エリオナイト-オフレタイト型ゼオライトの合成と触媒特性

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Erionite-offretite (EO) type zeolite was synthesized at 100℃ from nearly clear solutions and hydrogels in the system Na_2O-K_2O-TMA_2O-Al_2O_3-SiO_2-H_2O. It was identified by X-ray diffractometry, electron diffractometry, SEM, TG-DTA and chemical analysis, and further its catalytic properties over the H form in the conversion reaction of methanol to hydrocarbons was cheked. The SiO_2/Al_2O_3 molar ratio (R value) of the aluminosilicate framework enhanced with increasing R value of the reactant mixture. Electron diffraction patterns of the EO type zeolite showed diffuse odd-l spots with streaks parallel to c indicating disorder of the structure. This indicates.the presence of lamellae with ordered domains of erionite in offretite matrix. With the increase of the R value, the diffuse odd-l spots had a tendency to become strong in intensity and to be elongated in streak. However, the EO type zeolite formed in a high alumina region gave weak intensities of the odd-l spots despite the high R value of the framework. Catalytic activities in the methanol conversion over the H form catalysts varied with difference of the R values. The catalysts having relatively low or high R value tended to show lower activities than the catalysts having the intermediate R values, with a few exception. The catalysts with the intermediate R values were apt to show high selectivities to light olefins, compared with the other catalysts. In view of these results, it would be preferable that the EO type zeolite in our reaction system is classified as follows : Disordered type I zeolite, ZSM-34 , and Disordered type II zeolite, In this order, the intensities of the odd-l spots tended to increase.
日本粘土学会の論文
1989-03-20

エリオナイト-オフレタイト型ゼオライトの合成と触媒特性

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