Thermal Characteristics, Kinetic Models, and Volatile Constituents during the Energy Conversion of Bituminous SARA Fractions in Air
Thermal Characteristics, Kinetic Models, and Volatile Constituents during the Energy Conversion of Bituminous SARA Fractions in Air
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DOI：
10.1021/acsomega.0c02023
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发表时间：
2020-08
期刊：
影响因子：
4.1
通讯作者：
Wenjing Xia;Tao Xu
中科院分区：
文献类型：
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作者：
Wenjing Xia;Tao Xu
为了了解热特性，非等温动力学模型，和挥发性组分的沥青材料的能量转换过程中的馏分水平，差示扫描量热-质谱测试进行沥青的四个馏分，包括饱和分，芳烃，胶质和沥青质（SARA）。在此基础上，建立了SARA各组分的三维非等温动力学模型，并对各组分的挥发性成分进行了讨论。结果表明，随着升温速率的增大，各阶段的分解温度范围增大，各组分的起始分解温度、峰值温度和燃尽温度均向高温方向移动。SARA馏分的整个能量转化过程以放热反应为主。饱和烃和芳烃各阶段的能量转化机理符合不同的非等温动力学模型。而胶质和沥青质的能量转化机理相似，均符合三维扩散模型的雅阁。所建立的各阶段非等温动力学模型能够较好地描述SARA组分的能量转化过程。随着升温速率的增加，饱和烃和芳烃释放的小分子挥发分增加，而大分子挥发分减少。树脂的情况正好相反，但沥青质释放的所有挥发物都增加了。最后，加热速率对SARA馏分排放的气态产物的组成影响不大，但对SARA馏分挥发物的释放量有影响。SARA馏分的主要常见挥发物是CO2、H2O、甲醇、肼、丙炔、乙醛和丙烷。该研究有助于进一步揭示沥青材料的能量转换机理。
To understand the thermal characteristics, nonisothermal kinetic models, and volatile constituents during the energy conversion of bituminous materials at the fraction level, differential scanning calorimetry–mass spectrometry tests were performed on bituminous four fractions, including saturates, aromatics, resins, and asphaltenes (SARA). Then, three-dimensional (3D) nonisothermal kinetic models of SARA fractions were established and volatile constituents of SARA fractions were discussed. Results indicate that when the heating rate is increased, the decomposition temperature ranges in each stage increase and the initial decomposition, peak, and burn-out temperatures of each SARA fraction all shift to high temperatures. Also, the whole energy conversion processes of SARA fractions are mainly exothermic reactions. Additionally, the energy conversion mechanism in each stage of saturates and aromatics accords with different nonisothermal kinetic models. However, the energy conversion mechanisms of resins and asphaltenes are similar and both accord with the 3D diffusion models. Further, the established nonisothermal kinetic models in each decomposition stage of SARA fractions are feasible to describe the energy conversion processes of SARA fractions. The released small molecular volatiles from saturates and aromatics increase when the heating rate is increased, but the macromolecular volatiles are decreased. The opposite is true for resins, but all volatiles emitted from asphaltenes are increased. Finally, the heating rate has little influence on the constituents of emitted gaseous products from SARA fractions but shows an effect on the release amount of volatiles from SARA fractions. The main common volatiles of SARA fractions are CO2, H2O, methanol, hydrazine, propyne, acetaldehyde, and propane. This study contributes to further reveal the energy conversion mechanisms of bituminous materials.