Barrier Discharge Reactor Research Articles

Investigation of flow characteristics in a twin-surface dielectric barrier discharge reactor by Schlieren imaging

Dielectric barrier discharges are an emerging technology for the plasma-catalytic removal of volatile organic compounds and other gas purification challenges such as the removal of O2 traces from H2. Packed-bed reactors are mainly used for these applications, but surface dielectric barrier discharges (SDBDs) typically printed on thin dielectric plates are promising alternatives for the treatment of large volumetric flow rates due to their low flow resistance causing a low pressure drop. Especially for SDBDs the flow conditions are crucial, because the active plasma filled volume covering the mentioned plates with a typical thickness of 0.1 mm is small in comparison to the overall reactor volume with a typical distance of some tens of millimeters to the reactor wall. In this study, the flow conditions of a twin-SDBD were investigated by Schlieren imaging applied in converting O2 traces in H2 containing gas mixtures to H2O and compared to fluid dynamics simulations. Schlieren imaging was used to visualize local gradients of the refractive index inside the SDBD reaction chamber, while gas composition, dissipated power, or flow rate were varied. Without a plasma discharge, laminar flow dominates, resulting in a conversion below 10% over a Pt-coated electrode configuration in the reaction of O2 traces with H2. With the plasma discharge, full conversion was achieved for the same reaction without catalyst, although the plasma is also confined to the surface of the electrode configuration. Schlieren structures covering the complete cross section of the reaction chamber were observed, showing that strong radial mass transport is induced by the plasma. The shape and extent of the Schlieren structures is ascribed to a superimposition of gas flow, thermal expansion from the plasma volume, thermal buoyancy as well as an electrohydrodynamic force between the electrodes and the grounded reactor walls. Fluid dynamics simulations show vortex formation above and below the electrode, created by the electrohydrodynamic force further implying extensive mass transport by the plasma, which is visualized in addition by carbonaceous deposits on the reactor lid. This emerging deposition pattern during toluene decomposition closely corresponds to the electrode geometry. It is proposed that the reaction proceeds only in the active plasma volume and that reactive species transported to the bulk gas phase only have a minor contribution. Thus, the degree of conversion of the SDBD reactor is not only determined by the chemical reactivity in the plasma volume, but also by its plasma-induced mass transport resulting in efficient gas mixing. These findings reveal new possibilities to improve SDBD reactors for gas purification applications based on their favorable flow conditions.

Nonthermal Plasma‐Assisted CO2‐H2O Conversion over NiO and Co3O4 Supported on CeO2

AbstractTransformation of CO2 into value‐added chemicals remains a key challenge. Herein, nonthermal plasma (NTP)‐activated CO2‐H2O conversion over BaTiO3‐mixed NiO/CeO2 (Ni/Ce+) and Co3O4/CeO2 (Co/Ce+) catalysts is demonstrated. In a continuous‐flow dielectric barrier discharge reactor and under ambient conditions, optimum Co/Ce+ showed formation rates of CO and O2 of (43.6 ± 3.1) and (20.8 ± 0.7) μmol g−1h−1, respectively. CO2 conversion was found to be dependent on a combination of the basicity of the catalyst surface, CO2 flow rate, plasma input power, and relative humidity. Subsequently, kinetic analysis suggested that the activation energies over Ni/Ce+, Co/Ce+, and NiCo/Ce+ are 35.68, 15.61, and 25.88 kJ mol−1, respectively. By combining these findings, a plausible reaction mechanism that can facilitate understanding the trend of product formation is also provided.

Removal of free cyanide in dry-milled cassava flour using atmospheric nonthermal plasma treatment

The primary concern for the cassava industry is reducing hydrogen cyanide (HCN) in the final product to a level that meets the Codex standard. Wet milling and drying to produce cassava starch can reduce cyanide compounds to levels that are safe for human consumption and meet international regulations, but at a high cost in terms of water. The purpose of this study was to investigate the effect of atmospheric nonthermal (ANT) plasma treatment on the removal of free cyanide from dry-milled cassava flour, as well as other physical and chemical properties. To generate cold plasma, helium was used as the feed gas in a dielectric barrier discharge reactor. The results show that the first-order kinetic model can explain the fraction degradation of cyanide by ANT plasma. The rate of HCN fraction removal increased from 0.0116 min−1 to 0.0453 min−1 and 0.0119 min−1 to 0.0349 min−1 with increasing voltage level (10–20 kV) when the initial HCN were 143 ± 7 and 233 ± 5 mg kg−1 dw, respectively. The 20 kV-15 min ANT plasma treatment of cassava flour containing 143 ± 7 mg kg−1 dw reduced 35.7% of HCN without affecting starch crystallinity, protein, fiber, fat, or moisture content, but significantly changed the pasting properties (P < 0.05).

Dry reforming in a dielectric barrier discharge reactor with non-uniform discharge gap: Effects of metal rings on the discharge behavior and performance

The application of dielectric barrier discharge (DBD) plasma reactors is promising in various environmental and energy processes, but is limited by their low energy yield. In this study, we put a number of stainless steel rings over the inner electrode rod of the DBD reactor to change the local discharge gap and electric field, and we studied the dry reforming performance. At 50 W supplied power, the metal rings mostly have a negative impact on the performance, which we attribute to the non-uniform spatial distribution of the discharges caused by the rings. However, at 30 W supplied power, the energy yield is higher than at 50 W and the placement of the rings improves the performance of the reactor. More rings and with a larger cross-sectional diameter can further improve the performance. The reactor with 20 rings with a 3.2 mm cross-sectional diameter exhibits the best performance in this study. Compared to the reactor without rings, it increases the CO2 conversion from 7% to 16 %, the CH4 conversion from 12% to 23%, and the energy yield from 0.05 mmol/kJ supplied power to 0.1 mmol/kJ (0.19 mmol/kJ if calculated from the plasma power), respectively. The presence of the rings increases the local electric field, the displaced charge and the discharge fraction, and also makes the discharge more stable and with more uniform intensity. It also slightly improves the selectivity to syngas. The performance improvement observed by placing stainless steel rings in this study may also be applicable to other plasma-based processes.

Degradation of trichloroethylene by double dielectric barrier discharge (DDBD) plasma technology: Performance, product analysis and acute biotoxicity assessment

Trichloroethylene is carcinogenic and poorly degraded by microorganisms in the environment. Advanced Oxidation Technology is considered to be an effective treatment technology for TCE degradation. In this study, a double dielectric barrier discharge (DDBD) reactor was established to decompose TCE. The influence of different condition parameters on DDBD treatment of TCE was investigated to determine the appropriate working conditions. The chemical composition and biotoxicity of TCE degradation products were also investigated. Results showed that when SIE was 300 J L−1, the removal efficiency could reach more than 90%. The energy yield could reach 72.99 g kWh−1 at low SIE and gradually decreased with the increase of SIE. The k of the Non-thermal plasma (NTP) treatment of TCE was about 0.01 L J−1. DDBD degradation products were mainly polychlorinated organic compounds and produced more than 373 mg m−3 ozone. Moreover, a plausible TCE degradation mechanism in the DDBD reactors was proposed. Lastly, the ecological safety and biotoxicity were evaluated, indicating that the generation of chlorinated organic products was the main cause of elevated acute biotoxicity.

NaCl aqueous solution as a novel electrode in a dielectric barrier discharge reactor for highly efficient ozone generation

Ozone (O3) generated by a dielectric barrier discharge (DBD) is widely used in various industrial processes. In this study, NaCl aqueous solution was used as a novel electric power transmission electrode in a DBD reactor (instead of a traditional metal electrode) for highly efficient ozone generation. The results demonstrated that a high O3 yield of 242 g kWh−1 with a concentration of 14.6 g m−3 O3 was achieved. The power transmission mechanism works because NaCl aqueous solution behaves as a capacitor when an alternating pulse voltage below 8 kHz is used. Compared with the resistance of the discharge barrier and discharge space, the resistance of NaCl aqueous solution can be ignored, which ensures that O3 is generated efficiently. It is expected that O3 generation using NaCl aqueous solution as a novel electrode in a DBD reactor could be an alternative technology with good application prospects.

Soot oxidation over V/ZSM-5 catalysts in a dielectric barrier discharge (DBD) reactor: Performance enhancement by transition metal (Mn, Co and Fe) doping

The oxidation of soot particles over a series of M-V/ZSM-5 (M = Mn, Co and Fe) catalysts was examined in a cylindrical dielectric barrier discharge (DBD) plasma reactor. Soot particles were completely removed in plasma reactor at 60th minute of reaction. The Mn-V/ZSM-5 catalyst showed higher catalytic activity of soot particles than Co-V/ZSM-5, Fe-V/ZSM-5 and VOx/ZSM-5 catalyst in the plasma reactor. However, the variation in CO2 selectivity was opposite to the change in soot oxidation rate. Catalyst characterizations of N2 adsorption-desorption, X-ray diffraction (XRD), X-ray photoelectron spectrometry (XPS) and temperature programmed reduction of hydrogen (H2-TPR) were performed to gain insights of the relationships between catalyst properties and performance of plasma-catalytic soot oxidation. The results substantiated that the concentration of Oads had the most significant effect on the soot oxidation process, while the specific surface area of the M-V/ZSM-5 catalysts showed only minor influence. Moreover, the relative contents of oxygen and V5+ species of the M-V/ZSM-5 catalysts were also the major factors affecting soot oxidation. In addition, higher discharge power and oxygen content were conducive to accelerating soot oxidation. The stability tests showed that the Mn-V/ZSM-5 catalyst maintained good catalytic activity after three cycles of plasma-induced experiments.

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.

Structured Catalysts for Non-Thermal Plasma-Assisted Ammonia Synthesis

Ammonia has been intensively studied as a clean, sustainable fuel source and an efficient energy storage medium due to its effectiveness as a hydrogen carrier molecule. However, the currently used Haber–Bosch process requires a large fossil fuel input, high temperatures and pressures, as well as a significant capital investment. These constraints prevent decentralized and small-scale ammonia production at the level of small farms and local communities. Non-thermal plasma (NTP) can promote ammonia synthesis in operating conditions in which, in a conventional process, a catalyst is generally not active. In this study, the production of NTP-assisted catalytic ammonia at milder temperatures and ambient pressure was investigated. Four different structured catalysts were prepared and tested using an experimental plant based on a dielectric barrier discharge (DBD) reactor. The effect of the gas hourly space velocity (GHSV) was investigated, as well as the effect of the N2/H2 ratio on catalyst performance. The results evidenced that the best catalytic activity (about 4 mmol h−1 of produced NH3) was obtained using the 10Ni/zeolite 13X sample with the lowest energy consumption, thus highlighting the feasibility of this innovative technology in this field.

Plasma-assisted fluidized-bed atomic layer deposition of Pd-Cu nanoparticles on porous powder for CO2 hydrogenation

A novel plasma-assisted fluidized-bed atomic layer deposition process to synthesize Pd-Cu bimetallic nanoparticles is reported, using palladium hexafluoroacetylacetonate, copper(I)-N, N′-di-iso-propylacetamidinate and H2 plasma. The process allows us to uniformly deposit Pd-Cu nanoparticles in porous powder, which is a mixture of γ-Al2O3 (30 wt%), amorphous aluminum silicate (50 wt%) and molecular sieve (20 wt%) (ASM). With metal loadings of 13.1 and 2.5 mg g−1 for Pd and Cu, respectively, the afforded 13.1Pd-2.5Cu catalyst shows excellent catalytic performance for the hydrogenation of CO2 in a dielectric barrier discharge reactor with no intentional heating. Under the condition of discharge input power of 24.6 W, H2-to-CO2 ratio of 4 in feed gas, and gas hourly space velocity of 7595 h−1, the conversion of CO2 can reach as high as 38.0%, with the CH4 and CH3OH product selectivities of 6.7% and 12.8%, respectively. Density functional theory calculations are further employed to understand the associated CH3OH formation mechanism.

Exploring Simultaneous Upgrading and Purification of Biomass−Gasified Gases Using Plasma Catalysis

Tar and substantial CH4 and CO2 are contained in gasified fuels, which pose an obstacle to direct chemical synthesis, and this is a predominant challenge for biomass gasification technology. Herein, a packed−bed dielectric barrier discharge (DBD) reactor was built for simultaneous CH4 dry reforming and tar removal with a La−Ni/γ−Al2O3 catalyst. The interaction between CH4 dry reforming and tar removal in plasma catalysis was investigated. The results indicated that plasma catalysis can achieve high−efficiency simultaneous tar removal and CH4 dry reforming, as indicated by the reactants’ conversion (14% increase for CCH4 and CCO2 at 450 °C in the presence of tar and a 37% increase for the tar removal rate at 360 °C when CH4 and CO2 were introduced), and the mechanism for mutual promotion of CH4 dry reforming and tar removal was elucidated through catalyst characterization results. In addition, a possible reaction mechanism for tar removal via plasma catalysis was proposed. These findings provide valuable insights for simultaneous upgrading and purification of gases generated by biomass gasification.

OZONE GENERATOR BASED ON SURFACE DIELECTRIC BARRIER DISCHARGE WITH PULSE POWER SUPPLY

A pilot model of an ozone generator with a pulsed power supply has been developed. The ozone generator can be used for disinfection of domestic and industrial premises, in medicine and the chemical industry. Ozone is generated by a surface dielectric barrier discharge reactor (SDBD), consisting of 18 parallel-connected quartz tubes, inside and outside of which spiral the stainless steel high-voltage electrodes are wound. The measurements of the main parameters of the ozone generator showed that the ozone concentration reached 57 mg/l, and the output ozone concentration is 9.4 g/h. The developed design takes into account the technical features of the implementation of a particular type of discharge used, allows reducing energy consumption for ozone generation, having improved output parameters.

Insights into the Role of Nanorod-Shaped MnO2 and CeO2 in a Plasma Catalysis System for Methanol Oxidation.

Published papers highlight the roles of the catalysts in plasma catalysis systems, and it is essential to provide deep insight into the mechanism of the reaction. In this work, a coaxial dielectric barrier discharge (DBD) reactor packed with γ-MnO2 and CeO2 with similar nanorod morphologies and particle sizes was used for methanol oxidation at atmospheric pressure and room temperature. The experimental results showed that both γ-MnO2 and CeO2 exhibited good performance in methanol conversion (up to 100%), but the CO2 selectivity of CeO2 (up to 59.3%) was much higher than that of γ-MnO2 (up to 28.6%). Catalyst characterization results indicated that CeO2 contained more surface-active oxygen species, adsorbed more methanol and utilized more plasma-induced active species than γ-MnO2. In addition, in situ Raman spectroscopy and Fourier transform infrared spectroscopy (FT-IR) were applied with a novel in situ cell to reveal the major factors affecting the catalytic performance in methanol oxidation. More reactive oxygen species (O22-, O2-) from ozone decomposition were produced on CeO2 compared with γ-MnO2, and less of the intermediate product formate accumulated on the CeO2. The combined results showed that CeO2 was a more effective catalyst than γ-MnO2 for methanol oxidation in the plasma catalysis system.

Reaction mechanism explorations on non-thermal plasma reforming of CO2-CH4 by combining kinetics modeling and emission spectroscopy measurements

Plasma-based dry reforming in an atmospheric dielectric barrier discharge (DBD) reactor has been thoroughly studied by combination of experiments and detailed kinetics simulation. With the assistances of in-situ optical emission spectroscopy (OES) measurements and reaction pathway analysis based on plasma kinetic simulation considering non-constant electric field and thermal effects, this study provided deep insights into the reaction mechanism of plasma-based dry reforming under varied feeding gas composition, gas residence time and operation temperature. A CH4 conversion as high as 44.76 % could be achieved without catalyst at 300 °C, with an SEI of 78 J/cm3 and feeding CH4 ratio of 50 %. Increase of feeding CH4 proportions were found to enhance the generation of C2 and C3 hydrocarbons. Consistently, the OES analysis showed that the relative intensities of spectra bands induced by deexcitation of CH, CO, and C2 also increased monotonically. With the same increment in SEI, increasing gas residence time led to larger promotions in CH4 and CO2 conversion, as being compared to increase of input power. The reason could be explained as that CH4 and CO2 molecules experienced more successive micro-discharges with a longer gas residence time, so more energy would be devoted into CH4/CO2 conversion, whereas more energy was dissipated into heat as rudely increased the discharge power due to the limit of reaction time. CO2 conversion continuously decreased with increasing gas temperature, owing to the recombination of CO and O enhanced at higher gas temperatures. Reaction pathway analysis showed that CH4 conversion was mainly induced by electronic dissociation and ionization at the discharge stage, while CO2 was mainly converted by recombination reaction CO2 + CH2 → CH2O + CO and also electron collision vibrational reaction e + CO2 → e + CO2(vn). The formation of C2 hydrocarbon products was supposed to follow the path of CH4 ↔ CH3/CH → C2H6 ↔ C2H5 ↔ C2H4 → C2H2.

Effect of non-thermal plasma dielectric barrier discharge reactor on the quality of biomass gasification product gas from the gasifier

The primary goal of this research is to determine the effect of key processing parameters of dielectric barrier discharge (DBD) reactor on the components concentration of the fuel gas produced during the biomass gasification. By changing key processing parameters such as plasma input power, flow rate, and temperature, the performance of the DBD reactor is assessed. When the power is increased from 5 to 40 W, the concentrations of CO2 and H2 decrease to 12.9% and 18.5%, respectively, while the concentration of CO increases to 17.2%. At 40 W and 65 ml/min, the amount of tar compound significantly drops from 33 g/Nm3 to less than 1 g/Nm3. However, as input power increases, the concentration of C1–C5 hydrocarbons also tends to rise. The highest concentration of C1–C5 was around 0.60% at 40 W. As the flow rate increases, the concentration of CO2 increases while the concentration of CO tends to decrease at all measured power levels, the maximum concentration of CO2 was at 120 ml/min, whereas the minimum concentration of CO is seen under same conditions. With an increase in flow rate, the concentration of CH4 shows a decreasing tendency. It is seen that at 40 W, the concentration of CO and H2 drops as the temperature rises up to 400 °C. In contrast, there is a rising trend in the concentration of CO2, CH4, and tar compounds while increasing temperature. Hence, the DBD reactor appears to have a profound influence on a gas component produced during biomass gasification.

Nano-Au supported on CeO2 for plasma catalytic degradation of n-undecane: Enhancement of activity and stability

n-Undecane (C11) is a typical alkane pollutant, accounting for 6 % of the total volatile organic compounds (VOCs) emitted from the printing industry in China. A dielectric barrier discharge (DBD) reactor coupled with a catalyst of abundant oxygen vacancies prepared by Au nanoparticles 100 % loading on CeO2 was developed for the plasma catalytic degradation of C11. Compared with CeO2, CeO2/γ-Al2O3, Au/γ-Al2O3, and Au/CeO2/γ-Al2O3, Au/CeO2 exhibited significantly higher C11 oxidation performance with 98.8 % C11 conversion and 97.9 % COx selectivity. The strong interaction between nanosized Au and CeO2 enhanced the ratios of Ce3+/(Ce3++Ce4+) and Au+/(Au++Au0), resulting in the formation of abundant oxygen vacancies with the highest band gap energy, which facilitated C11 oxidation. In addition, the reservation of reactive oxygen species generated by gas discharges on Au/CeO2 catalyst synergistically promoted C11 complete oxidation, thus improving the oxidation stability within 600 min with stable C11 conversion and COx selectivity. This work presents an effective strategy to regulate the performance of catalysts for VOCs oxidation, and demonstrates that the plasma catalytic degradation of VOCs is feasible.

Synergistic effect of plasma power and temperature on the cracking of toluene in the N2 based product gas

In this research, a dielectric barrier discharge (DBD) reactor is used to study the cracking of the toluene into C1–C6 hydrocarbons. The combined effect of parameters such as temperature (20–400 °C) and plasma power (10–40 W) was investigated to evaluate the DBD reactor performance. The main gaseous products from the decomposition of toluene include lower hydrocarbon (C1–C6). The cracking of toluene increases with power at all temperatures (20–400 °C). On the otherhand, it decreases from 92.8 to 73.1% at 10 W, 97.2 to 80.5% at 20, 97.5 to 86.5% at 30 W, and 98.4 to 93.7% at 40 W with raising the temperature from 20 to 400 °C. Nonetheless, as the temperature and plasma input power increase, the methane yield increases. At 40 W, the maximum methane yield was 5.1%. At 10 and 20 W, the selectivity to C2 increases as the temperature rises up to 400 °C. At 30 and 40 W, it began to drop after 300 °C due to the formation of methane and the yield of methane increases significantly beyond this temperature.

Synergistic effects of plasma and catalyst in formaldehyde conversion over a Ni/α-Al2O3 catalyst in a dielectric barrier discharge reactor

Plasma-catalytic conversion of formaldehyde, as a representative volatile organic compound, in a dielectric barrier discharge reactor over a NiOx/α-Al2O3 catalyst was studied. Effects of plasma treatment on the physicochemical properties of the catalyst were studied and XPS analysis showed that plasma treatment increased the surface contribution of more active sites (i.e. Ni2+ and adsorbed O). However, the physical properties of the catalyst, including BET surface area and porosity, did not significantly change after plasma exposure. Presence of oxygen in the plasma-catalytic process improved conversion efficiency. Individual roles of plasma and catalyst in the selective conversion of formaldehyde to CO2, as the desired product, were decoupled. It was found that, in the oxygen-containing atmosphere, plasma can enhance formaldehyde conversion due to the facilitating role of O2-derived intermediates, such as ozone, while catalyst improves selectivity toward CO2 through catalyzing the complete oxidation path. Catalysts can make a substantial improvement in CO2 selectivity compared to the corresponding plasma-only conditions, even in an oxygen-free environment. Comparison between plasma-only, catalyst-only, and plasma-catalytic conditions with in-plasma catalyst (IPC) and post-plasma catalyst (PPC) configurations showed that CO2 yield decreased in the following order: IPC > PPC > catalyst-only > plasma-only. Superior performance under IPC conditions was due to: i) the improved catalyst properties upon plasma treatment; ii) facilitated CHO formation due to the impacts of both plasma and catalyst; iii) dominance of catalytic reaction steps after CHO formation resulting in the improved CO2 selectivity in the presence of a catalyst. The CO2 yield in the IPC system was greater than the summation of CO2 yield in the plasma-only and catalyst-only conditions, demonstrating the synergistic effects of plasma and catalyst. These results provide new insights into the facilitating role of oxygen in formaldehyde conversion, the beneficial role of catalyst in CO2 selectivity, and synergistic effects of plasma and catalyst in formaldehyde conversion over a NiOx/α-Al2O3 catalyst.

Ru- and Rh-Based Catalysts for CO2 Methanation Assisted by Non-Thermal Plasma

The need to reduce the concentration of CO2 in the atmosphere is becoming increasingly necessary since it is considered the main factor responsible for climate change. Carbon Capture and Utilization (CCU) technology offers the opportunity to obtain a wide range of chemicals using this molecule as a raw material. In this work, the catalytic Non-Thermal Plasma (NTP)-assisted hydrogenation of CO2 to CH4 (methanation reaction) in a Dielectric Barrier Discharge (DBD) reactor was investigated. Four different Ru- and Rh-based catalysts were prepared starting from γ-Al2O3 spheres, characterized and tested in both thermal and NTP-assisted methanation under different operating conditions. The experimental tests evidenced the very positive effect of the NTP application on the catalytic performance, highlighting that for all the catalysts the same CO2 conversion was reached at a temperature 150 °C lower with respect to the conventional thermal reaction. Among the prepared catalysts, the bimetallic ones showed the best performance, reaching a CO2 conversion of 97% at about 180 °C with a lower energy consumption with respect to similar catalysts present in the literature.

Plasma catalytic technology for CH4 and CO2 conversion: A review highlighting fluidized‐bed plasma reactor

AbstractThe plasma catalytic valorization of gases, particularly CH4 and CO2, has gained increasing attention. Value‐added chemicals, such as syngas and ethene, can be formed under mild conditions when temperature‐decoupled plasma activation and multistep feasible catalytic conversion are combined. In this sense, efficient plasma–catalyst interaction is of key importance, for which, however, plasma catalysis, as an emerging technology, is still poorly studied, where new catalyst design and investigation took up the most effort. In this perspective work, the challenging but equally important plasma–catalyst interaction is discussed, comparatively analyzing which type of plasma, catalyst bed, is the most promising. Representative plasma catalytic systems with their characteristic features are summarized, where the intrinsic capability of fluidized‐bed dielectric barrier discharge (FB‐DBD) reactor to maximize the plasma–catalyst interaction is highlighted. Furthermore, ongoing research on FB plasma catalysis is reviewed, based on which the superiority of FB‐DBD to other candidates, especially the most widely used packed‐bed DBD reactor, is critically evaluated. In addition, the perspectives of FB‐DBD, including challenges and development potential, are discussed.