Departamento de Fisicoquímica y Control de Calidad, Complejo Tecnológico Pilcaniyeu, Centro Atómico Bariloche, Comisión Nacional de Energía Atómica, SC de Bariloche, Río Negro, Argentina.
J Phys Chem A. 2012 Mar 8;116(9):2062-70. doi: 10.1021/jp210457r. Epub 2012 Feb 22.
The reactive system La(2)O(3)(s)-Cl(2)(g) was studied in the temperature range 260-950 °C. The reaction course was followed by thermogravimetry, and the solids involved were characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy. The results showed that the reaction leads to the formation of solid LaOCl, and for temperatures above 850 °C, the lanthanum oxychloride is chlorinated, producing LaCl(3)(l). The formation of the oxychloride progresses through a nucleation and growth mechanism, and the kinetic analysis showed that at temperatures below 325 °C the system is under chemical control. The influence of diffusive processes on the kinetics of production of LaOCl was evaluated by studying the effect of the reactive gas flow rate, the mass of the sample, and the chlorine diffusion through the boundary layer surrounding the solid sample. The conversion curves were analyzed and fitted according to the Johnson-Mehl-Avrami description, and the reaction order with respect to the chlorine partial pressure was obtained by varying this partial pressure between 10 and 70 kPa. The rate equation was obtained, which includes the influence of the temperature, chlorine partial pressure, and reaction degree.
研究了温度范围在 260-950°C 之间的反应体系 La(2)O(3)(s)-Cl(2)(g)。通过热重分析跟踪反应过程，并用 X 射线衍射、扫描电子显微镜和能量色散光谱对涉及的固体进行了表征。结果表明，反应导致形成固体 LaOCl，并且在 850°C 以上的温度下，氧化氯被氯化，生成 LaCl(3)(l)。氧氯化物的形成通过成核和生长机制进行，动力学分析表明，在 325°C 以下的温度下，该体系处于化学控制之下。通过研究反应气体流速、样品质量以及通过固体样品周围边界层的氯气扩散对 LaOCl 生成动力学的影响，评估了扩散过程对氧氯化物生成动力学的影响。根据 Johnson-Mehl-Avrami 描述对转化率曲线进行了分析和拟合，并通过在 10 至 70kPa 之间改变该分压获得了对氯气分压的反应级数。得到了包含温度、氯气分压和反应程度影响的速率方程。
