- LCS Valoris
Once every year, about 30 Nobel Laureates convene at Lindau to meet the next generation of leading scientists: 400-500 undergraduates, PhD students, and post-doc researchers from all over the world. The Lindau Nobel Laureate Meetings foster the exchange among scientists of different generations, cultures, and disciplines. Eng-Poh Ng and Siddulu Naidu (former students at the […]
Désolé, cet article est seulement disponible en Anglais Américain. Pour le confort de l’utilisateur, le contenu est affiché ci-dessous dans une autre langue. Vous pouvez cliquer le lien pour changer de langue active. CrystEngComm, 2017,19, 5100-5105 By: Moussa Zaarour, Olivier Perez, Philippe Boullay, Jörn Martens, Boriana Mihailova, Konstantin Karaghiosoff, Lukáš Palatinus and Svetlana Mintova Abstract A […]
by Davide Lorito, Haoguang Li, Arnaud Travert, Françoise Maugé, Frédéric C. Meunier, Yves Schuurman, Claude Mirodatos https://doi.org/10.1016/j.cattod.2017.06.041 Highlights Combined DRIFTS and SSITKA analyses boost methanation mechanism understanding. Original methanation kinetic modeling is based on physically meaningful parameters. Coke deposition, Ni sintering and bio-syngas poisons combine as deactivating agents. Kinetic modeling as a guideline for further development of bio-syngas methanation. Abstract A combined operando DRIFT and SSITKA study of […]
by Federico Azzolina-Jury and Frédéric Thibault-Starzyk Abstract Zeolite H-USY doped with nickel (14% wt.) was used as a catalyst in the plasma-assisted CO2 hydrogenation under partial vacuum. CO was found to be the main product of the reaction and it is generated by plasma-assisted CO2 dissociation in the gas phase. The CO2 molecules vibrationally excited by plasma are also adsorbed […]
by James Redfern, Kamila Goldyn, Joanna Verran, Richard Retoux, LubomiraTosheva, SvetlanaMintova https://doi.org/10.1016/j.micromeso.2017.06.046 Highlights Preparation of copper-containing zeolite nanocrystals in stable colloidal suspensions Cu-containing zeolite nanocrystals active against six ESKAPE species Application of Cu-containing zeolite nanocrystals for sanitization of surfaces in healthcare settings. Abstract Antimicrobial resistance is a global threat with catastrophic forecasts in terms […]
by Małgorzata Łukarska, Aldona Jankowska, Jacek Gapiński, Samuel Valable, Clement Anfray, Benjamin Menard, Svetlana Mintova and Stanislaw Kowalak 10.1039/C7NJ01427A New J. Chem., 2017 Abstract The composites consisting of fluorescein (F) entrapped inside various zeolite structures (i.e. FAU, LTL, MFI, LTA) were prepared by the catalytic synthesis of the dye from the precursors (phthalic anhydride and […]
Zeolites are very well-known as catalysts, ion-exchangers and adsorbents in industry. As any crystal, they are never perfectly organized and defects are always present; one of the most annoying is due to missing tetrahedral atoms leading to the presence of silanols (Si-OH groups). These weak points are where zeolites are attacked and loose some of […]
Heterogeneous single-site catalysts consist of isolated, well-defined, active sites that are spatially separated in a given solid and, ideally, structurally identical. In this review, the potential of metal–organic frameworks (MOFs) and covalent organic frameworks (COFs) as platforms for the development of heterogeneous single-site catalysts is reviewed thoroughly. In the first part of this article, synthetic strategies and progress in the implementation of such sites in these two classes of materials are discussed. Because these solids are excellent playgrounds to allow a better understanding of catalytic functions, we highlight the most important recent advances in the modelling and spectroscopic characterization of single-site catalysts based on these materials. Finally, we discuss the potential of MOFs as materials in which several single-site catalytic functions can be combined within one framework along with their potential as powerful enzyme-mimicking materials. The review is wrapped up with our personal vision on future research directions.
Le magazine PRISME de l’Université de Caen vient de publier un article suite aux travaux conjoints du CRISMAT et du LCS : Le PDF est disponible ICI.
Sandra a recu le prix du Poster du GECAT dans la session depollution automobile pour son affiche intitulée « Ba transformation on NSR catalysts during NOx adsorption/desorption: Effect of support material by in situ and operando IR study » PDF
The review describes the most significant recent results achieved in France in the field of heterogeneous catalysis over the last 10 years. It focusses on the research carried out in the French academic laboratories, often in close collaboration with some industrial partners.
Cold VCl3-plasma is employed for the preparation of highly dispersed vanadium oxide clusters on nanosized zeolite. Different types of zeolite, such as EMT, FAU (z.X) and Beta are used. The activity of thus prepared catalysts is studied in the selective photooxidation of methanol under polychromatic visible and UV irradiations. The physicochemical properties and catalytic performance of plasma treated zeolite Beta (P-V2O5@Beta) catalyst is compared with zeolite Beta (V2O5@Beta) and amorphous silica (V2O5@SiO2) impregnated vanadium oxide catalysts. Pure V2O5 is used as a reference material. The set of catalytic data shows that plasma prepared zeolite Beta based catalyst displays the highest activity. Complementary characterization techniques including XRD, N2-sorption, FTIR, ionic exchange, pyridine adsorption, Raman, NMR, TPR and EDX-TEM are used to study the impact of the preparation approach on the physicochemical properties and catalytic performance of photocatalysts.
K-F zeolite nanocrystals (structure code EDI) are synthesized from a template-free Al2O3–SiO2–K2O–H2O precursor system. The use of a very reactive organic-template-free gel system (4SiO2: 1Al2O3: 16K2O: 160H2O) enables the crystallization of EDI-type nanosized zeolite to accomplish within 3 h at 100 °C. The K-F zeolite crystals have flattened cuboid shape morphology (ca. 27 nm) and they tend to agglomerate and form secondary spherical particles (ca. 310 nm). The K-F zeolite nanocrystals have high alumina content (Si/Al ratio = 1.10) and high crystalline solid yield (79%) offering a promising route for large-scale production of hydrophilic zeolite nanoparticles.
Partenariat entre Normandie AeroSpace et l’institut Carnot ESP Le 16 février 2017, Normandie AeroSpace (NAE)1 et l’institut Carnot ESP2 (Energie et Systèmes de Propulsions) ont signé un partenariat afin de mutualiser leurs efforts pour accélérer la recherche et le développement en Energie et Systèmes de Propulsion sur le territoire Normand. Cet accord vise à faciliter […]
Atomic substitutions are a central feature of the physicochemical properties of an increasing number of solid-state materials. The complexity that this chemical disorder locally generates in otherwise crystalline solids poses a major challenge to the understanding of the relationships between the structure and properties of materials at the atomic and molecular level. Strategies designed to efficiently explore the ensemble of local chemical environments present in disordered crystals and predict their signatures in local spectroscopies such as solid-state nuclear magnetic resonance (NMR) are therefore essential. Focusing on the Ga/Si disorder in the framework of rubidium-exchanged gallosilicate natrolite zeolite (Rb-PST-1) with a high Ga content (Si/Ga = 1.28), we show how the structure-generation approach implemented in the new program supercell (Okhotnikov et al., J. Cheminf. 2016) provides an excellent basis for the understanding of complex experimental spectroscopic data. Furthermore, we describe how exhaustive explorations of atomic configurations can be performed to seek local structural ordering and/or disordering factors. In the case of Rb-PST-1, we more specifically explore the possibility to form and to detect the presence of thermodynamically unfavorable Ga-O-Ga connectivity. While particularly adapted to the description of dense materials, we demonstrate that this approach may successfully be used to reproduce and interpret the distributions of local structural distortions (i.e., the geometrical disorder) resulting from the chemical disorder in systems as complex as microporous zeolites.
An optical detection of volatile organic compounds (VOCs) using nanosized zeolites functionalized with pyrylium salts is presented. Nanosized zeolite crystals firstly are functionalized with pyrylium salt (para-dimethylamino-2,4,6-triphenylthiopyrylium tetrafluoroborate, PNS). Then the optical response of the pyrylium-functionalized nanozeolites towards volatile organic compounds is investigated. Two possible modes of zeolite functionalization are proposed based on: (1) ion exchange between the pyrylium and sodium cations (Na+) in the zeolite (Si-O−-Al active sites), and (2) adsorption via electrostatic interaction between the electron lone-pair of amine of the PNS and the orbital vacancy of Al on the zeolite surface (Lewis acid sites). The experimental results verify that the great number of Lewis acid sites of the nanozeolites led to a significant adsorption of the PNS (mode 2) causing the hypsochromic (band shift to lower wavelength) shift in the visible light absorbance. Pyrylium-functionalized nanozeolites demonstrate a good sensitivity and reversibility toward volatile organic compounds investigated in this work.
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Coupler comprising side-polished optical fiber and tantalum pentoxide (Ta2O5) waveguide coated with 330 nm hydrophobic MFI-type zeolite films was utilized as chemical sensor for acetone vapors. The thickness of the zeolite films was selected through theoretical modeling of the resonant wavelength shift in order to achieve the highest possible sensitivity. The spectral positions of the resonances were determined through solving of the characteristics equations for the coupled waveguides and finding their mode effective refractive indices. The optical quality of the coupler surface, that is responsible for the proper operation of the device, was controlled through 3D optical imaging prior to and after deposition of the zeolite films. The application of side-polished optical fiber–Ta2O5 waveguide coupler covered with hydrophobic zeolite film for acetone vapor sensing was demonstrated and discussed.
Communiqué de Presse du CNRS Le 22 avril prochain, les citoyens du monde entier sont appelés à participer à une grande marche pour les sciences. Cette initiative a été lancée par des scientifiques américains pour faire face à « de nouvelles politiques (qui) menacent d’entraver davantage la capacité des chercheurs de mener à bien leurs […]
Among NOX emission sources, the automotive industry and specifically Diesel engines are the main pollutants. Selective catalytic reduction by Hydrocarbons (HC-SCR) may lead to efficiencies as high as 70% in reducing NOX into N2 specially by using economical catalysts (zeolites). We report here an HC-SCR study using acetylene (C2H2) as a reducing agent that presents intersting activity at low temperatures. A ferrierite zeolite catalyst was used and modified by the introduction of either copper or iron and the NOX reduction activity was analysed by InfraRed (IR) operando techniques subsequent to a preliminary IR in-situ characterization. The later technique allowed the identification of the species formed on the surface after NO or C2H2 adsorption at room temperature. The thermal stability of adsorbed acetylene was also investigated. The obtained information on vibrational bands typical for adsorbed species served as an input for the IR operando study. Cu-HFER catalyst presents a strong redox character upon room temperature interaction with NO as well as a strong affinity for C2H2 adsorption. However, Fe-HFER shows a higher NOX reduction efficiency when submitted to SCR conditions. Indeed, iron ions enhance the NO oxidation into NO2 that seems to be more reactive with C2H2. The reaction mechanism was revealed by an FT-IR operando study coupled with 15NO isotopic labelling that proved the formation of hydrocyanic acid and isocyanate species as key intermediate species.