8 results match your criteria Journal of Catalysis[Journal]

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Direct evidence of atomic-scale structural fluctuations in catalyst nanoparticles.

J Catal 2017 May 3;349:149-155. Epub 2017 Apr 3.

Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, MD 20899-6203, USA.

Rational catalyst design requires an atomic scale mechanistic understanding of the chemical pathways involved in the catalytic process. A heterogeneous catalyst typically works by adsorbing reactants onto its surface, where the energies for specific bonds to dissociate and/or combine with other species (to form desired intermediate or final products) are lower. Here, using the catalytic growth of single-walled carbon nanotubes (SWCNTs) as a prototype reaction, we show that the chemical pathway may in-fact involve the entire catalyst particle, and can proceed via the fluctuations in the formation and decomposition of metastable phases in the particle interior. Read More

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http://dx.doi.org/10.1016/j.jcat.2017.03.009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5520650PMC
May 2017
13 Reads

Binuclear copper(II) complexes discriminating epimeric glycosides and - and -glycosidic bonds in aqueous solution.

J Catal 2016 Jun;338:349-364

Department of Chemistry and Biochemistry and Center for Nanoscience, University of Missouri - St. Louis, St. Louis, MO 63121, USA.

Two chiral binuclear copper(II) complexes were synthesized and characterized for the first time as efficient chemoselective catalysts for the hydrolysis of aryl glycosides and disaccharides in aqueous solution at near neutral pH. Under these conditions, discrimination of epimeric aryl -glycopyranosides was observed both by 29-fold different reaction rates and 3-fold different proficiency of the catalyst. Additionally, large differentiation of the nature of - and - glycosidic bond in aryl glycosides as model compounds is apparent, but also noted in selected disaccharides. Read More

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http://dx.doi.org/10.1016/j.jcat.2015.12.026DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5033522PMC
June 2016
14 Reads

Selectivity and Mechanism of Thermal Decomposition of β-diketones on ZnO Powder.

J Catal 2015 Sep;330:145-153

University of Delaware, Department of Chemistry and Biochemistry, Newark, DE 19716.

The thermal chemistry of β-diketones underlies a number of catalytic processes related both to the catalytic reactions yielding commodity chemicals and to the production of supported transition metal catalysts themselves. The mechanisms of decomposition during thermal transformation of three β-diketones, acetylacetone (acacH), 1,1,1-trifluoroacetylacetone (tfacH), and 1,1,1,5,5,5-hexafluoroacetylacetone (hfacH), were studied on ZnO powder surface using Fourier-transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and Density functional theory (DFT) computational investigation. The initial O-H dissociation leads to the formation of corresponding β-diketonates in all the cases investigated. Read More

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http://dx.doi.org/10.1016/j.jcat.2015.07.021DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4545501PMC
September 2015
24 Reads

ZnO is a CO(2)-selective steam reforming catalyst.

J Catal 2013 Jan;297(C):151-154

Institute of Physical Chemistry, University of Innsbruck, Innrain 52a, A-6020 Innsbruck, Austria.

ZnO was tested as possible methanol and - since formaldehyde is one of the key intermediates in methanol conversion reactions - also as formaldehyde steam reforming catalyst. Catalytic experiments in a batch as well as a flow reactor resulted in highly selective steam reforming, though at low specific activities, of formaldehyde and methanol over ZnO toward CO(2) (selectivity of 95-99.6%). Read More

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http://dx.doi.org/10.1016/j.jcat.2012.10.003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3546163PMC
January 2013
17 Reads

CO(2)-selective methanol steam reforming on In-doped Pd studied by in situ X-ray photoelectron spectroscopy.

J Catal 2012 Nov;295(2-3):186-194

Institute of Physical Chemistry, University of Innsbruck, Innrain 52a, A-6020 Innsbruck, Austria ; Department of Inorganic Chemistry, Fritz-Haber-Institute of the Max-Planck-Society, Faradayweg 4-6, D-14195 Berlin, Germany.

In situ X-ray photoelectron spectroscopy (in situ XPS) was used to study the structural and catalytic properties of Pd-In near-surface intermetallic phases in correlation with previously studied PdZn and PdGa.Room temperature deposition of ∼4 monolayer equivalents (MLEs) of In metal on Pd foil and subsequent annealing to 453 K in vacuum yields a ∼1:1 Pd/In near-surface multilayer intermetallic phase. This Pd(1)In(1) phase exhibits a similar "Cu-like" electronic structure and indium depth distribution as its methanol steam reforming (MSR)-selective multilayer Pd(1)Zn(1) counterpart. Read More

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http://linkinghub.elsevier.com/retrieve/pii/S002195171200256
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http://dx.doi.org/10.1016/j.jcat.2012.08.008DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3485566PMC
November 2012
28 Reads

In situ XPS study of methanol reforming on PdGa near-surface intermetallic phases.

J Catal 2012 Jun;290(C):126-137

Institute of Physical Chemistry, University of Innsbruck, Innrain 52a, A-6020 Innsbruck, Austria.

In situ X-ray photoelectron spectroscopy and low-energy ion scattering were used to study the preparation, (thermo)chemical and catalytic properties of 1:1 PdGa intermetallic near-surface phases. Deposition of several multilayers of Ga metal and subsequent annealing to 503-523 K led to the formation of a multi-layered 1:1 PdGa near-surface state without desorption of excess Ga to the gas phase. In general, the composition of the PdGa model system is much more variable than that of its PdZn counterpart, which results in gradual changes of the near-surface composition with increasing annealing or reaction temperature. Read More

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http://dx.doi.org/10.1016/j.jcat.2012.03.009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3405296PMC
June 2012
13 Reads

Synthesis, catalytic activity, and leaching studies of a heterogeneous Pd-catalyst including an immobilized bis(oxazoline) ligand.

J Catal 2012 Feb;286(9):30-40

Institute for Process and Particle Engineering, Graz University of Technology, Inffeldgasse 21a, A-8010 Graz, Austria.

The synthesis and characterization of a novel catalytic system including Pd(OAc)(2) attached to a bis(oxazoline) (=BOX) ligand that is covalently bonded to 3-mercaptopropyl-functionalized silica gel is presented. The catalyst was tested for Suzuki-Miyaura reactions of different aryl halides with phenylboronic acid. The heterogeneity of the catalytic system was investigated using different approaches, indicating that there is virtually no Pd leaching into the reaction solution under the applied reaction conditions. Read More

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http://dx.doi.org/10.1016/j.jcat.2011.10.013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3405295PMC
February 2012
7 Reads

Cu-ZSM-5: A biomimetic inorganic model for methane oxidation.

J Catal 2011 Dec 14;284(2):157-164. Epub 2011 Nov 14.

Center for Surface Chemistry and Catalysis, K.U.Leuven, Kasteelpark Arenberg 23, B-3001 Leuven, Belgium.

The present work highlights recent advances in elucidating the methane oxidation mechanism of inorganic Cu-ZSM-5 biomimic and in identifying the reactive intermediates that are involved. Such molecular understanding is important in view of upgrading abundantly available methane, but also to comprehend the working mechanism of genuine Cu-containing oxidation enzymes. Read More

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http://dx.doi.org/10.1016/j.jcat.2011.10.009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3593946PMC
December 2011
11 Reads
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