Coaxial Dielectric Barrier Discharge Research Articles

Kinetic Modeling Analysis of Ar Addition to Atmospheric Pressure N2-H2 Plasma for Plasma-Assisted Catalytic Synthesis of NH3.

Zero-dimensional kinetic modeling of atmospheric pressure Ar-N2-H2 nonthermal plasma was carried out to gain mechanistic insights into plasma-assisted catalytic synthesis of ammonia. Ar dilution is a common technique for tailoring plasma discharge properties and has been shown to enhance NH3 formation when added to N2-H2 plasma. The kinetic model was developed for a coaxial dielectric barrier discharge quartz wool-packed bed reactor operating at near room temperature using a kHz-frequency plasma source. With 30% Ar mixed in a 1:1 N2-H2 plasma at 760 Torr, we find that NH3 production is dominated by Eley-Rideal (E-R) surface reactions, which heavily involve surface NHx species derived from N and H radicals in the gas phase, while the influence of excited N2 molecules is negligible. This is contrary to the commonly proposed mechanism that excited N2 molecules created by Penning excitation of N2 by Ar(4s) and Ar(4p) play a significant role in assisting NH3 formation. Our model shows that the enhanced NH3 formation upon Ar dilution is unlikely due to the interactions between Ar and H species, as excited Ar atoms have a weak effect on H radical formation through H2 dissociation compared to electrons. We find that excited Ar atoms contribute to 28% of the N radical production in the gas phase via N2 dissociation, while the rest are dominated by electron-impact dissociation. Furthermore, Ar species play a negligible role in the product NH3 dissociation. N2 conversion sensitivity analyses were carried out for electron number density (ne) and reduced electric field (E/N), and contributions from Ar to gas-phase N radical production were quantified. The model can provide guidance on potential reasons for observing enhanced NH3 formation upon Ar dilution in N2-H2 plasma beyond changes in the discharge characteristics.

Dynamics of NO, N2O, and ONOOH in atmospheric-pressure air dielectric barrier discharge: decoupling energy density and gas temperature effects varying with discharge voltage

The dose regulation of reactive nitrogen species is crucial for biomedical applications. In this study, we develop a global chemical kinetics model comprising 92 species and 1018 reactions to investigate the regulatory dynamics of three types of reactive nitrogen species, i.e. NO, N2O, and ONOOH, which vary with the discharge voltage in an air coaxial dielectric barrier discharge. Based on the experimental results, the model can describe the density variations of NO, N2O, and ONOOH. The simulation results indicate that the O, NO3− , NO2− , and O3 are essential intermediate species related to NO generation; N, NO2, O-, N2*, and O(1D) are essential intermediate species related to N2O generation; and O2− , NO, NO2, OH, O4− , and O3 are essential intermediate species related to ONOOH generation. The individual and comprehensive effects of the energy density and gas temperature on the densities of NO, N2O, and ONOOH and the corresponding intermediate species are quantified under increasing discharge voltages. The simulation results indicate that the energy density is the primary factor affecting the number density of NO, N2O, and ONOOH, whereas the gas temperature exerts a completely different effect on these three species. These insights are valuable for plasma applications in biomedicine, where the selective and controlled production of reactive nitrogen species is key for achieving the desired plasma performance.

Tailoring the surface acidity of catalyst to enhance nonthermal plasma-assisted ammonia synthesis rates

We report nonthermal plasma-assisted catalytic ammonia synthesis from N2 and H2 molecules at near ambient conditions in a custom-built coaxial dielectric barrier discharge plasma reactor. Here, we strategically designed catalysts to facilitate dissociation of strong nitrogen bond and desorption of NH3 molecules. This work demonstrates the use of empty orbitals of boron doped in graphitic carbon nitride (BCN) to activate nitrogen molecules, by creating electron-deficient sites, under nonthermal plasma conditions. Transition metals (Co and Fe) further contribute to the ammonia generation by altering the amount of weak acid sites of the BCN catalyst. As a result, at 20.16 kJ L−1, the maximum ammonia synthesis rate of ∼2.48mmolg−1h−1 was achieved by Co-BCN that corresponds to energy efficiency of 2.09 g-NH3 kWh−1, which was ca. 2.89-folds higher than that of plasma only. Evidently, dual mechanisms at play, leading to enhanced ammonia synthesis rates. Our strategy of tailoring catalyst structure provides a roadmap for engineering synergy with nonthermal plasma towards targeted applications.

Degradation of dyes using reactive species of atmospheric pressure dielectric barrier discharge formed by a pencil plasma jet

The dye degradation efficacy of the cold plasma pencil jet is presented in the present investigation. Dye degradation studies were performed using air plasma, six different types of selected dyes (erythrosine, metanil yellow, sudan I, crystal violet, rhodamine B, and Indigo). The degradation of dyes is analyzed using UV visible spectroscopy, total organic carbon, and chemical oxygen demand. The results showed complete degradation of all types of dyes in UV visible analysis with minimum time for indigo (3 min) and maximum time for erythrosine (45 min). Moreover, erythrosine (k = 1.08 mg l−1 min−1), sudan I (k = 3.46 mg l−1 min−1), rhodamine B (k = 3.955 mg l−1 min−1), and Indigo (k = 18.915 mg l−1 min−1) follows approximate zeroth-order degradation kinetic, and metanil yellow (k = 0.094 min−1) and crystal violet (k = 0.25 min−1), closer to first-order degradation kinetics. Additionally, a substantial enhancement in mineralization and reduction in chemical oxygen demand of all the dyes occurs after plasma treatment. In this study, air plasma is produced in the cylindrical coaxial dielectric barrier discharge configuration. Electrical characterization of plasma is performed and the plasma species are identified using optical emission spectroscopy. The toxicity of plasma degraded dyes solutions toward freshwater algae species (Chlorella Sorokiniana and Chlorella Pyrenoidosa) are significantly low compared to virgin dyes solutions. The study reveals that pencil plasma jet substantially degrades dyes as well as converts the dyes solutions non-toxic.

Electrical characterization and imaging of discharge morphology in a small-scale packed bed dielectric barrier discharge

Packed bed dielectric barrier discharges (DBDs) exhibit an improved energy efficiency and selectivity in nonthermal plasma based gas conversion. They enable the direct interaction between plasma and catalyst. In this contribution a compact coaxial DBD reactor enabling the end-on imaging of the discharge with and without packed beds is studied. The discharge morphology is correlated with electrical measurements such as voltage-charge (V-Q) plots. The studies are performed for different packed bed materials, binary gas compositions of argon and carbon dioxide, voltage amplitudes, average powers, and pressures. The analysis points outs the role of parasitic capacitances and parasitic discharges as often overlooked aspects. The introduction of the packed bed material into the coaxial barrier discharge arrangement increases the total capacitance, but the barrier of the outer glass tube mostly determines the maximum effective dielectric capacitance. The choice of the packed bed material determines the voltage threshold and the average discharge power. The investigations leads to a revision of the equivalent circuit for packed bed barrier discharge reactors, which also accounts the properties of different filling materials.

Physicochemical Characteristics and Antimicrobial Efficacy of Plasma-Activated Water Produced by an Air-Operated Coaxial Dielectric Barrier Discharge Plasma

In this study, Plasma-Activated Water (PAW) was synthesized using a coaxial Dielectric Barrier Discharge (DBD) reactor, benefiting from the elevated capacity of air-flow-assisted DBD discharges to enhance nitrogen-based species concentration. By manipulating operational parameters, including gas flow rate, activation time, and DI water volume, we achieved significant concentrations of reactive oxygen and nitrogen species (RONS). As a result, the PAW obtained displayed pronounced physicochemical attributes: a pH of 2.06, an ORP of 275 mV, conductivity of 3 mS/cm, and TDS of 1200 mg/L. A pivotal aspect of this research was the evaluation of the reactor’s efficiency, as indicated by metrics like the specific input energy and ozone efficiency yield. The antimicrobial potential of the PAW was also assessed against pathogenic microbes, with remarkable reductions in viability for both Staphylococcus aureus and Escherichia coli (99.99%) and a more moderate decrease for Candida albicans (37%). These findings underscore the capability of coaxial DBD reactors in crafting high-quality PAW with significant antimicrobial properties, necessitating further studies to validate its broad-spectrum and safe applications.

Effects of the ground-electrode temperature on electrical and optical characteristics of a coaxial dielectric barrier discharge in atmospheric pressure air

The applied power and electron energy are believed to play important roles in plasma applications, which can be significantly altered by controlling the ground-electrode temperature in a coaxial dielectric barrier discharge (DBD). The effects of the ground-electrode temperature on the electrical and optical characteristics of the DBD were investigated in atmospheric pressure air. The results show that the breakdown voltage decreases, and the number of discharge pulses, the transferred charges, and the applied power increase with the electrode temperature, while the peak current tends to decrease when the electrode temperature is below −35 °C and above 25 °C, respectively. When the electrode temperature remains constant, the breakdown voltage increases and the applied power decreases with the gap distance. The applied power increases with the applied voltage. The dielectric capacitance, the total capacitance, and the gap capacitance at the electrode temperature below −35 °C are generally higher than those at the electrode temperature above 25 °C. Moreover, they change in the same trend when the electrode temperature and the applied voltage increase. The dielectric and total capacitances increase while the gap capacitance decreases. The relative intensities of the spectral lines increase with the electrode temperature. The electron, vibrational, and rotational temperatures increase with the electrode temperature above 25 °C. However, the electron and vibrational temperatures increase and decrease with the electrode temperature below −35 °C. The secondary emission coefficients and electron energy distributions with the electrode temperature were discussed.

Sterilization of Water-Based Cutting Fluids Using Compact Air-Cooled Coaxial Dielectric Barrier Discharge Reactor with Bubbler

Odor and discoloration in water-based cutting fluids are caused by the growth of microorganisms and putrefying bacteria. This significantly reduces cutting performance, prevents rust, and deteriorates the working environment. To overcome these drawbacks, we developed a compact air-cooled coaxial dielectric barrier discharge (DBD) with a bubbler. Bacteria and microorganisms living in waste cutting fluids were sterilized by the high concentration of ozone produced under the optimized conditions of the compact air-cooled coaxial DBD. Moreover, it was confirmed that 99.99% of bacteria and microorganisms were completely removed. Ozone was found to not affect property changes such as the composition, concentration, and pH of the water-based cutting fluids. The chromaticity and complex odor of waste cutting liquids were thus found to have been improved by the effects of microorganism and bacterial sterilization. We conclude that the proposed a compact air-cooled coaxial DBD with a bubbler is an efficient method for sterilizing water-based cutting fluids.

Chain scission modification mode in plasma catalytic n-undecane decomposition: In situ probing of intermediates and reaction pathways

To provide insight into the mechanism of plasma-catalytic long-chain alkane oxidation from the aspect of chain scission, n-undecane (C11H24) decomposition over γ-Al2O3 and Ag/γ-Al2O3 were investigated in a coaxial dielectric barrier discharge (DBD) reactor. The highest n-undecane conversion (89.7 %) and CO2 selectivity (SCO2, 40.0 %) were achieved in Plasma + Ag/γ-Al2O3 system. It was found that the simultaneous activation of O3 and C11H24 played a very important role in chain scission, which could be promoted by the formation of Ag-O-Al entity introduced by the strong interaction between Ag and γ-Al2O3. Different chain scission behaviors and reaction pathways were proposed by a combined analysis of GC-MS and in-situ DRIFTS. In Plasma + Ag/γ-Al2O3 system, the reaction of chain scission and oxidation preferred to take place in the middle of the chain, producing the ketone and aldehyde species with low carbon number, which were easy to be converted to CO2 and H2O. Instead, without the highly efficient activation of O3 and C11H24, the oxidation of the C11H24 over the surface of γ-Al2O3 was more likely to take place on the edge of the chain, leading to the accumulation of long-chain aldehyde, which lower values of C11H24 conversion and SCO2 (45.6 % and 21.7 %, respectively) in Plasma + γ-Al2O3 system.

Plasma-catalytic pyrolysis of polypropylene for hydrogen and carbon nanotubes: Understanding the influence of plasma on volatiles

Plasma-catalytic pyrolysis was developed for upgrading polypropylene (PP) pyrolysis volatiles to co-produce carbon nanotubes (CNTs) and hydrogen. To uncover the role of plasma on the plastic catalytic pyrolysis process, the pyrolysis of polypropylene (PP) over Fe/γ-Al2O3 was carried out in a two-stage pyrolysis system with a coaxial dielectric barrier discharge (DBD) plasma reactor. The results showed that the plastic pyrolysis volatiles were further cleaved and activated with plasma, resulting in more active carbon species for the growth of CNTs. Compared to conventional catalytic pyrolysis, plasma addition shifted the initial formation temperature of CNTs to a lower ambient temperature by ∼100 °C, and significantly promoted the conversion of liquid and gaseous products to CNTs and hydrogen, with higher carbon and hydrogen yields of ∼322 mg/gplastic and 30 mmol/gplastic, respectively. In addition, the degree of graphitization of the CNTs in the presence of the plasma was significantly enhanced with less defectivity. The influence of catalytic temperature variation caused by plasma on CNTs growth was also discussed from the perspective of volatile evolution. This work highlights the potential of plasma-catalytic pyrolysis for the production of hydrogen and high-value carbon materials from plastic waste.

Generation of the high power by a coaxial dielectric barrier discharge with a perforated electrode in atmospheric pressure air

The power is believed to play an important role in the treatment effects in both direct and indirect plasma applications. Generation of the high power has been realized by using a perforated inner electrode for a coaxial dielectric barrier discharge (DBD) in atmospheric pressure air. Compared with a non-perforated inner electrode, the perforated electrode has a 10%–20% and 10%–30% increase in the applied power and the discharge power, respectively. The strengthened local electric field of the perforated electrode in the coaxial DBD provides favorable conditions for the generation of the micro-discharge, thus increasing the power. To shed light on the reasons for the increase in the power, an extensive analysis of the optical and electrical characteristics of the DBD with the perforated electrode and the non-perforated one was carried out, including transferred charge, total current, number of discharge pulses, dielectric capacitance, gap capacitance, vibrational and rotational temperatures, and electron temperature trend.

Simulation study of DBD discharge characteristics and active particle-assisted methane combustion

This paper established a model of the coaxial dielectric barrier discharge (DBD). Ar-CH4 is fed into the mixture as a working gas. Using 10.0 kHz as power research in different voltage and dielectric materials and medium thickness has influences on producing active particle mole fraction. The simulation results show that when the voltage increase, the molar concentration of O3 and H energetic particles increase obviously. When the thickness of the medium increases, the molar concentration of O3 and H decreases. When the dielectric constant of the dielectric material increases, the molar concentration of O3 and H also increases. The molar concentration of OH active particles also changed, but the law was unclear. At the same time, when the discharge voltage is 15 kV, the dielectric thickness is 2 mm, the dielectric constant is 3.75, and the DBD discharge is uniform and stable, the molar concentration of O3 and H is 0.069% and 0.056% respectively. The corresponding concentrations of O3 and H active particles were introduced into the established methane combustion reaction model. The study found that the joining of O3 and H energetic particles make the reaction begin to move significantly ahead of time. That has a promoting effect on the rate of the methane combustion reaction. In the methane combustion reaction model with different equivalence ratios, O3 with a molar concentration of 0.069% and H with a molar concentration of 0.056% introduced, it is concluded that these two active particles also have a tremendous promoting effect on the expansion of the thin burning limit of methane.

Investigation of silver nanoparticle synthesis with various nonthermal plasma reactor configurations

In this work is investigated the effect of nonthermal plasma reactor configurations on the synthesis of silver nanoparticle (AgNP) comparing three reactor configurations: (i) coaxial dielectric barrier discharge (DBD), (ii) like-free ground DBD, and (iii) corona plasma discharge. To make the AgNP synthesis cost-effective and eco-friendly, no reducing agent was used and to get stable particles, instead inexpensive sucrose was used as capping agent. The formation and stability of AgNP were verified using ultraviolet–visible (UV–Vis) spectroscopy and energy dispersive spectroscopy (EDS). The concentration and stability of AgNP were found to be dependent on various process parameters, with the optimal conditions of applied voltage, gas flow rate, treatment time, nozzle distance, silver nitrate concentration and sucrose concentration determined at 12 kV, 1.5 L/min, 180 s, 1.0 cm, 0.5 mM, and 20 mM, respectively. The surface morphology and particle size distribution (PSD) obtained with transmission electron microscopy (TEM) showed that the nanoparticle (NP) synthesized by coaxial DBD and corona plasma were spherical in shape with a wide PSD, and their average size was 6.2 nm and 9.6 nm, respectively. On the other hand, those NP synthesized by like-free ground DBD were mostly spherical, along with a few hexagon and triangular shapes. With like-free ground DBD, the PSD was found to be significantly narrower, and the average particle size was 20 nm which is bigger compared to NP synthesized by coaxial DBD and corona plasma. Better performance of AgNP synthesis by the like-free ground DBD is most likely due to higher energy delivery capacity.

Efficient deactivation of aerosolized pathogens using a dielectric barrier discharge based cold-plasma detergent in environment device for good indoor air quality

Air pollution is one of the top 5 risks causing chronic diseases according to WHO and airborne transmitted pathogens infection is a huge challenge in the current era. Long living pathogens and small size aerosols are not effectively dealt with by the available indoor air purifiers. In this work, a dielectric barrier discharge (DBD) based portable cold-plasma detergent in environment device is reported and its disinfection efficiency has been analyzed in the indoor environment of sizes up to 3 × 2.4 × 2.4 m3. The deactivation efficiency of total microbial counts (TMCs) and total fungal counts (TFCs) is found to be more than 99% in 90 min of continuous operation of the device at the optimized parameters. The complete inactivation of MS2 phage and Escherichia coli bacteria with more than 5 log reduction (99.999%) has also been achieved in 30 min and 90 min of operation of the device in an enclosed environment. The device is able to produce negative ions predominantly dominated by natural plasma detergent along with positive ions in the environment similar to mother nature. The device comprises a coaxial DBD geometry plasma source with a specially designed wire mesh electrode of mild steel with a thickness of 1 mm. The need for feed gas, pellets and/or differential pressure has been eliminated from the DBD discharge source for efficient air purification. The existence of negative ions for more than 25 s on average is the key advantage, which can also deactivate long living pathogens and small size aerosols.

Non-Oxidative Ethane Dehydrogenation in a Packed-Bed DBD Plasma Reactor

Plasma-assisted conversion of ethane (C2H6) can produce value-added chemical building blocks using green electricity. Here we employ a simple packed-bed coaxial dielectric barrier discharge (DBD) reactor to convert C2H6 at mild operating conditions unattainable by conventional thermocatalysis. Ethylene (C2H4), acetylene (C2H2), and methane (CH4) are the main products along with small fractions of C3 and C4 hydrocarbons. Interestingly, the C2H4 selectivity is primarily correlated to C2H6 conversion, dominated by electron dissociation and recombination reactions irrespective of the dielectric properties of the packed bed material (SiO2, Al2O3, ZrO2, TiO2, and BaTiO3), packing material size, supplied power, and C2H6 concentration. While a distortion of the electric field and discharge propagation results in varying dissipated power as materials change, the C2H4 energy yield remains constant. The particle size appears to affect conversion mainly due to pressure alterations. Pd/SiO2 catalyst can change the selectivity, favoring saturated species by expending hydrogen.

Experimental study on burning velocity, structure, and NOx emission of premixed laminar and swirl NH3/H2/air flames assisted by non-thermal plasma

This paper investigates the effect of dielectric barrier discharge (DBD) plasma on premixed laminar and swirl NH3/H2 flames by applying a coaxial DBD to the unburned gas mixture. We focused on analyzing the flame structure, burning velocity, lean blow-off limit, and NOx emission characteristics of premixed NH3/H2 flames in the presence and absence of plasma. The mechanism of plasma-enhanced burning velocity was revealed through kinetic simulations based on the CHEMKIN software. The results indicate that DBD plasma can reduce the laminar flame height and increase the laminar burning velocity (LBV). The chemical kinetic effect is dominant for the enhancement of LBV, while the effect of hydrogen generated from ammonia dissociation and ozone is relatively weak. DBD plasma can significantly change the structure of the swirl flames, while has a slight effect on extending the lean blow-off limits of the swirl flames. Finally, emission measurements indicate that DBD plasma increases the NOx emissions for both the premixed laminar and swirl NH3/H2 flames. This effect can be attributed to the reaction pathways involving of H and OH radicals for NOx formation. It is assumed that the effect of hydrogen and DBD plasma on stability and burning velocity is synergistic, while the effect of hydrogen and plasma on NOx emissions is competitive.

Basic metal oxide integrated DBD packed bed reactor for the decomposition of CO2

A coaxial dielectric barrier discharge (DBD) reactor was used to perform catalytic non-thermal plasma for CO2 conversion under ambient conditions. A systematic study was made to understand the role of basic oxides in activating weakly acidic CO2. For this purpose, MO/γ-Al2O3 (M = Mg, Ca, Sr, and Ba) catalysts were synthesized and integrated with the DBD reactor. The applied voltage was varied from 16 kV to 22 kV to determine the effect of applied voltage on CO2 conversion. Plasma discharge generates high-energy electrons that activate the basic oxides. Integration of basic metal oxides with the non-thermal plasma reactor resulted in a higher CO2 conversion. The adsorption of weakly acidic CO2 on the basic sites is responsible for the higher conversion of catalytic plasma reactor over plasma reactor alone. Among the basic metal oxides studied, SrO loaded γ-Al2O3 resulted in the best conversion, where CO2 conversion of ∼ 12% and energy efficiency of ∼ 1.46 mmol kJ−1 was attained at a power of 1.8 W. The concentration of O2 and O3 was measured during the reaction. The hybridized system's superior performance may be due to increased charge deposition and altered gas-phase chemistry because of catalyst integration. BOLSIG + software was used to compute the mean electron energies and electron energy distribution function for various packing conditions.

Biomass volatiles reforming by integrated pyrolysis and plasma-catalysis system for H2 production: Understanding roles of temperature and catalyst

Biomass utilization is considered a carbon–neutral way to simultaneously tackle the energy crisis and environmental contamination. Challenges still exist to hinder its application, such as low products yield, tar blockage, harsh condition and inferior stability. This paper aims to study whether the newly developed integrated pyrolysis and plasma-catalysis system can be applied into practice of H2 production from real biomass volatiles, and to understand roles of temperature and catalyst. The experiments were performed in a two-stage reactor embedded with a coaxial dielectric barrier discharge plasma zone. Impacts of operating conditions (i.e. discharge power, steam input, heat supply and catalyst packing) on H2 production were investigated. The results show that proper input of discharge power and steam can promote H2 production. Heating supply is recognized as two different effects on plasma-only and plasma-catalysis systems, since reaction temperature elevation acts as inhibitor to plasma characters and cut down the contribution of plasma reforming. After packing bimetallic Ni-Fe/γ-Al2O3 catalyst into plasma, optimal 47.65 mmol/g of H2 can be attained at reforming temperature of 500 ℃, with synergy effects observed. Plasma-catalysis system also outperformed in tar cracking, tar elimination and stability test, attributed to plasma assistance. This work provides an alternative to construct a new plasma-catalysis process for H2 production from biomass volatiles or to couple plasma technology with existing biomass conversion industries for preferable energy and fuel production, highlighting its promising commercialization prospects.

Testing of Sr-Doped ZnO/CNT Photocatalysts for Hydrogen Evolution from Water Splitting under Atmospheric Dielectric Barrier Plasma Exposure.

Nonthermal plasma is a well-recognized environmentally advantageous method for producing green fuels. This work used different photocatalysts, including PZO, SxZO, and SxZCx for hydrogen production using an atmospheric argon coaxial dielectric barrier discharge (DBD)-based light source. The photocatalysts were produced using a sol-gel route. The DBD discharge column was filled with water, methanol, and the catalyst to run the reaction under argon plasma. The DBD reactor was operated with a 10 kV AC source to sustain plasma for water splitting. The light absorption study of the tested catalysts revealed a decrease in the band gap with an increase in the concentration of Sr and carbon nanotubes (CNTs) in the Sr/ZnO/CNTs series. The photocatalyst S25ZC2 demonstrated the lowest photoluminescence (PL) intensity, implying the most quenched recombination of charge carriers. The highest H2 evolution rate of 2760 μmol h-1 g-1 was possible with the S25ZC2 catalyst, and the lowest evolution rate of 56 μmol h-1 g-1 was observed with the PZO catalyst. The photocatalytic activity of S25ZC2 was initially high, which decreased slightly over time due to the deactivation of the photocatalyst. The photocatalytic activity decreased from 2760 to 1670 μmol h-1 g-1 at the end of the process.

Non-Thermal Plasma Incorporated with Cu-Mn/γ-Al2O3 for Mixed Benzene Series VOCs’ Degradation

In this work, a coaxial dielectric barrier discharge (DBD) reactor was constructed to degrade the mixture of toluene and o-xylene, two typical benzene series. The Cu-MnO2/γ-Al2O3 series catalysts prepared by redox and impregnation methods were filled into the plasma device to degrade VOCs synergistically and explore the degradation effect. The experimental results showed that the introduction of a Cu-doped MnO2 catalyst significantly improved the pollutants’ removal efficiency and CO2 selectivity, and greatly inhibited the formation of by-products. Among them, Cu0.15Mn/γ-Al2O3 showed the highest removal efficiency (toluene was 100% and o-xylene was 100%), and the best CO2 selectivity (92.73%). The XRD, BET, XPS and SEM results confirmed that the synergistic effect between Cu and Mn in the Cu-Mn solid solution could promote the amount and reducibility of the surface active oxygen species, which improved the catalytic performance. Finally, the toluene and o-xylene decomposition pathways in the NTP catalytic system were speculated according to the detected organic matter. This work provides a theoretical and experimental basis for the application of DBD-catalyzed hybrid benzene series VOCs.