Dielectric synergistic effect of Ca(OH) 2 on the microwave pyrolysis of coal: Heating enhancement and product distribution optimization

Abstract As an essential energy source, the efficient and comprehensive utilization of coal has a profound impact on carbon emissions. Microwave pyrolysis achieves rapid and uniform heating by internal dielectric polarization, enhancing heat transfer efficiency significantly during coal pyrolysis. This study investigated the effects of microwave radiation power, Ca(OH) 2 addition, and coal dosage on coal pyrolysis and also revealed the mechanism of the effect of low, medium, and high calcium hydroxide addition on pyrolysis. The results show that Ca(OH) 2 not only increases the temperature rise limit to 1134 °C by enhancing the dielectric loss factor of coal but also increases the coal tar yield to 24.70% in the coal pyrolysis process. Appropriate microwave power, Ca(OH) 2 /coal ratio, and pulverized coal dosage can further promote the coal tar production. This study provided a new method for rapid and profound pyrolysis of coal.