نتایج جستجو برای: iron catalyst

تعداد نتایج: 184386  

Journal: :American journal of physiology. Gastrointestinal and liver physiology 2002
Antonello Pietrangelo

Iron is essential for fundamental cell functions but is also a catalyst for chemical reactions involving free radical formation, potentially leading to oxidative stress and cell damage. Cellular iron levels are therefore carefully regulated to maintain an adequate substrate while also minimizing the pool of potentially toxic "free iron." The main control of body iron homeostasis in higher organ...

2007
Weiling Deng Colin Carpenter Nan Yi Maria Flytzani-Stephanopoulos

We compare the activity and relevant gold species of nanostructured gold–cerium oxide and gold–iron oxide catalysts for the CO oxidation by dioxygen and water. Well dispersed gold nanoparticles in reduced form provide the active sites for the CO oxidation reaction on both oxide supports. On the other hand, oxidized gold species, strongly bound on the support catalyze the water-gas shift reactio...

2006
Hee Cheul Choi Chongwu Zhou Joon Won Park

Direct formation of iron phosphate nanoparticles on solid substrates with a narrow size distribution (average diameter = 2.2 nm) has been achieved by a simple spontaneous reaction of ferric chloride and phosphoric acid on hydroxyl-terminated SiO2/Si substrates. Single-walled carbon nanotubes (SWNTs) are grown in high yield from the synthesized iron phosphate nanoparticles by thermal chemical va...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2017
Nancy Li D Kwabena Bediako Ryan G Hadt Dugan Hayes Thomas J Kempa Felix von Cube David C Bell Lin X Chen Daniel G Nocera

Iron doping of nickel oxide films results in enhanced activity for promoting the oxygen evolution reaction (OER). Whereas this enhanced activity has been ascribed to a unique iron site within the nickel oxide matrix, we show here that Fe doping influences the Ni valency. The percent of Fe3+ doping promotes the formation of formal Ni4+, which in turn directly correlates with an enhanced activity...

Journal: :Physical review letters 2004
Toshinari Ichihashi Jun-Ichi Fujita Masahiko Ishida Yukinori Ochiai

The tubulization process of amorphous carbon nanopillars was observed in situ by transmis-sion electron microscopy. Amorphous carbon nanopillars were transformed into graphitic tubules by annealing at 650-900 degrees C in the presence of iron nanoparticles. A molten catalyst nanoparticle penetrated an amorphous carbon nanopillar, dissolving it, and leaving a graphite track behind. An iron nanop...

2017
Tim N Gieshoff Uttam Chakraborty Matteo Villa Axel Jacobi von Wangelin

The replacement of noble metal technologies and the realization of new reactivities with earth-abundant metals is at the heart of sustainable synthesis. Alkene hydrogenations have so far been most effectively performed by noble metal catalysts. This study reports an iron-catalyzed hydrogenation protocol for tri- and tetra-substituted alkenes of unprecedented activity and scope under mild condit...

2015
Chi Wai Cheung Fedor E. Zhurkin Xile Hu

Selective catalytic synthesis of Z-olefins has been challenging. Here we describe a method to produce 1,2-disubstituted olefins in high Z selectivity via reductive cross-coupling of alkyl halides with terminal arylalkynes. The method employs inexpensive and nontoxic catalyst (iron(II) bromide) and reductant (zinc). The substrate scope encompasses primary, secondary, and tertiary alkyl halides, ...

2012
Krasimir Ivanov Dimitar Dimitrov Boyan Boyanov

The paper relates to a catalyst, comprising copperchromium spinel, coated on carrier γ-Al2O3. The effect of preparation conditions on the active component composition and activity behavior of the catalysts is discussed. It was found that the activity of carbon monoxide, DME, formaldehyde and methanol oxidation reaches a maximum at an active component content of 20 – 30 wt. %. Temperature calcin...

2014
Carolina Solis Maldonado Javier Rivera De la Rosa Carlos J. Lucio-Ortiz Aracely Hernández-Ramírez Felipe F. Castillón Barraza Jaime S. Valente

The role of iron in two modes of integration into alumina catalysts was studied at 0.39 wt% Fe and tested in trichloroethylene combustion. One modified alumina was synthesized using the sol-gel method with Fe added in situ during hydrolysis; another modification was performed using calcined alumina, prepared using the sol-gel method and impregnated with Fe. Several characterization techniques w...

Journal: :Environmental science and pollution research international 2014
Barbara Fontaine Marios Drosos Pierluigi Mazzei

We evaluated the catalytic activity of a water-soluble iron-porphyrin in an oxidative coupling reaction to form covalent bonds between 2,4-dichlorophenol (2,4-DCP) and humic molecules. The biomimetic catalysis in the presence of H₂O₂ was tested in the dark and in daylight, and changes in reaction products were revealed by high-performance liquid chromatography (HPLC) and nuclear magnetic resona...

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