介孔分子筛MSU-X合成条件对结构及热稳定性影响的XRD研究  

Study on the Influences of Synthesis Conditions on Structure and Thermal Stability of Mesoporous MSU-X Silicas by X-ray Diffraction

作　　者：林世军[1] 周春晖[1] 盛小飞[1] 李小年[1] 李杰[1] 葛忠华[1] 

机构地区：[1]浙江工业大学化工与材料学院催化新材料研究所,浙江杭州310032

出　　处：《高校化学工程学报》2006年第6期938-944,共7页Journal of Chemical Engineering of Chinese Universities

基　　金：国家自然科学基金项目(20541002);中国石化集团公司科研项目(X504034);浙江省自然科学基金项目(Y405064)。

摘　　要：以十八烷基聚氧乙烯醚(C18EO10)为模板剂,以正硅酸乙酯(TEOS)和硅酸钠分别为硅源,研究了不同pH值、反应温度、反应时间、原料比等条件下,合成的全硅MSU-X型介孔分子筛产物的结构变化规律,并通过焙烧和水热处理,考察了MSU-X介孔材料的结构稳定性。实验采用粉末多晶X射线衍射技术,分析了合成条件对MSU-X介孔分子筛结构和稳定性的影响。结果表明:以正硅酸乙酯为硅源,原料摩尔比为TEOS:C18EO10:H2O=1:0.225:150,凝胶pH值为2,晶化温度为55℃,晶化时间48h,相应的MSU-X材料具有较好的热稳定性和水热稳定性。相比之下,以硅酸钠为硅源得到的MSU-X材料,具有更高的短程有序度,孔壁厚、孔径小,稳定性优于以正硅酸乙酯为硅源合成的MSU-X产物,经900℃焙烧2h或760℃水蒸气处理7h后仍保持其孔道结构。The silica MSU-X type mesoporous molecular sieves were synthesized by using the polyoxyethylene stearyl ether （C18EO10） as template, the tetraethyl orthosilicate （TEOS） and sodium silicates as silica source, respectively. By the help of powder X-ray diffraction, the effects of the synthesis conditions, such as the reaction temperature and time, the pH value and the molar ratio of reactants, on the structure and the thermal stability of the synthesized MSU-X mesoporous molecular sieves were studied. The results show that, when the TEOS is used as silica source and under the reaction conditions of the molar ratio TEOS： C18EO10：H2O=1：0.225：150, pH=2, crystallization temperature-55℃ and crystallization time=2 h, the synthesized silica MSU-X mesoporous molecular sieve with good thermal stability and hydrothermal stability can be obtained. And when the sodium silicate solution is used as silica source, the synthesized silica MSU-X mesoporous molecular sieve will possess thicker pore walls and smaller pore sizes, and hence its pore structure can be retained even after calcination at 900℃ for 2 h or treated by water vapor at 760℃. Therefore its thermal stability is better than that of the one prepared by using TEOS as silica source.

关 键 词：介孔分子筛 水热合成 硅酸钠 正硅酸乙酯 热和水热稳定性 模板剂 

分 类 号：TQ424.25[化学工程]