摘要
以尿素为沉淀剂制备纳米镁铝水滑石(LDH),结合X射线衍射(XRD)、傅里叶变换红外光谱(FT-IR)、扫描电子显微镜(SEM)和热重-差热分析(TG-DTA)表征方法,研究了纳米LDH的热分解过程及其动力学。结果表明,纳米LDH热分解存在两个阶段:当热分解温度在410～527 K时,纳米LDH失去表面吸附水和层间结合水,其热分解动力学方程为随机核化Aurami方程Ⅰ;当温度在604～768 K时,纳米LDH Brucite层脱去羟基,CO_3^(2-)以CO_2形式逸出,其热分解动力学方程为三维扩散球形对称Jander方程。
Nano Mg-Al hydrotalcite （LDH） was prepared by coprecipitation using urea as precipitation agent and was characterized by means of X-ray diffraction （XRD）, Fourier-transform infrared spectra （FT-IR） , scanning electron microscope （SEM） and thermogravimetric-differential thermal analysis （TG-DTA）. Thermal decomposition mechanism and kinetics of nano Mg-Al hydrotalcite were also investigated. The results showed that the first phrase （410-527 K） was due to the dehydration of loosely bound water on the surface and in the interlayer space and the mechanism was conformed to stochastic equation of nuclear Aurami Ⅰ. The second phrase （604-768 K） was due to the removal of hydroxyl groups in the metal hydroxide layers and CO2 generation resulting from the decomposition of CO3^2- presented in the interlayer space as charge-balancing anion, and the mechanism of thermal decomposition was conformed to three-dimensional diffusion spherical symmetry Jander equation.
出处
《化学反应工程与工艺》
CAS
CSCD
北大核心
2010年第4期309-314,共6页
Chemical Reaction Engineering and Technology
基金
国家高技术研究发展计划资助项目(2003AA214061)
中国科学院知识创新工程重要方向性项目(KSCX2-YW-G-075)
关键词
水滑石
动力学
热分解
机理
表征
hydrotalcite
kinetic
thermal decomposition
mechanism
characterization
