(中南大学 资源加工与生物工程学院, 长沙 410083)
摘 要: 在系统分析非等温固相反应特点的基础上， 建立了非等温脱水反应速率方程。 采用非等温热重法、 通过计算机辅助计算，对高岭石脱水反应动力学规律进行了研究。 结果表明： 由于高岭石晶体结构中内、 外羟基脱除的顺序不同， 其脱水反应机制在反应分数(α)为0.7左右时发生改变。在反应前期(0<α<0.7)时， 脱水反应遵循二维扩散控制规律，脱水反应表观活化能为159.682 kJ/mol、 表观频率因子为1.007×1010/min。
关键字: 高岭石; 非等温热重法; 动力学；脱水反应
（ School of Resources Processing and Bioengineering,
Central South University, Changsha 410083, China）
Abstract: Based on the systematical analysis of the characteristics of the non-isothermal solid-reactions, a rate equation of dehydroxylation reactions was founded. And the kinetics of dehydroxylation of kaolinite was investigated by using non-isothermal thermogravimetric method with the aid of computer. It is found that, the mechanism of dehydroxylation of kaolinite converts at the reaction fraction of 0.7, because the —OH groups in interlamellar space associated with the alumina sheets lose more easily than those in intralamellar space between the silica and alumina sheets. When the reaction fraction is below 0.7, the thermal dehydroxylation of kaolinite is found to be controlled by two-dimensional diffusion-controlled. The apparent activation energy and apparent pre-exponential Arrhenius factor of the reaction are obtained as 159.682 kJ/mol and 1.007×1010/min, respectively.
Key words: kaolinite; non-isothermal thermogravimetry; kinetics; dehydroxylation
