Herein,we described a new method to improve the synthesis process of AlH₃（electrochemical method）and the synthesis,characterization,detailed thermal properties and comparation to alane of a new amine·alane adduct.In this work,we determined the optimal electrolysis conditions for the preparation of solvated AlH₃·THF adduct by electrolyzing NaAlH₄.Then,we converted AlH₃·THF into a more stable adduct（AlH₃·TEA）,which is suitable as intermediates for the regeneration of alane.Theα-AlH₃ was obtained by heating the AlH₃·TEA adduct as described for approximately 1 h at 85℃.The traditional liquid phase method is the most mature method for synthesizingα-AlH₃,which has been used until now.Therefore,We compared theα-AlH₃ synthesized by electrochemical electrolysis with the traditional liquid phase method by XRD,FTIR,elemental analysis and TG-DSC,etc The results showed that the purity,hydrogen content and purity and the hydrogen release performance of?-AlH₃ prepared by electrochemical method were very close to the traditional liquid phase method.Moreover,from the aspect of synthetic method,the electrochemical synthesis ofα-AlH₃ itself has the advantages of simple process conditions and large-scale preparation,which must have broad application prospects in the future.Finally,We have presented the synthesis and characterization of AlH₃·1,3,5-trimethylhexahydro-1s-triazine adduct by NMR,IR,XRD,SEM and Elemental analysis studies.Because of more coordination point of this ligand and high stability due to its small tension trazine ring,AlH₃·1,3,5-trimethylhexahydro-1s-triazine adduct exhibits polymeric structures in the solid state and is far more stable than the related amine·alane adducts.The possibility of using AlH₃·1,3,5-trimethylhexahydro-1s-triazine adduct to replaceα-AlH₃ in the application of propellant is explored from the aspect of synthesis methods,combustion performance and stability by comparation with alane.As a result,the synthesis of AlH₃·1,3,5-trimethylhexahydro-1s-triazine has the advantages of high safety,simple process and possibility of large-scale production.To our study,the approximative combustion performance and much better stability of AlH₃·1,3,5-trimethylhexahydro-1s-triazine adduct makes this alane adduct a prospective energetic materials with broad application.