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Structure-activity relationships in heterogeneous catalysis demand the development of original preparation routes to create catalyst sets with extended surface properties. Pure zirconia is a bifunctional catalyst which shows a high versatility in acid-base catalysis. The present work aims to synthesize a set of zirconia catalysts with various acid-base reactivities. It proposes a new route to prepare pure zirconia using sodium alginate, a low-cost biosourced polymer. This zirconia phase is compared to samples obtained from two more conventional preparation routes, namely precipitation and sol-gel. Upon calcination (500 – 900°C), the alginate-derived zirconia maintains a high specific area, which can be explained by the high dispersion of the zirconyl species in the ionogel precursor. Moreover, the three types of catalysts have distinct acid-base properties, as shown by CO2 adsorption and catalysis (methylbutynol model reaction). The alginate-derived ZrO2 has a higher and more stable amphoteric reactivity than the phases obtained by precipitation and sol-gel, which can be rationalized by a higher level of Lewis acid-base pairs.
The evolution of Ba sites in two distinct NOx storage and reduction (NSR) catalysts that are based on alumina or zirconia-titania mixed oxide (ZrO2-TiO2 or ZT) during NOx adsorption/desorption was investigated by in situ and operando IR spectroscopy. Based on various evidences from the in situ study, medium sized Ba sites on alumina supported fresh catalysts are proposed to experience sintering under NOx adsorption to form bigger particles, while for ZT, initially possessing smaller sized Ba particles, the formation of a thin layer or very fine particles of Ba would proceed under the same condition. This evolution can also be affirmed by observations from the operando IR study showing that NOx adsorption on ZT supported catalyst is initially faster than on alumina supported catalyst (time on stream lower than 300 sec), but after long adsorption time (about 50 min) the two catalysts show similar storage capacity. This new mechanistic insight suggests that NOx ad/desorption rate, which is critical for optimizing NSR performance, needs to be controlled by support materials whose interaction with the Ba particles not only determines their initial size (fresh catalyst) but also their resistance towards sintering during the NOx adsorption.
Stable luminescent silver clusters in nanosized EMT zeolite suspension were prepared and directly observed with high-resolution transmission electron microscopy (HRTEM). The luminescence of the Ag clusters remains stable in time due to their stabilization within the sodalite cages (0.7 nm) of the EMT zeolite nanocrystals. In addition to the experimental results, the first principle Density Functional Theory (DFT) computations showed that hydrated neutral clusters up to octamer (Ag8) with a diameter of 0.47 nm were stabilized in the sodalite cages of the EMT zeolite, trough binding of silver atom(s) to the zeolite oxygen(s). The silver clusters exhibit molecular-like emission properties (lem = 395 nm and t1/2 ≤ 1 ns) that are in a good agreement with the HRTEM and DFT results. The stabilization of charge silver species in the form of weakly interacting dimer or trimer was observed too, which was based on the microsecond lifetime of the emission band measured at 545 nm. The high stability combined with the luminescence properties of silver clusters in the EMT zeolite nanocrystals will be of great advantage for applications such as bio imaging and bio sensing.
Le(La) candidat(e) devra s’intégrer au Laboratoire Catalyse et Spectrochimie grâce à ses compétences en spectroscopies IR, Raman ou autres techniques pour la compréhension ou le développement de matériaux catalytiques. Une connaissance des méthodes operando sera très appréciée.
Le(La) candidat(e) devra démontrer qu’il(elle) peut développer de manière autonome des recherches originales dans le développement des outils ou méthodologies spectroscopiques appliquées aux matériaux pour la catalyse avec des applications nécessaires à la transition énergétique, c.-à-d. dans le domaine de la production de nouvelles énergies, de la dépollution, et/ou de la valorisation ou stockage des gaz à effet de serre. Une bonne connaissance des matériaux/ou méthodes de caractérisations concernés par ces thématiques est indispensable.
[JOB] We are seeking for a pHD candidate to work on ” Fuels Production from renewable energy and CO2 via hydrogen vector ” : The objective of this thesis is to develop a methanation pilot plant which would react hydrogen produced from renewable sources with carbon dioxide to produce methane.
by M. Denoual , D. Robbes, S. Inoue, Y. Mita, J. Grand, H. Awala, S. Mintova New concept of microfabricated thermal resonant gas sensor comprising of a cantilever-like thermal device covered with a selective zeolite layer associated to heat feedback electronics is presented. Sensing principle exploits the thermal resonant frequency shift caused by mass variations upon gas adsorption in the zeolite layer; […]
Sorry, this entry is only available in French. For the sake of viewer convenience, the content is shown below in the alternative language. You may click the link to switch the active language. Jacob a été accueilli au Laboratoire Catalyse et Spectrochimie en 1990. Il avait été recommandé par San de Beer de l’Université Technologique […]
It is with a great sorrow that we announce that Jacob van Gestel passed away this Sunday after a long illness. Jacob has played an important role as a teacher and researcher at the University of Caen and particularly at the Catalysis and Spectrochemistry Laboratory (LCS). Jacob was a specialist in kinetic for heterogeneous catalysis. […]
Technopôle du Madrillet – 675, Avenue de l’Université / 76801 Saint-Etienne-du-Rouvray cedex http://www.carnot-esp.fr Type de recrutement : Type de contrat : CDD 6 mois évolutif CDI Niveau d’expérience : niveau Bac +5 Rémunération : 38k€ bruts/annuel, selon profil et expérience, incl.3ème mois + mutuelle, Lieu : Seine-Maritime, Saint Etienne du Rouvray Prise de fonction : […]
Crystallography : Electron diffraction locates hydrogen atoms Diffraction-based analytical methods are widely used in laboratories, but they struggle to study samples that are smaller than a micrometer in size. Researchers from the Laboratoire de cristallographie et sciences des matériaux (CNRS/Ensicaen/Unicaen), the Laboratoire catalyse et spectrochimie (CNRS/Ensicaen/Unicaen)1, and the Academy of Sciences of the Czech Republic have […]
Position of hydrogen in isolated nanocrystals revealed by electron diffraction
Hydrogen positions in single nanocrystals revealed by electron diffraction.
L. Palatinus*, P. Brázda, P. Boullay*, O. Perez, M. Klementová, S. Petit, V. Eigner, M. Zaarour and S. Mintova, Science 355, 166-169 (2017).
The formation of colloidal AlPO-5 nanocrystals were studied under hydrothermal and microwave conditions in the presence of a new templating agent, 1-ethyl-2,3-dimethylimidazolium hydroxide ([edmim]OH).
Pr. Marco Daturi: The synergy between four laboratories (the LCS of Caen, the ILV / IMAP of Versailles / Paris, the ICGM of Montpellier and the Korean KRICT) with unique skills in synthesis, advanced characterization and modeling of materials, to design an ordered organic-inorganic porous hybrid system, commonly called the Metal Organic Framework (MOF), capable of preferentially fixing nitrogen gas, even in the presence of other gases.
Genuine sponges of the infinitely small, nanoporous materials make it possible to selectively capture molecules of gas, vapor or liquid, a phenomenon that is of major interest in many industrial processes. A French-Korean consortium comprising researchers from the Institut Charles Gerhardt Montpellier (CNRS / Montpellier University / ENSCM), the Paris Institute of Pore Materials (CNRS / ENS / ESPCI) and the Catalysis and Spectrochemistry Laboratory (CNRS / Normandie University / ENSICAEN) has identified a crystallized porous hybrid material which, once dehydrated, is able to purify natural gas and air by selectively fixing nitrogen gas in the presence of methane or oxygen. Published in the journal Nature Materials, this work makes it possible to envisage more efficient industrial processes of gas separation.
We report mesoporous metal–organic framework materials containing accessible Cr(III) sites, able to thermodynamically capture N2 over CH4 and O2.
Membre Distingué Junior de la SCF Le titre de « Membre Distingué Junior » peut être décerné à une personne de moins de 45 ans ayant été membre de la SCF les trois années précédentes sans discontinuité, et étant à l’origine de travaux représentant une avancée notable dans un des domaines de la chimie, ou […]
Sorry, this entry is only available in French. For the sake of viewer convenience, the content is shown below in the alternative language. You may click the link to switch the active language. En chimie : La synthèse efficace et moins polluante des cristaux de zéolithes La publication : Hussein Awala et al., Nature Materials, 14, 47, 2015. Le résultat : Cet […]
Sorry, this entry is only available in French. For the sake of viewer convenience, the content is shown below in the alternative language. You may click the link to switch the active language. Ingénieur en synthèse chimique. Mission L’ingénieur de recherche coordonnera le développement et la mise en oeuvre de méthodes, de techniques de […]
Today, humanity has two major priorities that are often linked: finding a new energy resource and controlling the global warming. Among the different available energy sources, natural gas (NG) as methane is the most abundant. Its proven world reserves are steadily increasing and currently correspond to the estimation of world crude oil resources. However, the […]
Study by in situ and operando spectroscopy of the relationships between the adsorption sites properties of MOFs (Metal Organic Frameworks) and their catalytic properties for model reactions CNRT conference room, 2nd floor, Tuesday December 20, 2016 10:00 AM Jury members for this public thesis : Mme Nathalie Steunou, Professeur, Université de Versailles M. Carlo Lamberti, […]