Efficient activation of the Co/SBA-15catalyst by high-frequency AC-DBD plasma thermal effects for toluene removal

Dielectric barrier discharge(DBD)plasma excited by a high-frequency alternating-current(AC)power supply is widely employed for the degradation of volatile organic compounds(VOCs).However,the thermal effect generated during the discharge process leads to energy waste and low energy utilization efficiency.In this work,an innovative DBD thermally-conducted catalysis(DBD-TCC)system,integrating high-frequency AC-DBD plasma and its generated thermal effects to activate the Co/SBA-15 catalyst,was employed for toluene removal.Specifically,Co/SBA-15 catalysts are closely positioned to the ground electrode of the plasma zone and can be heated and activated by the thermal effect when the voltage exceeds 10 k V.At12.4 k V,the temperature in the catalyst zone reached 261℃ in the DBD-TCC system,resulting in an increase in toluene degradation efficiency of 17%,CO_(2)selectivity of 21.2%,and energy efficiency of 27%,respectively,compared to the DBD system alone.In contrast,the DBD thermally-unconducted catalysis(DBD-TUC)system fails to enhance toluene degradation due to insufficient heat absorption and catalytic activation,highlighting the crucial role of AC-DBD generated heat in the activation of the catalyst.Furthermore,the degradation pathway and mechanism of toluene in the DBD-TCC system were hypothesized.This work is expected to provide an energy-efficient approach for high-frequency AC-DBD plasma removal of VOCs.

Experimental and numerical study on atmospheric-pressure air dielectric barrier discharge via 50 Hz/5000 Hz dual-frequency excitation

A dual-frequency(DF)dielectric barrier discharge,excited by the superposition of a 50 Hz low frequency(LF)and a 5000 Hz intermediate frequency(IF),is proposed to enhance discharge.The effect of the LF voltage component on the breakdown behaviour of the DF discharge during different periods has been studied both experimentally and numerically.The number of high-current pulses rises as the LF voltage increases.The statistical analysis shows that the number of the current pulse amplitude above 80 mA in the DF discharge reaches nearly 6 times that in the IF discharge.Additionally,the total discharge energy in the DF discharge is significantly higher than that in the IF discharge.The simulation re-produces the temporal variation of the breakdown behaviours in the DF discharge.The simulated results reveal that the maximal electric field strength of the breakdown process is greater in the DF discharge compared to the IF discharge during a half-period of DF.Finally,the comparison between the IF and DF discharges exhibits that the LF voltage regulates the accumulation of residual charged species on the dielectric surface after the breakdown by modulating the residual voltage between the air gap.