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Pavarelli G.,University of Bologna | Velasquez Ochoa J.,University of Bologna | Caldarelli A.,University of Bologna | Puzzo F.,University of Bologna | And 3 more authors.

We investigated the synthesis of maleic anhydride by oxidehydration of a bio-alcohol, 1-butanol, as a possible alternative to the classical process of n-butane oxidation. A vanadyl pyrophosphate catalyst was used to explore the one-pot reaction, which involved two sequential steps: 1)1-butanol dehydration to 1-butene, catalysed by acid sites, and 2)the oxidation of butenes to maleic anhydride, catalysed by redox sites. A non-negligible amount of phthalic anhydride was also formed. The effect of different experimental parameters was investigated with chemically sourced 1-butanol, and the results were then confirmed by using genuinely bio-sourced 1-butanol. In the case of bio-1-butanol, however, the purity of the product remarkably affected the yield of maleic anhydride. It was found that the reaction mechanism includes the oxidation of butenes to crotonaldehyde and the oxidation of the latter to either furan or maleic acid, both of which are transformed to produce maleic anhydride. MA and PA together: Maleic anhydride (MA) can be produced by the one-pot oxidehydration of bio-1-butanol with a vanadyl pyrophosphate catalyst. The reaction mechanism includes the oxidation of butenes to crotonaldehyde and the oxidation of the latter to either furan or maleic acid, both of which are transformed to produce maleic anhydride. © 2015 Wiley-VCH Verlag GmbH & Co. KGaA. Source

Aresta M.,Consorzio Interuniversitario Reattivita Chimica e Catalisi | Acquaviva M.I.,CNR Institute of Neuroscience | Baruzzi F.,CNR Institute of Sciences of Food Production | Noce R.M.L.,CNR Institute of Neuroscience | And 4 more authors.
World Journal of Microbiology and Biotechnology

In this study 28 bacterial strains, isolated from greenwaters-polluted-soil, were investigated for their ability to grow in presence of phenols added to Mineral Basal Medium (MBM) in aerobic conditions. In particular, three of them were found to be able to use as sole carbon source phenol, cathecol, caffeic acid and ferulic acid with efficiency ranging from 76% (phenol in 5 days, millimolar concentration from 3.7 10-2 to 9 10-3) to 95% (ferulic acid in 2 days millimolar concentration from 6.8 10-1 to 3 10-2). For these strains the taxonomic position was studied by amplification and sequencing of 16S rRNA genes. The isolated strains were classified belonging to Arthrobacter sulfureus, Pseudomonas synxantha and Pseudomonas oryzihabitans. Noteworthy, for the first time such Pseudomonas strains have been shown to be able to use polyphenols as the only carbon source in vitro. In fact, to the best of our knowledge, this kind of study were not done on Ps. Synxantha, while it was recently shown the ability of P. oryzihabitans to degrade catechol. These findings may open to new biotechnological applications for the degradation of polyphenols. © 2009 Springer Science+Business Media B.V. Source

Lee J.G.,Korea University | Kim D.-Y.,Korea University | Lee J.-H.,Korea University | Kim M.-W.,Korea University | And 7 more authors.
ACS Applied Materials and Interfaces

We demonstrate production of nanotextured p-type cupric oxide (CuO) films via a low-cost scalable supersonic cold spray method in open air conditions. Simply sweeping the spray nozzle across a substrate produced a large-scale CuO film. When used as hydrogen evolution photocathodes, these films produced photocurrent densities (PCD) of up to 3.1 mA/cm2 under AM1.5 illumination, without the use of a cocatalyst or any additional heterojunction layers. Cu2O particles were supersonically sprayed onto an indium tin oxide (ITO) coated soda lime glass (SLG) substrate, without any solvent or binder. Annealing in air converted the Cu2O films to CuO, with a corresponding decrease in the bandgap and increase in the fraction of the solar spectrum absorbed. Annealing at 600 °C maximized the PCD. Increasing the supersonic gas velocity from ∼450 to ∼700 m/s produced denser films with greater surface roughness, in turn producing higher PCD. The nanoscale texture of the films, which resembles the skin of a dinosaur, enhanced their performance, leading to one of the highest PCD values in the literature. We characterized the films by X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy, scanning electron microscopy, and transmission electron microscopy to elucidate the origins of their outstanding performance. This supersonic cold spraying deposition has the potential to be used on a commercial scale for low cost mass production. © 2016 American Chemical Society. Source

Zardi P.,University of Milan | Pozzoli A.,University of Milan | Pozzoli A.,Consorzio Interuniversitario Reattivita Chimica e Catalisi | Pozzoli A.,Liverpool John Moores University | And 4 more authors.
Dalton Transactions

A mechanism for the aziridination of olefins by aryl azides (ArN3), promoted by ruthenium(ii) porphyrin complexes, is proposed on the basis of kinetic and theoretical studies. All the recorded data support the involvement of a mono-imido ruthenium complex as the active intermediate in the transfer of the nitrene moiety "ArN" to the olefin. The selectivity of the aziridination vs. the uncatalysed triazoline formation can be enhanced by fine-tuning the electronic features of the porphyrin ligand and the olefin/azide catalytic ratio. The DFT study highlights the importance of an accessible triplet ground state of the intermediate ruthenium mono-imido complex to allow the evolution of the aziridination process. © The Royal Society of Chemistry 2015. Source

Maidich L.,University of Sassari | Maidich L.,Consorzio Interuniversitario Reattivita Chimica e Catalisi | Maidich L.,University of Pavia | Dettori G.,University of Sassari | And 8 more authors.

Steric and electronic factors in rollover C-H bond activation of substituted 2,2′-bipyridines, mediated by platinum(II), have been investigated by comparing the influence of two substituents, CH3 and CF3, on the progress of the reaction. The substituents were chosen to have similar steric hindrance but different electronic effects and were placed in position 6 (i.e., near one of the nitrogen atoms) or in position 5, which allows, in part, electronic and steric influence to be distinguished. The ligands studied, 6-methyl-2,2′-bipyridine, 5-methyl-2,2′-bipyridine, 6-trifluoromethyl-2,2′-bipyridine, and 5-trifluoromethyl-2,2′-bipyridine, were compared to unsubstituted 2,2′-bipyridine in the reaction with the electron-rich complex [Pt(Me)2(DMSO)2]. The electron-withdrawing CF3 group was found to have a significant effect in accelerating the cyclometalation reaction. The substituent in position 6 influences the stability of the intermediate adduct [Pt(N,N)(Me)2] (N,N = chelated bipyridine), as indicated by density functional theory calculations. The steric hindrance of substituted bipyridines was also evaluated by defining and measuring the angle ζ in [Pt(N,N)(Me)2] adducts. The presence of a substituent in position 6 causes destabilization of the adduct, acceleration of the cyclometalation reaction, and regioselectivity of C-H bond activation. © 2015 American Chemical Society. Source

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