Microwave absorption properties and quantum chemistry of organic sulfur compounds in coal.

The microwave absorption properties of dielectrics determine the promotion degree of microwave energy to chemical reaction. The wave‐absorbing characteristics of organic sulfur compounds in high‐sulfur coking coal need to be studied to improve the efficiency of microwave desulfurization of coal. In this study, the imaginary part of complex dielectric constants (ε′′) and dielectric loss tangent (tan σ) of benzene mercaptan, difurfuryl disulfide, and benzothiophene were characterized. The dipole moment, molecular configuration, and frontier molecular orbital energy of organic sulfur compounds were simulated and calculated under the different external energy fields. The migration law of mercaptan, sulfide, and thiophene in coal in microwave field were analyzed. The results show that the ε'′ and tan σ of benzothiophene slightly changed with the change in microwave frequency in the frequency range of 500–2500 MHz, and the microwave absorption properties are weaker than those of benzene mercaptan and difurfuryl disulfide. Therefore, difurfuryl disulfide and benzene mercaptan molecules are more active in the microwave field than benzothiophene. The sulfur components in benzene mercaptan and difurfuryl disulfide can dissociate in the form of small inorganic sulfur molecules of carbon sulfides and disulfides, respectively. After microwave irradiation, the relative content of mercaptan and thioether in coal was decreased, whereas the relative content of thiophene remained almost unchanged. [ABSTRACT FROM AUTHOR]