Preparation And Characterization Open Framework Zeotype Germanates

The study of open framework germanates has been one of the great interests in zeotype systems. Due to their various second building unit, the different framework structures have been prepared, which lead to the special pore structures (such as large pores, low-framework density and chiral structure), the open framework zeotype germanates with different topology have been reported. However, the poor thermal stability of the pure germanates make the limitation of their application. It is constructive to study the Si-modified germanates in order to stabilize the germanates framework.In this thesis, we choose hydro(solvo)-thermal system to prepare several open-framework germanates and Ge9, Ge10 cluster silicongermanates with distilled water, germanium dioxide and some different organic amines as templet. The compounds are characterized by single crystal, powder X-ray diffraction, FTIR, SEM and TGA-DSC analysis.We synthesized 3D Ge-pharmacosiderite structure with 2-methyl pentanethylenediamine (MPMD), and it had 8-rings building by the Ge10 clusters. A series of silicongermanates containing different silicon content were synthesized with ethylenediamine (EN) as templet and TEOS as silicon source, and their structures build by Ge7, Ge9 clusters with higher thermal stability. Then series of silicongermanates containing different silicon content were synthesized with MPMD as templet and a sodium silicate source, and their structures build by Ge10 clusters.We tested hydrogen storage capacity of open framework zeotype germanates with Ge7 and Ge9 clusters. The measured uptake of up to 4.0 wt % at -196℃and lower pressure 0.2 bar is recorded with the sample after ion-exchange. It will be important in the future to the application of germanates with large pores and low-framework density.