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“Plasma-based dry reforming : improving the conversion and energy efficiency in a dielectric barrier discharge”. Snoeckx R, Zeng YX, Tu X, Bogaerts A, RSC advances 5, 29799 (2015). http://doi.org/10.1039/C5RA01100K
Abstract: Dry reforming of methane has gained significant interest over the years. A novel reforming technique with great potential is plasma technology. One of its drawbacks, however, is energy consumption. Therefore, we performed an extensive computational study, supported by experiments, aiming to identify the influence of the operating parameters (gas mixture, power, residence time and frequency) of a dielectric barrier discharge plasma on the conversion and energy efficiency, and to investigate which of these parameters lead to the most promising results and whether these are eventually sufficient for industrial implementation. The best results, in terms of both energy efficiency and conversion, are obtained at a specific energy input (SEI) of 100 J cm−3, a 1090 CH4CO2 ratio, 10 Hz, a residence time of 1 ms, resulting in a total conversion of 84% and an energy efficiency of 8.5%. In general, increasing the CO2 content in the gas mixture leads to a higher conversion and energy efficiency. The SEI couples the effect of the power and residence time, and increasing the SEI always results in a higher conversion, but somewhat lower energy efficiencies. The effect of the frequency is more complicated: we observed that the product of frequency (f) and residence time (τ), being a measure for the total number of micro-discharge filaments which the gas molecules experience when passing through the reactor, was critical. For most cases, a higher number of filaments yields higher values for conversion and energy efficiency. To benchmark our model predictions, we also give an overview of measured conversions and energy efficiencies reported in the literature, to indicate the potential for improvement compared to the state-of-the art. Finally, we identify the limitations as well as the benefits and future possibilities of plasma technology.
Keywords: A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT)
Impact Factor: 3.108
Times cited: 67
DOI: 10.1039/C5RA01100K
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“Band-gap tuning of graphene by Be doping and Be, B co-doping : a DFT study”. Ullah S, Hussain A, Syed WA, Saqlain MA, Ahmad I, Leenaerts O, Karim A, RSC advances 5, 55762 (2015). http://doi.org/10.1039/c5ra08061d
Abstract: First-principles density functional theory (DFT) calculations were carried out to investigate the structural and electronic properties of beryllium (Be) doped and Be and boron (B) co-doped graphene systems. We observed that not only the concentration of impurity atoms is important to tune the band-gap to some desired level, but also the specific substitution sites play a key role. In our system, which consists of 32 atoms, a maximum of 4Be and, in the co-doped state, 2Be and 3B atom substitutions are investigated. Both dopants are electron deficient relative to C atoms and cause the Fermi level to shift downward (p-type doping). A maximum band gap of 1.44 eV can be achieved on incorporation of 4Be atoms. The introduction of Be is more sensitive in terms of geometry and stability than B. However, in opening the energy gap, Be is more effective than B and N (nitrogen). Our results offer the possibility to modify the band-gap of graphene sufficiently for utilization in diverse electronic device applications.
Keywords: A1 Journal article; Condensed Matter Theory (CMT)
Impact Factor: 3.108
Times cited: 33
DOI: 10.1039/c5ra08061d
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“Au@UiO-66 : a base free oxidation catalyst”. Leus K, Concepcion P, Vandichel M, Meledina M, Grirrane A, Esquivel D, Turner S, Poelman D, Waroquier M, Van Speybroeck V, Van Tendeloo G, García H, Van Der Voort P;, RSC advances 5, 22334 (2015). http://doi.org/10.1039/c4ra16800c
Abstract: We present the in situ synthesis of Au nanoparticles within the Zr based Metal Organic Framework, UiO-66. The resulting Au@UiO-66 materials were characterized by means of N-2 sorption, XRPD, UV-Vis, XRF, XPS and TEM analysis. The Au nanoparticles (NP) are homogeneously distributed along the UiO-66 host matrix when using NaBH4 or H-2 as reducing agents. The Au@UiO-66 materials were evaluated as catalysts in the oxidation of benzyl alcohol and benzyl amine employing O-2 as oxidant. The Au@MOF materials exhibit a very high selectivity towards the ketone (up to 100%). Regenerability and stability tests demonstrate that the Au@UiO-66 catalyst can be recycled with a negligible loss of Au species and no loss of crystallinity. In situ IR measurements of UiO-66 and Au@UiO-66-NaBH4, before and after treatment with alcohol, showed an increase in IR bands that can be assigned to a combination of physisorbed and chemisorbed alcohol species. This was confirmed by velocity power spectra obtained from the molecular dynamics simulations. Active peroxo and oxo species on Au could be visualized with Raman analysis.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT)
Impact Factor: 3.108
Times cited: 38
DOI: 10.1039/c4ra16800c
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“New insights into the mesophase transformation of ethane-bridged PMOs by the influence of different counterions under basic conditions”. Lin F, Meng, Kukueva E, Mertens M, Van Doorslaer S, Bals S, Cool P, RSC advances 5, 5553 (2015). http://doi.org/10.1039/c4ra15849k
Abstract: The counterions are of crucial importance in determining the mesostructure and morphology of ethanebridged PMO materials synthesized under basic conditions. By using CTABr as the surfactant, the final PMO materials show a 2-D hexagonal (p6mm) mesophase, while PMO materials with cubic (Pm (3) over barn ) mesostructure are obtained when CTACl or CTA(SO4)(1)/(2) are used. With gradually replacing CTABr by CTACl or CTA(SO4) (1)/(2) while keeping the total surfactant concentration constant, a clear p6mm to Pm (3) over barn 3n mesophase evolution process is observed. For a given gel composition, the mesophase of ethanebridged PMO materials can also be adjusted by the addition of different sodium salts. In short, the effect of the counterions on the mesophase can be attributed to the binding strength of the ions on the surfactant micelles, which follows the Hofmeister series (SO42- < Cl- < Br-< NO3- < SCN-). Furthermore, it is found that the hydrolysis and condensation rate of the organosilica precursor also plays an important role in the formation of the final mesostructure
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Laboratory of adsorption and catalysis (LADCA)
Impact Factor: 3.108
Times cited: 6
DOI: 10.1039/c4ra15849k
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