Non‐oxidative methane coupling to C<sub>2</sub> hydrocarbons in a microwave plasma reactor

Minea, Teofil; Bekerom, D C M van den; Peeters, Floran; Zoethout, E.; Graswinckel, M.F.; Sanden, M.C.M. van de; Cents, Toine; Lefferts, Leon; Rooij, G.J. van

doi:10.1002/ppap.201800087

Cited by 28 publications

(47 citation statements)

References 47 publications

(55 reference statements)

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“…The rotation temperature was 1,800 K, which was sufficient for the pyrolysis. Many research works confirmed that warm plasmas, such as spark discharge, MW, and GA, are dominated by the thermal reactions rather than the electron collision reactions …”

Section: Resultsmentioning

confidence: 99%

“…Many research works confirmed that warm plasmas, such as spark discharge, MW, and GA, are dominated by the thermal reactions rather than the electron collision reactions. [44][45][46] The temporal evolution (2 ns/5 ns) of the OES in filamentary discharge were investigated to obtain further insight into the chemical processes. Figure 10a illustrates the time variation of the emission intensities of CH(A-X) and C 2 (516 nm) along the current in the filamentary discharge.…”

Section: Gas Temperaturementioning

confidence: 99%

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Non‐oxidative methane conversion in diffuse, filamentary, and spark regimes of nanosecond repetitively pulsed discharge with negative polarity

Sun

Shuai

Gao

et al. 2019

Plasma Processes & Polymers

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Methane conversion for higher hydrocarbons was carried out in the diffuse, filamentary, and spark regimes of nanosecond repetitively pulsed discharge with negative polarity in a pin‐to‐plate reactor. The diffuse discharge was characterized as a regime with low‐plasma energy, and only trace hydrogen and C2H6 were found in this regime. In filamentary regime, the conversion rate reached 2.2–7.6% with energy conversion efficiency (ECE) of 8.8–12.7%. Meanwhile the selectivity of C2H6, C2H4, C2H2, and C3 were 24.3–18.6%, 9.3–7%, 5.6–7.3%, and 0–5%, respectively. As for the spark regime, C2H2 became the main hydrocarbon product with the selectivity of 12.8%, conversion rate of 44.7–74.4% and ECE of 12.3%. Electrical measurements and ICCD photographs showed that the short pulse could prevent the streamer turning into spark discharge, and thus realize smooth transitions among each regime. Optical emission spectroscopy was used to investigate the plasma chemistry in each regime. It found that the highest spectral line, gas temperature, and electron density varied in these regimes. These results suggested that, comparing with electron impact reactions, the thermal chemistry became more and more important as the plasma energy increased.

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Section: Resultsmentioning

confidence: 99%

Section: Gas Temperaturementioning

confidence: 99%

Non‐oxidative methane conversion in diffuse, filamentary, and spark regimes of nanosecond repetitively pulsed discharge with negative polarity

Sun

Shuai

Gao

et al. 2019

Plasma Processes & Polymers

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“…Furthermore, the coke production under conventional heating was double of that obtained under MW heating [128]. In addition, Minea et al tested a microwave plasma reactor for the MNOC, detecting at low gas temperatures, ethane selectivities up to 60% due to plasma chemistry while, at higher temperatures, the thermal effect became greater leading to the formation of acetylene and deposits [129]. In more recent times, Julian et al, continued their studies on the non-oxidative coupling of methane performed using a Mo/ZSM-5@SiC structured catalyst [130].…”

Section: Of 58mentioning

confidence: 99%

Microwaves and Heterogeneous Catalysis: A Review on Selected Catalytic Processes

et al. 2020

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Since the late 1980s, the scientific community has been attracted to microwave energy as an alternative method of heating, due to the advantages that this technology offers over conventional heating technologies. In fact, differently from these, the microwave heating mechanism is a volumetric process in which heat is generated within the material itself, and, consequently, it can be very rapid and selective. In this way, the microwave-susceptible material can absorb the energy embodied in the microwaves. Application of the microwave heating technique to a chemical process can lead to both a reduction in processing time as well as an increase in the production rate, which is obtained by enhancing the chemical reactions and results in energy saving. The synthesis and sintering of materials by means of microwave radiation has been used for more than 20 years, while, future challenges will be, among others, the development of processes that achieve lower greenhouse gas (e.g., CO 2 ) emissions and discover novel energy-saving catalyzed reactions. A natural choice in such efforts would be the combination of catalysis and microwave radiation. The main aim of this review is to give an overview of microwave applications in the heterogeneous catalysis, including the preparation of catalysts, as well as explore some selected microwave assisted catalytic reactions. The review is divided into three principal topics: (i) introduction to microwave chemistry and microwave materials processing; (ii) description of the loss mechanisms and microwave-specific effects in heterogeneous catalysis; and (iii) applications of microwaves in some selected chemical processes, including the preparation of heterogeneous catalysts.A chemical process is conventionally energized by means of conductive heating with a steam boiler as a typical heat source. Nevertheless, a large variety of other forms of energy can be applied for PI, including ultrasounds (for reactions or crystal nucleation), light (in photocatalytic processes), electric fields (in extraction or for orientation of molecules), or microwaves. The microwave (dielectric) heating of materials has been known for a long time, and microwave ovens have been developed from more than 60 years. The studies by Gedye et al. in 1986 and 1988 [3,4] opened a period of very intensive investigation of the microwave effects on chemical reactions in homogeneous systems. Since then, hundreds of research papers have been published, and research has also expanded toward heterogeneous catalysis and its related chemical processes. This review gives an overview of the application of microwave technology to heterogeneous catalysis, including various chemical processes, as well as to the preparation of catalysts.

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“…Consequently, Therefore, it seems possible that the inorganic material in the producer gas was melted in the plasma core and deposited on the cooler walls of the quartz tube. The problem of deposit interfering with the microwaves transfer and plasma stability is a common issue in the MWP processing of carbon sources [42,51]. Finally, another important factor that may have caused a difference in the conversion rate could have been connected with the hydrogen concentration.…”

Section: Comparison Of the Simulated And The Sewage Sludge-derived Prmentioning

confidence: 99%

Sewage Sludge-Derived Producer Gas Valorization with the Use of Atmospheric Microwave Plasma

Wnukowski

Kordylewski

Łuszkiewicz

et al. 2019

Waste Biomass Valor

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Atmospheric microwave plasma was applied to the processing of the partially cleaned producer gas obtained from sewage sludge gasification. The plasma processing resulted in residual tar compounds conversion and changes in the gas composition. During the tests with a different gas flow rates and microwave power inputs, liquid and gaseous samples were collected to evaluate the plasma reactor's performance. The conversion efficiency ranged from 19 to 100% and it depended on the specific energy input (SEI), gas flow rate, initial tar concentration, and the nature of the tars compounds. Generally, it was shown that the conversion rate increased with the SEI and that the aliphatic, cyclic and substituted compounds were converted much easier than benzene. Moreover, applying plasma led to the production of heavier aromatics (i.e. naphthalene, indene, acenaphthylene) but the rise in their concentration was significantly smaller than the amount of converted compounds. The gas composition changes revealed in the increase of H 2 and CO concentration that was an effect of hydrocarbons and CO 2 conversion. Additionally, it was indicated that the microwave plasma reactor's performance was noticeably worse than in the case of the laboratory test with a simulated producer gas. This was mainly attributed to differences in the reactors' geometry, lower hydrogen concentration and the presence of inorganic deposit on the reactor's walls that might have inhibited microwaves transfer. In general, the microwave plasma technology seems promising in the context of cleaning and upgrading the producer gas, however, further optimization research is necessary to make it more reliable and less energy consuming. Graphic AbstractBiomass-derived producer gas treatment in the context of tar conversion is a current and important research issue. Many plasma techniques have been investigated to solve the problem of tar's presence. However, most of them considered simplified model mixtures of gas and a model tar compound. There is a negligible amount of research that applies a real producer gas obtained in the gasification process. Moreover, none of them includes microwave plasma, which has a few promising features considering producer gas valorization. Therefore, the main goal and novelty of this work were to investigate the microwave plasma treatment of the gas derived from sewage sludge gasification and to compare it with the results obtain in laboratory research using model mixtures.

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Non‐oxidative methane coupling to C₂ hydrocarbons in a microwave plasma reactor

Cited by 28 publications

References 47 publications

Non‐oxidative methane conversion in diffuse, filamentary, and spark regimes of nanosecond repetitively pulsed discharge with negative polarity

Non‐oxidative methane conversion in diffuse, filamentary, and spark regimes of nanosecond repetitively pulsed discharge with negative polarity

Microwaves and Heterogeneous Catalysis: A Review on Selected Catalytic Processes

Sewage Sludge-Derived Producer Gas Valorization with the Use of Atmospheric Microwave Plasma

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Non‐oxidative methane coupling to C2 hydrocarbons in a microwave plasma reactor

Cited by 28 publications

References 47 publications

Non‐oxidative methane conversion in diffuse, filamentary, and spark regimes of nanosecond repetitively pulsed discharge with negative polarity

Non‐oxidative methane conversion in diffuse, filamentary, and spark regimes of nanosecond repetitively pulsed discharge with negative polarity

Microwaves and Heterogeneous Catalysis: A Review on Selected Catalytic Processes

Sewage Sludge-Derived Producer Gas Valorization with the Use of Atmospheric Microwave Plasma

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Non‐oxidative methane coupling to C₂ hydrocarbons in a microwave plasma reactor