Co-based heterogeneous catalysts from well-defined Α-diimine complexes : Discussing the role of nitrogen

Ar-BIANs and related \uce\ub1-diimine Co complexes were wet impregnated onto Vulcan\uc2\uae XC 72 R carbon black powder and used as precursors for the synthesis of heterogeneous supported nanoscale catalysts by pyrolysis under argon at 800\uc2\ua0\uc2\ub0C. The catalytic materials feature a core-shell structure composed of metallic Co and Co oxides decorated with nitrogen-doped graphitic layers (NGr). These catalysts display high activity in the liquid phase hydrogenation of aromatic nitro compounds (110\uc2\ua0\uc2\ub0C, 50 bar H2) to give chemoselectively substituted aryl amines. The catalytic activity is closely related to the amount and type of nitrogen atoms in the final catalytic material, which suggests a heterolytic activation of dihydrogen

Bewertung anthropogener Stadtboeden. Teilprojekt 4: Schwermetallbindung technogener Boeden - Stadtbodenkartierung Rostock Abschlussbericht

Im Rahmen des Projektes wurde eine Konzeptbodenkarte fuer das Stadtgebiet Rostock erstellt. Den Ausgangspunkt dafuer bildete die Sammlung und Auswertung vorhandener Unterlagen. Die folgenden Karten wurden fuer die Stadtbodenkartierung mit Hilfe des geographischen Informationssystems Arc/Info digitalisiert: Bodenschaetzung, MMK, geologische Karte, Moorkartierung, forstliche Standortkartierung, Moortiefenkarte nach Geinitz (1887). Zur Charakterisierung der anthropogenen Beeinflussung wurden Informationen zur Versiegelung, Realnutzung, zu Aufschuettungen und Altablagerungen sowie ueber Kriegszerstoerungen digital verarbeitet. Da bisher keine Kartierung der Versiegelungsgrade und keine Realnutzungskartierung fuer Rostock vorlagen, wurden diese Karten im Rahmen des Projektes erarbeitet. Die thematischen Ebenen wurden im Anschluss verschnitten. Die Gesamtkonzeptkarte fuer das Stadtgebiet Rostock wurde aus der Ueberlagerung der Einzelkonzeptkarten zu Grundwassereinfluss, Nutzungseinfluss und natuerlicher Bodeninventur erstellt. Den Einheiten wurden Bodengesellschaften zugeordnet. Letztlich wurden fuer Rostock 35 Einheiten der Konzeptbodenkarte ausgewiesen. Zur Ueberpruefung der Einheiten der Konzeptbodenkarte wurden Detaillkartierungen auf Flaechen folgender Nutzungsarten durchgefuehrt: Wohnbebauung, Kernstadt, Gaerten, Parks, Friedhoefe, Industrie- und Militaerstandorte. 26 Leitprofile wurden angesprochen und bodenphysikalisch bzw. bodenchemisch untersucht. Fuer die Horizonte der Leitprofile wurden ebenfalls die Schwermetallgesamtgehalte fuer die Elemente Zn, Cu, Pb und Cd bestimmt. Das Teilvorhaben umfasst ausserdem Untersuchungen zu den Schwermetallen (SM) Cu, Pb, Cd, Zn und Ni in technogenen Substraten (tS) aus Kiel, Eckernfoerde, Halle und Rostock (11 Leitprofile). (orig./SR)Within the framework of the project a conceptional soil map for the urban area of Rostock was drawn up. The starting point was formed by the collection and analysis of available information. The following maps were digitised with the help of the geographical information system Arc/Info: Soil estimation, middle scaled map of agricultural sites, geology, maps of bogs and forest sites, map of the bog-depth sourrounding the river Warnow by Geinitz from 1887. To characterise the influence by man information about impermeable covered areas, actual land use, thrown up areas and disposal sites as well as war-destroyed sites were digitally used. Till the beginning of this project no information about impermeable covered areas and about the actual land use were available. That's why these two maps were created within the framework of the project on the base of topographical maps, aerial photographs and results of on-site-captures. Afterwards the thematic layers were overlapped. The general conceptional map for the urban area of Rostock was created out of the three separate conceptional maps about groundwater-influence, natural soil inventory and man-influence. Soil societies were assigned to the units of this general conceptional map. At the end 35 units were given for Rostock. Detailed mappings were taken on areas of the following kinds of use: Living areas, city centre, gardens, parks, graveyards, industrial and military sites. 26 main profiles were described and soil-physically and soil-chemically examined. The total contents of the heavy metals Zn, Cu, Pb and Cd were determined for the horizons of the main profiles. The subproject of Rostock is also concerned with investigations on the heavy metals (hM) Cu, Pb, Cd, Zn and Ni in technological substrates (tS) from Kiel, Eckernfoerde, Halle and Rostock (11 main soil profiles). (orig./SR)SIGLEAvailable from TIB Hannover: F97B1320+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman

Co-based heterogeneous catalysts from well-defined complexes: synthesis and applications

\u3b1-Diimines represent a family of nitrogen chelating ligands which found various applications in homogeneous catalysis.1,2 Here we report the first example of employing these ligands for the synthesis of Co-based supported heterogeneous catalysts starting from their well-defined complexes (Figure 1). The structure of these new materials, elucidated by XRD, XPS, TEM, Raman, TPD and TPR techniques, involves the simultaneous presence of metallic Co and Co oxides nanoparticles in contact with nitrogen-doped graphene (NDGr, derived by the pyrolysis of the nitrogen ligand) in a core-shell structure. These catalysts were successfully applied to the hydrogenation of aromatic nitro compounds. The reaction proceeds with a low catalyst loading (0.5 mol %, 10 mg/mmol) affording substituted anilines in high selectivities and yields. Furthermore, a close correlation with both the amount and the type of nitrogen in the NDGr-based catalytic material was established

Bridging coordination chemistry and heterogeneous catalysis: Co/BIAN complexes for nitroarene hydrogenation catalysts

Transition-metal based nitrogen-doped modified carbon composites are attractive tools in the catalysis field. Their unique electronic, chemical and physic properties permit the preparation of active and recyclable catalysts which applications range from organic synthesis, pollutants remediation, electrocatalysis and energy-related transformations. An efficient way to synthetize them involve the pyrolysis of well-defined metal complexes immobilized on various supports. In this study, we present the preparation, characterization and application of seven different Co-based catalysts in which the nitrogen network is provided by the pyrolysis of Co/BIAN complexes supported on Vulcan carbon. These materials show a core-shell architecture that allows achieving excellent selectivities in the hydrogenation of various substituted nitroaromatics. Straightforward kinetic experiments allow us to correlate the catalytic activity with the amount and type of nitrogen (determined by CHN and XPS analyses) present in the materials. Finally, based on the collected whole data, a reaction mechanism that involves a heterolytic activation of the dihydrogen molecule was postulated

Photophysical and Electrochemical Properties of Pyrimidopteridine‐Based Organic Photoredox Catalysts

Herein we describe the synthesis and photophysical and electrochemical characterization of pyrimidopteridine-based photoredox catalysts. The pyrimidopteridines can be obtained from the corresponding N-oxides through photo-mediated oxygen atom transfer to a sacrificial acceptor molecule on gramscale. The presence of a triplet excited state was evidenced by means of transient absorption spectroscopy. Pyrimidopteridines are potent excited state oxidants with excited state reduction potentials exceeding +2.10 V vs. SCE in MeCN. The catalytic activity is illustrated in the photo-mediated oxidative annulation of 2-phenylbenzoic acid

Synthesis of Nickel Nanoparticles with N-Doped Graphene Shells for Catalytic Reduction Reactions

The synthesis of novel nanoparticles is of general importance for the development of efficient heterogeneous catalysts. Herein, the preparation of carbon-supported nickel-based nanoparticles (NPs), modified by nitrogen-doped graphene layers, is reported for the first time. The resulting materials were characterized in detail by TEM, X-ray photoelectron spectroscopy (XPS), XRD, elemental analysis (EA), electron paramagnetic resonance (EPR), temperature-programmed reduction (TPR), BET, and Raman analysis. Initial catalytic tests revealed the potential of this class of compounds in hydrogenation reactions