新型层柱分子筛的骨架振动红外光谱研究

STUDIES ON IR FRAMEWORK VIBRATION SPECTRA OF MEW TYPE PILLARED CLAYS

云母-蒙脱土的骨架振动光谱不同于蒙脱土,在相应的位置,云母-蒙脱土的振动谱峰都是双蜂。利用凝胶分散法制备的硅交联蒙脱土,硅交联云母-蒙脱土及铝交联云母-蒙脱土,经450～500℃焙烧后,在1000～1200cm^(-1)和400～500cm^(-1)区间内相应于四面体的Si—O反对称伸缩及弯曲振动部分谱峰发生了高波数位移;而交联剂、粘土及未焙烧的层柱分子筛都不发生此现象。这表明只有经过高温焙烧后,交联剂与粘土才发生明显的化学作用,使四面体层结构重排。这对于交联机理的研究提供了依据。

The pillared clays including silica pillared montmorillomte (Si-CLM), silica pillared rectorite (Si-CLR) and alumina pillared rectorite(Al-CLR)were prepared by our new metho-gel dispersion method. The IRframework vibration spectra of 1000-1200 and 400-500cm-1 stem from tetrahedral antisymmetric stretching and Si-O bending vibration modes respectively. Compared with one vibration spectrum of montmorillonite, there are two vibration spectra of rectorite at the corresponding position. After calcination at 450--500℃ for 2 h, some spectra of pillared ciays shift to the higher frequency (CLR: A-47 cm-1; CLM. A = 14 cm-1), but under the same treatment conditions,the tetrahedral antisymmetric stre- tching vibration spectra of clays and pillaring agents remain unchanged, and the spectra of uncalcined pillared clays are similar to those of clays. This shows that after calcination there is a kind of chemical action between pillaring agent and clay. A pillaring mechanism is suggested that after calcination some tetrahedral silicon or aluminium reverse to gallery and react with pillaring agents whether or not there exists tetrahedral aluminium substitution in clays.