纳米氢氧化镁粉体的制备及热分解动力学研究

Preparation and Thermal Decomposition Kinetics of Magnesium Hydroxide Nano-particles

以氯化镁和尿素为原料,采用均匀沉淀法制备出厚度约为20 nm的片状纳米氢氧化镁粉体。利用热重分析法对片状纳米氢氧化镁粉体在不同升温速率下的热分解动力学进行研究,以期深入认识由纳米氢氧化镁粉体热分解得到纳米氧化镁粉体过程的物理化学本质。分别采用Coats-Redfern方程和Dolye方程,对热重分析数据进行了处理和拟合,得到了片状纳米氢氧化镁粉体热分解反应属于Avrami-Erofeev(n=1)的成核和生长为控制步骤的反应机理,其表观活化能E=131 kJ/mol,指前因子A=1.56×1010。

Taking magnesium chloride and urea as raw materials, sheet magnesium hydroxide nano-particles were prepared by homogeneous precipitation process. By using the thermal gravimetric analysis, the thermal decomposition of magnesium hydroxide nano-particles was studied at different heating rates for a deep understanding of the physical chemistry inbeing in this process which led to forming of magnesium oxide nano-particles. The Coats-Redfem and Dolye equations were used to do curve fitting. The computable results of kinetics of activation energy and pre-exponential were determined, It was that the activation energy = 131 kJ/mol, pre-exponential = 1.56 × 10^10. Decomposition reaction of magnesium hydroxide nano-particles was controlled by Avrami-Erofeev random nucleation and subsequent growth mechanism.