Effects of temperature and frequency on the dielectric properties of thiophene compounds and its application in coal microwave-assisted desulfurization

Tao, Ge; Cai, Chuanchuan; Min, Fanfei; Zhang, Mingxu

doi:10.1016/j.fuel.2021.121089

Cited by 17 publications

(12 citation statements)

References 40 publications

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“…8,9 The response of the medium to microwave depends on its own dielectric characteristics. 10,11 In the study of the microwave removal of organic sulfur in coal, the microwave absorption performance of organic sulfur in coal needs to be determined first.…”

Section: Introductionmentioning

confidence: 99%

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

Tao

Wang

et al. 2023

Asia-Pacific J Chem Eng

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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.

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Section: Introductionmentioning

confidence: 99%

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

Tao

Wang

et al. 2023

Asia-Pacific J Chem Eng

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“…Therefore, the results of coal desulfurization at different frequencies of microwaves produce differences 16 . Compared with 2450 MHz microwave, thiophene compounds have stronger ability to absorb and transform microwave energy at 915 MHz frequency, and the microwave penetration depth is greater 17 . For the reactivity of different sulfur structures, thiols and thioethers are more efficient than thiophenes in absorbing electromagnetic energy and converting it into thermal energy 18…”

Section: Introductionmentioning

confidence: 99%

“…16 Compared with 2450 MHz microwave, thiophene compounds have stronger ability to absorb and transform microwave energy at 915 MHz frequency, and the microwave penetration depth is greater. 17 For the reactivity of different sulfur structures, thiols and thioethers are more efficient than thiophenes in absorbing electromagnetic energy and converting it into thermal energy. 18 This work aimed to explore the effects of factors in the coal desulfurization experiment under two microwave frequencies of 2450 and 915 MHz and the effect of microwave chemical desulfurization on the properties of coal.…”

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confidence: 99%

Effect of chemical desulfurization on coal properties and sulfur structure based on microwave technology

Zhou

Tao

Luo

et al. 2022

Asia-Pacific J Chem Eng

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Under the two frequency microwave conditions of 915 and 2450 MHz, orthogonal tests were designed to investigate the effects of organic acid reagent, microwave irradiation time, and mixing time of additives and coal samples on the desulfurization effect of coal. Results show that the effect of irradiation time on the experimental desulfurization efficiency under frequency microwave conditions is large and is the main factor. The desulfurization effect under 915 MHz microwave condition is better than 2450 MHz microwave condition. Two sets of experimental optimal coal samples were used for characterization and analysis. Thermogravimetric analysis revealed that the combustion temperature range of the coal samples is shortened and the integrated combustion index is considerably higher after the microwave irradiation experiment. Fourier‐transform infrared spectroscopy analysis showed that the overall chemical structure of the coal samples does not change significantly after the experimental treatment. X‐ray photoelectron spectroscopy analysis showed that the intensity of organic sulfur in coal samples is weakened after microwave irradiation, the characteristic peaks of thiols and thioethers are reduced to a great extent, and an increase in the intensity of sulfoxide organic sulfur is observed. On the basis of the results of experimental analysis and quantum chemical simulation calculations, the mechanism of organosulfur structure removal under the action of microwave is revealed.

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“…Therefore, the cost is high, the process is complex, and has an effect on the quality of coal [6,7]. Microwave desulfurization has the advantages of excellent environmental performance, and minimal core structure damage, but due to the weak absorption capacity of coal to microwave energy, the desulfurization efficiency is low when only microwave irradiation is used [8]. In addition, chemical reagents generally have good dielectric properties, which can improve the microwave energy absorption efficiency [9].…”

Section: Introductionmentioning

confidence: 99%

Effect on Combustion Properties of Coal Treated by Microwave Irradiation Combined with Sodium Hydroxide Solution

et al. 2021

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A Kentucky coal sample treated by microwave irradiation (MI) combined with sodium hydroxide solution was performed using a thermo-gravimetric analyzer (TGA) coupled to a Fourier transform infrared spectrometer (FTIR). The combustion properties and structural changes of coal under different conditions were investigated and compared. The results show that the desulfurization efficiency of coal samples increases with the increase of sodium hydroxide solution concentration. Microwave irradiation can significantly improve the desulfurization efficiency. The whole combustion process of the treated coal sample becomes longer; the combustion performance becomes worse. The total mass loss of coal treated samples is significantly reduced, and the temperature corresponding to the maximum weight loss rate decreases with the increase of sodium hydroxide concentration. The infrared spectra of the coal samples treated with microwave and 5% sodium hydroxide solution were basically unchanged, while the O containing groups and aromatic C-H groups increased in the coal samples treated with 20% sodium hydroxide solution.

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Effects of temperature and frequency on the dielectric properties of thiophene compounds and its application in coal microwave-assisted desulfurization

Cited by 17 publications

References 40 publications

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

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

Effect of chemical desulfurization on coal properties and sulfur structure based on microwave technology

Effect on Combustion Properties of Coal Treated by Microwave Irradiation Combined with Sodium Hydroxide Solution

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