The Study Of ?-AlH₃ Preparation By High-temperature Solidphase Crystal Transformation Of Etherates

With the depletion of traditional energy sources,countries have stepped up efforts to develop clean energy such as solar energy,wind energy,and hydrogen energy.At present,the development of hydrogen energy in various countries is mainly based on hydrogen storage materials that are easy to carry and have high H wt%.Among the various hydrogen storage materials,?-AlH₃ has attracted extensive attention from researchers due to its high H wt%?10.1%?,low hydrogen storage temperature?about 100??,and capability to store for a long time.In this thesis,the preparation process of?-AlH₃ was improved.The preparation conditions and crystal transformation mode of the etherate?AlH₃·n Et₂O?were improved,and the influence of the self-alteration of the etherate on the crystal transformation product during the preservation process was explored.Firstly,the rotary evaporation method,the precipitation method and the precipitation method were employed,and the etheratea,etherateb,etherate cetherated,etheratee and etherate f were prepared by using the diethyl ether method.The structure and morphology of the etherates were determined by XRD,SEM,and the results indicated similar structures.Secondly,the dynamic crystallography method was employed to crystallize the prepared etherates,and after a series of conditions optimization,it is concluded that AlH₃·n Et₂O is first subjected to dynamic transmutation at 95? for 15 min and then at N₂ atmosphere and atmospheric pressure for 45 min is the best condition.Under this condition,the newly prepared etherate a was subjected to deetherification and crystal transformation to prepare pure?-AlH₃ with H wt%of 9.2%.And the crystal transformation properties of other etherates were also investigated under these conditions.Finally,the effect of the decrease in ether content of the etherate a during storage at room temperature on the crystal form,H wt%,etc.of the crystalline product was studied.It has been found that etherate a will undergo slow de-etherification during storage at room temperature,and with the increase of storage time,the rate of de-etherification was accelerated?ether content decreased from 32%to 22%?,etherate a can be converted into pure?-AlH₃ within 10 days of preservation?ether content of 28%or more?,and can be transformed into AlH₃ during 21 days,but the etherates prepared by other methods do not crystallize after preserving for3 to 5 days.