TG-FTIR研究落叶松和废轮胎共热解失重及产物释放特性

利用热重红外法(TG-FTIR)考察了不同质量混合比例(1∶2、1∶1、2∶1)落叶松和废轮胎共热解失重、动力学规律及气相产物释放特性。共热解失重特性研究发现,温度低于366℃共热解主要表现为以落叶松为主的热降解行为,温度高于366℃主要表现为以废轮胎为主的热降解行为,热解效率随着落叶松加入比例的增大而提高。采用Coats-Redfern动力学模型对共热解动力学分析发现,主要失重阶段低温区(250~370℃)和高温区(370~480℃)热解行为均符合一级动力学规律,高温区活化能均明显低于低温区,随着落叶松加入比例的增大,活化能明显降低,使得热降解更容易发生。红外分析表明,共热解过程中主要生成含氧官能团的有机物及含氧小分子气体,6种小分子气体吸收峰析出强度由大到小依次为CO2CH4H2OCOSO2H2S,其中,废轮胎中的硫在落叶松降解过程中产生的氧自由基作用下主要转化为SO2。

Co-pyrolysis of waste tire and larch wood in TG-FTIR

The characteristics of thermal cracking, kinetics and product gas during co-pyrolysis of different mixtures of larch sawdust and waste tire (1:2, 1:1 and 2:1) were investigated using a thermogravimetric analyzer coupled with Fourier Transform Infrared (TG-FTIR). The weight loss curves show that the process of co-pyrolysis is dominated by the larch thermal degradation before 366℃ and by the rubber thermal degradation after 366℃. The pyrolysis efficiency is improved as the ratios of larch sawdust increase. The kinetic model of Coats-Redfern was used to analyze the kinetic behaviors. It is found that the pyrolysis behavior accords with the first-order kinetics, and the activation energy in the high temperature range (370~480℃) is much smaller than that in the low temperature range (250~370℃), moreover, the pyrolysis reaction is easier to occur because the activation energy decreases with increasing the ratios of larch sawdust. The results of infrared analysis show that the organics with oxygen-containing functional groups and small molecules are main product produced. During the process of pyrolysis, the amounts of six kinds of small molecular gases produced are in the order of CO₂>CH₄>H₂O>CO>SO₂>H₂S, and S is mainly converted to SO₂ due to the effect of oxygen free radical, which is produced in the thermal degradation of larch wood.