Abstract A study was undertaken to investigate the structure, electrical conductivity and dielectric properties of low-rank coals during microwave pyrolysis. The mechanism of dielectric response during microwave pyrolysis was also discussed. The pyrolysis conditions were a microwave power of 800 W and different radiation times; dielectric properties were measured using a vector network analyzer at a frequency of 2450 MHz, and the electrical conductivity was measured using a four-probe resistivity tester. Results show that with increasing microwave radiation time, the functional groups gradually cracked and fell off, and the structural order was gradually enhanced. In addition, the order of the structure increased the number of sp 2 -hybridized carbon atoms on a single plane and increased the delocalized electrons between the graphite crystal planes. The complex relative permittivity and resistivity of the semi-cokes exhibited a significant dependence on microwave radiation time and pyrolysis temperature, especially after 15 min of microwave radiation. By comparing the calculated and measured values of imaginary parts, it could be deduced that the electric conductive loss is also an important part of the microwave attenuation mechanism in the process of microwave pyrolysis, as important as the relaxation loss and the interface polarization loss.

中文翻译：

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微波热解低阶煤制半焦的结构、电导率和介电性能

摘要 研究了微波热解过程中低阶煤的结构、电导率和介电特性。还讨论了微波热解过程中介电响应的机制。热解条件为微波功率800W，辐射时间不同；使用矢量网络分析仪以 2450 MHz 的频率测量介电特性，使用四探针电阻率测试仪测量电导率。结果表明，随着微波辐射时间的增加，官能团逐渐开裂脱落，结构有序性逐渐增强。此外，结构的顺序增加了单个平面上 sp 2 -杂化碳原子的数量，并增加了石墨晶面之间的离域电子。半焦的复相对介电常数和电阻率表现出对微波辐射时间和热解温度的显着依赖性，尤其是在微波辐射 15 分钟后。通过比较虚部的计算值和实测值，可以推断导电损耗也是微波热解过程中微波衰减机制的重要组成部分，与弛豫损耗和界面极化损耗一样重要。特别是在微波辐射 15 分钟后。通过比较虚部的计算值和实测值，可以推断导电损耗也是微波热解过程中微波衰减机制的重要组成部分，与弛豫损耗和界面极化损耗一样重要。特别是在微波辐射 15 分钟后。通过比较虚部的计算值和实测值，可以推断导电损耗也是微波热解过程中微波衰减机制的重要组成部分，与弛豫损耗和界面极化损耗一样重要。