植物纤维的热裂解过程

Pyrolysis Process of Plant Fibers

天然植物纤维的相对分子质量大且结构、成分复杂,因此导致其热裂解的产物种类和成分分布也较为复杂。通过快速热解-全二维气相色谱-飞行时间质谱(Py-GC×GC-TOF/MS),热重-红外(TG-FT-IR)联用和原位红外(in situ FT-IR)等技术手段研究了6种不同天然纤维的热裂解过程,分别对不同纤维种类的热裂解温度、产物分布和主要产物类型进行了充分的研究和讨论。研究结果表明,纤维热解产物主要包括醇、醛、酮、酸、酯、碳氢化合物、脱水糖和CO_(2)等,不同天然植物纤维的热裂解产物种类差异性明显,得到的主要产物类型均有所不同。同时,原位红外光谱和时间质谱结果表明,热解产物与热解温度密切相关。原位红外实验结果表明,当热解温度低于100℃时,纤维结构表面的吸附水发生脱附,但是纤维结构不发生明显变化,当热解温度区间在100~200℃时,温度对裂解过程影响不大,而当温度超过300℃以后,纤维热解反应加剧且表面结构发生明显变化,产物主要有醛和酮。

The natural plant fiber has a large molecular weight and complex structure and composition,andits thermal cracking products and the composition distribution are also more complex.The fast pyrolysiscomprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry(Py-GC×GC-TOF/MS),thermogravimetry-Fourier transform infrared spectroscopy(TG-FT-IR),and in situ Fourier transforminfrared spectroscopy(in situ FT-IR)methods were used to study the thermal pyrolysis process of six differentnatural fibers.The distribution of thermal pyrolysis products of different fibers under different pyrolysistemperatures was investigated and the product form was fully discussed.The research results show that theproducts of fiber pyrolysis mainly include alcohols,aldehydes,ketones,acids,esters,hydrocarbons,dehydrated sugars and CO_(2),etc.The types of pyrolysis products of different natural plant fibers are obviouslydifferent,and the main product types obtained are all different.At the same time,the results of in situ infrared spectroscopy and mass spectrometry show that pyrolysis products are closely related to the pyrolysistemperature.The results of in situ infrared experiments show that when the pyrolysis temperature is lower than 100℃,the adsorbed water on the surface of the fiber structure is desorbed,but the fiber structure does notchange significantly.When the pyrolysis temperature range is 100~200℃,the temperature has little effecttoward the pyrolysis process.When the temperature exceeds 300℃,the fiber pyrolysis reaction intensifiesand the surface structure changes significantly,and the main products are aldehydes and ketones.