Low Specific Energy Input Research Articles

Experimental study and process evaluation of coproduction graphene, acetylene and hydrogen from methane pyrolysis by thermal plasma

This paper developed a process for the coproduction of graphene, acetylene and hydrogen from methane pyrolysis by thermal plasma. Bench-scale tests under three specific energy input (SEI) were carried out to investigate the morphology of carbon nanomaterials and the product selectivity. The process was evaluated by exergy and exergoeconomic analyses. Results indicated that a higher SEI improved the selectivity of graphene nanoflakes (GNFs) and reduced their defects. The product selectivity of GNFs played a critical role in the decrease of total fuel exergy per unit of GNFs as the SEI increased. The plasma reactor exhibited the highest exergy loss ratio in the entire process due to heat dissipation. The quenching device exhibited the second-highest exergy loss ratio in the process, stemming from irreversible entropy increase causing exergy loss. Improving the design of the plasma reactor to enhance thermal efficiency and implementing a feasible waste heat recovery system were identified as effective strategies to enhance exergy efficiency. Excluding consideration of co-products, GNFs with high SEI had the lowest cost of 199.41 CNY/kg, when co-products were considered, the lowest cost decreases by 30%, and the low SEI had the lowest GNFs cost at 140.71 CNY/kg. This indicated that there was enough investment potential to tailor the properties of GNFs produced by such processes for application scenarios. The unit exergy cost of GNFs decreased from 0.89 CNY/MJ to 0.80 CNY/MJ as the SEI of the plasma reactor increased. Subsequently, it rose to 1.16 CNY/MJ. Prioritizing the increase in investment costs for the plasma reactor to reduce exergy loss costs should be considered first, and optimizing the waste heat recovery process was also a key direction to minimize exergy loss costs.

Methane conversion using spark discharge-assisted laser-induced plasma (SD-LIP) with Pd catalyst: Non-oxidative hydrogen production

Today, methane combustion gives rise to the tremendous release of carbon dioxide into the atmosphere. Finding an efficient method to convert methane into value-added compounds has attracted significant attention, along with mitigating greenhouse gas emissions. Here, the spark discharge-assisted laser-induced plasma (SD-LIP) is investigated in conjunction with the palladium (Pd) catalyst. In the proposed electro-photocatalyst reactor, a Q-switched Nd:YAG laser with a pulse duration of 10 ns- 120 mJ/pulse is utilized to ignite the spark discharge. Laser irradiation plays a pivotal role in inducing electric breakdown by injecting electrons and Pd nanoparticles into the electrode gap at atmospheric pressure. The results indicate that the electron density increases against the traditional spark discharge method. The breakdown voltage notably decreases due to the inverse Bremsstrahlung (IB) phenomenon, reducing specific energy input (SEI). Consequently, energy conversion efficiency (ECE) improves by 14 % having a very low SEI, ranging from 1 to 3 kJ/L. Furthermore, the novel reactor design of SD-LIP reveals the creation of heavier hydrocarbons (Iso-butane) in favor of slight coke formation. Laser decarbonization slows down catalytic deactivation through successive shots. In fact, SD-LIP gives rise to high efficiency in the methane conversion to hydrogen, where high carbon balance preservation (>97 %) is realized.

Prospective electric heavy oil upgrading at ambient pressure by high energy electron beam

To alleviate increasing problems of greenhouse gas emissions, two approaches should be deployed: the development of sustainable energy technologies such as wind and solar to reduce the share of fossil fuels, and greener refining and upgrading technologies of fossil/bio-fuels. Here, we introduce an electric method that uses high energy electron beam to achieve heavy oil upgrading in a methane environment at ambient pressure with nearly zero GHG emissions. Two extra-heavy crude oil samples were treated by the electron beam at different conditions. Conversion and yields to gasoline and diesel range fuels were quantified. Detailed economic analysis shown that using low specific energy input (SEI or dose), 500 kJ/kg, <$1.5/barrel, this upgrading process converts heavy fractions (>C40, ∼20 $/barrel) to stable intermediate products (C10–C24, ∼75 $/barrel) in diesel range. No coke was found in treated oil. Product yields (C10–C24) were ∼9 molecules/100 eV, comparable with thermal methods. Sufficient product separation is crucial to the success of this method. This method is electrically driven, easily adaptable to renewable intermittent electricity. It has potentially zero GHG emissions, and is attractive for on-site upgrading of heavy/bio fuels and integration with distributed renewable energy.

Low-energy ammonium recovery by a combined bio-electrochemical and electrochemical system

Bio-electrochemical systems (BESs) can recover ammonium at low specific energy inputs and can produce hydrogen gas. A reason hampering development of large-scale applications for ammonium recovery is the general instability of the bio-generated current and the thereby variable TAN (ammonia and ammonium) effluent concentrations. Electrochemical systems for ammonium recovery, such as the hydrogen recycling electrochemical system (HRES), can fine-tune the applied current, but require higher specific energy inputs than BES, and may require an additional external hydrogen supply in case of HRES. This research presents for the first time an integrated BES and HRES system for ammonium recovery to combine the advantages of both types of systems to achieve high TAN removal efficiency at low specific energy input. The HRES was able to partially compensate for BES instability, which resulted in an overall high TAN removal efficiency (89–95 %) at an increased energy demand of 5.2–10.2 MJ/kgN. When the BES was performing stably and efficiently, the HRES removed almost all of remaining TAN at up to 99.8 % overall TAN removal efficiency, requiring 9.2 MJ/kgN. The combined system can remove TAN down to much lower effluent concentrations at little to no additional energy input. These results indicate that combining BES and HRES in one system can result in TAN recovery that is more efficient than in each system separately, which could facilitate new application possibilities for (bio-)electrochemical ammonium recovery.

Mechanochemical Synthesis of RuCo/MgTiO3 Catalysts for Nonthermal Plasma-Assisted Ammonia Synthesis

The development of robust yet effective catalysts is vital for promoting nonthermal plasma (NTP)-assisted ammonia (NH3) synthesis toward practical applications. Herein, we report a simple mechanochemical synthesis method (via ball milling) for preparing bimetallic RuCo supported on MgTiO3 catalyst (i.e., RuCo/MgTiO3-6-500) to be used in NTP-assisted catalytic NH3 synthesis. The physicochemical properties of the developed catalysts were investigated systematically with respect to the relevant process parameters of ball milling. Catalytic tests showed that, at a low specific energy input of 15 kJ L–1, the developed RuCo/MgTiO3-6-500 catalyst exhibited a high NH3 synthesis rate and an energy efficiency of ∼50 μmol min–1 gcat–1 and 1.54 gNH3kWh–1, respectively, which outperformed the monometallic Ru or Co control catalysts. Additionally, the energy barriers were calculated as a function of N2/H2 ratio for the NTP-catalytic NH3 synthesis over RuCo/MgTiO3-6-500, and the results were interpreted together with the activity data measured during the catalysis. It was found that the energy barrier approach may not be appropriate for discussing the energy required for the dynamics of interest in the NTP-catalytic system. Compared to MgTiO3-packed and plasma-alone systems, results by in situ optical emission spectroscopic (OES) diagnosis of the plasma-catalytic systems showed that the presence of active metal sites (i.e., Ru and/or Co) could intensify the activation and dissociation rates of N2 and H2 molecules, showing the relatively higher peak intensity of NH, N2*, N2+, and Hα species. However, based on the obtained information, the possible roles of Ru and/or Co in NTP-assisted ammonia synthesis system are difficult to be identified.

Application of Emerging Cell Disintegration Techniques for the Accelerated Recovery of Curcuminoids from Curcuma longa

Curcuminoids, the bioactive compounds with many beneficial effects on human health, exist in Curcuma longa (turmeric). In the present study, the impact of different cell disintegration techniques to enhance total curcuminoid recovery (TC) from fresh and dried turmeric was investigated. The impact of thermal pretreatment (TP), ultrasound pretreatment (UP), enzyme pretreatment (EP), and pulsed electric field pretreatment (PEF) on the recovery of curcumin (CUR), demethoxycurcumin (DMC), and bis-demethoxycurcumin (BDMC) from fresh and dried turmeric were studied. The cell disintegration index (Zp) and high-performance liquid chromatography (HPLC) analysis of curcuminoids were performed to evaluate the efficiency of the applied techniques. With fresh turmeric, the highest curcuminoid recovery was 83.6 mg/g dry basis with EP. The highest structural tissue damage was obtained with UP achieving a cell disintegration level of 92.5%. The technology with the highest time-saving and low specific energy input was PEF with a total curcuminoid recovery of 80.9 mg/g dry basis. Working with dried turmeric, the drying required high specific energy input for 72 h at 50 °C; however, the untreated dried sample reached 125.3 mg/g dry basis of TC without further pretreatment after drying.

Plasma-Induced Catalytic Conversion of Nitrogen and Hydrogen to Ammonia over Zeolitic Imidazolate Frameworks ZIF-8 and ZIF-67.

Microporous crystals have emerged as highly appealing catalytic materials for the plasma catalytic synthesis of ammonia. Herein, we demonstrate that zeolitic imidazolate frameworks (ZIFs) can be employed as efficient catalysts for the cold plasma ammonia synthesis using an atmospheric dielectric barrier discharge reactor. We studied two prototypical ZIFs denoted as ZIF-8 and ZIF-67, with a uniform window pore aperture of 3.4 Å. The resultant ZIFs displayed ammonia synthesis rates as high as 42.16 μmol NH3/min gcat. ZIF-8 displayed remarkable stability upon recycling. The dipole-dipole interactions between the polar ammonia molecules and the polar walls of the studied ZIFs led to relatively low ammonia uptakes, low storage capacity, and high observed ammonia synthesis rates. Both ZIFs outperform other microporous crystals including zeolites and conventional oxides in terms of ammonia production. Furthermore, we demonstrate that the addition of argon to the reactor chamber can be an effective strategy to improve the plasma environment. Specifically, the presence of argon helped to improve the plasma uniformity, making the reaction system more energy efficient by operating at a low specific energy input range allowing abundant formation of nitrogen vibrational species.

Plasma-enhanced low temperature NH3-SCR of NOx over a Cu-Mn/SAPO-34 catalyst under oxygen-rich conditions

In this work, a dielectric barrier discharge (DBD) plasma-enhanced NH3-selective catalytic reduction (NH3-SCR) of NOx over a Cu-Mn/SAPO-34 catalyst at low temperatures (<200 °C) and oxygen-rich conditions (14 vol.%) has been investigated using a two-stage post-plasma-catalytic (PPC) configuration. The results show a maximum NOx removal of 80 % and a 100 % N2 selectivity without NH3 slip or the formation of by-products at a low specific energy input (SEI) of 32 J/L. Adding water vapor (5.7 vol.%) into the plasma NH3-SCR process does not negatively affect the removal of NOx, while the presence of C3H6 enhances the removal of NOx. In situ diffuse reflectance infrared spectroscopy (DRIFTS) combined with optical emission spectroscopic diagnostics has been employed to elucidate the reaction mechanism in the plasma-catalytic removal of NOx. We find that the formation of NO2 via NO oxidation in the first stage plasma gas-phase reaction enhances the Eley-Rideal (E–R) reaction on the surface of the Cu-Mn/SAPO-34 catalyst in the second stage catalytic NH3-SCR of NOx. The Cu-Mn/SAPO-34 catalyst shows stable performance in the plasma-enhanced NH3-SCR of NOx after 5 cycles of catalyst regeneration. This work has successfully demonstrated a promising low-temperature plasma-catalytic solution for the effective NH3-SCR of NOx.

A novel energy efficient path for nitrogen fixation using a non-thermal arc.

Plasma-assisted nitrogen fixation is a promising sustainable and clean alternative to the classical Haber–Bosch process. However, the high energy consumption and low production rate of plasma-assisted nitrogen fixation limit its application. This study shows that the non-thermal (non-equilibrium) enhancement of the arc plasma significantly reduces the energy consumption of nitrogen fixation. The highest energy efficiency with high NO selectivity is observed with a low specific energy input (SEI). However, the highest production rate is reached at a high SEI. The studied process offers high NO selectivity (up to 95%) with low energy consumption (∼48 GJ per tN) at 0.1 kJ L−1 SEI, which is much lower than the previously reported value of plasma-assisted atmospheric nitrogen fixation and is close to that of the Haber–Bosch process.

N-decane decomposition by microsecond pulsed DBD plasma in a flow reactor

N-decane decomposition with plasma to obtain prone detonation gaseous fuel is investigated by adopting fuel liquid film feeding mode at applied voltage of 10 kV and 15 kV, discharge frequency of 300–3000 Hz with interval 100 Hz. The result shows that the discharge parameters can regulate the composition and the concentration of the cracked products. When the composition of the product is unchanged, the concentration and proportion of the components can be increased as the discharge frequency becomes higher. The hydrogen concentration increases 3.4 times and 2.3 times respectively for the applied voltage of 15 kV and 10 kV as the discharge frequency is increased from 500 to 3000 Hz. However, the voltage has no effect on the proportion of the components, and increasing the voltage only increases the concentration of the species. For selectivity, raising the discharge frequency can greatly increase the species selectivity of hydrogen and acetylene that are most prone to detonate. The selectivities of hydrogen and acetylene are the highest at 15 kV and 3 kHz, reaching 18.40% and 4.22% respectively, and at this time, the selectivity of ethylene is the lowest, which is 60.4%. Besides, it is confirmed that high selectivity can be achieved at the lower specific energy input causing by low-voltage/high-frequency discharge. Through the analysis of the bond dissociation energy, there is a competitive relationship between the production of ethylene, ethane and pentane which all consume ethyl, and two possible pathways for the production of acetylene are put forward.

Selectivity control of H2/O2 plasma reaction for direct synthesis of high purity H2O2 with desired concentration

Low selectivity is one of the key problems which limit the application of plasma in chemical fields. High selectivity and concentration of H2O2 are critical in the direct synthesis of H2O2. Herein, we report that the selectivity of the H2/O2 plasma reaction can be controlled by specific energy input (SEI), i.e. low SEI leads to high H2O2 selectivity. When the SEI was fixed at 2.08J/ml, the H2O2 selectivity reached 91% with 17% O2 conversion, and a H2O2 solution with high concentration (90wt.%) was achieved. Plasma diagnostics and theoretical calculation results indicate that, low SEI results in low electron density, which leads to high H2O2 selectivity but low O2 conversion. Furthermore, the collision cross sections of H2 and O2 molecules with electrons indicate that the H2/O2 plasma, with average electron energy of 1–1.5eV, can synthesize H2O2 with high selectivity and high O2 conversion.

Determination of quantitative structure-property and structure-process relationships for graphene production in water

A scalable method for graphene and few-layer graphene (FLG) production by graphite delamination in aqueous solutions of the nonionic surfactant TWEEN®80 (TW80) using stirred-media mills is presented. Delaminated product analysis using statistical Raman spectroscopy yielded extensive processing-structure-property relationships that revealed how stress intensity and specific energy input, i.e., the process parameters, govern the yield of graphene production and defect formation. The dispersed carbon concentration increased but the content and the quality of the FLG product decreased sharply with higher specific energy input. The FLG content of the product was up to 90%, especially for low specific energy input. Moreover, Raman analyses revealed that stress intensities greater than about 1 nJ were related to significant defect formation in the product particles. Another key parameter for graphene production is solvent viscosity. The FLG concentration in the product increased by a factor of 10 when the solvent’s viscosity was increased from 1 to 6 mPa·s because shear- and friction-induced delamination was enhanced and in-plane fracture was reduced due to dampening of bead motion. Based on the processing-structure-property relationships found, we propose that the delamination process can be designed in such way that the product consists, almost totally, of FLG and that single-layer graphene is produced. The scalability of graphene production by stirred-media delamination was demonstrated when an increase in the batch size from 0.2 to 2 L had no significant effect on product quality.

Simultaneous dissociation of CO2 and H2O to syngas in a surface-wave microwave discharge

In this research, conversion of carbon dioxide and water vapor into value-added chemicals has been investigated in a pulsed surfacewave sustained microwave discharge operating under different conditions. Formation of syngas (CO/H2) was observed. The influence of the gas mixture ratio, the specific energy input (SEI), Espec, and the feed flow rate on H2 and CO production, was studied. It is found that syngas with a ratio close to 1 can be produced when CO2 – H2O ratio in the gas mixture is 50:50. The optimum SEI for H2 and CO formation for this gas mixture ratio is 1.6 eV/mol. Experiments carried out with Ar/H2O showed that the presence of CO2 supports the H2 formation at low SEI. Increasing the feed flow rate, i.e. reducing the residence time, hinders the H2 yield while the CO yield initially decreases and reaches a stable level. The highest energy conversion efficiency is calculated to be at low SEI and low flow rate. Optical emission spectroscopy measurements show that comparatively high dissociation rates correspond to low gas temperatures.

A parametric study of non-thermal plasma synthesis of silicon nanoparticles from a chlorinated precursor

Silicon nanoparticles (Si NPs) synthesized in non-thermal plasma with silicon tetrachloride (SiCl4) are anticipated as a non-toxic and inexpensive Si source for important applications. This study examines the crystallinity, yield, and size distribution of Si NPs in terms of specific energy input (SEI) for 2.5–65 J cm‒3 and the H2/SiCl4 ratio (1–10). The particle growth mechanism is discussed comprehensively. Atomic hydrogen (H) production using non-thermal plasma is the primary important step for SiCl4 dechlorination at low temperatures. The Si NP yield increases with SEI (plasma power divided by total gas flow) because SiCl4 conversion increases with energy fed into the unit volume of the feed gas. At low SEI, Si NPs were mostly in amorphous material because of insufficient plasma heating. A maximum yield of 50 wt% was obtained when SEI = 10 J cm‒3 (H2/SiCl4 = 10) with a crystal fraction of about 1%. Increased SEI is necessary to improve crystal fraction, but excessive SEI decreases the NP yield remarkably. The NP yield losses correspond to increasing NP-free thin film growth on the reactor wall. Mass spectrometry shows that SiCl4 is highly decomposed with greater SEI. Hydrogen chloride (HCl) increases as a by-product. At higher SEI, particle nucleation and subsequent growth are suppressed.

The Processing Behavior of Liquid Sn/Molten Polyethylene during Internal Mixing

Abstract In our study, liquid tin (Sn) was mixed with molten polyethylene using an internal mixer; the interfacial tension between the liquid Sn and molten polyethylene was measured using the deformed drop retraction method. The results showed that liquid Sn separated when the Sn content was higher than approximately 2 % by volume because of the interfacial tension of up to 167 mN/m and the 106-fold viscosity difference between the liquid Sn and the molten polyethylene. When Sn separation did not occur, the effects of the mixing time and rotary speed on the degree of mixing and the Sn particle size were analyzed using thermogravimetric analysis and scanning electron microscopy. The results showed that the effects of mixing time and rotary speed on the degree of mixing and Sn particle size can be combined as the impact of specific energy input. With increasing specific energy input, the degree of mixing initially increased and subsequently remained constant, while the Sn particle size initially decreased and subsequently remained constant. The refinement of the dispersed phase was completed with a low specific energy input, but the homogenization of the dispersed phase required a higher specific energy input to achieve completion, revealing the relationship between distributive mixing and dispersive mixing.

Combined treatment of alkaline and disperser for improving solubilization and anaerobic biodegradability of dairy waste activated sludge

An investigation into the influence of combined alkaline and disperser pretreatment on sludge disintegration was studied. The effects of four variables, alkalines (NaOH, KOH, Ca(OH)2), treatment time (15–180min), pH (8–11) and rpm (4000–24,000) were investigated. The effect of sludge pretreatment was evaluated by COD solubilization, suspended solids reduction and biogas production. The best performances, in terms of COD solubilization, SS reduction and biogas production, were the ones that occurred for specific energy input of 4544kJkg−1 TS for NaOH at pH10, were found to be 24%, 23.3% and 76%, higher than the control, respectively. Not only the increase in biogas production was investigated, excluding protein hydrolysis was also performed successfully by this combined pretreatment even at low specific energy input. Thus, this chemo-mechanical is an effective method for enhancement of biodegradability and it laid the basis to produce higher biogas quantities, to improve clean energy generation from WAS.

Plasma assisted dissociation of hydrogen sulfide

Dissociation of hydrogen sulfide has been studied in four different discharges: AC corona, dielectric barrier, streamer, and contracted glow discharge. All experiments were done in a single geometry, close to a plug flow reactor, with the goal of fair comparison. The performance of corona discharge and DBD was studied in the initial gas temperature range of 300–1200 K. A specific energy requirement (SER) was calculated as function of energy input for each type of discharge and compared with earlier experimental results and modeling. The results showed that discharges with high E/n and low specific energy input (corona, DBD, and streamer) perform much worse than those with low E/n (contracted glow discharge) where specific energy input was high and gas temperature was elevated. The SER for non-thermal dissociation was 12–14 eV/molec. However, in the case of the contracted glow discharge, SER decreased to 2.4 eV/molec. This SER is close to the value predicted by thermodynamic equilibrium modeling. Further reduction of SER in a plug flow reactor does not seem possible.

Combined (alkaline + ultrasonic) pretreatment effect on sewage sludge disintegration

The individual effects of alkaline (pH 8-13) and ultrasonic (3750–45,000 kJ/kg TS) pretreatments on the disintegration of sewage sludge were separately tested, and then the effect of combining these two methods at different intensity levels was investigated using response surface methodology (RSM). In the combined pretreatment, ultrasonic treatment was applied to the alkali-pretreated sludge. While the solubilization (SCOD/TCOD) increase was limited to 50% in individual pretreatments, it reached 70% in combined pretreatment, and the results clearly showed that preconditioning of sludge at high pH levels played a crucial role in enhancing the disintegration efficiency of the subsequent ultrasonic pretreatment. By applying regression analysis, the disintegration degree (DD) was fitted based on the actual value to a second order polynomial equation: Y = −172.44 + 29.82 X 1 + 5.30 × 10 −3 X 2 − 7.53 × 10 −5 X 1 X 2 − 1.10 X 1 2 − 1.043 × 10 −7 X 2 2, where X 1, X 2, and Y are pH, specific energy input (kJ/kg TS), and DD, respectively. In a 2D contour plot describing the tendency of DD with respect to pH and specific energy input, it was clear that DD increased as pH increased, but it seemed that DD decreased when the specific energy input exceeded about 20,000 kJ/kg TS. This phenomenon tells us that there exists a certain point where additional energy input is ineffective in achieving further disintegration. A synergetic disintegration effect was also found in the combined pretreatment, with lower specific energy input in ultrasonic pretreatment yielding higher synergetic effect. Finally, in order to see the combined pretreatment effect in continuous operation, the sludge pretreated with low intensity alkaline (pH 9)/ultrasonic (7500 kJ/kg TS) treatment was fed to a 3 L of anaerobic sequencing batch reactor after 70 days of control operation. CH 4 production yield significantly increased from 81.9 ± 4.5 mL CH 4/g COD added to 127.3 ± 5.0 mL CH 4/g COD added by pretreatment, and this enhanced performance was closely related to the solubilization increase of the sludge by pretreatment. However, enhanced anaerobic digestion resulted in 20% higher soluble N concentration in the reactor, which would be an additional burden in the subsequent nitrogen removal system.

De‐agglomeration and Dispersion of Nano‐TiO2 in an Agitator Bead Mill

The de‐agglomeration and dispersion of nano‐TiO2 powder is little reported, although nano‐TiO2 powder has been widely used due to its unique optical properties. In this study, an agitator bead mill (MiniZETA 03E, Netzsch) accompanied with an ultrasonicator was employed to de‐agglomerate the nano‐TiO2 powder in butyl acetate, and the effects of ultrasonic pretreatment, dispersant dosage, agitation speed, solid content of TiO2 suspension, and bead diameter were systemically investigated. It is found that ultrasonic pretreatment leads to short grinding time to reach the limiting fineness, low specific energy input, and small limiting mean size. All other technical parameters have also some influence on the limiting fineness and grinding time. However, the former strongly depends on agitation speed while the latter on both agitation speed and dispersant dosage. A solvent‐borne nano‐TiO2 suspension with limiting mean size of 110 nm can be successfully result under the optimal technical conditions and showed excellent UV‐shielding property and transparence when it was incorporated into polyester/melamine coatings.

Methane Conversion and Reforming by Nonthermal Plasma on Pins

Nonthermal plasma on pins means nonthermal or nonequilibrium plasmas produced between two pin electrodes, pin-to-plane, or multipin configurations working at atmospheric pressure. In this paper, it is shown that nonthermal plasma on pins can produce not only the corona discharges but also the homogeneous glow discharge and pseudo glow discharge by using a 1−2 kHz ac power supply. The electrode configurations and input power control the amplitude and duration of the discharge current pulses. It is found that the discharge conditions determined the product selectivity in direct nonoxidative methane conversion. The glow discharge produces acetylene, ethylene, and ethane in approximately equal quantities, while the corona discharge is mainly selective to acetylene. In the pseudo glow discharge, the product distribution can be controlled by the specific energy input. With lower specific energy input, the product distribution is almost the same as that in glow discharge, while with higher specific energy input,...