THF-FER沸石的系列研究 Ⅰ.晶体结构稳定性

Studies on THF-FER Zeolite Ⅰ. Stability of Crystal Structure

四氢呋喃 (THF) Na2 O SiO2 Al2 O3 H2 O体系水热合成的THF FER沸石 ,经酸交换 -焙烧脱THF(Ⅰ )或焙烧脱THF 酸交换 (Ⅱ )的不同方式处理 ,均可制得低钠H FER沸石 .经XRD ,2 7Al与2 9SiMASNMR ,低温氮吸附等表征证明 ,通过 12 73K高温的热处理和 10 73K饱和水蒸气下的水热处理 ,H FER沸石骨架保持高度稳定 .在高温水蒸气作用下 ,Si( 2Al)容易从骨架上脱离 ,而Si( 1Al)则保持相对稳定 .以 (Ⅱ )方式处理 ,制备的H FER沸石在水热条件下易产生较多的硅羟基缺陷 .经高温热和水热处理后 ,H FER沸石孔道结构基本保持完美。

THF-FER (ferrierite) zeolite was synthesized in the reactant system of tetrahydrofuran (THF)-Na 2O-SiO 2-Al 2O 3-H 2O. H-FER with very low content of sodium was prepared by two means, ion-exchange-detemplate by calcination (Ⅰ) and detemplate by calcination-ion-exchange (Ⅱ). The structural stability and the effect of de-aluminum in the framework of H-FER zeolite were investigated by XRD, 27Al and 29Si MAS NMR as well as the adsorption of nitrogen at 77 K. The framework of H-FER zeolite exhibits very high stability, even calcined at 1273 K for 2 h and treated at 1073 K for 10 h in air flow saturated with water vapor. The H-FER zeolite prepared by means of (Ⅱ) includes the treatment with saturated water vapor at high temperature, Si(2Al) in the framework of H-FER zeolite was easily removed from the framework, whereas the content of Si(1Al) was relatively unchanged. The perfection and the opening of the porous structure for H-FER zeolite still remain after thermal and hydrothermal treatment at high temperature.