نتایج جستجو برای: cu catalysts

تعداد نتایج: 92695  

Journal: :Dalton transactions 2010
Elena Sperotto Gerard P M van Klink Gerard van Koten Johannes G de Vries

The copper-mediated aromatic nucleophilic substitution reactions developed by Fritz Ullmann and Irma Goldberg required stoichiometric amounts of copper and very high reaction temperatures. Recently, it was found that addition of relatively cheap ligands (diamines, aminoalcohols, diketones, diols) made these reactions truly catalytic, with catalyst amounts as low as 1 mol% or even lower. Since t...

Journal: :Physical chemistry chemical physics : PCCP 2015
Ming Ma Kristina Djanashvili Wilson A Smith

In this work, we report a new synthesis method to prepare a Cu nanowire electrocatalyst for selective CO2 reduction at room temperature and atmospheric pressure. Cu nanowire array electrodes were prepared through a two-step synthesis of Cu(OH)2 and CuO nanowire arrays on Cu foil substrates and a subsequent electrochemical reduction of the CuO nanowire arrays. The Cu nanowire arrays are able to ...

Journal: :Catalysts 2021

Cu-mordenite (Cu-MOR) catalysts with different copper loadings were prepared, characterized and examined in continuous, gas-flow synthesis of methyl acetate (MA) by dimethyl ether (DME) carbonylation. Improved activity selectivity observed for Cu-MOR up to 1 wt% Cu X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR) temperature-programmed reduction hydrogen (H2-TPR) us...

Journal: :Chemistry 2013
Ken Motokura Daiki Kashiwame Naoki Takahashi Akimitsu Miyaji Toshihide Baba

Copper diphosphine complexes have been found to be highly active and selective homogeneous catalysts for the hydrosilylation of CO2. The structure of the phosphine ligands strongly affects their catalytic activity. Turnover number (TON) reaches 70,000 after 24 hours with 1,2-bis(diisopropylphosphino)benzene as a ligand under 1 atmosphere of CO2. (1)H and (13)C NMR spectra, carried out under the...

2008
Ming Xie Jiesheng Wang Chee Huei Lee Yoke Khin Yap

The growth of silicon nanotubes (SiNTs) by a dual-RF-plasma treatment technique is reported here. These SiNTs are vertically aligned and self-assembled from Si substrates at 500 °C by the use of Cu catalysts. Their diameters are ~50 to 80 nm with tubular wall thickness of ~10-15nm. Cu vapors were found partially filled inside the SiNTs. This is a novel technique that can convert bulk materials ...

Journal: :The Journal of chemical physics 2013
Ngoc Linh Nguyen Stefano de Gironcoli Simone Piccinin

Ag-Cu alloy catalysts for ethylene epoxidation have been shown to yield higher selectivity towards ethylene oxide compared to pure Ag, the unique catalyst employed in the industrial process. Previous studies showed that under oxidizing conditions Cu forms oxide layers on top of Ag. Using first-principles atomistic simulations based on density functional theory, we investigate the reaction mecha...

Journal: :Angewandte Chemie 2006
Sebastian Polarz Jennifer Strunk Vladislav Ischenko Maurits W E van den Berg Olaf Hinrichsen Martin Muhler Matthias Driess

Metal oxides are highly important as components in heterogeneous catalysts. It is also well established that as the building blocks of nanoscaled materials get smaller, surfaces become increasingly important in determining their properties. Very early on, researchers found that catalytic activity is only indirectly related to the surface area; in fact it depends on the density of active sites. ...

2013
Seiki Wada Kazuki Oka Kentaro Watanabe Yasuo Izumi

Synthesis of dimethyl carbonate (DMC) from CO2 and methanol under milder reaction conditions was performed using reduced cerium oxide catalysts and reduced copper-promoted Ce oxide catalysts. Although the conversion of methanol was low (0.005-0.11%) for 2 h of reaction, DMC was synthesized as low as 353 K and at total pressure of as low as 1.3 MPa using reduced Cu-CeO2 catalyst (0.5 wt% of Cu)....

Journal: :Dalton transactions 2013
Vincent César Cécile Barthes Yoann C Farré Stéphane V Cuisiat Bernard Y Vacher Rémy Brousses Noël Lugan Guy Lavigne

The anionic malonate-derived N-heterocyclic carbenes (maloNHCs) react cleanly and rapidly with copper chloride to generate the anionic complexes of type [(maloNHC)CuCl]·Li, which crystallize in the solid state either in an oligomeric trimer arrangement or in polymeric helixes depending on the substitution pattern and the solvent. Ten zwitterionic heteroleptic Cu(I) complexes combining the anion...

Journal: :Nanoscale 2017
Kihyun Shin Liang Zhang Hyesung An Hyunwoo Ha Mi Yoo Hyuck Mo Lee Graeme Henkelman Hyun You Kim

We use density functional theory calculations of Pt@Cu core@shell nanoparticles (NPs) to design bifunctional poison-free CO oxidation catalysts. By calculating the adsorption chemistry under CO oxidation conditions, we find that the Pt@Cu NPs will be active for CO oxidation with resistance to CO-poisoning. The CO oxidation pathway at the Pt-Cu interface is determined on the Pt NP covered with a...

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