碱式碳酸钴非等温热分解动力学

摘要

利用热重分析及X线衍射技术,考察不同升温速率下碱式碳酸钴的热分解特性,研究碱式碳酸钴热分解动力学.用模型函数法(Coats-Redfern和Achar法)和非模型法(Kissinger法和Flynn-Wall-Ozawa法)分析计算热分解过程第2阶段的动力学参数.研究结果表明:在空气气氛下,碱式碳酸钴的热分解过程分2个阶段进行(碱式碳酸钻在303 K左右开始失去结晶水:493 K时无水盐分解,至625 K以上基本分解完毕,产物为四氧化三钴),其中分解过程质量损失率为29.5%,与理论值相符:产物表观活化能E为106.139～144.537 kJ/mol,lgA(A为指前因子)为9.396～11.868,机理函数为成核与长大模型.%Kinetics and thermal decomposition behavior of basic cobalt carbonate was investigated using TG and XRD at various heating rates. Kinetic parameters of decomposition of basic cobalt carbonate for the second-stage was calculated and analyzed using model-fitting (Coats-Redfern method and Achar method) and model-free (Kissinger method and Flynn-Wall-Ozawa method). The results show that the decomposition process of basic cobalt carbonate is divided into two stages: the crystallization water begins to dehydrate at 303 K, decomposition of basic cobalt carbonate follows at 493 K and changes into Co3O4 powder decomposition completely above 625 K in air atmosphere. The mass loss of decomposition of basic cobalt carbonate is 29.5％, which is in good agreement with the theoretical mass loss.Activation energy E and 1g A are 106.139-144.537 kJ/mol and 9.396-11.868, respectively. The mechanism function is nucleation and growth model.