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A multiple-capillary Ar plasma jet was successfully generated by an advanced dielectric barrier discharge reactor. The reactor consisted of four quartz capillaries arranged separately and covered by two ring-shaped electrodes, which were isolated by a liquid dielectric. The advantages of the reactor included less Ar consumption (ranging from 1 to 3 L/min to obtain a total cross-sectional area of four individual plasma flow components of 3.14 mm2 at the capillary orifices) and low gas temperatures (not exceeding 40 °C). The obtained temperature is suitable for implementing various biomedical applications such as wound healing, dental treatment, and cancer therapy. Furthermore, the plasma jet spread when it interreacted with dielectric materials or skin, resulting in an enlarged effective plasma treatment area of approximately 8 mm2. Analysis of optical emission spectra of the plasma jet indicated the existence of several reactive species, suggesting that the plasma device holds potential for biomedical applications and material surface treatments. [ABSTRACT FROM AUTHOR]

The dependence of the plasma discharge performance on the size of the honeycomb monolith in a sandwich-type honeycomb monolith plasma reactor operated under humidified air conditions was investigated. In addition, the effect of the feed gas temperature on the plasma discharge was also examined in the low-temperature range (25 °C–42 °C), which is similar to the typical temperature of the actual surrounding ambient air. The results showed that variation of the temperature significantly affects the discharge power, i.e., the discharge power decreases with increasing temperature. The results also indicated that, in the absence of the honeycomb monolith in the reactor, the plasma discharge did not occur inside the discharge zone created by two parallel perforated disks. However, when the honeycomb monolith was sandwiched between the two electrodes, the discharge developed between them because of the generated surface discharge spread through the honeycomb channels. Interestingly, a parallel relationship exists between monoliths with two different diameters in terms of their energy density and energy efficiency for O3 generation. These results suggest that the use of a monolith with a small diameter, instead of the original large commercial monolith, is sufficient when conducting research on the honeycomb discharge, as it facilitates experimental design. [ABSTRACT FROM AUTHOR]

This document is a correction notice for an article titled "Generation of Multiple Jet Capillaries in Advanced Dielectric Barrier Discharge for Large-Scale Plasma Jets" published in the journal Plasma Chemistry & Plasma Processing. The correction states that the co-author name "Quang Hung Trinh" was inadvertently missed in the original version of the article, but has now been included in the author group. The publisher, Springer Nature, remains neutral regarding jurisdictional claims and institutional affiliations. The corrected article can be found online at the provided link. [Extracted from the article]

The effects of the position of the current probe on electrical measurements as well as those of typical materials on the current of a He plasma jet during the interaction of the plasma jet with surface materials were investigated using a dielectric barrier discharge reactor, in which the two electrodes were isolated from ambient air by electrical insulating oil. Here, we demonstrate accurate discharge power measurement obtained by positioning the current probe between the two electrodes rather than on the ground wire. The emission current of the plasma jet increased sharply upon the interaction with a ground-connected metal surface, because in this case, the surface functioned as a second ground electrode. Similarly, important is that the average velocity of a plasma bullet can be estimated from the phase shift of the current waveforms at different positions. The phase shift can be monitored by an oscilloscope using a cursor tool during the plasma discharge process. The average velocity of the plasma bullets in this paper ranged from 56 to 266 km/s. [ABSTRACT FROM AUTHOR]

This work focused on the factors affecting the effective generation of corona discharge plasma in a honeycomb catalyst reactor. Pd, Co, and Ag were used as the active metal catalysts to investigate the plasma formation and decomposition of ethylene. Unlike the Ag-coated honeycomb catalyst, which resulted in excessive arcing, the Co-coated honeycomb monolith was able to generate stable plasma, but the discharge power was insufficient to decompose ethylene at an acceptable level. The incorporation of a small amount of Pd with Co significantly enhanced the discharge power and the ethylene removal performance. The catalytic activity of the prepared catalyst for the removal of ethylene was evaluated using plasma catalytic oxidation and thermal catalytic oxidation. ANOVA was used to assess the effect of single process factors and their relationships in the plasma process. All the process factors such as specific energy input (SEI), ethylene concentration, and flow rate were found to affect the ethylene conversion, CO 2 selectivity, and energy efficiency (EE). Under the optimal conditions, i.e., an SEI of 80 J/L, an ethylene concentration of 20 ppm, and a flow rate of 20 L/min, the ethylene conversion was 85 %, CO 2 selectivity was 70 %, and EE was 0.86 g/kW h. [Display omitted] • Stable corona plasma formation using Co/ZSM-5/monolith and Co-Pd/ZSM-5/monolith. • Bimetallic catalyst shows better catalytic activity than monometallic catalyst. • Ag/ZSM-5/monolith creates numerous arcing and poor plasma formations. • ANOVA with F-test investigates the relationship between the influential factors and NTP reaction activity. [ABSTRACT FROM AUTHOR]

This study focused on the removal of styrene using a metal-coated monolith (MCM) catalyst integrated with non-thermal plasma. The MCM catalyst was prepared by depositing a ZSM-5 support impregnated with a combination of three metals (Co, Pd, La) on a practical-scale honeycomb monolith. A comparative study with a commercial metal-coated monolith (CMCM) of the same dimensions was conducted to evaluate the effectiveness of the MCM with respect to styrene removal. The plasma discharge in the monolith was characterized by measuring the voltage and current waveforms and optical emission spectroscopy (OES). The electric power of the plasma discharge largely depended on the metal loading, flow rate, and humidity of the feed gas. The removal efficiency of styrene (inlet concentration: 20 parts per million, volumetric (ppm)) was examined using both plasma catalytic oxidation (PCO) and thermal catalytic oxidation (TCO), to enable the effect of plasma to be clearly assessed. PCO with the MCM catalyst achieved styrene removal efficiency of nearly 100% at a specific energy input (SEI) of 40 J/L, whereas the CMCM catalyst achieved 92% removal for identical SEI. In comparison, TCO with the MCM and CMCM catalysts required high temperatures of 420 °C and 480 °C, respectively, for the complete removal of styrene. In addition, the CO 2 selectivity of the MCM catalyst was higher at 83% compared with 75% for the CMCM at SEI of 40 J/L. The optimal silica binder content for the deposition of a robust washcoat layer was found to be approximately 5%. [Display omitted] • Uniform robust coating layer of ZSM-5 was obtained using the washcoating method. • Uniform honeycomb plasma was generated using the MCM/CMCM catalysts. • Styrene was removed at room temperature using plasma catalytic oxidation. [ABSTRACT FROM AUTHOR]

The challenge that needs to be overcome regarding the removal of nitrogen oxides (NOx) and soot from exhaust gases is the low activity of the selective catalytic reduction of NOx at temperatures fluctuating from 150 to 350 °C. The primary goal of this work was to enhance the conversion of NOx and soot simulant by employing a Ag/α-Al2O3 catalyst coupled with dielectric barrier discharge plasma. The results demonstrated that the use of a plasma-catalyst process at low operating temperatures increased the removal of both NOx and naphthalene (soot simulant). Moreover, the soot simulant functioned as a reducing agent for NOx removal, but with low NOx conversion. The high efficiency of NOx removal required the addition of hydrocarbon fuel. In summary, the combined use of the catalyst and plasma (specific input energy, SIE ≥ 60 J/L) solved the poor removal of NOx and soot at low operating temperatures or during temperature fluctuations in the range of 150–350 °C. Specifically, highly efficient naphthalene removal was achieved with low-temperature adsorption on the catalyst followed by the complete decomposition by the plasma-catalyst at 350 °C and SIE of 90 J/L. [ABSTRACT FROM AUTHOR]

Nitrogen fixation (NF) was investigated in a rotational gliding arc plasma based on various energy inputs, flow rates, and N 2 :O 2 ratios under atmospheric conditions. For practical application, the effect of water content in the feed, self-heating during plasma discharge, prolonged operation, and comparison between plasma and thermal process for N 2 oxidation were also conducted. The comparison results reveal that NF by the gliding arc plasma is superior to the thermal process in terms of NO x yield and energy consumption at low temperatures and atmospheric pressure. Herein, energy input and flow rate are two controlled factors that significantly influence NO x production rate. Simultaneously, O 2 content played a crucial role in determining NO x yield, selectivity of NO/NO 2, and energy consumption. Observations during plasma discharge indicated an initial rise in gas and reactor body temperatures, coinciding with decrease in total NO x formation. Moreover, the presence of water had a negative effect on NO x yield. Accordingly, the optimized conditions for NF by gliding arc plasma for NO x formation was identified at a N 2 to O 2 ratio of 3:2 without water vapor in the feed gas. Furthermore, a 14-h continuous operational test validated the robustness of our reactor configuration, affirming its long-term viability. The study concludes by performing oxidation of the NO x gas followed by dissolution in water, successfully generating nitric acid. These findings underscore the potential of gliding arc plasma for efficient NF processes, offering insights into optimal operational conditions and downstream applications for nitric acid generation. [Display omitted] • Effective N 2 oxidation to form NO x by gliding arc plasma. • Optimized gas feed ratio for the plasma process was N 2 :O 2 = 3: 2. • Water vapor in feed led to a decrease in NO x yield and energy efficiency. • Efficient operation of reactor for long duration with stable NO x generation. • HNO 3 was produced via N 2 fixation. [ABSTRACT FROM AUTHOR]

[Display omitted] • In-plasma is superior to injected-plasma catalysis for NO x removal at low temperatures. • Significant synergy between plasma and catalyst for NO x removal at low temperatures. • NO x removal efficiency up to 70% by assisting plasma at [200–250 °C] temperature. • Energy delivery through plasma is better than a thermal process for NO x removal. • Injected-plasma catalysis has potential applications in circumstantial high-throughput gas. Plasma-assisted hydrocarbon selective catalytic reduction (HC-SCR) of NO x was investigated by a packed Ag/γ-Al 2 O 3 catalyst in a dielectric barrier discharge reactor at low temperatures. The effect of plasma discharge on NO x removal was investigated with two methods for comparison, in- and injected-plasma catalysis systems. In-plasma catalysis comprised a plasma-catalytic discharge with the entire feed gas, and injected-plasma catalysis incorporated a part of feed gas consisting of dodecane pretreated with the plasma-catalytic discharge and mixed with the remaining gas before passing through the catalyst-alone stage. Here, using the surface response method with temperature and specific energy input (SEI) as independent variables, the results revealed that energy delivery through plasma gained more NO x removal efficiency than that by thermal catalyst process; a set of SEI and temperature is needed to obtain a similar level of NO x removal. There is a significant synergy between plasma and catalyst in in-plasma catalysis at low temperatures (≤250 °C) that increased NO x removal efficiency up to Δη = 50% (SEI = 137 J/L; T = 200 °C). In-plasma catalysis is superior to injected-plasma catalysis for enhancing the NO x removal and widening the temperature window of effective NO x removal owing to the plasma-catalytic interface in-plasma catalysis supplies. Interestingly, the results also revealed that the plasma in the catalyst for both methods did not always improve the NO x removal efficiency. The plasma had a negative effect on NO x removal at sufficient temperature and SEI. As a result, the in-plasma catalysis presented a high NO x removal efficiency; it can be higher than 70% at temperatures of 200–250 °C. However, injected-plasma catalysis has potential applications in circumstantial high-throughput gas due to low plasma energy consumption by adjusting the entire feed to plasma-treated gas ratio. [ABSTRACT FROM AUTHOR]

[Display omitted] • Stable plasma generation in reactor configuration comprising multiple honeycomb monoliths. • Linear relationship between discharge power and increased number of monoliths. • High ethylene adsorption capacity in an open channeled monolith catalyst at humid conditions. • Higher ethylene removal efficiency with high energy yield at low energy requirement. • Simplified overall system and operation at atmospheric conditions. Dilute ethylene (C 2 H 4) was removed in a novel plasma reactor comprising multiple honeycomb monoliths consisting of up to four PdO/ZSM-5/monolith catalysts. These monoliths were packed in a tubular reactor separated by mesh electrodes alternatively grounded or connected to a high voltage (HV) power source. The effect of the number of monoliths on the discharge power, adsorption, and removal of C 2 H 4 was investigated. Additionally, the influence of the energy input, C 2 H 4 inlet concentration, and gas flow rate on the C 2 H 4 abatement was examined. The adsorption capacity, C 2 H 4 conversion, and energy efficiency were observed to increase as the number of monoliths increased. The effect of the palladium (Pd) loading technique, namely ion exchange (IE), incipient wetness impregnation (IM), and combined IE-IM, IE followed by IM, on the C 2 H 4 adsorption was also studied. The combined IE-IM method presented an exceptional adsorption capacity of ∼136 µmol/g catalyst under humid conditions despite nonpolar nature of C 2 H 4. C 2 H 4 removal was performed via both continuous and cycled storage-discharge (CSD) plasma-catalytic oxidation processes. The CSD process was conducted in two ways: with intermittent C 2 H 4 feed (CSD-IEF) and with maintained C 2 H 4 feed (CSD-MEF), both comprising intermittent plasma discharge. Intriguingly, the performance of the CSD-MEF process was superior (56 J/L, 1.61 g/kWh) to that of the CSD-IEF (119 J/L, 0.98 g/kWh), and continuous process (∼228 J/L, 0.53 g/kWh) in terms of energy efficiency as well as the overall simplicity of the system. [ABSTRACT FROM AUTHOR]

Combined removal of n-heptane and CO using a catalytic reactor coupled with dielectric barrier discharge plasma was investigated over several metal oxide catalysts including bare γ-Al 2 O 3 , Ag 2 O/γ-Al 2 O 3 , MnO/γ-Al 2 O 3 , RuO 2 /γ-Al 2 O 3 and PdO/γ-Al 2 O 3 . In order to effectively utilize the heat generated during plasma discharge for enhancing catalytic reactions, the plasma-catalytic reactor was thermally insulated by covering it with a glass wool jacket. Plasma propagated radially outward from the central high-voltage electrode with gradually increasing the applied voltage, and the temperature decreased with the radial distance due to the decreased plasma intensity, exhibiting a volcanic temperature distribution. The increased reactor temperature could improve the removal of CO and the selectivity toward CO 2 . The results obtained from separate experiments of n-heptane and CO removal showed that the PdO/γ-Al 2 O 3 was the best for the simultaneous removal purpose. The effects of specific input energy ( SIE ), oxygen content, reaction temperature and PdO loading on the simultaneous removal of n-heptane and CO and the formation of byproducts were examined. The removal efficiencies of n-heptane obtained with different catalysts were similar to one another, whereas the removal of CO strongly depended on the type of catalyst. The catalytic activity for the oxidation of CO followed the order: MnO/γ-Al 2 O 3 < Ag 2 O/γ-Al 2 O 3 < RuO 2 /γ-Al 2 O 3 < PdO/γ-Al 2 O 3 . In the present plasma-catalytic hybrid reactor, the mixture of n-heptane and CO was mainly converted into CO 2 , and under an optimized condition, the selectivity toward CO 2 reached 100%. [ABSTRACT FROM AUTHOR]

The effective removal of acetaldehyde by humidified air plasma was investigated with a high throughput of contaminated gas in a sandwiched honeycomb catalyst reactor at surrounding ambient temperature. Here, acetaldehyde at the level of a few ppm was successfully oxidized by the honeycomb plasma discharge despite the harsh condition of large water content in the feed gas. The conversion rate of acetaldehyde increased significantly with the presence of catalysts coating on the surface channels. The increased conversion rate was also obtained with a high specific energy input (SEI) and total flow rate. Interestingly, the conversion changed negligibly under the acetaldehyde concentration range from 5 to 20 ppm. However, the conversion rate decreased toward increased water amount in the feed gas. Notably, about 60% of acetaldehyde in the feed was oxidized under SEI of 40 J/L at water amounts ≤ 2.5%, approximately 0.5 g/kWh for acetaldehyde removal. Also, the plasma-catalyst reaction was superior to the thermal reactive catalyst for acetaldehyde removal in airborne pollutants. In comparison with other plasma-catalyst sources for acetaldehyde removal, the energy efficiency under the condition is comparable. Moreover, the honeycomb plasma discharge features high throughput, avoiding pressure drop, and straightforward reactor configuration, suggesting potential practical applications. [Display omitted] • Generation of large humid air plasma volume by a sandwich honeycomb plasma reactor. • Capable of practical plasma application for acetaldehyde removal in atmosphere. • Treating high throughput of simulated indoor emission of acetaldehyde. • High efficiency acetaldehyde removal although humid conditions. [ABSTRACT FROM AUTHOR]

The effect of the reactor configuration and several key parameters such as the gas temperature, humidity, and flow rate on the corona discharge plasma in honeycomb monoliths was investigated. The AC corona discharge-based plasma reactor consisted of two parallel electrodes (perforated disk/wire-mesh) placed at both ends of the honeycomb monolith. Although the wire-mesh electrode offers increased sharpness, the perforated disk electrode, where the corona discharge started at the sharp edges of the holes, produced more discharge power because of the larger effective electrode area. Loading a small amount of metal onto the monolith was found to increase the discharge power significantly. Coating the monolith with a zeolite such as ZSM-5 (Si/Al: 23.9) led to a decrease in the discharge power because of its hydrophobic nature and large surface area. The result also revealed that the operating temperature, the humidity of the feed gas, and the gas velocity were key factors affecting the discharge performance. The discharge power was inversely proportional to the temperature. On the other hand, the use of a high-velocity feed gas with high water vapor content was found to be particularly advantageous for obtaining high discharge power. ga1 • A honeycomb plasma reactor for practical-environmental applications. • Successful generation of large-volume air plasma in commercial monoliths. • Enhancing discharge power by metal-coating over commercial monolith. • Increase in discharge power with increasing either air flow rate or humidity. [ABSTRACT FROM AUTHOR]

• The methane conversion shows its maximum in terms of particle size. • The concept of microelectrodes explains the existence of maximum conversion. • By adjusting particle size, selectivity can be controlled without catalyst. • In terms of coke formation, non-porous silica particles are favored. • Coke is more produced when large particles are used. A dielectric barrier discharge (DBD) plasma reactor was employed for non-oxidative coupling of methane. The coupling reaction in the DBD plasma bed was conducted near atmospheric pressure and room temperature. In the bed, dielectric materials such as ordered mesoporous silica (KIT-6), sea sand silica, and α-Al 2 O 3 were employed. This non-catalytic reaction system could successfully activate C H bond to produce methyl radicals and light hydrocarbons without additional thermal energy and oxidant molecules. The gap distance between dielectric particles was determined by their sizes, which was experimentally shown. The effects of gap distance were found significant on the conversion and the selectivity. The existence of maximum conversion at a specific gap distance was experimentally observed and could be described successfully by using a newly developed concept of micro-electrodes. Based on the concept, the minimum threshold electric potential difference between the dielectric particles could be successfully estimated, where the conversion was shown to be maximized. Furthermore, it seemed quite possible to control the compositions of ethane, ethylene, and acetylene by properly adjusting the size or the gap distance of particles. [ABSTRACT FROM AUTHOR]