Fe-Si-ZSM-12型分子筛的合成及其性能的研究

STUDIES ON THE SYNTHESIS AND PROPERTIES OF Fe-Si-ZSM-12 ZEOLITES

本文用水热法在SiO_2-FeNH_4(SO_4)_2-MTEACl-NaOH-H_2O体系内合成出了用铁全部取代铝的Fe-Si-ZSM-12型沸石分子筛。实验结果表明,Na_2O/SiO_2、MTEA^+/SiO_2和SiO_2/Fe_2O_3比对分子筛的形成和结晶度有很大影响,Fe-Si-ZSM-12的晶化速度比较缓慢,延长晶化时间则容易转化为α-SiO_2。Fe-Si-ZSM-12的X射线衍射谱图与Al-Si-ZSM-12的基本相同,吸附数据表明,其孔径略大于Al-Si-ZSM-12的孔径,热稳定性则劣于Al-Si-ZSM-12的热稳定性。

Fe-Si-ZSM-12 zeo(?)ites have been synthesized from SiO_2-FeNH_4(SO_4)_2-MTEACl-NaOH-H_2O system by hydrothermal method. The crystallinity of the product was strongly dependentt on MTEA^+/SiO^2 Na_2O/SiO_2 and SiO_2/Al_2O_3 ratios in the reaction mixture. The crystallization kinetic curve indicated that the crystallization rate of Fe-Si-ZS M-12 zeolite was slow and the crystal phasd could easily be transformed from Fe-Si-ZSM-12 to α-SiO_2 when the crystallization time was prolonged. The XRD pattern of Fe-Si-ZSM-12 matched well with that of Al-SiZSM-12. Adsorption data showed that the pore size of Fe-Si-ZSM-12 was slightly larger than that of Al-Si-ZSM-12. The thermal stability of the former was inferior than that of the latter.