(中南大學 資源加工與生物工程學院, 長沙 410083)
摘 要: 在系統(tǒng)分析非等溫固相反應特點的基礎上， 建立了非等溫脫水反應速率方程。 采用非等溫熱重法、 通過計算機輔助計算，對高嶺石脫水反應動力學規(guī)律進行了研究。 結果表明： 由于高嶺石晶體結構中內(nèi)、 外羥基脫除的順序不同， 其脫水反應機制在反應分數(shù)(α)為0.7左右時發(fā)生改變。在反應前期(0<α<0.7)時， 脫水反應遵循二維擴散控制規(guī)律，脫水反應表觀活化能為159.682 kJ/mol、 表觀頻率因子為1.007×1010/min。
關鍵字: 高嶺石; 非等溫熱重法; 動力學；脫水反應
HUANG Zhu-cheng, QIU Guan-zhou
（ 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
