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Shahabi Nejad M.,Isfahan University of Technology | Ghasemi G.,Isfahan University of Technology | Martinez-Huerta M.V.,Institute of Catalysts and Petroleochemistry | Ghiaci M.,Isfahan University of Technology
Journal of Molecular Catalysis A: Chemical | Year: 2015

In the present work, the selective liquid phase oxidation of cyclohexene mainly to 2-cyclohexe-1-one has been investigated over gold nanoparticles (GNPs) with molecular oxygen in a solvent-free condition. Gold nanoparticles were synthesised on two modified supports of silica and bentonite. In this respect the surface of silica and bentonite was modified with organic ligands consist of thiol and thioester groups. The catalysts were characterized by TEM, XPS, N2 adsorption/desorption, FT-IR, and CHNS techniques. TEM images show that the gold nanoparticles over modified bentonite and silica have diameters in the range 0f 50 and less than 10 nm, respectively. The results show that the catalytic activity of gold nanoparticles over modified silica, SiO2-pA-Acrylate-Thioamide-Au (0), is much better than the gold nanoparticles immobilized on the modified bentonite, MEDPT@CP-bentonite-Au (0). The catalytic activity over SiO2-pA-Acrylate-Thioamide-Au (0) recycled catalyst remained at a satisfactory state after at least 4 cycles. Activity tests were carried out in an autoclave under solvent-free conditions. In order to obtain maximum conversion, the reaction parameters such as reaction temperature and time were optimized. Under optimized conditions, a maximum of 92% conversion and 97% selectivity was achieved with the SiO2-pA-Acrylate-Thioamide-Au (0) catalyst. © 2015 Elsevier B.V. All rights reserved. Source


Aghabarari B.,Islamic Azad University | Dorostkar N.,Isfahan University of Technology | Ghiaci M.,Isfahan University of Technology | Amini S.G.,Islamic Azad University | And 2 more authors.
Journal of the Taiwan Institute of Chemical Engineers | Year: 2014

Three new highly acidic ionic liquids based on 4-sulfobenzyl imidazolium hydrogensulfate and with different length of the alkyl chain were screened as catalysts for the esterification of oleic acid with methanol. The ionic liquids were characterized by FT-IR, 1H NMR, 13C NMR and CHNS analyses. The reaction parameters, such as reaction temperature, molar ratio, catalyst loading, reaction time and stability were studied. The experimental results indicated that acidic ionic liquid with the longest alkyl chain performed the best activity, due to the less strict hindrance. Finally, the methyl oleate was produced with 95.0% yield at lower time (6h) under the optimized reaction conditions. Furthermore, different alcohols and fatty acids were investigated and the results showed that the length of alkyl chain and degree of saturation of fatty acid affects the catalytic activity of the best catalyst. © 2013 Taiwan Institute of Chemical Engineers. Source


Ghiaci M.,Isfahan University of Technology | Dorostkar N.,Isfahan University of Technology | Martinez-Huerta M.V.,Institute of Catalysts and Petroleochemistry | Fierro J.L.G.,Institute of Catalysts and Petroleochemistry | Moshiri P.,Isfahan University of Technology
Journal of Molecular Catalysis A: Chemical | Year: 2013

The selective liquid phase oxidation of cyclohexene to 2-cyclohexe-1-one and 1,2-cyclohexanediol has been investigated over gold nanoparticles (GNPs) with molecular oxygen in a solvent-free condition. The gold nanoparticles were immobilized on thiolated chitosan derivative (TChD), by grafting thiol groups on the support. The catalyst was characterized by XPS, N2 adsorption/desorption, TEM, FT-IR and UV-vis spectroscopy. TEM results show that the majority of Au particles have diameters in the range of 3-6 nm. X-ray photoelectron spectroscopy (XPS) revealed the coexistence of both oxidized and metallic gold species on the surface of TChD. The results show that the catalytic performance of GNPs/TChD is quite remarkable and the catalytic activity over recycled catalyst remains at a high level after at least 4 cycles. Activity tests were carried out in an autoclave at 80 C without any solvent. In order to obtain maximum conversion, the reaction parameters such as reaction temperature and time were optimized. Under optimized conditions, a maximum of 87% conversion and 70% selectivity was achieved with the GNPs/TChD catalyst. © 2013 Elsevier B.V. All rights reserved. Source


Ensafi A.A.,Isfahan University of Technology | Jafari-Asl M.,Isfahan University of Technology | Dorostkar N.,Isfahan University of Technology | Ghiaci M.,Isfahan University of Technology | And 2 more authors.
Journal of Materials Chemistry B | Year: 2014

New hybrid chitosan derivatives (chitosan (Chit)), amine group grafted chitosan (N-Chit), and thiol group grafted chitosan (S-Chit) modified-carbon (carbon nanotubes or graphite) were prepared and used as supports for Cu-nanoparticles. The synthesized materials were characterized with different methods such as transmission electron microscopy, Brunauer-Emmett-Teller and cyclic voltammetry. The electrocatalytic effect of the nanohybrid was investigated in the reduction of hydrogen peroxide and the oxidation of glucose. It was found that the Cu nanoparticles decorate on the modified chitosan-CNT (Cu@M-Chit-CNT) exhibit a remarkable catalytic performance for H 2O2 reduction and glucose oxidation. Hydrodynamic amperometry was used for the electrochemical determination of H 2O2 and glucose. The linear range for H2O 2 was from 0.1 to 1000 μmol L-1 with a detection limit of 0.025 μmol L-1, whereas the linear range for glucose was from 0.5 to 1000 μmol L-1 with a detection limit of 0.05 μmol L -1. In addition, Cu@N-Chit-CNT/GCE and Cu@Chit-CNT/GCE showed a good selectivity for H2O2 and glucose detection in the presence of dopamine, ascorbic acid and uric acid. The kinetic parameters such as the electron transfer coefficient and the catalytic reaction rate constant were also determined for glucose and H2O2. Finally, the modified electrode is the most sensitive probe ever reported and can be used to achieve the real-time quantitative detection of H2O2 and glucose for biological applications. © 2014 The Royal Society of Chemistry. Source

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