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Fakhardji, W., Szabo, P., El-Kader, M., Haskopoulos, A., Maroulis, G. & Gustafsson, M. (2019). Collision-induced absorption in Ar–Kr gas mixtures: A molecular dynamics study with new potential and dipole data. Journal of Chemical Physics, 151(14), Article ID 144303.
Open this publication in new window or tab >>Collision-induced absorption in Ar–Kr gas mixtures: A molecular dynamics study with new potential and dipole data
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2019 (English)In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 151, no 14, article id 144303Article in journal (Refereed) Published
Abstract [en]

We have implemented a scheme for classical molecular dynamics simulations of collision-induced absorption. The program has been applied to a gas mixture of argon (Ar) and krypton (Kr). The simulations are compared with accurate quantum dynamical calculations. The comparisons of the absorption coefficients show that classical molecular dynamics is correct within 10% for photon wave numbers up to 220 cm−1 at a temperature of 200 K for this system. At higher temperatures, the agreement is even better. Molecular dynamics accounts for many-body interactions, which, for example, give rise to continuous dimer formation and destruction in the gas. In this way, the method has an advantage compared with bimolecular classical (trajectory) treatments. The calculations are carried out with a new empirical Ar–Kr pair potential. This has been obtained through extensive analysis of experimental thermophysical and transport properties. We also present a new high level ab initio Ar–Kr potential curve for comparison, as well as ab initio interaction-induced dipole curves computed with different methods. In addition, the Ar–Kr polarizability and hyperpolarizability are reported. A comparison of the computed absorption spectra with an experiment taken at 300 K shows satisfactory agreement although a difference in absolute magnitude of 10%–15% persists. This discrepancy we attribute mainly to experimental uncertainty.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2019
National Category
Atom and Molecular Physics and Optics Physical Chemistry Other Physics Topics
Research subject
Applied Physics
Identifiers
urn:nbn:se:ltu:diva-76352 (URN)10.1063/1.5099700 (DOI)000500356200026 ()31615255 (PubMedID)2-s2.0-85073264154 (Scopus ID)
Funder
The Kempe FoundationsKnut and Alice Wallenberg Foundation
Note

Validerad;2019;Nivå 2;2019-10-15 (johcin)

Available from: 2019-10-10 Created: 2019-10-10 Last updated: 2019-12-20Bibliographically approved
Szabo, P. & Gustafsson, M. (2019). Formation of the NH molecule and its isotopologues through radiative association. Monthly notices of the Royal Astronomical Society, 483(3), 3574-3578
Open this publication in new window or tab >>Formation of the NH molecule and its isotopologues through radiative association
2019 (English)In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 483, no 3, p. 3574-3578Article in journal (Refereed) Published
Abstract [en]

The rate coefficients and the cross-sections for the formation of imidogen (NH) molecule (and its isotopologues: 15NH and ND) through radiative association are determined by employing quantum mechanical perturbation theory, classical Larmor formula, and Breit–Wigner theory. We suggest the radiative association process as possible route for NH production in diffuse interstellar clouds.

Place, publisher, year, edition, pages
Oxford Journals, 2019
Keywords
molecular processes, scattering, ISM: atoms, ISM: clouds, ISM: molecules
National Category
Atom and Molecular Physics and Optics Composite Science and Engineering Other Physics Topics
Research subject
Applied Physics
Identifiers
urn:nbn:se:ltu:diva-73251 (URN)10.1093/mnras/sty3246 (DOI)000462280000046 ()
Funder
The Kempe FoundationsKnut and Alice Wallenberg Foundation
Note

Validerad;2019;Nivå 2;2019-04-10 (oliekm)

Available from: 2019-03-19 Created: 2019-03-19 Last updated: 2019-04-10Bibliographically approved
Góger, S., Szabo, P., Czakó, G. & Lendvay, G. (2018). Flame Inhibition Chemistry: Rate Coefficients of the Reactions of HBr with CH3 and OH Radicals at High Temperatures Determined by Quasiclassical Trajectory Calculations. Energy & Fuels, 32(10), 10100-10105
Open this publication in new window or tab >>Flame Inhibition Chemistry: Rate Coefficients of the Reactions of HBr with CH3 and OH Radicals at High Temperatures Determined by Quasiclassical Trajectory Calculations
2018 (English)In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 32, no 10, p. 10100-10105Article in journal (Refereed) Published
Abstract [en]

Reactions of HBr with radicals are involved in atmospheric chemistry and in the mechanism of operation of bromine-containing flame retardants. The rate coefficients for two such reactions, HBr + OH and HBr + CH3, are available from earlier experiments at near or below room temperature, relevant for atmospheric chemistry, and in this domain, the activation energy for both has been found to be negative. However, no experimental data are available at combustion temperatures. In this work, to provide reliable data needed for modeling the action of brominated flame suppressants, we used the quasiclassical trajectory (QCT) method in combination with high-level ab initio potential energy surfaces to evaluate the rate coefficients of the two title reactions at combustion temperatures. The QCT calculations have been validated by reproducing the experimental rate coefficients at room temperature. At temperatures between 600 and 3200 K, the QCT rate coefficients display positive activation energies. We recommend the following extended Arrhenius expressions to describe the temperature dependence of the thermal rate coefficients: k6 = (9.86 ± 2.38) × 10–16T(1.23±0.03) exp[(5.93 ± 0.33) kJ mol–1/RT] cm3 molecule–1 s–1 for the HBr + OH → H2O + Br reaction, and k–2 = (4.06 ± 2.72) × 10–18T(1.83±0.08) exp[(7.53 ± 0.18) kJ mol–1/RT] cm3 molecule–1 s–1 for the HBr + CH3 → CH4 + Br reaction. The latter is in very good agreement with the formula proposed by Burgess et al. [Burgess, D. R., Jr.; Babushok, V. I.; Linteris, G. T.; Manion, J. A. A Chemical Kinetic Mechanism for 2-Bromo-3,3,3-trifluoropropene (2-BTP) Flame Inhibition. Int. J. Chem. Kinet. 2015, 47, 533−619, DOI: 10.1002/kin.20923]. The conventional transition state theory has been tested against the rate data obtained by the QCT method and was found to overestimate not only the rate coefficients but also the activation energies

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2018
National Category
Other Physics Topics
Research subject
Applied Physics
Identifiers
urn:nbn:se:ltu:diva-68839 (URN)10.1021/acs.energyfuels.8b00989 (DOI)000448087000006 ()2-s2.0-85047092946 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-11-19 (johcin) 

Available from: 2018-05-22 Created: 2018-05-22 Last updated: 2019-03-27Bibliographically approved
Fehér, K., Nagy, E., Szabo, P., Juzsakova, T., Srankó, D., Gömöry, Á., . . . Skoda-Földes, R. (2018). Heterogeneous azide–alkyne cycloaddition in the presence of a copper catalyst supported on an ionic liquid polymer/silica hybrid material. Applied organometallic chemistry, 32(6), Article ID e4343.
Open this publication in new window or tab >>Heterogeneous azide–alkyne cycloaddition in the presence of a copper catalyst supported on an ionic liquid polymer/silica hybrid material
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2018 (English)In: Applied organometallic chemistry, ISSN 0268-2605, E-ISSN 1099-0739, Vol. 32, no 6, article id e4343Article in journal (Refereed) Published
Abstract [en]

Heterogeneous copper catalysts were prepared by the deposition of CuI on a hybrid material consisting of silica and a polymer with imidazolium moieties. The solid materials were characterised using solid‐phase NMR, Fourier transform infrared, Raman and X‐ray photoelectron spectroscopies and Brunauer–Emmett–Teller measurements. The formation of copper–carbene complexes was proved from Raman spectra and the results were supported by density functional theory calculations. The catalyst could be recycled efficiently with low loss of copper. Metal leaching was proved to be facilitated by the use of conditions typical for a homogeneous system (the presence of a polar solvent or the addition of a tertiary amine). Besides simple model reactions, the best catalyst was found to be suitable for the synthesis of triazoles of more elaborate structure, such as ferrocene or steroid derivatives.

Place, publisher, year, edition, pages
John Wiley & Sons, 2018
National Category
Other Physics Topics
Research subject
Applied Physics
Identifiers
urn:nbn:se:ltu:diva-68625 (URN)10.1002/aoc.4343 (DOI)000434047600010 ()
Available from: 2018-05-04 Created: 2018-05-04 Last updated: 2018-06-21Bibliographically approved
Szabo, P. & Gustafsson, M. (2017). A surface-hopping method for semiclassical calculations of cross sectionsfor radiative association with electronic transitions. Journal of Chemical Physics, 147, Article ID 094308.
Open this publication in new window or tab >>A surface-hopping method for semiclassical calculations of cross sectionsfor radiative association with electronic transitions
2017 (English)In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 147, article id 094308Article in journal (Refereed) Published
Abstract [en]

A semiclassical method based on surface-hopping techniques is developed to model the dynamics of radiative association with electronic transitions. It can be proven that this method is an extension of the established semiclassical formula used in the characterization of diatomic molecule-formation. Our method is tested for diatomic molecules. It gives the same cross sections as the former semiclassical formula but, contrary to the former method, it allows us to follow the fate of the trajectories after the emission of a photon. This means that we can characterize the rovibrational states of the stabilized molecules. Using semiclassical quantization, we can obtain quantum state-resolved cross sections or emission spectra for the radiative association process. The calculated semiclassical state-resolved spectra show general agreement with the result of quantum mechanical perturbation theory. Furthermore, our surface-hopping model is not only applicable for the description of radiative association but it can be used for semiclassical characterization of any molecular process where spontaneous emission occurs

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2017
National Category
Other Physics Topics
Research subject
Applied Physics
Identifiers
urn:nbn:se:ltu:diva-65537 (URN)10.1063/1.5000573 (DOI)000409946200022 ()28886643 (PubMedID)2-s2.0-85029324034 (Scopus ID)
Note

Validerad;2017;Nivå 2;2017-09-08 (andbra)

Available from: 2017-09-08 Created: 2017-09-08 Last updated: 2018-07-10Bibliographically approved
Szabo, P., Zsirka, B., Fertig, D., Horváth, E., Csizmadia, T. & Kristóf, J. (2017). Delaminated kaolinites as potential photocatalysts: Tracking degradation of Na-benzenesulfonate test compound adsorbed on the dry surface of kaolinite nanostructures. Catalysis Today, 287(Supplement C), 37-44
Open this publication in new window or tab >>Delaminated kaolinites as potential photocatalysts: Tracking degradation of Na-benzenesulfonate test compound adsorbed on the dry surface of kaolinite nanostructures
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2017 (English)In: Catalysis Today, ISSN 0920-5861, E-ISSN 1873-4308, Vol. 287, no Supplement C, p. 37-44Article in journal (Refereed) Published
Abstract [en]

Abstract Based on their bandgap values, kaolins can have semiconductive and photocatalytic properties enabling them to use as potential photocatalysts. Kaolinite nanostructures (Knano) and silver-coated kaolinite nanohybrids (Knano(Ag)) were made of ordered (Hinkley Index, HI=1.4) and disordered (HI=0.3) kaolins via intercalation/deintercalation. The book-type kaolin built up from tetrahedral(T)-octahedral(O) double layers has very low photocatalytic activity. At the same time the nanostructures made of individual TO layers show photochemical activity in spite of the fact that their bandgap values are comparable to those of the book-type ones. The presence of Ag on the surface significantly reduced the bandgap and shifted the excitation wavelength towards the visible range. This phenomenon supports the supposition that kaolinite has some semiconductive character. This work presents the connection between photocatalytic activity and morphology for the first time. The surface activity of kaolinite nanostructures and their Ag-hybrids was studied through the decomposition of sodium-benzenesulfonate (BS) test compound with attenuated total reflection Fourier transform infrared spectroscopy (FT-IR/ATR). BS decomposition can be detected on the Knano surface but with low efficiency. The presence of silver can significantly improve the mineralization efficiency. No correlation was found between the activity and the quantity of Ti and Fe contaminants and the amount of Ag on the surface. However, the activity could be correlated with the order-dependent morphology (mixture of semi-hexagonal and nanoscroll-type structures), the pore size and with the increase of the surface coverage.

Place, publisher, year, edition, pages
Elsevier, 2017
Keywords
Kaolinite nanostructures, Ag-nanohybrides, Photocatalysis, Mineralization, FT-IR spectroscopy
National Category
Materials Chemistry Other Physics Topics
Research subject
Applied Physics
Identifiers
urn:nbn:se:ltu:diva-66488 (URN)10.1016/j.cattod.2017.01.051 (DOI)
Available from: 2017-11-08 Created: 2017-11-08 Last updated: 2017-11-24Bibliographically approved
Hegedűs, P., Szabó-Bárdos, E., Horváth, O., Szabó, P. & Horváth, K. (2017). Investigation of a TiO2 photocatalyst immobilized with poly(vinyl alcohol). Catalysis Today, 284, 179-186
Open this publication in new window or tab >>Investigation of a TiO2 photocatalyst immobilized with poly(vinyl alcohol)
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2017 (English)In: Catalysis Today, ISSN 0920-5861, E-ISSN 1873-4308, Vol. 284, p. 179-186Article in journal (Refereed) Published
Abstract [en]

Immobilization of TiO2 photocatalyst was realized with application of poly(vinyl alcohol) (PVA). However, these PVA-based foils were too instable to be used for photocatalytic water cleaning. Their stability could be significantly enhanced by a thermal treatment, but this procedure generated various water-soluble derivatives such as aldehydes, ketones, and aromatic species. Photocatalytic pre-treatment of the foils proved to be suitable to remove these products from the surface of the composite. After three subsequent pre-treating cycles of irradiation and rinsing, the PVA-TiO2 foil became applicable for photocatalytic degradation of Triton X-100, a widely used non-ionic detergent. The composite catalyst kept its stability and efficiency even after some cycles of re-usage, while its surface underwent a perceptible, although quantitatively negligible degradation.

Place, publisher, year, edition, pages
Elsevier, 2017
Keywords
TiO based photocatalysis, Immobilization, Thermal decomposition of PVA, Organic pollutant, Triton X-100
National Category
Materials Chemistry Other Physics Topics
Research subject
Applied Physics
Identifiers
urn:nbn:se:ltu:diva-66489 (URN)10.1016/j.cattod.2016.11.050 (DOI)
Available from: 2017-11-08 Created: 2017-11-08 Last updated: 2017-11-24Bibliographically approved
Papp, M., Szabó, P., Srankó, D., Sáfrán, G., Kollár, L. & Skoda-Földes, R. (2017). Mono- and double carbonylation of aryl iodides with amine nucleophiles in the presence of recyclable palladium catalysts immobilised on a supported dicationic ionic liquid phase. RSC Advances, 7(70), 44587-44597
Open this publication in new window or tab >>Mono- and double carbonylation of aryl iodides with amine nucleophiles in the presence of recyclable palladium catalysts immobilised on a supported dicationic ionic liquid phase
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2017 (English)In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 7, no 70, p. 44587-44597Article in journal (Refereed) Published
Abstract [en]

Silica modified with organic dicationic moieties proved to be an excellent support for palladium catalysts used in the aminocarbonylation of aryl iodides. By an appropriate choice of the reaction conditions, the same catalyst could be used for selective mono- or double carbonylations leading to amide and α-ketoamide products, respectively. The best catalyst could be recycled for at least 10 consecutive runs with a loss of palladium below the detection limit. By the application of the new support, efficient catalyst recycling could be achieved under mild reaction conditions (under low pressure and in a short reaction time). Palladium-leaching data support a mechanism with dissolution—re-precipitation of the active palladium species.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2017
Keywords
catalysis
National Category
Materials Chemistry Other Physics Topics
Research subject
Applied Physics
Identifiers
urn:nbn:se:ltu:diva-65685 (URN)10.1039/C7RA04680D (DOI)000411021100071 ()2-s2.0-85029714089 (Scopus ID)
Available from: 2017-09-17 Created: 2017-09-17 Last updated: 2017-11-29Bibliographically approved
Zsirka, B., Horváth, E., Szabó, P., Juzsakova, T., Szilágyi, R. K., Fertig, D., . . . Kristóf, J. (2017). Thin-walled nanoscrolls by multi-step intercalation from tubular halloysite-10 Å and its rearrangement upon peroxide treatment. Applied Surface Science, 399, 245-254
Open this publication in new window or tab >>Thin-walled nanoscrolls by multi-step intercalation from tubular halloysite-10 Å and its rearrangement upon peroxide treatment
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2017 (English)In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 399, p. 245-254Article in journal (Refereed) Published
Abstract [en]

Surface modification of the halloysite-10 Å mineral with tubular morphology can be achieved by slightly modified procedures developed for the delamination of kaolinite minerals. The resulting delaminated halloysite nanoparticles have unexpected surface/morphological properties that display, new potentials in catalyst development. In this work, a four-step intercalation/delamination procedure is described for the preparation of thin-walled nanoscrolls from the multi-layered hydrated halloysite mineral that consists of (1) intercalation of halloysite with potassium acetate, (2) replacement intercalation with ethylene glycol, (3) replacement intercalation with hexylamine, and (4) delamination with toluene. The intercalation steps were followed by X-ray diffraction, transmission electron microscopy, N2adsorption-desorption, thermogravimetry, and infrared spectroscopy. Delamination eliminated the crystalline order and the crystallite size along the ‘c’-axis, increased the specific surface area, greatly decreased the thickness of the mineral tubes to a monolayer, and shifted the pore diameter toward the micropore region. Unexpectedly, the removal of residual organics from intercalation steps adsorbed at the nanoscroll surface with a peroxide treatment resulted in partial recovery of crystallinity and increase of crystallite size along the ‘c’-crystal direction. The d(001) value showed a diffuse pattern at 7.4–7.7 Å due to the rearrangement of the thin-walled nanoscrolls toward the initial tubular morphology of the dehydrated halloysite-7 Å mineral.

Place, publisher, year, edition, pages
Elsevier, 2017
Keywords
Halloysite nanoscrolls, Intercalation, Surface characterisation, Oxidative surface cleaning, Rearrangement of nanostructures
National Category
Materials Chemistry Other Physics Topics
Research subject
Applied Physics
Identifiers
urn:nbn:se:ltu:diva-66490 (URN)10.1016/j.apsusc.2016.12.053 (DOI)000393001700028 ()2-s2.0-85007179600 (Scopus ID)
Available from: 2017-11-08 Created: 2017-11-08 Last updated: 2017-11-24Bibliographically approved
Gergely, A., Locskai, R., Szabo, P., Krójer, A. & Kristóf, T. (2016). Hydrogen Sulphide Corrosion of Carbon and Stainless Steel Alloys Immersed in Mixtures of Renewable Fuel Sources and Tested Under Co-processing Conditions. Hungarian Journal of Industry and Chemistry, 44(1), 55-70
Open this publication in new window or tab >>Hydrogen Sulphide Corrosion of Carbon and Stainless Steel Alloys Immersed in Mixtures of Renewable Fuel Sources and Tested Under Co-processing Conditions
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2016 (English)In: Hungarian Journal of Industry and Chemistry, ISSN 2450-5102, Vol. 44, no 1, p. 55-70Article in journal (Refereed) Published
Abstract [en]

In accordance with modern regulations and directives, the use of renewable biomass materials as precursors for the production of fuels for transportation purposes is to be strictly followed. Even though, there are problems related to processing, storage and handling in wide range of subsequent uses, since there must be a limit to the ratio of biofuels mixed with mineral raw materials. As a key factor with regards to these biomass sources pose a great risk of causing multiple forms of corrosion both to metallic and non-metallic structural materials. To assess the degree of corrosion risk to a variety of engineering alloys like low-carbon and stainless steels widely used as structural metals, this work is dedicated to investigating corrosion rates of economically reasonable engineering steel alloys in mixtures of raw gas oil and renewable biomass fuel sources under typical co-processing conditions. To model a desulphurising refining process, corrosion tests were carried out with raw mineral gasoline and its mixture with used cooking oil and animal waste lard in relative quantities of 10% (g/g). Co-processing was simulated by batch-reactor laboratory experiments. Experiments were performed at temperatures between 200 and 300ºC and a pressure in the gas phase of 90 bar containing 2% (m3/m3) hydrogen sulphide. The time span of individual tests were varied between 1 and 21 days so that we can conclude about changes in the reaction rates against time exposure of and extrapolate for longer periods of exposure. Initial and integral corrosion rates were defined by a weight loss method on standard size of coupons of all sorts of steel alloys. Corrosion rates of carbon steels indicated a linear increase with temperature and little variation with composition of the biomass fuel sources. Apparent activation energies over the first 24-hour period remained moderate, varying between 35.5 and 50.3 kJ mol−1. Scales developed on carbon steels at higher temperatures were less susceptible to spall and detach. Nonetheless, moderate deceleration of corrosion rates as a function of time are due to the less coherent, frequently spalling and low compactness, higher porosity of the scales evolved at lower and higher temperatures, respectively. On the surface of high alloy steels, sulphide scales of an enhanced barrier nature formed during the induction periods and the layer formation mechanism was found to be assisted by the increasing temperature as initial reaction rates considerably decreased over time. Nevertheless, corrosion-related sulphide conversion of metals and mass loss of the high alloys are strongly affected by the composition of the biomass fuel sources especially animal waste lard. Thermal activation in the first 24 hours decreased from 68.9 to 35.2 kJ mol−1. A greater degree of failure to develop protective sulphide scales was experienced by changing to composition of the biomass fuel sources than the impact of thermal activation between a narrow temperature range at around 100ºC. In accordance with the literature, high free fatty acid contents lead to high corrosion rates accounted for direct corrosion of high alloy steels and assisted solubilisation of corrosion products. In addition, the pronounced acceleration of sulphide corrosion is connected to the diminishing inhibition effect of the sulphide scales

Place, publisher, year, edition, pages
De Gruyter Open, 2016
National Category
Physical Chemistry Other Physics Topics
Research subject
Applied Physics
Identifiers
urn:nbn:se:ltu:diva-66491 (URN)10.1515/hjic-2016-0007 (DOI)
Available from: 2017-11-08 Created: 2017-11-08 Last updated: 2017-11-24Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0002-0271-4846

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