Khalil Kamal M S, Elkabee Leena A, Murphy Brian
Department of Chemistry, College of Science, UAE University, P.O. Box 17551, Al-Ain, United Arab Emirates.
J Colloid Interface Sci. 2005 Jul 15;287(2):534-41. doi: 10.1016/j.jcis.2005.02.041.
Composite ceria/silica materials of 10 and 20% (w/w) were prepared by calcination, at 650 degrees C for 3 h, of the xerogels obtained by mixing the corresponding amount of a ceria precursor with freshly prepared sols of spherical silica particles (Stober particles) in their mother liquors. Two different ceria precursors were examined in this investigation. The first was a gel produced by the prehydrolysis of cerium(IV) isopropoxide in isopropanol medium, and the second was an aqueous solution of cerium(IV) ammonium nitrate. Different textural and morphological characteristics that developed by calcination were investigated by TGA, FTIR, XRD, SEM, and analyses of N2 adsorption isotherms. The results indicated that ceria dispersion and formation of mesoporous textural composite materials produced by the second precursor, cerium(IV) ammonium nitrate, are better than those produced by the first precursor, prehydrolyzed cerium(IV) isopropoxide. The results are discussed in terms of the effect of precursors and mixing media on nucleation and growth of ceria particles and their protection from sintering on calcination at the test temperature.
通过在650摄氏度下煅烧3小时，由相应量的二氧化铈前驱体与新制备的球形二氧化硅颗粒（斯托伯颗粒）母液溶胶混合得到的干凝胶，制备了10%和20%（w/w）的复合二氧化铈/二氧化硅材料。本研究考察了两种不同的二氧化铈前驱体。第一种是通过异丙醇介质中铈（IV）异丙醇盐的预水解产生的凝胶，第二种是硝酸铈（IV）铵的水溶液。通过热重分析（TGA）、傅里叶变换红外光谱（FTIR）、X射线衍射（XRD）、扫描电子显微镜（SEM）以及N2吸附等温线分析，研究了煅烧后产生的不同结构和形态特征。结果表明，由第二种前驱体硝酸铈（IV）铵产生的二氧化铈分散和介孔结构复合材料的形成，优于由第一种前驱体预水解铈（IV）异丙醇盐产生的情况。根据前驱体和混合介质对二氧化铈颗粒成核和生长的影响以及在测试温度下煅烧时防止其烧结的作用，对结果进行了讨论。
