Fundamental study on removal of organic sulfur from coal by microwave irradiation

•Microwave desulfurization is significant for coal cleaning.•It is important to obtain the dielectric property data of each material and mixture involved in the microwave activation.•The dielectric loss of organic sulfur compounds has a significantly higher rate at a frequency of 915 MHz than of 2450 MHz.•Microwave energy desulfurization from coal was investigated at different frequencies.•Desulfurization rate of selected coal sample can reach 6.9% at the 915 MHz, but only 1.1% at 2450 MHz.

Many kinds of desulfurization reaction can be efficiently enhanced by 2450 MHz frequency microwave irradiation. Yet little experimental work on 915 MHz frequency microwave has been devoted to coal desulfurization. In this study, the dielectric properties of different kinds of organic sulfur compounds have been studied in abroad frequency range from 100 MHz to 3000 MHz range using the transmission reflection method. It was found that the microwave heating effect of the organic sulfur compounds at the frequency of 915 MHz is better than 2450 MHz. The desulfurization experiments of Xinyang coal were conducted using different microwave frequencies, which desulfurization rate can reach 6.9% at 915 MHz, but only 1.1% at 2450 MHz. The results showed that the desulfurization from coal by microwave irradiation at the frequency of 915 MHz is better than 2450 MHz. It may provide some theory reference for removing of organic sulfur from coal by microwave radiation due to its unique selective and volumetric heating capacity.

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