Nadezhda I. Maksimova

The Catalytic Use of Onion-like Carbon Materials for Styrene Synthesis by Oxidative Dehydrogenation of Ethylbenzene

-hybridizednanostructuredcarbonhasreceivedincreasingattention both from a fundamental point of view and forpotential applications. A large variety of new fullerene-related materials (giant fullerenes, nanotubes, nanospheres,nanocones, nanofolders, nanobundles, onion-like carbons(OLCs)) have been synthesized.

Carbon Nanofilaments in Heterogeneous Catalysis: An Industrial Application for New Carbon Materials?

Special carbon! Carbon nanofilaments differ from graphite and soot catalysts in their high stability during the oxidative dehydrogenation of ethylbenzene to styrene. The high yields of styrene achieved suggest that a first industrial application of carbon nanofilaments in catalysis is possible.

Study of multiwalled graphite nanotubes and filaments formation from carbonized products of polyvinyl alcohol via catalytic graphitization at 600–800°C in nitrogen atmosphere

Abstract The catalytic graphitization of amorphous carbon matrix was carried out at the temperature range of 600–800°C in nitrogen atmosphere. Amorphous carbon matrix with uniformly distributed Fe particles was obtained via catalytic carbonization of polyvinyl alcohol (PVA) at temperatures up to 600°C in nitrogen atmosphere. Using transmission electron microscopy (TEM), selected area diffraction (SAD), scanning electron microscopy (SEM), and X-ray diffractometry (XRD), graphite structures of three types were found in products of catalytic graphitization of amorphous carbon matrix: multiwalled graphite shells wrapping the catalyst particles, cockle-shelled graphite filaments (CSF), and multiwalled graphite nanotubes (MWNT). We suppose that the formation of CSF proceeds through the dissolution of amorphous carbon in the metal, transformation of the catalyst particles into a liquid state, and transfer of dissolved carbon via intermediates to growing filaments. Graphite nanotubes nucleate at the matrix surface and then grow in the porous space of the matrix.

Catalytic synthesis of carbon nanostructures from polymer precursors

Abstract Carbon nanostructures were prepared by decomposition of polyethylene and polyvinyl alcohol using an iron catalyst at 600–750°C under a nitrogen flow. Heating a uniform distribution of catalyst particles in the polymer bulk to 600°C under flowing nitrogen led to the formation of amorphous carbon incorporating uniformly distributed catalyst particles. Subsequent heating of the samples to 750°C in a nitrogen flow led to the catalytic graphitization of the amorphous carbon matrix with the formation of different carbon nanostructures, i.e. carbon nanotubes. The mechanism of the formation of the obtained carbon nanostructures is discussed.

Zwiebelförmige Kohlenstoffe als Katalysatoren in der Styrolsynthese durch oxidative Dehydrierung von Ethylbenzol

Seit der Entdeckung der Fullerene 1985[1] erf‰hrt die Chemie sp2-hybridisierter nanostrukturierter Kohlenstoffe sowohl aus grunds‰tzlichen ‹berlegungen als auch wegen potentieller Anwendungen zunehmendes Interesse. Eine Vielzahl verwandter Materialien wie Riesenfullerene, Nanorˆhren, Nanokugeln, Nanokegel, Nanob ndel oder zwiebelfˆrmige Kohlenstoffe (OLCs, onion-like carbons) wurde synthetisiert.[2] Ihre einzigartigen chemischen und physikalischen Eigenschaften sollten neue Anwendungen ermˆglichen, etwa in den Bereichen Nano-Engineering und -elektronik, f r optoelektronische Sensoren, dreidimensionale Kompositmaterialien, Mikrofilter, magnetische Materialien und in der Katalyse.[3] Die Forschung zu OLCs beschr‰nkt sich zurzeit auf eine Weiterentwicklung der Synthesemethoden und Untersuchung ihrer physikalischen und chemischen Eigenschaften.[4] Wegen ihrer nahezu perfekten graphitischen und trotzdem gespannten Strukturen kˆnnten diese Materialien aus geschlossenen kugelfˆrmigen Kohlenstoffschalen katalytische Eigenschaften aufweisen. folgender Adresse in Gro britannien angefordert werden: Cambridge Crystallographic Data Centre, 12, Union Road, Cambridge CB21EZ; Fax: ( 44)1223-336-033; oder deposit@ccdc.cam.ac.uk).

Catalytic activity of carbon nanotubes and other carbon materials for oxidative dehydrogenation of ethylbenzene to styrene

Abstract Different carbons, i.e. carbon black, graphite and multiwalled nanotubes were tested as catalysts for oxidative dehydrogenation of ethylbenzene to styrene. The influence of the catalyst structure was determined on the catalytic activity and selectivity, and the catalyst stability in the oxidative dehydrogenation of ethylbenzene. In comparison to carbon black and graphite, multiwalled carbon nanotubes were found to exhibit the highest performance in the reaction. Carbon nanotubes as catalyst gave the highest styrene selectivity at maximum conversion. The characterization of the carbon nanotubes and the other carbon materials before and after the catalytic tests was conducted by several techniques, e.g. TEM, XRD and BET area measurements. This comparative characterization of the fresh and tested catalysts indicates that structural modifications in the nature of the catalysts occurred during the reaction. These modifications could be correlated with the changing catalytic behavior with time-on-stream.