CXN天然沸石的研究 V. 结构超稳化

以离子交换结合控制焙烧的方法分别制得结构超稳化高硅H-STI-I和H-STI-II沸石. EDX, ²⁹Si MAS NMR, ²⁷Al MAS NMR, FT-IR等表征证明, 其骨架硅铝原子比分别为4.43和10.62. 分段程序升温焙烧后的沸石样品经粉末XRD表征表明, 其结构热稳定性达到1000 ℃以上. 结构稳定化沸石呈现反映微孔特性的I型吸附等温线, 吸附孔道完美、开放. 经历过酸处理的H-STI-II沸石, 结构缺陷增多, 其热稳定性、比表面积及孔容积略低于H-STI-I.

Studies on CXN Natural Zeolite V. Ultra-stabilization of Structure

The samples of ultra-stable high-silica H-STI-I and H-STI-II zeolites were prepared using the method of ion-exchange combined with controlled calcinations. Characterizations with EDX, ²⁹Si MAS NMR, ²⁷Al MAS NMR and FT-IR indicate that the framework Si/Al ratios of H-STI-I and H-STI-II are 4.43 and 10.62, respectively. Investigations of the samples obtained in the processs of stage-temperature-programmed calcinations with XRD proved that the structure stability of both samples could be kept at temperature up to 1000 ℃. Type I isotherms of N₂ adsorption at 77 K illuminated that the ultra-stable H-STI samples possessed perfect channel systems with opening micro-pore structures. The more structural defects in the framework of H-STI-II, which has been treated with acid in the process of preparation, led to worse thermal stability, lower surface area and pore volume than those of H-STI-I.