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Author Van Alphen, S.; Hecimovic, A.; Kiefer, C.K.; Fantz, U.; Snyders, R.; Bogaerts, A. pdf  url
doi  openurl
  Title Modelling post-plasma quenching nozzles for improving the performance of CO2 microwave plasmas Type A1 Journal Article
  Year (down) 2023 Publication Chemical engineering journal Abbreviated Journal  
  Volume 462 Issue Pages 142217  
  Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)  
  Abstract Given the ecological problems associated to the CO2 emissions of fossil fuels, plasma technology has gained

interest for conversion of CO2 into value-added products. Microwave plasmas operating at atmospheric pressure

have proven to be especially interesting, due to the high gas temperatures inside the reactor (i.e. up to 6000 K)

allowing for efficient thermal dissociation of CO2 into CO and O2. However, the performance of these high

temperature plasmas is limited by recombination of CO back into CO2 once the gas cools down in the afterglow.

In this work, we computationally investigated several quenching nozzles, developed and experimentally tested

by Hecimovic et al., [1] for their ability to quickly cool the gas after the plasma, thereby quenching the CO

recombination reactions. Using a 3D computational fluid dynamics model and a quasi-1D chemical kinetics

model, we reveal that a reactor without nozzle lacks gas mixing between hot gas in the center and cold gas near

the reactor walls. Especially at low flow rates, where there is an inherent lack of convective cooling due to the

low gas flow velocity, the temperature in the afterglow remains high (between 2000 and 3000 K) for a relatively

long time (in the 0.1 s range). As shown by our quasi-1D chemical kinetics model, this results in a important loss

of CO due to recombination reactions. Attaching a nozzle in the effluent of the reactor induces fast gas quenching

right after the plasma. Indeed, it introduces (i) more convective cooling by forcing cool gas near the walls to mix

with hot gas in the center of the reactor, as well as (ii) more conductive cooling through the water-cooled walls of

the nozzle. Our model shows that gas quenching and the suppression of recombination reactions have more

impact at low flow rates, where recombination is the most limiting factor in the conversion process.
 
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000962382600001 Publication Date 2023-03-03  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1385-8947 ISBN Additional Links UA library record; WoS full record; WoS citing articles  
  Impact Factor 15.1 Times cited Open Access OpenAccess  
  Notes This research was supported by the Excellence of Science FWO-FNRS project (FWO grant ID GoF9618n, EOS ID 30505023), the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No 810182 – SCOPE ERC Synergy project), and through long-term structural funding (Methusalem). The calculations were performed using the Turing HPC infrastructure at the CalcUA core facility of the Universiteit Antwerpen (UAntwerpen), a division of the Flemish Supercomputer Center VSC, funded by the Hercules Foundation, the Flemish Government (department EWI) and the UAntwerpen. Approved Most recent IF: 15.1; 2023 IF: 6.216  
  Call Number PLASMANT @ plasmant @c:irua:195889 Serial 7250  
Permanent link to this record
 

 
Author Van Alphen, S.; Hecimovic, A.; Kiefer, C.K.; Fantz, U.; Snyders, R.; Bogaerts, A. pdf  url
doi  openurl
  Title Modelling post-plasma quenching nozzles for improving the performance of CO2 microwave plasmas Type A1 Journal Article
  Year (down) 2023 Publication Chemical engineering journal Abbreviated Journal  
  Volume 462 Issue Pages 142217  
  Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)  
  Abstract Given the ecological problems associated to the CO2 emissions of fossil fuels, plasma technology has gained

interest for conversion of CO2 into value-added products. Microwave plasmas operating at atmospheric pressure

have proven to be especially interesting, due to the high gas temperatures inside the reactor (i.e. up to 6000 K)

allowing for efficient thermal dissociation of CO2 into CO and O2. However, the performance of these high

temperature plasmas is limited by recombination of CO back into CO2 once the gas cools down in the afterglow.

In this work, we computationally investigated several quenching nozzles, developed and experimentally tested

by Hecimovic et al., [1] for their ability to quickly cool the gas after the plasma, thereby quenching the CO

recombination reactions. Using a 3D computational fluid dynamics model and a quasi-1D chemical kinetics

model, we reveal that a reactor without nozzle lacks gas mixing between hot gas in the center and cold gas near

the reactor walls. Especially at low flow rates, where there is an inherent lack of convective cooling due to the

low gas flow velocity, the temperature in the afterglow remains high (between 2000 and 3000 K) for a relatively

long time (in the 0.1 s range). As shown by our quasi-1D chemical kinetics model, this results in a important loss

of CO due to recombination reactions. Attaching a nozzle in the effluent of the reactor induces fast gas quenching

right after the plasma. Indeed, it introduces (i) more convective cooling by forcing cool gas near the walls to mix

with hot gas in the center of the reactor, as well as (ii) more conductive cooling through the water-cooled walls of

the nozzle. Our model shows that gas quenching and the suppression of recombination reactions have more

impact at low flow rates, where recombination is the most limiting factor in the conversion process.
 
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000962382600001 Publication Date 2023-03-03  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1385-8947 ISBN Additional Links UA library record; WoS full record; WoS citing articles  
  Impact Factor 15.1 Times cited Open Access OpenAccess  
  Notes This research was supported by the Excellence of Science FWO-FNRS project (FWO grant ID GoF9618n, EOS ID 30505023), the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No 810182 – SCOPE ERC Synergy project), and through long-term structural funding (Methusalem). The calculations were performed using the Turing HPC infrastructure at the CalcUA core facility of the Universiteit Antwerpen (UAntwerpen), a division of the Flemish Supercomputer Center VSC, funded by the Hercules Foundation, the Flemish Government (department EWI) and the UAntwerpen. Approved Most recent IF: 15.1; 2023 IF: 6.216  
  Call Number PLASMANT @ plasmant @c:irua:195889 Serial 7259  
Permanent link to this record
 

 
Author Mercer, Er.; Van Alphen, S.; van Deursen, Cf.a.m.; Righart, Tw.h.; Bongers, Wa.; Snyders, R.; Bogaerts, A.; van de Sanden, Mc.m.; Peeters, Fj.j. url  doi
openurl 
  Title Post-plasma quenching to improve conversion and energy efficiency in a CO2 microwave plasma Type A1 Journal article
  Year (down) 2023 Publication Fuel Abbreviated Journal  
  Volume 334 Issue Pages 126734  
  Keywords A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)  
  Abstract Transforming CO2 into value-added chemicals is crucial to realizing a carbon–neutral economy, and plasma-based conversion, a Power-2-X technology, offers a promising route to realizing an efficient and scalable process. This paper investigates the effects of post-plasma placement of a converging–diverging nozzle in a vortex-stabilized 2.45 GHz CO2 microwave plasma reactor to increase energy efficiency and conversion. The CDN leads to a 21 % relative increase in energy efficiency (31 %) and CO2 conversion (13 %) at high flow rates and near-atmospheric conditions. The most significant performance improvement was seen at low flow rates and sub-atmospheric pressure (300 mbar), where energy efficiency was 23 % and conversion was 28 %, a 71 % relative increase over conditions without the CDN. Using CFD simulations, we found that the CDN produces a change in the flow geometry, leading to a confined temperature profile at the height of the plasma, and forced extraction of CO to the post-CDN region.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000891307400008 Publication Date 2022-11-26  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0016-2361 ISBN Additional Links UA library record; WoS full record; WoS citing articles  
  Impact Factor 7.4 Times cited Open Access OpenAccess  
  Notes This research was supported by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement No 810182 – SCOPE ERC Synergy project) and the Excellence of Science FWO-FNRS project (FWO grant ID GoF9618n, EOS ID 30505023). The computational resources and services used in this work were provided by the HPC core facility CalcUA of the Universiteit Antwerpen, and VSC (Flemish Supercomputer Center), funded by the Research Foundation – Flanders (FWO) and the Flemish Government. In addition, this work has been carried out as part of the Plasma Power to Gas research program with reference 15325, which is by the Netherlands Organization for Scientific Research (NWO) and Alliander N.V. Approved Most recent IF: 7.4; 2023 IF: 4.601  
  Call Number PLASMANT @ plasmant @c:irua:192784 Serial 7235  
Permanent link to this record
 

 
Author Van Alphen, S. url  openurl
  Title Modelling plasma reactors for sustainable CO2 conversion and N2 fixation Type Doctoral thesis
  Year (down) 2023 Publication Abbreviated Journal  
  Volume Issue Pages 202 p.  
  Keywords Doctoral thesis; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)  
  Abstract 200 years ago, humanity started the industrial revolution by discovering fossil fuels, which lead to unprecedented technological advancements. However it has become alarmingly clear that the major environmental concerns associated with fossil fuels require a short-term transition from a carbon-based energy economy to a sustainable one based on green electricity. A key step concerning this transition exists in developing electricity-driven alternatives for chemical processes that rely on fossil fuels as a raw material. A technology that is gaining increasing interest to achieve this, is plasma technology. Using plasmas to induce chemical reactions by selectively heating electrons in a gas has already delivered promising results for gas conversion applications like CO2 conversion and N2 fixation, but plasma reactors still require optimization to be considered industrially competitive to existing fossil fuel-based processes and emerging other electricity-based technologies. In this thesis I develop computational models to describe plasma reactors and identify key mechanisms in three different plasma reactors for three different gas conversion applications, i.e. N2 fixation, combined CO2-CH4 conversion and CO2 splitting. I first developed models to describe a new rotating gliding arc (GA) reactor operating in two arc modes, which, as revealed by my model, are characterized by distinct plasma chemistry pathways. Subsequently, my colleague and I study the quenching effect of an effusion nozzle to this rotating GA reactor, reaching the best results to date for N2 fixation into NOx at atmospheric pressure, i.e., NOx concentrations up to 5.9%, at an energy cost down to 2.1 MJ/mol. Afterwards, I investigate the possible improvement of N2 admixtures in plasma-based CO2 and CH4 conversion, as significant amounts of N2 are often found in industrial CO2 waste streams, and gas separations are financially costly. Through combining my models with the experiment from a fellow PhD student, we reveal that moderate amounts of N2 (i.e. around 20%) increase both the electron density and the gas temperature to yield an overall energy cost reduction of 21%. Finally, I model quenching nozzles for plasma-based CO2 conversion in a microwave reactor, to explain the enhancements in CO2 conversion that were demonstrated in experiments. Through computational modelling I reveal that the nozzle introduces fast gas quenching resulting in the suppression of recombination reactions, which have more impact at low flow rates, where recombination is the most limiting factor in the conversion process.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos Publication Date  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN ISBN Additional Links UA library record  
  Impact Factor Times cited Open Access  
  Notes Approved Most recent IF: NA  
  Call Number UA @ admin @ c:irua:194811 Serial 7270  
Permanent link to this record
 

 
Author Van Alphen, S.; Ahmadi Eshtehardi, H.; O'Modhrain, C.; Bogaerts, J.; Van Poyer, H.; Creel, J.; Delplancke, M.-P.; Snyders, R.; Bogaerts, A. pdf  url
doi  openurl
  Title Effusion nozzle for energy-efficient NOx production in a rotating gliding arc plasma reactor Type A1 Journal article
  Year (down) 2022 Publication Chemical Engineering Journal Abbreviated Journal Chem Eng J  
  Volume 443 Issue Pages 136529  
  Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)  
  Abstract Plasma-based NOx production is of interest for sustainable N2 fixation, but more research is needed to improve its performance. One of the current limitations is recombination of NO back into N2 and O2 molecules immediately after the plasma reactor. Therefore, we developed a novel so-called “effusion nozzle”, to improve the perfor­mance of a rotating gliding arc plasma reactor for NOx production, but the same principle can also be applied to other plasma types. Experiments in a wide range of applied power, gas flow rates and N2/O2 ratios demonstrate an enhancement in NOx concentration by about 8%, and a reduction in energy cost by 22.5%. In absolute terms, we obtain NOx concentrations up to 5.9%, at an energy cost down to 2.1 MJ/mol, which are the best values reported to date in literature. In addition, we developed four complementary models to describe the gas flow, plasma temperature and plasma chemistry, aiming to reveal why the effusion nozzle yields better performance. Our simulations reveal that the effusion nozzle acts as very efficient heat sink, causing a fast drop in gas tem­perature when the gas molecules leave the plasma, hence limiting the recombination of NO back into N2 and O2. This yields an overall higher NOx concentration than without the effusion nozzle. This immediate quenching right at the end of the plasma makes our effusion nozzle superior to more conventional cooling options, like water cooling In addition, this higher NOx concentration can be obtained at a slightly lower power, because the effusion nozzle allows for the ignition and sustainment of the plasma at somewhat lower power. Hence, this also explains the lower energy cost. Overall, our experimental results and detailed modeling analysis will be useful to improve plasma-based NOx production in other plasma reactors as well.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000800010600003 Publication Date 0000-00-00  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1385-8947 ISBN Additional Links UA library record; WoS full record; WoS citing articles  
  Impact Factor 15.1 Times cited Open Access OpenAccess  
  Notes This research was supported by the Excellence of Science FWO-FNRS project (FWO grant ID GoF9618n, EOS ID 30505023), the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No 810182 – SCOPE ERC Synergy project), and through long-term structural funding (Methusalem). The calculations were performed using the Turing HPC infrastructure at the CalcUA core facility of the Universiteit Antwerpen (UAntwerpen), a division of the Flemish Supercomputer Center VSC, funded by the Hercules Foundation, the Flemish Government (depart­ment EWI) and the UAntwerpen. Approved Most recent IF: 15.1  
  Call Number PLASMANT @ plasmant @c:irua:188283 Serial 7057  
Permanent link to this record
 

 
Author Van Alphen, S.; Slaets, J.; Ceulemans, S.; Aghaei, M.; Snyders, R.; Bogaerts, A. pdf  url
doi  openurl
  Title Effect of N2 on CO2-CH4 conversion in a gliding arc plasmatron: Can this major component in industrial emissions improve the energy efficiency? Type A1 Journal Article;Plasma-based CO2-CH4 conversion
  Year (down) 2021 Publication Journal Of Co2 Utilization Abbreviated Journal J Co2 Util  
  Volume 54 Issue Pages 101767  
  Keywords A1 Journal Article;Plasma-based CO2-CH4 conversion; Effect of N2; Plasma chemistry; Computational modelling; Gliding arc plasmatron; Plasma, laser ablation and surface modeling Antwerp (PLASMANT) ;  
  Abstract Plasma-based CO2 and CH4 conversion is gaining increasing interest, and a great portion of research is dedicated to adapting the process to actual industrial conditions. In an industrial context, the process needs to be able to process N2 admixtures, since most industrial gas emissions contain significant amounts of N2, and gas separations are financially costly. In this paper we therefore investigate the effect of N2 on the CO2 and CH4 conversion in a gliding arc plasmatron reactor. The addition of 20 % N2 reduces the energy cost of the conversion process by 21 % compared to a pure CO2/CH4 mixture, from 2.9 down to 2.2 eV/molec (or from 11.5 to 8.7 kJ/L), yielding a CO2 and CH4 (absolute) conversion of 28.6 and 35.9 % and an energy efficiency of 58 %. These results are among the best reported in literature for plasma-based DRM, demonstrating the benefits of N2 present in the mix. Compared to DRM results in different plasma reactor types, a low energy cost was achieved. To understand the underlying mechanisms of N2 addition, we developed a combination of four different computational models, which reveal that the beneficial effect of N2 addition is attributed to (i) a rise in the electron density (increasing the plasma conductivity, and therefore reducing the plasma power needed to sustain the plasma, which reduces the energy cost), as well as (ii) a rise in the gas temperature, which accelerates the CO2 and CH4 conversion reactions.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000715057300005 Publication Date 2021-10-28  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2212-9820 ISBN Additional Links UA library record; WoS full record; WoS citing articles  
  Impact Factor 4.292 Times cited Open Access OpenAccess  
  Notes This research was supported by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innova­ tion programme (grant agreement No 810182 – SCOPE ERC Synergy project), the Excellence of Science FWO-FNRS project (FWO grant ID GoF9618n, EOS ID 30505023), and through long-term structural fund­ing (Methusalem). The calculations were performed using the Turing HPC infrastructure at the CalcUA core facility of the Universiteit Ant­werpen (UAntwerpen), a division of the Flemish Supercomputer Center VSC, funded by the Hercules Foundation, the Flemish Government (department EWI) and the UAntwerpen. Approved Most recent IF: 4.292  
  Call Number PLASMANT @ plasmant @c:irua:184044 Serial 6827  
Permanent link to this record
 

 
Author van ‘t Veer, K.; van Alphen, S.; Remy, A.; Gorbanev, Y.; De Geyter, N.; Snyders, R.; Reniers, F.; Bogaerts, A. pdf  url
doi  openurl
  Title Spatially and temporally non-uniform plasmas: microdischarges from the perspective of molecules in a packed bed plasma reactor Type A1 Journal article
  Year (down) 2021 Publication Journal Of Physics D-Applied Physics Abbreviated Journal J Phys D Appl Phys  
  Volume 54 Issue 17 Pages 174002  
  Keywords A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)  
  Abstract Dielectric barrier discharges (DBDs) typically operate in the filamentary regime and thus exhibit great spatial and temporal non-uniformity. In order to optimize DBDs for various applications, such as in plasma catalysis, more fundamental insight is needed. Here, we consider how the millions of microdischarges, characteristic for a DBD, influence individual gas molecules. We use a Monte Carlo approach to determine the number of microdischarges to which a single molecule would be exposed, by means of particle tracing simulations through a full-scale packed bed DBD reactor, as well as an empty DBD reactor. We find that the fraction of microdischarges to which the molecules are exposed can be approximated as the microdischarge volume over the entire reactor gas volume. The use of this concept provides good agreement between a plasma-catalytic kinetics model and experiments for plasma-catalytic NH3 synthesis. We also show that the concept of the fraction of microdischarges indicates the efficiency by which the plasma power is transferred to the gas molecules. This generalised concept is also applicable for other spatially and temporally non-uniform plasmas.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000618776000001 Publication Date 2021-04-29  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0022-3727 ISBN Additional Links UA library record; WoS full record; WoS citing articles  
  Impact Factor 2.588 Times cited Open Access OpenAccess  
  Notes Excellence of Science FWO-FNRS project, FWO grant ID GoF9618n ; Flemish Government, project P2C (HBC.2019.0108) ; H2020 European Research Council, grant agreement No 810182 – SCOPE ERC Synergy pr ; This research was supported by the Excellence of Science FWO-FNRS project (FWO Grant ID GoF9618n, EOS ID 30505023), the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (Grant Agreement No 810182—SCOPE ERC Synergy project) and by the Flemish Government through the Moonshot cSBO project P2C (HBC. 2019.0108). The calculations were performed using the Turing HPC infrastructure at the CalcUA core facility of the Universiteit Antwerpen (UAntwerpen), a division of the Flemish Supercomputer Center VSC, funded by the Hercules Foundation, the Flemish Government (department EWI) and the UAntwerpen. The authors would also like to thank Hamid Ahmadi Eshtehardi for discussions on the plasma-kinetic DBD model and Yannick Engelmann for discussions on the surface kinetics model. Approved Most recent IF: 2.588  
  Call Number PLASMANT @ plasmant @c:irua:175878 Serial 6674  
Permanent link to this record
 

 
Author Van Alphen, S.; Jardali, F.; Creel, J.; Trenchev, G.; Snyders, R.; Bogaerts, A. pdf  url
doi  openurl
  Title Sustainable gas conversion by gliding arc plasmas: a new modelling approach for reactor design improvement Type A1 Journal article
  Year (down) 2021 Publication Sustainable energy & fuels Abbreviated Journal Sustainable Energy Fuels  
  Volume 5 Issue 6 Pages 1786-1800  
  Keywords A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)  
  Abstract Research in plasma reactor designs is developing rapidly as plasma technology is gaining increasing interest for sustainable gas conversion applications, like the conversion of greenhouse gases into value-added chemicals and renewable fuels, and fixation of N<sub>2</sub>from air into precursors of mineral fertilizer. As plasma is generated by electric power and can easily be switched on/off, these applications allows for efficient conversion and energy storage of intermittent renewable electricity. In this paper, we present a new comprehensive modelling approach for the design and development of gliding arc plasma reactors, which reveals the fluid dynamics, the arc behaviour and the plasma chemistry by solving a unique combination of five complementary models. This results in a complete description of the plasma process, which allows one to efficiently evaluate the performance of a reactor and indicate possible design improvements before actually building it. We demonstrate the capabilities of this method for an experimentally validated study of plasma-based NO<sub>x</sub>formation in a rotating gliding arc reactor, which is gaining increasing interest as a flexible, electricity-driven alternative for the Haber–Bosch process. The model demonstrates the importance of the vortex flow and the presence of a recirculation zone in the reactor, as well as the formation of hot spots in the plasma near the cathode pin and the anode wall that are responsible for most of the NO<sub>x</sub>formation. The model also reveals the underlying plasma chemistry and the vibrational non-equilibrium that exists due to the fast cooling during each arc rotation. Good agreement with experimental measurements on the studied reactor design proves the predictive capabilities of our modelling approach.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000631643300013 Publication Date 2021-02-22  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 2398-4902 ISBN Additional Links UA library record; WoS full record; WoS citing articles  
  Impact Factor Times cited Open Access OpenAccess  
  Notes Fonds Wetenschappelijk Onderzoek, GoF9618n ; Vlaamse regering, HBC.2019.0107 ; European Research Council, 810182 ; This research was supported by the Excellence of Science FWOFNRS project (FWO grant ID GoF9618n, EOS ID 30505023), the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement no. 810182 – SCOPE ERC Synergy project), the 1798 | Sustainable Energy Fuels, 2021, 5, 1786–1800 Approved Most recent IF: NA  
  Call Number PLASMANT @ plasmant @c:irua:177540 Serial 6745  
Permanent link to this record
 

 
Author Jardali, F.; Van Alphen, S.; Creel, J.; Ahmadi Eshtehardi, H.; Axelsson, M.; Ingels, R.; Snyders, R.; Bogaerts, A. pdf  url
doi  openurl
  Title NOxproduction in a rotating gliding arc plasma: potential avenue for sustainable nitrogen fixation Type A1 Journal article
  Year (down) 2021 Publication Green Chemistry Abbreviated Journal Green Chem  
  Volume 23 Issue 4 Pages 1748-1757  
  Keywords A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)  
  Abstract The fast growing world population demands food to survive, and nitrogen-based fertilizers are essential to ensure sufficient food production. Today, fertilizers are mainly produced from non-sustainable fossil fuels<italic>via</italic>the Haber–Bosch process, leading to serious environmental problems. We propose here a novel rotating gliding arc plasma, operating in air, for direct NO<sub>x</sub>production, which can yield high nitrogen content organic fertilizers without pollution associated with ammonia emission. We explored the efficiency of NO<sub>x</sub>production in a wide range of feed gas ratios, and for two arc modes: rotating and steady. When the arc is in steady mode, record-value NO<sub>x</sub>concentrations up to 5.5% are achieved which are 1.7 times higher than the maximum concentration obtained by the rotating arc mode, and with an energy consumption of 2.5 MJ mol<sup>−1</sup>(or<italic>ca.</italic>50 kW h kN<sup>−1</sup>);<italic>i.e.</italic>the lowest value so far achieved by atmospheric pressure plasma reactors. Computer modelling, using a combination of five different complementary approaches, provides a comprehensive picture of NO<sub>x</sub>formation in both arc modes; in particular, the higher NO<sub>x</sub>production in the steady arc mode is due to the combined thermal and vibrationally-promoted Zeldovich mechanisms.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000629630600021 Publication Date 2021-01-28  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1463-9262 ISBN Additional Links UA library record; WoS full record; WoS citing articles  
  Impact Factor 9.125 Times cited Open Access OpenAccess  
  Notes Fonds Wetenschappelijk Onderzoek, GoF9618n 30505023 ; H2020 European Research Council, 810182 ; This research was supported by a Bilateral Project with N2 Applied, the Excellence of Science FWO-FNRS project (FWO grant ID GoF9618n, EOS ID 30505023) and by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement no 810182 – SCOPE ERC Synergy project). The calculations were performed using the Turing HPC infrastructure at the CalcUA core facility of the Universiteit Antwerpen (UAntwerpen), a division of the Flemish Supercomputer Center VSC, funded by the Hercules Foundation, the Flemish Government (department EWI) and the UAntwerpen. We also thank J.-L. Liu for the RGA design, L. Van ‘t dack and K. Leyssens for MS calibration and practical support, and K. Van ‘t Veer for the fruitful discussions on plasma kinetic modelling and for calculating the electron energy losses. Approved Most recent IF: 9.125  
  Call Number PLASMANT @ plasmant @c:irua:176022 Serial 6678  
Permanent link to this record
 

 
Author Slaets, J.; Aghaei, M.; Ceulemans, S.; Van Alphen, S.; Bogaerts, A. pdf  url
doi  openurl
  Title CO2and CH4conversion in “real” gas mixtures in a gliding arc plasmatron: how do N2and O2affect the performance? Type A1 Journal article
  Year (down) 2020 Publication Green Chemistry Abbreviated Journal Green Chem  
  Volume 22 Issue 4 Pages 1366-1377  
  Keywords A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)  
  Abstract In this paper we study dry reforming of methane (DRM) in a gliding arc plasmatron (GAP) in the presence of N<sub>2</sub>and O<sub>2</sub>. N<sub>2</sub>is added to create a stable plasma at equal fractions of CO<sub>2</sub>and CH<sub>4</sub>, and because emissions from industrial plants typically contain N<sub>2</sub>, while O<sub>2</sub>is added to enhance the process. We test different gas mixing ratios to evaluate the conversion and energy cost. We obtain conversions between 31 and 52% for CO<sub>2</sub>and between 55 and 99% for CH<sub>4</sub>, with total energy costs between 3.4 and 5.0 eV per molecule, depending on the gas mixture. This is very competitive when benchmarked with the literature. In addition, we present a chemical kinetics model to obtain deeper insight in the underlying plasma chemistry. This allows determination of the major reaction pathways to convert CO<sub>2</sub>and CH<sub>4</sub>, in the presence of O<sub>2</sub>and N<sub>2</sub>, into CO and H<sub>2</sub>. We show that N<sub>2</sub>assists in the CO<sub>2</sub>conversion, but part of the applied energy is also wasted in N<sub>2</sub>excitation. Adding O<sub>2</sub>enhances the CH<sub>4</sub>conversion, and lowers the energy cost, while the CO<sub>2</sub>conversion remains constant, and only slightly drops at the highest O<sub>2</sub>fractions studied, when CH<sub>4</sub>is fully oxidized into CO<sub>2</sub>.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000518034000032 Publication Date 2020-01-30  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1463-9262 ISBN Additional Links UA library record; WoS full record; WoS citing articles  
  Impact Factor 9.8 Times cited Open Access OpenAccess  
  Notes H2020 European Research Council, 810182 ; Fonds Wetenschappelijk Onderzoek, GoF9618n 12M7118N ; We acknowledge financial support from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No 810182 – SCOPE ERC Synergy project), the Excellence of Science FWO-FNRS project (FWO grant ID GoF9618n, EOS ID 30505023), and the FWO postdoctoral fellowship of M. A. (Grant number 12M7118N). This work was carried out in part using the Turing HPC infrastructure at the CalcUA core facility of the Universiteit Antwerpen, a division of the Flemish Supercomputer Center VSC, funded by the Hercules Foundation, the Flemish Government (department EWI) and the University of Antwerp. Approved Most recent IF: 9.8; 2020 IF: 9.125  
  Call Number PLASMANT @ plasmant @c:irua:167136 Serial 6339  
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Author Van Alphen, S.; Vermeiren, V.; Butterworth, T.; van den Bekerom, D.C.M.; van Rooij, G.J.; Bogaerts, A. pdf  url
doi  openurl
  Title Power Pulsing To Maximize Vibrational Excitation Efficiency in N2Microwave Plasma: A Combined Experimental and Computational Study Type A1 Journal article
  Year (down) 2020 Publication Journal Of Physical Chemistry C Abbreviated Journal J Phys Chem C  
  Volume 124 Issue 3 Pages 1765-1779  
  Keywords A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)  
  Abstract Plasma is gaining increasing interest for N2 fixation, being a flexible, electricity-driven alternative for the current conventional fossil fuel-based N2 fixation processes. As the vibrational-induced dissociation of N2 is found to be an energy-efficient pathway to acquire atomic N for the fixation processes, plasmas that are in vibrational nonequilibrium seem promising for this application. However, an important challenge in using nonequilibrium plasmas lies in preventing vibrational−translational (VT) relaxation processes, in which vibrational energy crucial for N2 dissociation is lost to gas heating. We present here both experimental and modeling results for the vibrational and gas temperature in a microsecond-pulsed microwave (MW) N2 plasma, showing how power pulsing can suppress this unfavorable VT relaxation and achieve a maximal vibrational nonequilibrium. By means of our kinetic model, we demonstrate that pulsed plasmas take advantage of the long time scale on which VT processes occur, yielding a very pronounced nonequilibrium over the whole N2 vibrational ladder. Additionally, the effect of pulse parameters like the pulse frequency and pulse width are investigated, demonstrating that the advantage of pulsing to inhibit VT relaxation diminishes for high pulse frequencies (around 7000 kHz) and long power pulses (above 400 μs). Nevertheless, all regimes studied here demonstrate a clear vibrational nonequilibrium while only requiring a limited power-on time, and thus, we may conclude that a pulsed plasma seems very interesting for energyefficient vibrational excitation.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000509438600001 Publication Date 2020-01-23  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1932-7447 ISBN Additional Links UA library record; WoS full record; WoS citing articles  
  Impact Factor 3.7 Times cited Open Access  
  Notes Fonds Wetenschappelijk Onderzoek, 30505023 GoF9618n ; This research was supported by the Excellence of Science FWO-FNRS project (FWO Grant ID GoF9618n, EOS ID 30505023). The calculations were performed using the Turing HPC infrastructure at the CalcUA core facility of the Universiteit Antwerpen (UAntwerpen), a division of the Flemish Supercomputer Center VSC, funded by the Hercules Foundation, the Flemish Government (department EWI) and the UAntwerpen. Approved Most recent IF: 3.7; 2020 IF: 4.536  
  Call Number PLASMANT @ plasmant @c:irua:165586 Serial 5443  
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Author Vereecke, G.; De Coster, H.; Van Alphen, S.; Carolan, P.; Bender, H.; Willems, K.; Ragnarsson, L.-A.; Van Dorpe, P.; Horiguchi, N.; Holsteyns, F. pdf  doi
openurl 
  Title Wet etching of TiN in 1-D and 2-D confined nano-spaces of FinFET transistors Type A1 Journal article
  Year (down) 2018 Publication Microelectronic engineering Abbreviated Journal  
  Volume 200 Issue Pages 56-61  
  Keywords A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)  
  Abstract In the manufacturing of multi-Vt FinFET transistors, the gate material deposited in the nano-spaces left by the removed dummy gate must be etched back in mask-defined wafer areas. Etch conformality is a necessary condition for the control of under-etch at the boundary between areas defined by masking. We studied the feasibility of TiN etching by APM (ammonia peroxide mixture, also known as SC1) in nano-confined volumes representative of FinFET transistors of the 7 nm node and below, namely nanotrenches with 1-D confinement and nanoholes with 2-D confinement. TiN etching was characterized for rate and conformality using different electron microscopy techniques. Etching in closed nanotrenches was conformal, starting and progressing all along the 2-D seam, with a rate that was 38% higher compared to a planar film. Etching in closed nanoholes proved also to be conformal and faster than planar films, but with a delay to open the 1-D seam that seemed to depend strongly on small variations in the hole diameter. However, holes between the fins at the bottom of the removed dummy gate, are not circular and do present 2-D seams that should lend themselves for an easier start of conformal etching as compared to the circular nanoholes used in this study. Finally, to explain the higher etch rate observed in nano-confined features, concentrations of ions in nanoholes were calculated taking the overlap of electrostatic double layers (EDL) into account. With negatively charged TiN walls, as measured by streaming potential on planar films, ammonium was the dominant ion in nanoholes. As no chemical reaction proposed in the literature for TiN etching matched with this finding, we proposed that the formation of ammine complexes, dissolving the formed Ti oxide, was the rate-determining step.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000449134800010 Publication Date 2018-09-21  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0167-9317 ISBN Additional Links UA library record; WoS full record; WoS citing articles  
  Impact Factor Times cited Open Access  
  Notes Approved no  
  Call Number UA @ admin @ c:irua:155414 Serial 8757  
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Author Uytdenhouwen, Y.; Van Alphen, S.; Michielsen, I.; Meynen, V.; Cool, P.; Bogaerts, A. pdf  url
doi  openurl
  Title A packed-bed DBD micro plasma reactor for CO 2 dissociation: Does size matter? Type A1 Journal article
  Year (down) 2018 Publication Chemical engineering journal Abbreviated Journal Chem Eng J  
  Volume 348 Issue Pages 557-568  
  Keywords A1 Journal article; Laboratory of adsorption and catalysis (LADCA); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)  
  Abstract DBD plasma reactors are of great interest for environmental and energy applications, such as CO2 conversion, but they suffer from limited conversion and especially energy efficiency. The introduction of packing materials has been a popular subject of investigation in order to increase the reactor performance. Reducing the discharge gap of the reactor below one millimetre can enhance the plasma performance as well. In this work, we combine both effects and use a packed-bed DBD micro plasma reactor to investigate the influence of gap size reduction, in combination with a packing material, on the conversion and efficiency of CO2 dissociation. Packing materials used in this work were SiO2, ZrO2, and Al2O3 spheres as well as glass wool. The results are compared to a regular size reactor as a benchmark. Reducing the discharge gap can greatly increase the CO2 conversion, although at a lower energy efficiency. Adding a packing material further increases the conversion when keeping a constant residence time, but is greatly dependent on the material composition, gap and sphere size used. Maximum conversions of 50–55% are obtained for very long residence times (30 s and higher) in an empty reactor or with certain packing material combinations, suggesting a balance in CO2 dissociation and recombination reactions. The maximum energy efficiency achieved is 4.3%, but this is for the regular sized reactor at a short residence time (7.5 s). Electrical characterization is performed to reveal some trends in the electrical behaviour of the plasma upon reduction of the discharge gap and addition of a packing material.  
  Address  
  Corporate Author Thesis  
  Publisher Place of Publication Editor  
  Language Wos 000434467000055 Publication Date 2018-05-03  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1385-8947 ISBN Additional Links UA library record; WoS full record; WoS citing articles  
  Impact Factor 6.216 Times cited 22 Open Access Not_Open_Access: Available from 03.05.2020  
  Notes We acknowledge financial support from the European Fund for Regional Development through the cross-border collaborative Interreg V program Flanders-the Netherlands (project EnOp), the Fund for Scientific Research (FWO; Grant Number: G.0254.14N) and an IOF-SBO (SynCO2Chem) project from the University of Antwerp. Approved Most recent IF: 6.216  
  Call Number PLASMANT @ plasmant @c:irua:151238 Serial 4956  
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