磷酸钴铵的合成及热分解动力学研究

Synthesis and Characterization of Ammonium Cobalt Phosphate Hydrate via A Low-Heating Solid-State Reaction

关键词:  磷酸钴铵  低热固相反应  热分解

Key words:  (NH₄)₃CoPO₄·H₂O  solid state reaction  thermal decomposition

摘要:

以CoCl₂·6H₂O和(NH₄)₃PO₄·3H₂O为原料,在适量表面活性剂聚乙二醇-400的存在下,先在室温下研磨反应混合物进行固相反应,然后将反应混合物在80℃下保温陈化4h,接着用水洗去混合物中可溶性的无机盐,然后在110℃下烘干2h,得到(NH₄)₃CoPO₄·H₂O晶体材料。用XRD,IR,SEM及TG/DTA对产物进行表征。采用热重差热法(TG/DTA)分析研究该产物的热分解过程。结果表明,(NH₄)₃CoPO₄·H₂O在105~800℃有2个显著的失重平台,这2个失重过程机理函数所对应的活化能、频率因子(LnA)及热分解机理机理函数分别为:(a)E=97.83kJ/mol,lnA=23.26 s^-1,[-ln (1-a)];(b)E=87.36kJ/mol,lnA=15.60 s^-1,1-(1-a)^1/2。

Abstract:

The crystalline (NH₄)₃CoPO₄·H₂O was prepared in the presence of surfactant PEG-400 with fully ground CoCl₂·6H₂O and (NH₄)₃PO₄·3H₂O as raw materials by a solid-state at room temperature, the reaction mixtures were aged at 80℃for 4h, then washed with water to remove soluble inorganic salts and dried at 110℃ for 2h to obtain the crystals of (NH₄)₃CoPO₄·H₂O. The products were characterized with XRD, IR, SEM and TG/DTA. Study on thermal decomposition kinetics of α-LiZnPO₄·H₂O by thermo-gravimetric-differential thermal analysis (TG-DTA), The results showed that the thermal decomposition of the (NH₄)₃CoPO₄·H₂O was carred in two well-defined weight loss processes. The Activationenergy (E), frequency factor (1nA) and mechanism function[g (α)]for the two processes are:(a)E=97.83kJ/mol, lnA=23.26 s^-1,[-ln (1-a)]; (b)E=87.36kJ/mol, lnA=15.60 s^-1, 1-(1-a)^1/2。