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133 results on '"Loridant, Stéphane"'

6. Investigating the Dynamics of Pt/CeO2 Catalysts at the Powder Agglomerate Scale by Combining In Situ Hyperspectral Raman Imaging and SEM‐EDX Analysis.

Author

Molinet‐Chinaglia, Clément, Piccolo, Laurent, and Loridant, Stéphane

Subjects
IMAGE analysis, ATOM trapping, CATALYSTS, OXIDATION-reduction reaction, LOW temperatures, SURFACE diffusion
Abstract

The dynamics of Pt/CeO2 catalysts is a hot topic since its knowledge can be used to (re)generate more active sites for redox reactions, even at low temperature (<500 °C). While numerous works focus on the atomic scale, the spatial extent of Pt surface diffusion is poorly known. In this work, it is evaluated at the powder agglomerate scale using an original methodology combining SEM‐EDX analysis and in situ optical/microRaman hyperspectral imaging performed on a Pt/CeO2+CeO2 mechanical mixture. No intergranular diffusion of platinum during redox cycles at 500 °C is revealed by these techniques, in particular by the Raman images of Ce3+ and peroxo species, which are highly sensitive to the presence of Pt atoms. It strongly suggests that Pt surface diffusion takes place only at the nanometer scale and could be limited by atom trapping on Pt/CeO2 agglomerates. Our method for investigating diffusion processes at the micrometer scale may be extended to other thermochemical conditions and other materials. [ABSTRACT FROM AUTHOR]

Published
2023
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9. Contributors

Author

Abraham, Jiji, primary, Agarwal, Nipanshu, additional, Albrecht, Hugo, additional, Mohammed, Arif P., additional, Blencowe, Anton, additional, Dychalska, Anna, additional, George, Soney C., additional, Kala, Mooleparambil S., additional, Kalarikkal, Nandakumar, additional, Loridant, Stéphane, additional, Ajith Kumar, M.P., additional, Mayeen, Anshida, additional, Mazumder, Avik, additional, Mohan Bhagyaraj, Sneha, additional, Nair, Maya S., additional, Nair, Anju K., additional, Ninan, Neethu, additional, Nnamchi, Paul S., additional, Nowicka, Ariadna B., additional, Obayi, Camillus S., additional, Oluwafemi, Oluwatobi Samuel, additional, Philip, Reji, additional, Poluri, Krishna Mohan, additional, Reghunadhan, Arunima, additional, Sankar, Pranitha, additional, Shaji, Leyana K., additional, Szybowicz, Mirosław, additional, Thankappan, Sharika, additional, and Thomas, Sabu, additional

Published
2018
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15. In situ Generation of Intimacy in MnOx+SAPO‐34 Mechanical Mixture for the Conversion of Syngas to Light Olefins.

Author

Coudercy, Christophe, Prevot, Mathieu S., Afanasiev, Pavel, and Loridant, Stéphane

Subjects
SYNTHESIS gas, ALKENES, INTIMACY (Psychology), MIXTURES, SCANNING electron microscopy
Abstract

Bifunctional MnOx+SAPO‐34 catalysts were evaluated for the conversion of syngas to light olefins (OXZEO process). They were prepared, either by mechanical mixing of 100 μm‐scale particles agglomerates, or by mixing of ethanol suspensions, containing homogeneously distributed micrometer‐scale primary particles of oxide and zeolite. The selectivity to light olefins, initially lower for the mechanical mixture, reached the value of the suspension mixture after a 14 h on‐stream period. This convergence was explained from SEM images by in situ breaking of SAPO‐34 agglomerates present in the mechanical mixture and dispersion of SAPO‐34 crystals among MnOx primary particles, decreasing the contact distance between the two catalytic functions. These results evidence the importance of intimacy at the micrometer scale to improve the catalytic properties in the OXZEO process. [ABSTRACT FROM AUTHOR]

Published
2023
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21. Nano-Structuration of WO 3 Nanoleaves by Localized Hydrolysis of an Organometallic Zn Precursor: Application to Photocatalytic NO 2 Abatement.

Author

Castello Lux, Kevin, Fajerwerg, Katia, Hot, Julie, Ringot, Erick, Bertron, Alexandra, Collière, Vincent, Kahn, Myrtil L., Loridant, Stéphane, Coppel, Yannick, and Fau, Pierre

Subjects
METALLIC oxides, COMPOSITE materials, ION recombination, HYDROLYSIS, NANOCOMPOSITE materials
Abstract

WO3 is a known photocatalytic metal oxide frequently studied for its depollution properties. However, it suffers from a high recombination rate of the photogenerated electron/holes pair that is detrimental to its performance. In this paper, we present a new chemical method to decorate WO3 nanoleaves (NLs) with a complementary metal oxide (ZnWO4) in order to improve the photocatalytic performance of the composite material for the abatement of 400 ppb NO2 under mild UV exposure. Our strategy was to synthesize WO3·2H2O nanoleaves, then, to expose them, in water-free organic solution, to an organometallic precursor of Zn(Cy)2. A structural water molecule from WO3·2H2O spontaneously decomposes Zn(Cy)2 and induces the formation of the ZnO@WO3·H2O nanocomposite. The material was characterized by electronic microscopy (SEM, TEM), TGA, XRD, Raman and solid NMR spectroscopies. A simple thermal treatment under air at 500 °C affords the ZnWO4@WO3 nanocomposite. The resulting material, additionally decorated with 1% wt. Au, presents a remarkable increase (+166%) in the photocatalytic abatement of NO2 under UV compared to the pristine WO3 NLs. This synthesis method paves the way to the versatile preparation of a wide range of MOx@WO3 nanocomposites (MOx = metal oxide). [ABSTRACT FROM AUTHOR]

Published
2022
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22. Unraveling Ce3+ detection at the surface of ceria nanopowders by UPS analysis.

Author

Cardenas, Luis, Molinet-Chinaglia, Clément, and Loridant, Stéphane

Abstract

A sequential analysis using Ultra-violet Photoelectron Spectroscopy (UPS) and X-ray Photoelectron Spectroscopy (XPS) on ceria nanopowders has been implemented to identify the influence of the X-ray beam on the surface of this oxide. For the first time, UPS analysis evidenced the photoreductive effect of XPS analysis on ceria after an oxidative in situ pretreatment, leading to an overestimation of the Ce3+/Ce4+ ratio obtained by XPS. Based on this spectroscopy methodology, UPS imposes itself as a leading technique for analyzing powders with minimal impact on the authentic chemical state, thus paving the way for identifying the real ratio of Ce4+ and Ce3+ of ceria after oxidative and reductive in situ treatments. [ABSTRACT FROM AUTHOR]

Published
2022
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38. Experimental Microkinetic Approach of De-NO x by NH 3 on V 2 O 5 /WO 3 /TiO 2 Catalysts. 6. NH 3 –H 2 O Coadsorption on TiO 2 -Based Solids and Competitive Temkin Model

Author

Giraud, François, Couble, Julien, Geantet, Christophe, Guilhaume, Nolven, Loridant, Stéphane, Gros, Sebastien, Porcheron, Lynda, Kanniche, Mohamed, Bianchi, Daniel, Institut de recherches sur la catalyse et l'environnement de Lyon (IRCELYON), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), IRCELYON-Energies, carburants, intermédiaires pour le développement durable (ECI2D), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Chalmers University of Technology [Göteborg], and EDF (EDF)

Subjects
[CHIM.GENI]Chemical Sciences/Chemical engineering, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2018

39. Experimental Microkinetic Approach of De-NO x by NH 3 on V 2 O 5 /WO 3 /TiO 2 Catalysts. 5. Impacts of the NH 3 -H 2 O Coadsorption on the Coverage of Sulfated TiO 2 -Based Solids

Author

Giraud, François, Couble, Julien, Geantet, Christophe, Guilhaume, Nolven, Loridant, Stéphane, Gros, Sebastien, Porcheron, Lynda, Kanniche, Mohamed, Bianchi, Daniel, Institut de recherches sur la catalyse et l'environnement de Lyon (IRCELYON), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), IRCELYON-Energies, carburants, intermédiaires pour le développement durable (ECI2D), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Chalmers University of Technology [Göteborg], and EDF (EDF)

Subjects
[CHIM.GENI]Chemical Sciences/Chemical engineering, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2018

40. Catalytic conversion of beech wood pyrolytic vapors

Author

Giraud, François, Couble, Julien, Loridant, Stéphane, Gros, Sébastien, Porcheron, Lynda, Kanniche, Mohamed, Bianchi, Daniel, Margeriat, Alexandre, Bouzeggane, Alissa, Lorentz, Chantal, Laurenti, Dorothée, Guilhaume, N., Mirodatos, Claude, Geantet, Christophe, Schuurman, Yves, Institut de recherches sur la catalyse et l'environnement de Lyon (IRCELYON), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), IRCELYON-Catalyse Hétérogène pour la Transition Energétique (CATREN), Université de Lyon-Université de Lyon-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), IRCELYON-RMN (RMN), and IRCELYON-Ingéniérie, du matériau au réacteur (ING)

Subjects
inorganic chemicals, Wood liquefaction, Hydrogen, 020209 energy, Ex-situ catalysis, Inorganic chemistry, chemistry.chemical_element, 02 engineering and technology, 7. Clean energy, Oxygen, complex mixtures, Analytical Chemistry, Catalysis, 0202 electrical engineering, electronic engineering, information engineering, Pyrolytic carbon, Acid catalysts, Zeolite, Deoxygenation, ComputingMilieux_MISCELLANEOUS, [CHIM.CATA]Chemical Sciences/Catalysis, 021001 nanoscience & nanotechnology, [SDE.ES]Environmental Sciences/Environmental and Society, [CHIM.THEO]Chemical Sciences/Theoretical and/or physical chemistry, Fuel Technology, chemistry, Ni/HMFI-90, GCxGC, 0210 nano-technology, Carbon, Pyrolysis
Abstract

RMN+ECI2D:ING+ABZ:CLO:DLA:NOG:CMI:CGE:YSC; International audience; Catalytic fast pyrolysis (CFP) of beech wood chips was undertaken in a laboratory-scale fixed bed reactor equipped with a biomass semi-continuous dispenser. During pyrolysis, chars are retained on a quartz frit and the pyrolytic vapors are entrained through a fixed-bed catalyst to be converted. Several acidic catalysts such as zeolites H-Beta, zeolite HMFI and 5% Ni supported on HMFI were screened in this equipment. The Ni/HMFI catalyst was also tested in the presence of 1 vol.% of hydrogen in the feed stream. Mass and carbon balances were carefully checked and the gas, liquids and solids fractions were analyzed in-depth to evaluate the impact of the catalyst compared to thermal conversion. In the presence of a catalyst, with a low catalyst-to-biomass ratio of 0.1, a lower amount of bio-oil was formed but it contained less oxygen. The bio-oils were characterized by bi-dimensional GC (GCxGC) coupled with MS and FID detectors. The amount of gaseous products also increased in the presence of all catalysts. In addition of the deoxygenation, gel-permeation chromatography (GPC) showed a decrease of the highest molecular masses in the bio-oil after catalytic treatment, which confirms the conversion of some oligomers. The presence of Ni enhanced the deoxygenation reactions while the addition of H2 is also beneficial to the bio-oil composition.

Published
2018

44. Unravelling water effects on solid acidic catalysts: Case study of TiO 2 /SiO 2 for dehydration of isobutanol

Author

Buniazet, Zoé, Couble, Julien, Bianchi, Daniel, Rivallan, Mickael, Cabiac, Amandine, Maury, Sylvie, Loridant, Stéphane, Institut de recherches sur la catalyse et l'environnement de Lyon (IRCELYON), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), and IFP Energies nouvelles (IFPEN)

Subjects
Isomerization, Solid acid catalysts, In situ FTIR acidity measurements, Isobutanol, [CHIM]Chemical Sciences, Bio-olefins, Butenes, [CHIM.CATA]Chemical Sciences/Catalysis, Water effects, Bio-alcohols Dehydration
Abstract

International audience; The understanding of water effects on solid acid catalysts is a key issue in developing efficient processesto produce olefins by bio-alcohols dehydration. In this work, the effects of water on TiO2/SiO2 catalysts forthe gas phase conversion of isobutanol into linear olefins have been unraveled, using for the first timein situ acidity measurements achieved with a flowing NH3 probe and water vapor containing gas mixturesat adsorption equilibrium in the temperature range of the reaction. Such compounds, preparedby grafting titania onto mesoporous silica, contain well-dispersed TiO2 amorphous clusters anchoredby TiAOASi linkages, leading to much higher catalytic activity than TiO2 and SiO2. They yielded onlydehydration products, among which 30% were linear butenes. Furthermore, their activity was significantlyimproved by addition of water into the feed, whatever the contact time. Acidity measurementsindicated that TiO2/SiO2 mixed oxides were mostly of Lewis type after activation at 450 C. However,in situ FTIR acidity measurements showed that addition of H2O to NH3/He gas mixture has no influenceon the number of Lewis sites, while weak Brønsted sites were formed on other sites. This formation, dueto a shift of equilibrium depending on both the temperature and the H2O partial pressure, corresponds tothe hydrolysis of TiAOASi bonds, generating OH acidic groups and enhancing catalytic activity underwater vapor. The novel type of acidity measurements used in this work appear powerful and can beapplied to other acidic heterogeneous catalysts.

Published
2017

46. Experimental Microkinetic Approach of De-NO x by NH 3 on V 2 O 5 /WO 3 /TiO 2 Catalysts. 3. Impact of Superficial WO z and V x O y /WO z Groups on the Heats of Adsorption of Adsorbed NH 3 Species

Author

Giraud, François, Geantet, Christophe, Guilhaume, Nolven, Loridant, Stéphane, Gros, Sebastien, Porcheron, Lynda, Kanniche, Mohamed, Bianchi, Daniel, IRCELYON-Energies, carburants, intermédiaires pour le développement durable (ECI2D), Institut de recherches sur la catalyse et l'environnement de Lyon (IRCELYON), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), Chalmers University of Technology [Göteborg], and EDF (EDF)

Subjects
[CHIM.GENI]Chemical Sciences/Chemical engineering, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2015

47. Acidic Properties of Alkaline-Earth Phosphates Determined by an Experimental-Theoretical Approach

Author

Blanco, Elodie, Gu, Qingyi, Couble, Julien, Martin, Lucile, Onfroy, Thomas, Costentin, Guylène, Paul, Jean-François, Michel, Carine, and Loridant, Stéphane

Abstract

Alkaline-earth phosphates efficient in the dehydration of lactic acid to acrylic acid were previously shown to contain a surface mono/dihydrogen phosphate amorphous layer composed of M2+cations and both P═O and POH groups. In this work, acidic properties of such a layer were determined combining Fourier transform infrared (FTIR) spectra achieved at the dehydrated state and under water vapor and density functional theory (DFT) simulations of nondefective and defective MPOH structure. The FTIR spectra of adsorbed pyridine and lutidine revealed the presence of moderate Lewis acid sites (LAS) and of POH groups interacting by H-bonding without significant protonation. DFT calculations were key to interpret FTIR spectra after adsorption of NH3: when solely adsorbed, NH3interacts with the LAS on both the nondefective surface and the defective surface, whereas the POH for which H points up toward the gas phase are reoriented downward. Brønsted acid sites (BAS) were shown to form under water vapor. This phenomenon was shown by DFT to arise from a more acidic character of HPO42–species for the nondefective surface and casual formation of nondefective surface leading to higher amount of H2PO4–species, which are more acidic BAS.

Published
2020
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48. Experimental Microkinetic Approach of De-NO x by NH 3 on V 2 O 5 /WO 3 /TiO 2 Catalysts. 2. Impact of Superficial Sulfate and/or V x O y Groups on the Heats of Adsorption of Adsorbed NH 3 Species

Author

Giraud, François, Geantet, Christophe, Guilhaume, Nolven, Loridant, Stéphane, Gros, Sebastien, Porcheron, Lynda, Kanniche, Mohamed, Bianchi, Daniel, IRCELYON-Catalyse Hétérogène pour la Transition Energétique (CATREN), Institut de recherches sur la catalyse et l'environnement de Lyon (IRCELYON), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC), Chalmers University of Technology [Göteborg], EDF (EDF), and Kanniche, Mohamed

Subjects
[CHIM.GENI]Chemical Sciences/Chemical engineering, [CHIM.GENI] Chemical Sciences/Chemical engineering, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2014

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