茉莉花茶废弃物的热解特性及其产物

Pyrolysis characteristics and pyrolysis products of jasmine tea waste

为了探讨茉莉花茶废弃物的热解过程及温度对产物的影响,采用固定热解反应器和热重红外联用仪(TG-FTIR)对其进行了研究,结果表明,茉莉花茶废弃物解产生的固体量随温度升高而降低,气体产量随温度升高而增加,热解得到的液体量比例随热解温度不同而不同,表明茉莉花茶热解产物随热解温度不同而不同。热解产物主要有CO_2、水、醇及含C=C的有机物和生物焦固体。500℃下制得的生物焦比表面积较低,仅为0.720 9 m^2·g^(-1),经活化处理后的生物焦比表面积明显增大。经CO_2和H_2O活化后得到的生物焦的BET比表面积分别升至139.503 3 m^2·g^(-1)和122.527 6 m^2·g^(-1)。茉莉花茶热解的质量损失主要由于有机物挥发,用Coats-Redfern法对茉莉花茶废弃物热解过程进行模拟,得热解过程符合气体扩散模型,热解活化能约为60 kJ·mol^(-1);因此,气体扩散是茉莉花茶废弃物热解过程中主要的限制因素。

Pyrolysis process of jasmine tea waste and the effect of reaction temperature on the product yield were investigated by TG-FTIR,using a fixed-bed reactor.The composition and content of pyrolytic product（gases,liquids,and solids） varied with the temperature.The char yield reduced,and the gas yield increased as the temperature increased.The gases evolved from jasmine tea waste,including CO_2,H_2O,alcohol,and C=C,were detected by TG-FTIR analysis.The specific surface area of char produced at 500 ℃ was low,about0.720 9 m2·g（-1）.The surface area of the char formed by activation with CO_2 and H_2O increased to 139.503 3m2·g（-1）and 122.527 6 m2·g（-1）,respectively.The mass loss was mainly attributed to the volatilization of organic matter from the thermogravimetric analysis curve.The Coats-Redfern method was applied to study the pyrolysis process of jasmine tea waste.The results of the fitting indicated that a diffusion model followed the pyrolysis mechanism of jasmine tea waste.The calculated activation energy was approximately 60 kJ·mol（-1）.In short,gas diffusion was the main limiting factor in jasmine tea waste pyrolysis.