茶多酚的成炭性能及热分解动力学研究

Study on Carbonization and Thermal Decomposition Kinetics of Tea Polyphenols

研究了茶多酚宏观成炭的变化过程,通过同步热分析仪在不同气氛下选取不同升温速率对茶多酚进行了热失重(TG)试验,并采用Kissinger和Ozawa法计算了茶多酚在不同气氛下的活化能。结果表明,茶多酚受热后会生成膨胀炭层,且高温时能够保留完整的碳骨架;茶多酚的热稳定性良好,加热温度超过200℃时才进入快速失重状态,加热温度达到800℃时,茶多酚在氮气中的残炭率为29.69%,在空气中的残炭率为9%;茶多酚在氮气中的平均活化能大于在空气中的平均活化能,但在加热初期,在空气中的活化能比在氮气中的高。

This paper reported a study on the change process of the macro-carbon formation of tea polyphenols. Thermogravimetry was conducted for tea polyphenols using a synchronous thermal analyzer in different atmospheres and at different heating rates. The Kissinger’s and Ozawa’s methods were employed to calculate the activation energy of tea polyphenols in different atmospheres. The results indicated that an expanded carbon layer was formed for tea polyphenols after heated,and it could retain a complete carbon skeleton at high temperatures. Tea polyphenols exhibited a good thermal stability. There is a rapid weight loss only when heating temperature exceeds 200 ℃. The carbon residue rate of tea polyphenols reached 29. 69 wt% in nitrogen at a heating temperature of 800 ° C,and the carbon residue rate reached9 wt% in air. The average activation energy of tea polyphenols in nitrogen was greater than that in air. However,the activation energy in air was greater than that in nitrogen in the initial heating stage.