Benzene hydrogenation on nickel/honeycomb catalysts

Monolithic supported nickel catalysts were investigated in benzene hydrogenation between 100 and 280 °C. The conversion of benzene to cyclohexane reaches a maximum around 210 °C with a maximum yield at a ratio p^oH₂/p^oBz=3. The experimental results and some kinetic aspects are discussed.

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100 280 °C. 210 °C p^oH₂/p^oB=3. .

     

Temperature-programmed reduction. Metal-support interaction on supported monometallic Ru and Cu Catalysts

Ru and Cu samples supported on SiO₂, Al₂O₃ and MgO were studied by the temperature-programmed reduction (TPR) technique. Experiments were carried out both on unreduced impregnated salts and after oxidation of already reduced samples.The TPR profiles were found to be strongly dependent on the support used, indicating different degrees of interaction between the metal and the support, which can be ranked as MgOAl₂O₃>SiO₂. It is suggested that the interaction occurs through the formation of surface complexes difficult to reduce. The decrease in hydrogen consumption observed on the Ru samples with the number of TPR cycles is attributed to the difficulty in oxidizing large Ru particles.

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Zusammenfassung Auf SiO₂, Al₂O₃ und MgO aufgebrachte Ru- und Cu-Proben wurden mittels temperaturprogrammierter Reduktion (TPR) untersucht. Experimente wurden sowohl an unreduzierten Salzimprägnierungen als auch nach Oxydation von bereits reduzierten Proben ausgeführt. Die TPR-Profile sind stark vom benutzten Trägen abhängig, was auf unterschiedliche Grade der Wechselwirkung zwischen Metall und Träger hindeutet; die Reihenfolge ist MgOAl₂O₃>SiO₂. Es wird vermutet, daß das Wesen der Wechselwirkung in der Bildung von schwer reduzierbaren Oberflächenkomplexen zu suchen ist. Die bei Ru-Proben mit der Zahl der TPR-Zyklen beobachtete Verminderung des Wasserstoffverbrauchs wird mit der Schwierigkeit, große Ru-Partikel zu oxydieren, in Zusammenhang gebracht.

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- () SiO₂, l₂₃ MgO. , , , . , , MgO Al₂O₃>SiO₂. , , . , .

     

TPR Investigation of bimetallic Ru-Cu samples supported on SiO2, Al2O3 and MgO

Journal of Thermal Analysis and Calorimetry - Bimetallic Ru-Cu samples supported on SiO2, Al2O3 and MgO were studied by the temperature-programmed reduction (TPR) technique. Experiments were...     

Characterization and catalytic activity of unsupported FeV and K-FeV catalysts for diesel soot combustion

A microstructural characterization by XRD, FT-IR and temperature programmed reduction (TPR) of unsupported FeV and K-FeV catalysts, prepared by solid-state synthesis, is reported. The formation of FexVyOz mixed phases of different compositions has been evidenced depending on the V/Fe ratio and calcination temperature. The catalytic activity of the samples in the combustion of diesel soot has been investigated with the aim to understand the role of FexVyOz mixed phases in the title reaction. This revised version was published online in August 2006 with corrections to the Cover Date.     

Effect of pretreatment in benzene hydrogenation on Pt/nylon catalyst

Benzene hydrogenation on Pt/nylon catalyst produced cyclohexene and cyclohexane, in contrast to Pt/SiO₂ on which only cyclohexane was detected. Higher selectivity to cyclohexene was found at higher temperature and after air pretreatment. It is suggested that an oxidized platinum species is responsible for cyclohexene formation.

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Pt/ , Pt/SiO₂, . . , .

     

Catalytic oxidation of carbon monoxide over Au/Fe2O3 preparations

Low temperature catalytic oxidation of carbon monoxide has been studied over Au/Fe₂O₃. On the coprecipitated samples the catalytic activity shows a maximum at a gold content of about 5%. Calcination of Au/Fe₂O₃ decreases the catalytic activity and the stability. The catalytic activity measured is the highest ever reported in the literature on Au/Fe₂O₃ preparations.     

Refuse derived fuels pyrolysis

Refuse derived fuels (RDF) characterization and pyrolysis behaviour, carried out by means of thermogravimetric analysis, infrared and mass spectroscopy, are presented. Thermal degradation of RDF takes place through three main mass loss stages; the analyses of evolved gas allow us to discriminate the contributions of the different fractions (paper, LDPE, wood, rubber, etc.) to the global decomposition. Furthermore thermogravimetry (TG) was used for the determination of kinetic parameters, using the differential method. In order to set up the conditions of production of a good quality pyrolysis gas, the operating conditions of RDF in a pyrolysis reactor have been simulated. Data show that the volatile fraction grows with the temperature, together with the relative conversion, and that light volatile fraction (hydrogen, ethyne, etc.) gets richer, at the expense of superior homologous hydrocarbons.     

Functionalization of multi-walled carbon nanotubes with coumarin derivatives and their biological evaluation

We report the synthesis and the characterization of different multi-walled carbon nanotubes (MWCNTs) linked to natural molecules, 5,7-coumarins and/or oleic acid, obtained from purified pristine MWCNTs by a cascade of chemical functionalization. The activities of these modified MWCNTs were investigated in vitro on human umbilical vein endothelial cells (HUVECs) by evaluating their ability to influence cell viability and to induce cell apoptosis. Our data showed that pristine MWCNTs are markedly cytotoxic; conversely, the carboxylated carbon nanotubes, much more readily dispersed in aqueous solutions and CNT-Link, the key intermediate designed by us for the drug anchorage, are biocompatible at the tested concentrations (1 and 10 μg ml(-1)).     

A facile and ecofriendly functionalization of multiwalled carbon nanotubes by an old mesoionic compound

This work reports for the first time a straightforward solvent-free chemical procedure to gain access to Δ-1-pyrroline grafted onto multiwalled carbon nanotubes by the 1,3-dipolar cycloaddition of the mesoionic 4-methyl-2-phenyloxazol-5(4H)-one.