Norby P., Nørlund Christensen A., Hanson J. C.
Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973.
Inorg Chem. 1999 Mar 22;38(6):1216-1221. doi: 10.1021/ic980749z.
In situ synchrotron X-ray powder diffraction was used to investigate the crystallization of microporous transition metal-substituted aluminophosphates from nonaqueous media. The gels contained ethylene glycol and triethylamine as the template and were heated in quartz glass capillaries at temperatures up to 200 degrees C. The following crystalline products were formed: MnAPO-5, [AFI], CoAPO-5, [AFI], and AlPO(4)-5, [AFI]. Three nonaqueous systems were investigated in situ, where the crystallization of MAPO-5-type materials were followed. Solvothermal crystallization of MnAPO-5 and CoAPO-5 was studied, and the effect of adding HF as a mineralizing agent was investigated. Time-resolved powder diffraction data were collected using a translating imaging plate (TIP) camera, and crystallization curves were extracted using integrated diffraction peaks. Kinetic analysis of the crystallization curves was performed using an Avrami-type expression, alpha(t) = exp(-(kt)(n)()). Apparent activation energies were determined from Arrhenius plots: MnAPO-5, 94 kJ/mol; MnAPO-5(HF), 68 kJ/mol; CoAPO-5, 61 kJ/mol. Crystallization of CoAPO-5 is faster than for MnAPO-5, and the values for n obtained by fitting with the Avrami-type expression were significantly lower for CoAPO-5 than for MnAPO-5.
采用原位同步辐射X射线粉末衍射技术研究了非水介质中微孔过渡金属取代磷酸铝的结晶过程。凝胶中含有乙二醇和三乙胺作为模板，并在石英玻璃毛细管中加热至200℃。形成了以下结晶产物：MnAPO-5，[AFI]；CoAPO-5，[AFI]；以及AlPO(4)-5，[AFI]。对三个非水体系进行了原位研究，跟踪了MAPO-5型材料的结晶过程。研究了MnAPO-5和CoAPO-5的溶剂热结晶过程，并考察了添加HF作为矿化剂的效果。使用平移成像板（TIP）相机收集时间分辨粉末衍射数据，并使用积分衍射峰提取结晶曲线。利用Avrami型表达式α(t)=exp(-(kt)^n)对结晶曲线进行动力学分析。由Arrhenius图确定表观活化能：MnAPO-5为94 kJ/mol；MnAPO-5(HF)为68 kJ/mol；CoAPO-5为61 kJ/mol。CoAPO-5的结晶速度比MnAPO-5快，通过与Avrami型表达式拟合得到的n值，CoAPO-5明显低于MnAPO-5。
