Preparation And Property Regulation Of Metal Borohydride Ammoniate

Hydrogen energy is a clean,efficient,green and renewable energy,which is the mainstream direction of energy development in the future.In order to realize the large-scale application of hydrogen energy,it is necessary to break through the technical challenges of hydrogen production,storage/transportation and utilization.Among them,the development of an efficient and safe hydrogen storage method is the most critical point in the application of hydrogen energy.In this paper,zirconium borohydride ammoniate?Zr?BH₄?₄·8NH₃?is taken as the research object,focusing on the key scientific issues such as improving and exploring new synthetic methods,lowering the dehydrogenation temperature and improving the dehydrogenation purity of zirconium borohydride ammoniate.In order to obtain a high-capacity controllable dehydrogenation system with suitable dehydrogenation temperature and good kinetic performance,the methods of multicomponent compounding,catalyst addition and hydrolysis were synthetically used.By means of X-ray powder diffraction,mass spectrometry,thermogravimetry,Fourier transform infrared spectroscopy and scanning electron microscopy,Zr?BH₄?₄·8NH₃ and its composite system were characterized and analyzed,its composition regulation rule was mastered,its pyrolysis and hydrolysis reaction path and mechanism were revealed,which provided theoretical basis for the integration of hydrogen production and storage.This paper mainly discusses the following three aspects:Firstly,aiming at the shortcomings of traditional ball milling method to synthesize Zr?BH₄?₄·8NH₃,such as high preparation cost and low temperature?<20 ^oC?,its synthesis method was improveda new preparation process was developed.In order to reduce the cost and improve the safety of preparing Zr?BH₄?₄·8NH₃ by ball milling,Zr?BH₄?₄·8NH₃ was synthesized by substituting NaBH,which has similar chemical properties but cheaper and more stable,for LiBH₄ in traditional methods.Based on ball milling,a ball milling-evaporation condensation method?BM-PVD?was developed,and Zr?BH₄?₄·8NH₃was successfully synthesized at room temperature,which expanded the synthesis condition of Zr?BH₄?₄·8NH₃.Additioanlly,two synthetic methods of Zr?BH₄?₄·8NH₃ were studied:1)reaction ball milling in ammonia gas,and 2)ether extraction and then ammoniation.In the experiment of preparing Zr?BH₄?₄·8NH₃ by substituting NaBH₄ for LiBH₄,it was observed that NaBH₄ might obviously promote the dehydrogenation performance of Zr?BH₄?₄·8NH₃.Therefore,Zr?BH₄?₄·8NH₃-NaBH4 composite system was prepared by a simple hand-grinding method.The dehydrogenation performance of Zr?BH₄?₄·8NH₃-NaBH₄composite system was tested by TG-MS test.The dehydrogenation mechanism of Zr?BH₄?₄·8NH₃-NaBH4 composite system was elucidated by XRD,FT-IR and SEM test.Zr?BH₄?₄·8NH₃ has high hydrogen content?14.1 wt.%?.It has potential as a hydrolysis material for hydrogen production.Therefore,its hydrogen production performance and hydrolysis mechanism are discussed.Zr?BH₄?₄·8NH₃ was used as the material for hydrogen production by hydrolysis,and its hydrogen production performance was tested and its mechanism was analyzed by XRD,FT-IR and SEM tes.Its hydrogen production performance was regulated by changing the composition of hydrolysis solution,including NaCl,MgCl₂,CoCl₂,Al?OH?₃ and preparing ammonia-deficient Zr?BH₄?₄·xNH₃?x<8?samples.