协同导向法合成ZSM-5/ZSM-11共生分子筛

Synthesis of ZSM-5/ZSM-11 Intergrowth Zeolite via the Synergetic Directing Approach

使用四丁基铵(TBA^+)模板剂和Beta分子筛作晶种协同导向合成ZSM-5/ZSM-11共生分子筛。Beta分子筛晶种的加入扩大了ZSM-5/ZSM-11分子筛的合成相区,抑制了丝光沸石杂相的生成。研究了合成条件对共生结构中ZSM-5、ZSM-11的含量及分子筛晶体形貌的影响,发现相同条件下晶种添加量越大、合成碱度越小、投料硅铝比越高,共生结构中ZSM-11的含量越高,分子筛的晶粒尺寸越小。用X射线衍射(XRD)、扫描电镜(SEM)、N_2物理吸附(BET)、^(27)Al魔角旋转固体核磁(MAS-NMR)、NH_3程序升温脱附(NH_3-TPD)等对样品进行表征,发现ZSM-5/ZSM-11共生分子筛具有高的结晶度、丰富的孔结构、优良的Al的配位状态和强酸性,是具有潜在应用价值的优良催化剂。

The synthesis of ZSM-5/ZSM-11 intergrowth zeolite via the synergetic directing approach has been presented in this work, where tetrabutylammonium and zeolite Beta were used as organic template and seed, respectively. The addition of zeolite Beta as heterogeneous seed helped to expand the synthetic phase region of ZSM-5/ZSM-11 zeolite and inhibited the generation of the heterogeneous phase of the zeolite mordenite. The effects of synthesis conditions on the content of ZSM-5 and ZSM-11 in the intergrowth structure and the crystal morphology were investigated. It turned out that with the increase of the amount of Beta seed, the decrease of the synthesis alkalinity and higher initial SiO2/Al2O3 ratio, the content of ZSM-11 increased while the crystal size dropped-off. The intergrowth-structured samples were characterized by X-ray diffraction（XRD）, scanning electron microscopy（SEM）, N2 physical adsorption at 77 K, 27^Al magic angle spinning solid nuclear magnetic resonance（MAS NMR） and temperature-programmed desorption of NH3（NH3-TPD）. It was found that the ZSM-5/ZSM-11 intergrowth zeolites possessed high crystallinity, rich pore structure, outstanding coordination state of Al and strong acidity and was an excellent catalyst with the substantial potential value in industrial application.