新型介孔分子筛的合成与性能表征

SYNTHESIS AND CHARACTERIZATION OF NEW MESOPOROUS MOLECULAR SIEVES

利用天然矿物钾长石作为硅铝源前驱体 ,采用一步晶化法合成出含有NaX型沸石基本结构单元的新型介孔分子筛。采用XRD ,N2 吸附脱附曲线、红外光谱 (FTIR)、固体核磁共振、SEM等测试方法表征了样品的结构特征和性能。研究表明 :所合成的材料具有介孔分子筛的结构特征 ,孔壁含有NaX型沸石初级和二级结构单元 (共享氧原子的 [SiO4 ]和 [AlO4 ]四面体及双六元环 ) ;样品的粒度为 0 .3～ 0 .5 μm;其比表面积为 777m2 /g;平均孔径为 3.2nm ,孔壁厚度为 1 .7nm。固体核磁共振 ( 2 7AlMASNMR)表明 :样品经高温煅烧以后骨架中没有脱铝现象出现 ;TEM观察显示 :样品从侧面看为较好的指纹状 ,正面则为典型的六方孔道排列 ,即孔口为六方形的蜂窝状结构。合成的样品具有更好的水热稳定性能。

Using the potash as precursors, a new kind of molecular sieve which has the fundamental structure units of NaX zeolite was synthesized by hydrothermal synthesis method. The synthesized samples were characterized by means of XRD, FTIR spectra, nuclear magnetic resonance (NMR), SEM etc. Results show that the samples have a typical structure character of mesoporous molecular sieves MCM-41 and there are the primary and secondary structure units of NaX zeolite, they are [SiO4] and [AlO4] tetrahedron and double-six membered ring, which share the same oxygen atoms, on the pore wall. The granularity of samples is 0.3-0.5 μm and the average pore diameter is 3.2 nm, thickness of pore wall is 1.7 nm and the specific surface area is 777 m2/g. The 27Al magic angle spinning (MAS) NMR spectra prove that there is no extra framework Al in samples after calcining at high temperature. TEM shows that the sample exhibits fingerprint shape from side-view, typical hexagonal mesopore array from front view, i. e. samples possess substantial amounts of a hexagonal mesopore phase. It is found that a better hydrothermal stability of the sample is obtained.