中空球形氢氧化铝粉体的煅烧动力学分析

以硫酸铝为原料,尿素为沉淀剂,在一定的醇水比例及水热条件下,经过一定的干燥处理之后,得到了中空球形的氢氧化铝粉体.采用SEM、XRD测试和TG-DSC分析对粉体的微观结构及热分解和晶型转变过程进行了研究.利用Popescu法[1]和Doyle-Ozawa法[2]分析了粉体的煅烧动力学.分析结果表明:由Popescu法确定了样品煅烧过程的机理函数的积分形式为g(a)=[1-(1-a)1/3]2,属于D3模型,是球形对称的三维扩散过程.该过程的活化能E a=175.123 kJ/mol,指前因子A=1.877×109~1.711×1010,用Doyle-Ozawa法计算出该过程的活化能E a=167.677 kJ/mol.由上述两种方法的分析结果可以得知:不同的分析方法对同一个动力学过程的分析结果基本保持在误差允许范围之内(ΔE=E1-E2<10 kJ/mol).

Calcination Kinetics of Hollow Spheroid Aluminum Hydroxide Powder

Hollow spherical aluminum hydroxide powder was synthesized by hydrothermal method using alumi- num sulfate as raw material and urea as precipitation agent on certain proportion of alcohol-water and after a certain drying treatment. The microstructure, thermal decomposition and the crystal transition process of the ob- tained powder were studied by SEM, XRD and TG-DSC analysis. The calcination dynamics of the powder was analyzed by Popescu and Doyle-Ozawa methods. The analysis results show that the mechanism functions of the calcination process is g （a） = [ 1 - （ 1 - a） 1/3 ] 2 determined by Popescu method belonging to D 3 model and spherically symmetric three-dimensional diffusion process. The activation energy Ea of the process is 175. 123 kJ/ tool with a correlation coefficient of 0. 996 6 and a pre-exponential factor of 1. 877 ×109 - 1.711 × 10^10. How- ever,the activation energy of the process which is 167. 677 kJ/mol determined by Doyle-Ozawa method with a correlation coefficient of 0.991 6. The analysis results of the two methods for a dynamic process show a sub- stantially allowable error （ △E = E1 - E2 〈 10 kJ/mol）.