废轮胎作为一种典型的城市固体废物，由于具有耐酸、耐碱和耐生物特性，其清洁化处理难度较大。通过热解技术研究废轮胎的热解反应机理及热解油组分特性，进而可实现废轮胎的资源化利用。采用热重分析技术（TGA）对不同升温速率（5℃/min、10℃/min、15℃/min和20℃/min）下废轮胎的热解特性进行了系统研究，发现废轮胎热解过程主要发生在200～500℃温度区间，随着升温速率的增加，失重曲线（TG曲线）和失重速率曲线（DTG曲线）逐渐向高温方向偏移。采用3种等转化率法模型（Kissinger-Akahira-Sunose(KAS)模型、Ozawa-Flynn-Wall(OFW)模型和Friedman(FM)模型）对热失重数据进行了动力学分析。拟合结果表明，3种模型对应的表观活化能（Ea）分别为148～221 kJ/mol、150～221 kJ/mol和156～232 kJ/mol。随着转化率的升高，Ea和指前因子（A）呈先增大后减小趋势。在此基础上，通过OFW模型计算了不同转化率下的热力学参数（焓变（ΔH）、吉布斯自由能变（ΔG）和熵变（ΔS））。结果表明，随着转化率增加，ΔS和ΔH不断增大，在转化率达0.9时稍有降低，而对应的ΔG变化趋势与之相反。升温速率对热力学参数影响不明显。此外，利用气相色谱-质谱联用技术（GC-MS）对废轮胎热解油组分进行了分析，发现D-柠檬烯含量高达62.42%，具有较好的利用前景。研究结果对于废轮胎的资源化利用及热解技术的优化具有一定的指导意义。

Abstract

As a typical municipal solid waste, the scrap tyres are difficult to clean due to their acid, alkali and biological resistance.The purpose of this paper is to study the pyrolysis mechanism of scrap tyres and the characteristics of pyrolysis oil components, so as to realize the resource utilization of the scrap tyres. The degradation characteristics of scrap tyres at different heating rates（5 ℃/min,10 ℃/min, 15 ℃/min and 20 ℃/min） were systematically investigated using thermogravimetric analysis（TGA）. The results show that the pyrolysis process of the scrap tyres mainly occurres in the temperature range of 200 ℃ to 500 ℃, and the mass loss curves（TG curves） and mass loss rate curves（DTG curves） gradually shift toward the higher temperature zone with the increase of heating rate.Three iso-conversion methods（Kissinger-Akahira-Sunose（KAS） model, Ozawa-Flynn-Wall（OFW） model and Friedman（FM） model）were used for kinetic analyses of the mass loss data, for which the apparent activation energies（Ea） are obtained to be in the ranges of 148 kJ/mol to 221 kJ/mol, 150 kJ/mol to 221 kJ/mol and 156 kJ/mol to 232 kJ/mol, respectively. Ea and pre-exponential factor（A）tend to increase and then decrease with the increase of the conversion rate. Then, the thermodynamic parameters（enthalpy change（ΔH）, Gibbs free energy change（ΔG） and entropy change（ΔS）） at different conversion rates were calculated by the OFW model. The calculation results indicate that ΔS and ΔH increase gradually with the increase of conversion rate until the conversion rate reached 0.9,and the opposite trend is observed for the change of the corresponding ΔG. In general, the effect of heating rate on the thermodynamic parameters is not obvious. In addition, the pyrolysis oil derived from the scrap tyre pyrolysis at 500 ℃ was analyzed by gas chromatography-mass spectrometry（GC-MS）, and the results exhibite that the content of D-limonene is up to 62.42%, which has a good utilization prospect. The results have a certain guiding significance for the resource utilization of scrap tyres and the optimization of pyrolysis technology.

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