MFI/MFI核壳分子筛的合成及表征  

Synthesis and Characterization of MFI/MFI Core/Shell Zeolite

作　　者：周亚新[1] 管卉[1] 祁晓岚[1] 孔德金[1] 

机构地区：[1]中国石油化工股份有限公司上海石油化工研究院,上海201208

出　　处：《化学反应工程与工艺》2013年第4期314-320,共7页Chemical Reaction Engineering and Technology

基　　金：国家重点基础研究发展计划(973计划)(2009CB623501)

摘　　要：以低硅ZSM-5为核相,用柠檬酸对其表面预处理后,晶化合成了MFI/MFI核壳分子筛。通过X射线衍射、X射线光电子能谱、扫描电镜、透射电镜、N_2吸附/脱附及红外光谱对分子筛进行了表征。结果表明,表面酸处理对壳层的形成至关重要。核相未经过酸处理,表面不能形成MFI壳层。MFI/MFI核壳分子筛的壳层为球状纳米高硅MFI分子筛,壳层覆盖度高达99%。深入研究表明,核相酸处理后形成的表面富硅结构及出现的表面缺陷对高硅壳层颗粒的成核、生长有重要影响。在甲苯甲醇烷基化反应中,高硅MFI壳层使对二甲苯选择性达到61%,并明显提高了催化稳定性。After pre-treated with citric acid solution, the low-silica ZSM-5 crystals were used as core material to fabricate the MFI/MFI core/shell zeolite. The product was characterized by X-ray diffraction, N2 adsorption, scanning electron microscopy, transmission electron microscopy, X-photoelectron spectroscopy and infrared spectroscopy methods to determine the morphology and properties of the core/shell structures. The results showed that the pre-treatment process was crucial to form the shell. Without pre-treating the cores with acid, only twinned crystals were found in the product. While continuous high-silica MFI shell grew on the leached core, and the coverage was 99 %. Further investigation indicated that the silica-rich structure and surface defects which were formed during the dealumination process played an important role in the nucleation and growth of the high-silica shell zeolite. In toluene methylation, the high-silica MFI coating not only enhanced para-selectivity up to 61%, but also prevented the deactivation of the catalyst.

关 键 词：MFI结构 高硅壳层 核壳分子筛 柠檬酸处理 

分 类 号：O643.38[理学—物理化学]