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“Particle-in-cell/Monte Carlo simulations of a low-pressure capacitively coupled radio-frequency discharge: effect of adding H2 to an Ar discharge”. Neyts E, Yan M, Bogaerts A, Gijbels R, Journal of applied physics 93, 5025 (2003). http://doi.org/10.1063/1.1563820
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 2.068
Times cited: 15
DOI: 10.1063/1.1563820
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“PIC-MC simulation of an RF capacitively coupled Ar/H2 discharge”. Neyts E, Yan M, Bogaerts A, Gijbels R, Nuclear instruments and methods in physics research: B 202, 300 (2003). http://doi.org/10.1016/S0168-583X(02)01873-6
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 1.109
Times cited: 8
DOI: 10.1016/S0168-583X(02)01873-6
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“Reaction mechanisms of low-kinetic energy hydrocarbon radicals on typical hydrogenated amorphous carbon (a-C:H) sites: a molecular dynamics study”. Neyts E, Tacq M, Bogaerts A, Diamond and related materials 15, 1663 (2006). http://doi.org/10.1016/j.diamond.2006.02.003
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 2.561
Times cited: 18
DOI: 10.1016/j.diamond.2006.02.003
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“Bond switching regimes in nickel and nickel-carbon nanoclusters”. Neyts E, Shibuta Y, Bogaerts A, Chemical physics letters 488, 202 (2010). http://doi.org/10.1016/j.cplett.2010.02.024
Abstract: Understanding the fundamental dynamics in carbon nanotube (CNT) catalysts is of primary importance to understand CNT nucleation. This Letter reports on calculated bond switching (BS) rates in pure and carbon containing nickel nanoclusters. The rates are analyzed in terms of their temperature dependent spatial distribution and the mobility of the cluster atoms. The BS mechanism is found to change from vibrational to diffusional at around 900 K, with a corresponding strong increase in activation energy. Furthermore, the BS activation energy is observed to decrease as the carbon content in the cluster increases, resulting in an effective liquification of the cluster.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 1.815
Times cited: 20
DOI: 10.1016/j.cplett.2010.02.024
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“Modeling aspects of plasma-enhanced chemical vapor deposition of carbon-based materials”. Neyts E, Mao M, Eckert M, Bogaerts A CRC Press, Boca Raton, Fla, page 245 (2012).
Keywords: H1 Book chapter; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
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“A density-functional theory simulation of the formation of Ni-doped fullerenes by ion implantation”. Neyts E, Maeyens A, Pourtois G, Bogaerts A, Carbon 49, 1013 (2011). http://doi.org/10.1016/j.carbon.2010.11.009
Abstract: Using self-consistent KohnSham density-functional theory molecular dynamics simulations, we demonstrate the theoretical possibility to synthesize NiC60, the incarfullerene Ni@C60 and the heterofullerene C59Ni in an ion implantation setup. The corresponding formation mechanisms of all three complexes are elucidated as a function of the ion implantation energy and impact location, suggesting possible routes for selectively synthesizing these complexes.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 6.337
Times cited: 13
DOI: 10.1016/j.carbon.2010.11.009
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“Numerical simulation of hydrocarbon plasmas for nanoparticle formation and the growth of nanostructured thin films”. Neyts E, Eckert M, Mao M, Bogaerts A, Plasma physics and controlled fusion 51, 124034 (2009). http://doi.org/10.1088/0741-3335/51/12/124034
Abstract: This paper outlines two different numerical simulation approaches, carried out by our group, used for describing hydrocarbon plasmas in their applications for either nanoparticle formation in the plasma or the growth of nanostructured thin films, such as nanocrystalline diamond (NCD). A plasma model based on the fluid approach is utilized to study the initial mechanisms giving rise to nanoparticle formation in an acetylene plasma. The growth of NCD is investigated by molecular dynamics simulations, describing the interaction of the hydrocarbon species with a substrate.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 2.392
Times cited: 2
DOI: 10.1088/0741-3335/51/12/124034
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“Molecular dynamics simulations of the growth of thin a-C:H films under additional ion bombardment: influence of the growth species and the Ar+ ion kinetic energy”. Neyts E, Eckert M, Bogaerts A, Chemical vapor deposition 13, 312 (2007). http://doi.org/10.1002/cvde.200606551
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 1.333
Times cited: 14
DOI: 10.1002/cvde.200606551
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“Densification of thin a-C: H films grown from low-kinetic energy hydrocarbon radicals under the influence of H and C particle fluxes: a molecular dynamics study”. Neyts E, Bogaerts A, van de Sanden MCM, Journal of physics: D: applied physics 39, 1948 (2006). http://doi.org/10.1088/0022-3727/39/9/034
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 2.588
Times cited: 3
DOI: 10.1088/0022-3727/39/9/034
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“Effect of hydrogen on the growth of thin hydrogenated amorphous carbon films from thermal energy radicals”. Neyts E, Bogaerts A, van de Sanden MCM, Applied physics letters 88, 141922 (2006). http://doi.org/10.1063/1.2193803
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 3.411
Times cited: 35
DOI: 10.1063/1.2193803
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“Modeling PECVD growth of nanostructured carbon materials”. Neyts E, Bogaerts A, van de Sanden MCM, High temperature material processes 13, 399 (2009). http://doi.org/10.1615/HighTempMatProc.v13.i3-4.120
Abstract: We present here some of our modeling efforts for PECVD growth of nanostructured carbon materials with focus on amorphous hydrogenated carbon. Experimental data from an expanding thermal plasma setup were used as input for the simulations. Attention was focused both on the film growth mechanism, as well as on the hydrocarbon reaction mechanisms during growth of the films. It is found that the reaction mechanisms and sticking coefficients are dependent on the specific surface sites, and the structural properties of the growth radicals. The film growth results are in correspondence with the experiment. Furthermore, it is found that thin a-C:H films can be densified using an additional H-flux towards the substrate.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
DOI: 10.1615/HighTempMatProc.v13.i3-4.120
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“Reaction mechanisms and thin a-C:H film growth from low energy hydrocarbon radicals”. Neyts E, Bogaerts A, van de Sanden MCM, Journal of physics : conference series 86, 12020 (2007). http://doi.org/10.1088/1742-6596/86/1/012020
Abstract: Molecular dynamics simulations using the Brenner potential have been performed to investigate reaction mechanisms of various hydrocarbon radicals with low kinetic energies on amorphous hydrogenated carbon (a-C:H) surfaces and to simulate thin a-C:H film growth. Experimental data from an expanding thermal plasma setup were used as input for the simulations. The hydrocarbon reaction mechanisms were studied both during growth of the films and on a set of surface sites specific for a-C:H surfaces. Thin film growth was studied using experimentally detected growth species. It is found that the reaction mechanisms and sticking coefficients are dependent on the specific surface sites, and the structural properties of the growth radicals. Furthermore, it is found that thin a-C:H films can be densified using an additional H-flux towards the substrate.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Times cited: 22
DOI: 10.1088/1742-6596/86/1/012020
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“Unraveling the deposition mechanism in a-C:H thin-film growth: a molecular-dynamics study for the reaction behavior of C3 and C3H radicals with a-C:H surfaces”. Neyts E, Bogaerts A, van de Sanden MCM, Journal of applied physics 99, 014902 (2006). http://doi.org/10.1063/1.2150149
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 2.068
Times cited: 25
DOI: 10.1063/1.2150149
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“Molecular dynamics simulations for the growth of diamond-like carbon films from low kinetic energy species”. Neyts E, Bogaerts A, Gijbels R, Benedikt J, van den Sanden MCM, Diamond and related materials 13, 1873 (2004). http://doi.org/10.1016/j.diamond.2004.05.011
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 2.561
Times cited: 53
DOI: 10.1016/j.diamond.2004.05.011
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“Molecular dynamics simulation of the impact behaviour of various hydrocarbon species on DLC”. Neyts E, Bogaerts A, Gijbels R, Benedikt J, van de Sanden MCM, Nuclear instruments and methods in physics research: B: beam interactions with materials and atoms 228, 315 (2005). http://doi.org/10.1016/j.nimb.2004.10.063
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 1.109
Times cited: 19
DOI: 10.1016/j.nimb.2004.10.063
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“Macroscale computer simulations to investigate the chemical vapor deposition of thin metal-oxide films”. Neyts E, Bogaerts A, de Meyer M, van Gils S, Surface and coatings technology 201, 8838 (2007). http://doi.org/10.1016/j.surfcoat.2007.04.102
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 2.589
Times cited: 5
DOI: 10.1016/j.surfcoat.2007.04.102
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“Influence of internal energy and impact angle on the sticking behaviour of reactive radicals in thin a-C:H film growth: a molecular dynamics study”. Neyts E, Bogaerts A, Physical chemistry, chemical physics 8, 2066 (2006). http://doi.org/10.1039/b517563a
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 4.123
Times cited: 7
DOI: 10.1039/b517563a
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“Plasma-catalytic ammonia synthesis : packed catalysts act as plasma modifiers”. Ndayirinde C, Gorbanev Y, Ciocarlan R-G, De Meyer R, Smets A, Vlasov E, Bals S, Cool P, Bogaerts A, Catalysis today 419, 114156 (2023). http://doi.org/10.1016/J.CATTOD.2023.114156
Abstract: We studied the plasma-catalytic production of NH3 from H2 and N2 in a dielectric barrier discharge plasma reactor using five different Co-based catalysts supported on Al2O3, namely Co/Al2O3, CoCe/Al2O3, CoLa/Al2O3, CoCeLa/Al2O3 and CoCeMg/Al2O3. The catalysts were characterized via several techniques, including SEM-EDX, and their performance was compared. The best performing catalyst was found to be CoLa/Al2O3, but the dif-ferences in NH3 concentration, energy consumption and production rate between the different catalysts were limited under the same conditions (i.e. feed gas, flow rate and ratio, and applied power). At the same time, the plasma properties, such as the plasma power and current profile, varied significantly depending on the catalyst. Taken together, these findings suggest that in the production of NH3 by plasma catalysis, our catalysts act as plasma modifiers, i.e., they change the discharge properties and hence the gas phase plasma chemistry. Importantly, this effect dominates over the direct catalytic effect (as e.g. in thermal catalysis) defined by the chemistry on the catalyst surface.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Laboratory of adsorption and catalysis (LADCA); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 5.3
Times cited: 3
DOI: 10.1016/J.CATTOD.2023.114156
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“Harvesting Renewable Energy for Carbon Dioxide Catalysis”. Navarrete A, Centi G, Bogaerts A, Mart?n?ngel, York A, Stefanidis GD, Energy technology 5, 796 (2017). http://doi.org/10.1002/ente.201600609
Abstract: The use of renewable energy (RE) to transform carbon dioxide into commodities (i.e., CO2 valorization) will pave the way towards a more sustainable economy in the coming years. But how can we efficiently use this energy (mostly available as electricity or solar light) to drive the necessary (catalytic) transformations? This paper presents a review of the technological advances in the transformation of carbon dioxide by means of RE. The socioeconomic implications and chemical basis of the transformation of carbon dioxide with RE are discussed. Then a general view of the use of RE to activate the (catalytic) transformations of carbon dioxide with microwaves, plasmas, and light is presented. The fundamental phenomena involved are introduced from a catalytic and reaction device perspective to present the advantages of this energy form as well as the inherent limitations of the present state-of-the-art. It is shown that efficient use of RE requires the redesign of current catalytic concepts. In this context, a new kind of reaction system, an energy-harvesting device, is proposed as a new conceptual approach for this endeavor. Finally, the challenges that lie ahead for the efficient and economical use of RE for carbon dioxide conversion are exposed.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 2.789
Times cited: 15
DOI: 10.1002/ente.201600609
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“Grain size tuning of nanocrystalline chemical vapor deposited diamond by continuous electrical bias growth : experimental and theoretical study”. Mortet V, Zhang L, Eckert M, D'Haen J, Soltani A, Moreau M, Troadec D, Neyts E, De Jaeger JC, Verbeeck J, Bogaerts A, Van Tendeloo G, Haenen K, Wagner P, Physica status solidi : A : applications and materials science 209, 1675 (2012). http://doi.org/10.1002/pssa.201200581
Abstract: In this work, a detailed structural and spectroscopic study of nanocrystalline diamond (NCD) thin films grown by a continuous bias assisted CVD growth technique is reported. This technique allows the tuning of grain size and phase purity in the deposited material. The crystalline properties of the films are characterized by SEM, TEM, EELS, and Raman spectroscopy. A clear improvement of the crystalline structure of the nanograined diamond film is observed for low negative bias voltages, while high bias voltages lead to thin films consisting of diamond grains of only ∼10 nm nanometer in size, showing remarkable similarities with so-called ultrananocrystalline diamond. These layers arecharacterized by an increasing amount of sp2-bonded carbon content of the matrix in which the diamond grains are embedded. Classical molecular dynamics simulations support the observed experimental data, giving insight in the underlying mechanism for the observed increase in deposition rate with bias voltage. Furthermore, a high atomic concentration of hydrogen has been determined in these films. Finally, Raman scattering analyses confirm that the Raman line observed at ∼1150 cm−1 cannot be attributed to trans-poly-acetylene, which continues to be reported in literature, reassigning it to a deformation mode of CHx bonds in NCD.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 1.775
Times cited: 31
DOI: 10.1002/pssa.201200581
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“Characterization of nano-crystalline diamond films grown under continuous DC bias during plasma enhanced chemical vapor deposition”. Mortet V, Zhang L, Echert M, Soltani A, d' Haen J, Douheret O, Moreau M, Osswald S, Neyts E, Troadec D, Wagner P, Bogaerts A, Van Tendeloo G, Haenen K, Materials Research Society symposium proceedings (2009). http://doi.org/10.1557/PROC-1203-J05-03
Abstract: Nanocrystalline diamond films have generated much interested due to their diamond-like properties and low surface roughness. Several techniques have been used to obtain a high re-nucleation rate, such as hydrogen poor or high methane concentration plasmas. In this work, the properties of nano-diamond films grown on silicon substrates using a continuous DC bias voltage during the complete duration of growth are studied. Subsequently, the layers were characterised by several morphological, structural and optical techniques. Besides a thorough investigation of the surface structure, using SEM and AFM, special attention was paid to the bulk structure of the films. The application of FTIR, XRD, multi wavelength Raman spectroscopy, TEM and EELS yielded a detailed insight in important properties such as the amount of crystallinity, the hydrogen content and grain size. Although these films are smooth, they are under a considerable compressive stress. FTIR spectroscopy points to a high hydrogen content in the films, while Raman and EELS indicate a high concentration of sp2 carbon. TEM and EELS show that these films consist of diamond nano-grains mixed with an amorphous sp2 bonded carbon, these results are consistent with the XRD and UV Raman spectroscopy data.
Keywords: A3 Journal article; Electron microscopy for materials research (EMAT); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
DOI: 10.1557/PROC-1203-J05-03
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“Methane coupling in nanosecond pulsed plasmas: Correlation between temperature and pressure and effects on product selectivity”. Morais E, Delikonstantis E, Scapinello M, Smith G, Stefanidis GD, Bogaerts A, Chemical engineering journal 462, 142227 (2023). http://doi.org/10.1016/j.cej.2023.142227
Abstract: We present a zero-dimensional kinetic model to characterise specifically the gas-phase dynamics of methane
conversion in a nanosecond pulsed discharge (NPD) plasma reactor. The model includes a systematic approach to
capture the nanoscale power discharges and the rapid ensuing changes in electric field, gas and electron temperature,
as well as species densities. The effects of gas temperature and reactor pressure on gas conversion and
product selectivity are extensively investigated and validated against experimental work. We discuss the
important reaction pathways and provide an analysis of the dynamics of the heating and cooling mechanisms. H
radicals are found to be the most populous plasma species and they participate in hydrogenation and dehydrogenation
reactions, which are the dominant recombination reactions leading to C2H4 and C2H2 as main
products (depending on the pressure).
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 15.1
DOI: 10.1016/j.cej.2023.142227
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“Modelling the dynamics of hydrogen synthesis from methane in nanosecond‐pulsed plasmas”. Morais E, Bogaerts A, Plasma processes and polymers 21 (2024). http://doi.org/10.1002/ppap.202300149
Abstract: A chemical kinetics model was developed to characterise the gas‐phase dynamics of H<sub>2</sub>production in nanosecond‐pulsed CH<sub>4</sub>plasmas. Pulsed behaviour was observed in the calculated electric field, electron temperature and species densities at all pressures. The model agrees reasonably with experimental results, showing CH<sub>4</sub>conversion at 30% and C<sub>2</sub>H<sub>2</sub>and H<sub>2</sub>as major products. The underlying mechanisms in CH<sub>4</sub>dissociation and H<sub>2</sub>formation were analysed, highlighting the large contribution of vibrationally excited CH<sub>4</sub>and H<sub>2</sub>to coupling energy from the plasma into gas‐phase heating, and revealing that H<sub>2</sub>synthesis is not affected by applied pressure, with selectivity remaining unchanged at ~42% in the 1–5 bar range.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 3.5
DOI: 10.1002/ppap.202300149
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“Longitudinal hollow cathode copper ion laser: optimization of excitation and geometry”. Mihailova D, Grozeva M, Bogaerts A, Gijbels R, Sabotinov N, , 49 (2003)
Keywords: P3 Proceeding; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
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“Ionization density in hydrocarbon flames: numerical modelling”. Migoun A, Cenian A, Chernukho A, Bogaerts A, Gijbels R, Leys C, , 130 (2004)
Keywords: P3 Proceeding; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
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“CO 2 dissociation in a packed bed DBD reactor: First steps towards a better understanding of plasma catalysis”. Michielsen I, Uytdenhouwen Y, Pype J, Michielsen B, Mertens J, Reniers F, Meynen V, Bogaerts A, Chemical engineering journal 326, 477 (2017). http://doi.org/10.1016/j.cej.2017.05.177
Abstract: Plasma catalysis is gaining increasing interest for CO2 conversion, but the interaction between the plasma and catalyst is still poorly understood. This is caused by limited systematic materials research, since most works combine a plasma with commercial supported catalysts and packings. In the present paper, we study the influence of specific material and reactor properties, as well as reactor/bead configuration, on the conversion and energy efficiency of CO2 dissociation in a packed bed dielectric barrier discharge (DBD) reactor. Of the various packing materials investigated, BaTiO3 yields the highest conversion and energy efficiency, i.e., 25% and 4.5%.
Our results show that, when evaluating the influence of catalysts, the impact of the packing (support) material itself cannot be neglected, since it can largely affect the conversion and energy efficiency. This shows the large potential for further improvement of packed bed plasma reactors for CO2 conversion and other chemical conversion reactions by adjusting both packing (support) properties and catalytically active sites. Moreover, we clearly prove that comparison of results obtained in different reactor setups should be done with care, since there is a large effect of the reactor setup and reactor/bead configuration.
Keywords: A1 Journal article; Laboratory of adsorption and catalysis (LADCA); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 6.216
Times cited: 49
DOI: 10.1016/j.cej.2017.05.177
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“Altering conversion and product selectivity of dry reforming of methane in a dielectric barrier discharge by changing the dielectric packing material”. Michielsen I, Uytdenhouwen Y, Bogaerts A, Meynen V, Catalysts 9, 51 (2019). http://doi.org/10.3390/CATAL9010051
Abstract: We studied the influence of dense, spherical packing materials, with different chemical compositions, on the dry reforming of methane (DRM) in a dielectric barrier discharge (DBD) reactor. Although not catalytically activated, a vast effect on the conversion and product selectivity could already be observed, an influence which is often neglected when catalytically activated plasma packing materials are being studied. The alpha-Al2O3 packing material of 2.0-2.24 mm size yields the highest total conversion (28%), as well as CO2 (23%) and CH4 (33%) conversion and a high product fraction towards CO (similar to 70%) and ethane (similar to 14%), together with an enhanced CO/H-2 ratio of 9 in a 4.5 mm gap DBD at 60 W and 23 kHz. gamma-Al2O3 is only slightly less active in total conversion (22%) but is even more selective in products formed than alpha-Al2O3 BaTiO3 produces substantially more oxygenated products than the other packing materials but is the least selective in product fractions and has a clear negative impact on CO2 conversion upon addition of CH4. Interestingly, when comparing to pure CO2 splitting and when evaluating differences in products formed, significantly different trends are obtained for the packing materials, indicating a complex impact of the presence of CH4 and the specific nature of the packing materials on the DRM process.
Keywords: A1 Journal article; Laboratory of adsorption and catalysis (LADCA); Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 3.082
Times cited: 4
DOI: 10.3390/CATAL9010051
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“Plasma Catalysis Modeling: How Ideal Is Atomic Hydrogen for Eley–Rideal?”.Michiels R, Gerrits N, Neyts E, Bogaerts A, The Journal of Physical Chemistry C 128, 11196 (2024). http://doi.org/10.1021/acs.jpcc.4c02193
Abstract: Plasma catalysis is an emerging technology, but a lot of questions about the underlying surface mechanisms remain unanswered. One of these questions is how important Eley−Rideal (ER) reactions are, next to Langmuir−Hinshelwood reactions. Most plasma catalysis kinetic models predict ER reactions to be important and sometimes even vital for the surface chemistry. In this work, we take a critical look at how ER reactions involving H radicals are incorporated in kinetic models describing CO2 hydrogenation and NH3 synthesis. To this end, we construct potential energy surface (PES) intersections, similar to elbow plots constructed for dissociative chemisorption. The results of the PES intersections are in agreement with ab initio molecular dynamics (AIMD) findings in literature while being computationally much cheaper. We find that, for the reactions studied here, adsorption is more probable than a reaction via the hot atom (HA) mechanism, which in turn is more probable than a reaction via the ER mechanism. We also conclude that kinetic models of plasma-catalytic systems tend to overestimate the importance if ER reactions. Furthermore, as opposed to what is often assumed in kinetic models, the choice of catalyst will influence the ER reaction probability. Overall, the description of ER reactions is too much “ideal” in models. Based on our indings, we make a number of recommendations on how to incorporate ER reactions in kinetic models to avoid overestimation of their importance.
Keywords: A1 Journal Article; Plasma, laser ablation and surface modeling Antwerp (PLASMANT) ;
Impact Factor: 3.7
DOI: 10.1021/acs.jpcc.4c02193
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“Plasma Catalysis for CO2Hydrogenation: Unlocking New Pathways toward CH3OH”. Michiels R, Engelmann Y, Bogaerts A, Journal Of Physical Chemistry C 124, 25859 (2020). http://doi.org/10.1021/acs.jpcc.0c07632
Abstract: We developed a microkinetic model to reveal the effects of plasma-generated radicals, intermediates, and vibrationally excited species on the catalytic hydrogenation of CO2 to CH3OH on a Cu(111) surface. As a benchmark, we first present the mechanisms of thermal catalytic CH3OH formation. Our model predicts that the reverse water-gas shift reaction followed by CO hydrogenation, together with the formate path, mainly contribute to CH3OH formation in thermal catalysis. Adding plasma-generated radicals and intermediates results in a higher CH3OH turnover frequency (TOF) by six to seven orders of magnitude, showing the potential of plasma-catalytic CO2 hydrogenation into CH3OH, in accordance with the literature. In addition, CO2 vibrational excitation further increases the CH3OH TOF, but the effect is limited due to relatively low vibrational temperatures under typical plasma catalysis conditions. The predicted increase in CH3OH formation by plasma catalysis is mainly attributed to the increased importance of the formate path. In addition, the conversion of plasma-generated CO to HCO* and subsequent HCOO* or H2CO* formation contribute to CH3OH formation. Both pathways bypass the HCOO* formation from CO2, which is the main bottleneck in the process. Hence, our model points toward the important role of CO, but also O, OH, and H radicals, as they influence the reactions that consume CO2 and CO. In addition, our model reveals that the H pressure should not be smaller than ca. half of the O pressure in the plasma as this would cause O* poisoning, which would result in very small product TOFs. Thus, plasma conditions should be targeted with a high CO and H content as this is favorable for CH3OH formation, while the O content should be minimized.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT); Movement Antwerp (MOVANT)
Impact Factor: 3.7
DOI: 10.1021/acs.jpcc.0c07632
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“Post-plasma quenching to improve conversion and energy efficiency in a CO2 microwave plasma”. Mercer Er, Van Alphen S, van Deursen Cfam, Righart Twh, Bongers Wa, Snyders R, Bogaerts A, van de Sanden Mcm, Peeters Fjj, Fuel 334, 126734 (2023). http://doi.org/10.1016/j.fuel.2022.126734
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.
Keywords: A1 Journal article; Engineering sciences. Technology; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 7.4
DOI: 10.1016/j.fuel.2022.126734
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