具有介孔结构丝光沸石的合成与表征

基于丝光沸石骨架结构固有的晶体缺陷特征,提出诱导晶体结构缺陷和由结构缺陷衍生晶内介孔的研究方案。采用三元有机超分子胶束模板剂和两段变温晶化水热法,制备出丝光沸石基多级介孔材料。通过粉末X射线衍射、77K氮吸附–脱附、场发射透射电子显微镜、氨程序升温脱附对合成的介孔材料的晶相、形貌、介孔特征和水热稳定性进行了表征。结果表明：所合成的典型丝光沸石具有较高的相对结晶度,介孔比表面积和介孔体积分别为152.7m2/g和0.163 cm3/g;晶体内介孔在3～50 nm区间呈多级分布;其酸性质与微孔丝光沸石相匹配;水热稳定性较有序介孔材料MCM-41有显著提高。与聚集态纳米沸石组装介孔材料不同,合成的介孔丝光沸石晶体表面上介孔排布密度和尺寸分布缺乏均一性,故而由体相结构缺陷诱导形成的附加介孔呈显著无序状态。

Synthesis and Characterization of Mordenites with Mesoporous Structures

Based on the intrinsic crystal defects in the framework characters of mordenite (MOR), a protocol was proposed for intracrystalline mesopore formation from these crystal defects in the MOR phase. Several crystalline mesoporous materials with the MOR structure were synthesized via a hydrothermal method with two-staged temperature crystallizations using ternary organic supermolecular micelles as templates. The phase structure, morphology, mesopore feature and hydrothermal stability of these synthe- sized mesopore materials were characterized by powder X-ray diffraction, N 2 adsorption and desorption at 77 K, transmission electron microscope and NH 3 temperature-programmed desorption. The results indicate that the mesopore materials with the unique MOR phase synthesized have a higher relative crystallinity. The specific mesopore surface area and mesopore volume of the mesopore MOR material with the additional textural mesopores achieved 152.7 m 2 /g and 0.163 cm 3 /g, respectively, and the pore distribution is in the range of 3–50 nm. The acid capacity and acid strength distribution both were confirmed with the normal microporous MOR. The hydrothermal stability of the typical mesopore MOR was improved more availably than long-ordered MCM-41. Unlike other mesoporous materials assembled by the aggregate nanozeolite crystallites, the arrayed density and size of mesopores on the MOR crystal surface showed much less uniform, and hence the mesopores derived from the bulk structural defects presented the remarkable disordering character in texture.