后处理工艺制备多级孔Ti-BEA沸石及其环氧化催化性能

摘要

Hierarchically structured Ti-β zeolites were prepared using a two-step post-synthesis approach. The physicochemical properties of the resultant Ti-mβ-Sx materials were determined using various techniques, including X-ray diffraction, scanning electron microscopy, inductively coupled plasma atomic emission spectroscopy, transmission electron microscopy, and ultraviolet-visible and ultra-violet-Raman spectroscopies. The porous structures of the synthesized hierarchical Ti-β zeolites were well preserved. Their catalytic performance was compared with that of pure microporous Ti-βmaterials using alkene epoxidation as a model reaction. It was found that although comparable catalytic activities were obtained for both types of catalyst in the epoxidation of small molecules, e.g., cyclohexene, the synthesized hierarchical Ti-βgave an enhanced catalytic performance in the epoxidation of bulky 1-dodecene.%基于脱铝多级孔BEA沸石与二氯二茂钛的固相反应，开展了钛掺杂量可调的多级孔Ti-beta后处理工艺制备研究.对制备的多级孔Ti-beta样品的理化性质进行了表征，包括X射线衍射、氮气吸附脱附测试、扫描电镜、透射电镜、紫外可见吸收光谱和紫外拉曼光谱等.结果表明，多级孔BEA沸石具有较好的化学稳定性，脱铝-钛化的后处理过程未对样品多级孔结构产生明显影响. ；以环己烯和十二烯的烯烃环氧化为探针反应表征了合成多级孔Ti-beta与纯相微孔Ti-beta沸石的催化性能.结果表明，在小分子环己烯的环氧化反应中，多级孔Ti-beta沸石的催化活性(转化率59.4%)与微孔Ti-beta相当(转化率57.9%)；但是在较大分子十二烯的催化反应中，多级孔结构Ti-beta材料的催化性能(转化率11.1%)明显优于纯相微孔材料(转化率6.8%)，且产物中环氧化物选择性更高(分别为60.3%和37.8%).