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High Temperature Stability of Platinum Nanoparticles on Few-Layer Graphene Investigated by In Situ High Resolution Transmission Electron Microscopy

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Nano Research 2011年第5期4卷 511-521页

作者： Izabela Janowska Maria-Simona Moldovan ovidiu ersen Herve Bulou Kambiz Chizari Marc J. Ledoux Cuong Pham-Huu Laboratoire des MatEriaux Surfaces et ProcEdEs pour la Catalyse （LMSPC UMR 7515 CNRS） 25 rue Becquerel F-67087 Strasbourg Cedex 02 France Institut de Physique et Chimie des Materiaux de Strasbourg （IPCMS UMR 7504 CNRS） 23 rue du Loess F-67037 Strasbourg Cedex 08 France

Heterogeneous catalytic reactions involve the use of highly dispersed active phases such as metal, metal oxide, or metal sulphide nanoparticIes on thermally stable supports. Fluctuations of the reaction temperature during the reactions can induce sintering of the particles. The stability of such small particles represents a crucial parameter in the development of new families of catalysts with high activity in many fields. Here we report the stability of platinum nanoparticles （2-3 nm） on a few-layer graphene （FLG） surface as studied by in situ high temperature transmission electron microscopy.

关键词： Graphene platinium nanoparticles diffusion catalysis TEM annealing

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Carbon nanotubes decorated α-Al_2O_3 containing cobalt nanoparticles for Fischer-Tropsch reaction

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Journal of Energy Chemistry 2013年第2期22卷 279-289页

作者： Yuefeng Liu Thierry Dintzer ovidiu ersen Cuong Pham-Huu Laboratoire des Matriaux Surfaces et Procds pour la Catalyse (LMSPC) UMR 7515 CNRS-Universit de Strasbourg (UdS) 25 rue Becquerel 67087 Strasbourg Cedex 08 France Institut de Physique et Chimie des Matriaux de Strasbourg (IPCMS) UMR 7504 CNRS-Universit de Strasbourg (UdS) 23 rue du Loess 67037 Strasbourg Cedex 02 France

A new hierarchical composite consisted of multi-walled carbon nanotubes （CNTs） layer anchored on macroscopic a-A1203 host matrix was synthesized and used as support for Fischer-Tropsch synthesis （FTS）. The composite constituted by a thin shell of a homogeneous, highly entan-gled and structure-opened carbon nanotubes network and it exhibited a relatively high and fully accessible specific surface area of 76 m2.g-1, compared with that of 5 m2.g-1 of the original a-A1203support. The metal-support interaction between carbon nanotubes surface and cobalt precursor and high effective surface area led to a relatively high dispersion of cobalt nanoparticles. This hierarchically supported cobalt catalyst exhibited a high FTS activity along with an extremely high selectivity towards liquid hydrocarbons compared with the cobalt-based catalyst supported on pristine a-A1203 or on CNTs carriers. This improvement can attribute to the high accessibility of composite surface area com- paring with the macroscopic host structure alone or to the bulk CNTs where the nanoscopic dimension induced a dense packing with low mass transfer which favoured the problem of reactants competitive diffusion towards the cobalt active site. In addition, intrinsic thermal conductivity of decorated CNTs could help the heat dissipating throughout the catalyst body, thus avoiding the formation of local hot spots which appeared in high CO conversion under pure syngas feed in FTS reaction. Cobalt supported on CNTs decorated a-A1203 catalyst also exhibited satisfied high stability during more than 200 h on stream under relatively severe conditions compared with other catalysts reported in the literature. Finally, the macroscopic shape of such composite easily rendered its usage as catalyst support in a fixed-bed configuration without facing problems of transport and pressure drop as encountered with the bulk CNTs.

关键词： carbon nanotubes Fischer-Tropsch synthesis a-A1203 hierarchical support cobalt nanoparticles

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Microwave Synthesis of Large Few-Layer Graphene Sheets in Aqueous Solution of Ammonia

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Nano Research 2010年第2期3卷 126-137页

作者： Izabela Janowska Kambiz Chizari ovidiu ersen Spyridon Zafeiratos Driss Soubane Victor Da Costa Virginie Speisser Christine Boeglin Matthieu Houllé Dominique Bégin Dominique Plee Marc-Jacques Ledoux Cuong Pham-Huu Laboratoire des Matériaux Surfaces et Procédés pour la Catalyse(LMSPC)UMR7515 CNRS-Universitéde Strasbourg 25rue Becquerel67087 Strasbourg Cedex 08France Institut de Physique et Chimie des Matériaux de Strasbourg(IPCMS) UMR7504 CNRS-Universitéde Strasbourg 23rue du Loess67037 Strasbourg Cedex 02France Arkema Groupement de Recherche de Lacq(GRL)BP 3464170 LACQFrance

Few-layer graphene (FLG) sheets with sizes exceeding several micrometers have been synthesized by exfoliation of expanded graphite in aqueous solution of ammonia under microwave irradiation, with an overall yield approaching 8 wt.%. Transmission electron microscopy (in bright-field and dark-field modes) together with electron diffraction patterns and atomic force microscopy confirmed that this graphene material consisted mostly of mono-, bi- or few-layer graphene (less than ten layers). The high degree of surface reduction was confirmed by X-ray photoelectron and infrared spectroscopies. In addition, the high stability of the FLG in the liquid medium facilitates the deposition of the graphene material onto several substrates via low-cost solution-phase processing techniques, opening the way to subsequent applications of the material.

关键词： Graphene transmission electron microscopy(TEM) expanded graphite exfoliation microwaves

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Promotion effects of alkali metals on iron molybdate catalysts for CO_(2)catalytic hydrogenation

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Journal of Energy Chemistry 2023年第10期85卷 291-300,I0009页

作者： Yong Zhou Aliou Sadia Traore Deizi V.Peron Alan J.Barrios Sergei A.Chernyak Massimo Corda Olga V.Safonova Achim Iulian Dugulan ovidiu ersen Mirella Virginie Vitaly V.Ordomsky Andrei Y.Khodakov University of Lille CNRSCentrale LilleUniversity of ArtoisUMR 8181-UCCS-Unitéde Catalyse et Chimie du SolideLille F-59000France IPCMS UMR 7504 CNRSUniversitéde Strasbourg23 rue du LoessBP 43Cedex 267034 StrasbourgFrance PSI CH-5232 VilligenSwitzerland Fundamental Aspects of Materials and Energy Group Delft University of TechnologyMekelweg 15Delft 2629 JBNetherlands

CO_(2)hydrogenation is an attractive way to store and utilize carbon dioxide generated by industrial processes,as well as to produce valuable chemicals from renewable and abundant *** catalysts are commonly used for the hydrogenation of carbon oxides to ***-molybdenum catalysts have found numerous applications in catalysis,but have been never evaluated in the CO_(2)*** this work,the structural properties of iron-molybdenum catalysts without and with a promoting alkali metal(Li,Na,K,Rb,or Cs)were characterized using X-ray diffraction,hydrogen temperatureprogrammed reduction,CO_(2)temperature-programmed desorption,in-situ^(57)Fe Mossbauer spectroscopy and operando X-ray adsorption *** catalytic performance was evaluated in the CO_(2)*** the reaction conditions,the catalysts undergo the formation of an iron(Ⅱ)molybdate structure,accompanied by a partial reduction of molybdenum and carbidization of *** rate of CO_(2)conversion and product selectivity strongly depend on the promoting alkali metals,and electronegativity was identified as an important factor affecting the catalytic *** CO_(2)conversion rates were observed with the promoters having higher electronegativity,while low electronegativity of alkali metals favors higher light olefin selectivity.

关键词： CO_(2)utilization Iron molybdate catalysts Promotion Alkali metals Light olefins In-situ characterization

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Hierarchical zeolites by the controlled fluoride route

Hierarchical zeolites by the controlled fluoride route

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第19届全国分子筛学术大会

作者： Zhengxing Qin Georgian Melinte ovidiu ersen Jean-Pierre Gilson Svetlana Mintova Valentin Valtchev State Key Laboratory of Heavy Oil Processing College of chemical engineeringChina university of petroleum(East China) IPCMS Université de Strasbourg LCS ENSICAEN-University of Caen

＜正＞Recently,we have developed a new synthesis route to hierarchical zeolites,which is based on the etching in fluorideThe major advantage of this approach is the non selective extraction of silicon and aluminum from zeolite frameworks in a controllable *** tuning of the etching process allows controlling the stepwise framework dissolution from the extraction of a few atoms to the formation of extra-large mesopores.A

关键词： crystal engineering fluoride etching nanostructures zeolites

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Performance of Single Crystals House-of-Cards-like ZSM-5 in Ethanol-to-Hydrocarbons Conversion

Performance of Single Crystals House-of-Cards-like ZSM-5 in ...

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中国化学会第十九届全国催化学术会议

作者： Zhengxing Qin Ludovic Pinard Mohammed Amine Benghalem T.Jean Daou Georgian Melinte ovidiu ersen Shunsuke Asahina Jean-Pierre Gilson Valentin Valtchev China University of Petroleum (East China) Jilin University

The present study reports the unbiased NHF etching of a parent(Z) ZSM-5 zeolite resulting in houseof-cards-like single crystals(Z) containing large rectangular cavities surrounded by thin(15 – 30 nm), flat and highly... 详细信息

关键词： Zeolite House-of-cards-like NH4F etching Catalysis

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Alignment of Vertically Grown Carbon Nanostructures Studied by X-Ray Absorption Spectroscopy

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Materials Sciences and Applications 2014年第13期5卷 966-983页

作者： Jeannot Mane Mane Francois Le Normand Rolant Eba Medjo Costel Sorin Cojocaru ovidiu ersen Antoine Senger Carine Laffon Bridinette Thiodjio Sendja César Mbane Biouele Germain Hubert Ben-Bolie Pierre Owono Ateba Philippe Parent IPCMS UMR 7504 CNRSStrasbourgFrance Ecole Nationale Supérieure Polytechnique(National Advanced School of Engineering) Department of Mathematics and Physical SciencesThe University of YaoundéIYaoundeCameroon Physics Department Faculty of ScienceUniversity of YaoundéIYaoundeCameroon Physics Department Faculty of ScienceUniversity of DoualaDoualaCameroon LURE UMR CNRSCentre Universitaire Paris SudOrsayFrance

X-Ray Absorption Spectroscopy (XAS) on the carbon K edge of carbon nanostructures (nanotubes, nanofibers, nanowalls) is reported here. They are grown on plain SiO2 (8 nm thick)/Si(100) substrates by a Plasma and Hot Filaments-enhanced Catalytic Chemical Vapor Deposition (PE HF CCVD) process. The morphology and the nature of these carbon nanostructures are characterized by SEM, TEM and Raman spectroscopy. According to conditions of catalyst preparation and DC HF CCVD process, carbon nanotubes (CNTs), carbon nanofibers (CNFs), carbon nanowalls (CNWs), carbon nanoparticles (CNPs) with different orientation of the graphene plans or shells can be prepared. From the angular dependence of the incident light and geometrical morphology of the nanostructures, wide variations of the C K-edge intensity of the transitions to the empty π* and σ* states occur. A full lineshape analysis of the XAS spectra has been carried out using a home-made software, allowing estimating the relative proportion of π* and σ* transitions. A geometrical model of the angular dependence with the incidence angle of the light and the morphology of the carbon nanostructures is derived. With normalization to the HOPG (Highly Oriented Pyrolytic Graphite graphite) reference case, a degree of alignment can be extracted which is representative of the localized orientation of the graphitic carbon π bonds, accounting not only for the overall orientation, but also for local defects like impurities incorporation, structural defects ... This degree of alignment shows good agreement with SEM observations. Thus CNTs films display degrees of alignment around 50%, depending on the occurrence of defects in the course of the growth, whereas no special alignment can be detected with CNFs and CNPs, and a weak one (about 20%) is detected on CNWs.

关键词： X-Ray Absorption Spectroscopy Carbon Nanostructures(CNTs,CNFs,CNWs,CNPs) Plasma-and Hot Filaments-Enhanced Catalytic Chemical Vapor Deposition Geometrical Model Angular Dependence

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