Special Issue "Plasma Catalysis"

A special issue of Catalysts (ISSN 2073-4344). This special issue belongs to the section "Environmental Catalysis".

Deadline for manuscript submissions: 30 November 2018

Special Issue Editor

Guest Editor
Prof. Dr. Annemie Bogaerts

Department of Chemistry, Research Group PLASMANT, Universiteit Antwerpen, Universiteitsplein 1, 2610 Wilrijk-Antwerp, Belgium
Website | E-Mail
Interests: plasma; plasma catalysis; gas conversion; plasma–surface interactions; modeling; plasma chemistry; plasma reactor design; plasma medicine

Special Issue Information

Dear Colleagues,

Plasma catalysis is gaining increasing interest for various gas conversion applications, such as CO2 conversion into value-added chemicals and fuels, N2 fixation for the synthesis of NH3 or NOx, methane conversion into higher hydrocarbons or oxygenates. It is also widely used for air pollution control (e.g., VOC  remediation). Plasma catalysis allows thermodynamically difficult reactions to proceed at ambient pressure and temperature, due to activation of the gas molecules by energetic electrons created in the plasma. However, plasma is very reactive but not selective, and thus a catalyst is needed to improve the selectivity.

In spite of the growing interest in plasma catalysis, the underlying mechanisms of the (possible) synergy between plasma and catalyst are not yet fully understood. Indeed, plasma catalysis is quite complicated, as the plasma will affect the catalyst and vice versa. Moreover, due to the reactive plasma environment, the most suitable catalysts will probably be different from thermal catalysts. More research is needed to better understand the plasma–catalyst interactions, in order to further improve the applications.

Submissions to this Special Issue are welcome in the form of original research papers or short reviews that reflect the state of the art in the above-mentioned applications.  

Prof. Dr. Annemie Bogaerts
Guest Editor

Manuscript Submission Information

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Keywords

  • Plasma–catalyst interaction
  • CO2 conversion
  • N2 fixation
  • CH4 conversion
  • Air pollution control
  • Plasma catalysis synergy
  • Plasma reactor
  • Dielectric barrier discharge
  • Ambient conditions

Published Papers (5 papers)

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Research

Open AccessArticle Ammonia Plasma-Catalytic Synthesis Using Low Melting Point Alloys
Catalysts 2018, 8(10), 437; https://doi.org/10.3390/catal8100437
Received: 19 September 2018 / Revised: 30 September 2018 / Accepted: 30 September 2018 / Published: 3 October 2018
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Abstract
The Haber-Bosch process has been the commercial benchmark process for ammonia synthesis for more than a century. Plasma-catalytic synthesis for ammonia production is theorized to have a great potential for being a greener alternative to the Haber-Bosch process. However, the underlying reactions for
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The Haber-Bosch process has been the commercial benchmark process for ammonia synthesis for more than a century. Plasma-catalytic synthesis for ammonia production is theorized to have a great potential for being a greener alternative to the Haber-Bosch process. However, the underlying reactions for ammonia synthesis still require some detailed study especially for radiofrequency plasmas. Herein, the use of inductively coupled radiofrequency plasma for the synthesis of ammonia when employing Ga, In and their alloys as catalysts is presented. The plasma is characterized using emission spectroscopy and the surface of catalysts using Scanning Electron Microscope. A maximum energy yield of 0.31 g-NH3/kWh and energy cost of 196 MJ/mol is achieved with Ga-In (0.6:0.4 and 0.2:0.8) alloy at 50 W plasma power. Granular nodes are observed on the surface of catalysts indicating the formation of the intermediate GaN. Full article
(This article belongs to the Special Issue Plasma Catalysis)
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Open AccessArticle Plasma Oxidation of H2S over Non-stoichiometric LaxMnO3 Perovskite Catalysts in a Dielectric Barrier Discharge Reactor
Catalysts 2018, 8(8), 317; https://doi.org/10.3390/catal8080317
Received: 12 July 2018 / Revised: 22 July 2018 / Accepted: 23 July 2018 / Published: 2 August 2018
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Abstract
In this work, plasma-catalytic removal of H2S over LaxMnO3 (x = 0.90, 0.95, 1, 1.05 and 1.10) has been studied in a coaxial dielectric barrier discharge (DBD) reactor. The non-stoichiometric effect of the LaxMnO3
[...] Read more.
In this work, plasma-catalytic removal of H2S over LaxMnO3 (x = 0.90, 0.95, 1, 1.05 and 1.10) has been studied in a coaxial dielectric barrier discharge (DBD) reactor. The non-stoichiometric effect of the LaxMnO3 catalysts on the removal of H2S and sulfur balance in the plasma-catalytic process has been investigated as a function of specific energy density (SED). The integration of the plasma with the LaxMnO3 catalysts significantly enhanced the reaction performance compared to the process using plasma alone. The highest H2S removal of 96.4% and sulfur balance of 90.5% were achieved over the La0.90MnO3 catalyst, while the major products included SO2 and SO3. The missing sulfur could be ascribed to the sulfur deposited on the catalyst surfaces. The non-stoichiometric LaxMnO3 catalyst exhibited larger specific surface areas and smaller crystallite sizes compared to the LaMnO3 catalyst. The non-stoichiometric effect changed their redox properties as the decreased La/Mn ratio favored the transformation of Mn3+ to Mn4+, which contributed to the generation of oxygen vacancies on the catalyst surfaces. The XPS and H2-TPR results confirmed that the Mn-rich catalysts showed the higher relative concentration of surface adsorbed oxygen (Oads) and lower reduction temperature compared to LaMnO3 catalyst. The reaction performance of the plasma-catalytic oxidation of H2S is closely related to the relative concentration of Oads formed on the catalyst surfaces and the reducibility of the catalysts. Full article
(This article belongs to the Special Issue Plasma Catalysis)
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Open AccessArticle Plasma-Catalytic Mineralization of Toluene Adsorbed on CeO2
Catalysts 2018, 8(8), 303; https://doi.org/10.3390/catal8080303
Received: 6 July 2018 / Revised: 23 July 2018 / Accepted: 24 July 2018 / Published: 27 July 2018
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Abstract
In the context of coupling nonthermal plasmas with catalytic materials, CeO2 is used as adsorbent for toluene and combined with plasma for toluene oxidation. Two configurations are addressed for the regeneration of toluene saturated CeO2: (i) in plasma-catalysis (IPC); and
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In the context of coupling nonthermal plasmas with catalytic materials, CeO2 is used as adsorbent for toluene and combined with plasma for toluene oxidation. Two configurations are addressed for the regeneration of toluene saturated CeO2: (i) in plasma-catalysis (IPC); and (ii) post plasma-catalysis (PPC). As an advanced oxidation technique, the performances of toluene mineralization by the plasma-catalytic systems are evaluated and compared through the formation of CO2. First, the adsorption of 100 ppm of toluene onto CeO2 is characterized in detail. Total, reversible and irreversible adsorbed fractions are quantified. Specific attention is paid to the influence of relative humidity (RH): (i) on the adsorption of toluene on CeO2; and (ii) on the formation of ozone in IPC and PPC reactors. Then, the mineralization yield and the mineralization efficiency of adsorbed toluene are defined and investigated as a function of the specific input energy (SIE). Under these conditions, IPC and PPC reactors are compared. Interestingly, the highest mineralization yield and efficiency are achieved using the in-situ configuration operated with the lowest SIE, that is, lean conditions of ozone. Based on these results, the specific impact of RH on the IPC treatment of toluene adsorbed on CeO2 is addressed. Taking into account the impact of RH on toluene adsorption and ozone production, it is evidenced that the mineralization of toluene adsorbed on CeO2 is directly controlled by the amount of ozone produced by the discharge and decomposed on the surface of the coupling material. Results highlight the key role of ozone in the mineralization process and the possible detrimental effect of moisture. Full article
(This article belongs to the Special Issue Plasma Catalysis)
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Open AccessArticle DBD Plasma-ZrO2 Catalytic Decomposition of CO2 at Low Temperatures
Catalysts 2018, 8(7), 256; https://doi.org/10.3390/catal8070256
Received: 27 April 2018 / Revised: 9 June 2018 / Accepted: 14 June 2018 / Published: 23 June 2018
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Abstract
This study describes the decomposition of CO2 using Dielectric Barrier Discharge (DBD) plasma technology combined with the packing materials. A self-cooling coaxial cylinder DBD reactor that packed ZrO2 pellets or glass beads with a grain size of 1–2 mm was designed
[...] Read more.
This study describes the decomposition of CO2 using Dielectric Barrier Discharge (DBD) plasma technology combined with the packing materials. A self-cooling coaxial cylinder DBD reactor that packed ZrO2 pellets or glass beads with a grain size of 1–2 mm was designed to decompose CO2. The control of the temperature of the reactor was achieved via passing the condensate water through the shell of the DBD reactor. Key factors, for instance discharge length, packing materials, beads size and discharge power, were investigated to evaluate the efficiency of CO2 decomposition. The results indicated that packing materials exhibited a prominent effect on CO2 decomposition, especially in the presence of ZrO2 pellets. Most encouragingly, a maximum decomposition rate of 49.1% (2-mm particle sizes) and 52.1% (1-mm particle sizes) was obtained with packing ZrO2 pellets and a 32.3% (2-mm particle sizes) and a 33.5% (1-mm particle sizes) decomposing rate with packing glass beads. In the meantime, CO selectivity was up to 95%. Furthermore, the energy efficiency was increased from 3.3%–7% before and after packing ZrO2 pellets into the DBD reactor. It was concluded that the packing ZrO2 simultaneously increases the key values, decomposition rate and energy efficiency, by a factor of two, which makes it very promising. The improved decomposition rate and energy efficiency can be attributed mainly to the stronger electric field and electron energy and the lower reaction temperature. Full article
(This article belongs to the Special Issue Plasma Catalysis)
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Open AccessArticle Mode Transition of Filaments in Packed-Bed Dielectric Barrier Discharges
Catalysts 2018, 8(6), 248; https://doi.org/10.3390/catal8060248
Received: 15 May 2018 / Revised: 12 June 2018 / Accepted: 13 June 2018 / Published: 15 June 2018
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Abstract
We investigated the mode transition from volume to surface discharge in a packed bed dielectric barrier discharge reactor by a two-dimensional particle-in-cell/Monte Carlo collision method. The calculations are performed at atmospheric pressure for various driving voltages and for gas mixtures with different N
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We investigated the mode transition from volume to surface discharge in a packed bed dielectric barrier discharge reactor by a two-dimensional particle-in-cell/Monte Carlo collision method. The calculations are performed at atmospheric pressure for various driving voltages and for gas mixtures with different N2 and O2 compositions. Our results reveal that both a change of the driving voltage and gas mixture can induce mode transition. Upon increasing voltage, a mode transition from hybrid (volume+surface) discharge to pure surface discharge occurs, because the charged species can escape much more easily to the beads and charge the bead surface due to the strong electric field at high driving voltage. This significant surface charging will further enhance the tangential component of the electric field along the dielectric bead surface, yielding surface ionization waves (SIWs). The SIWs will give rise to a high concentration of reactive species on the surface, and thus possibly enhance the surface activity of the beads, which might be of interest for plasma catalysis. Indeed, electron impact excitation and ionization mainly take place near the bead surface. In addition, the propagation speed of SIWs becomes faster with increasing N2 content in the gas mixture, and slower with increasing O2 content, due to the loss of electrons by attachment to O2 molecules. Indeed, the negative O2 ion density produced by electron impact attachment is much higher than the electron and positive O2+ ion density. The different ionization rates between N2 and O2 gases will create different amounts of electrons and ions on the dielectric bead surface, which might also have effects in plasma catalysis. Full article
(This article belongs to the Special Issue Plasma Catalysis)
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