2207-01-4Relevant academic research and scientific papers
Chemically modified cyclodextrins as supramolecular tools to generate carbon-supported ruthenium nanoparticles: An application towards gas phase hydrogenation
Wyrwalski,Léger,Lancelot,Roucoux,Monflier,Ponchel
, p. 334 - 341 (2011)
A series of carbon-supported ruthenium catalysts was synthesized from zerovalent ruthenium nanoparticles stabilized by randomly methylated cyclodextrins (α-, β- and γ-CD) followed by their adsorption onto the carbon support. The catalysts were characterized by N2 physisorption and thermal analyses. The deposited ruthenium nanoparticles were characterized by transmission electron microscopy, which has highlighted predominantly spherical shapes with a mean diameter of 2.4 nm. Catalytic activity was investigated in the gas phase hydrogenation of o-, m- and p-xylene at 85 °C, both separately and in a two-component mixture (o- and p-xylene). The catalyst prepared by a 1:3 concentration ratio of RuCl3 to randomly methylated β-cyclodextrin exhibited the highest hydrogenation activity and stereoselectivity toward the formation of trans- dimethylcyclohexane. The β-cyclodextrin appeared as multifunctional molecular receptors enabling the stabilization and dispersion of the metallic nanoparticles onto the support and the promotion of the catalytic reaction through host-guest interactions.
TiO2-supported Rh nanoparticles: From green catalyst preparation to application in arene hydrogenation in neat water
Hubert, Claudie,Denicourt-Nowicki, Audrey,Beaunier, Patricia,Roucoux, Alain
, p. 1167 - 1170 (2010)
TiO2-supported Rh(0) nanoparticles were prepared by an easy method under mild conditions in neat water. They proved to be highly active catalysts for arene hydrogenation in water with TOFs up to 33333 h-1. The Royal Society of Chemistry 2010.
New ammonium surfactant-stabilized rhodium(0) colloidal suspensions: Influence of novel counter-anions on physico-chemical and catalytic properties
Guyonnet Bile, Elodie,Sassine, Rita,Denicourt-Nowicki, Audrey,Launay, Franck,Roucoux, Alain
, p. 6524 - 6531 (2011)
Novel anionic species, such as hydrogen carbonate (HCO3 -), fluoride (F-), triflate (CF3SO 3-), tetrafluoroborate (BF4-) and chloride (Cl-) were investigated as new partners of water soluble N,N-dimethyl-N-cetyl-N-(2-hydroxyethyl) ammonium salts, used as a protective agent of rhodium colloids. The effect of the surfactant polar head on the micellar behavior, size and morphology of the nanospecies was studied by adapted physico-chemical experiments (surface tension measurements, dynamic light scattering, thermogravimetric and TEM analyses) and discussed in terms of strong or weak stabilization of the growing nanoparticles surface. Finally, the influence of the nanoenvironment generated by the surfactant with various counter-anions was evaluated via the hydrogenation of aromatics.
The hydrogenation of o-, m-, and p-xylene over Ni/SiO2
Keane, Mark A.
, p. 347 - 355 (1997)
The gas phase hydrogenation of o-, m-, and p-xylene was studied over a Ni/SiO2 catalyst prepared by homogeneous precipita tion/deposition. The hydrogenation of each xylene yielded steroisomeric product mixtures of the saturated dimethylcyclohexane. The stereospecificity of the reaction is related to the nature of the reactant/catalyst interaction which governs the mode of addition of hydrogen to the carbons bearing the methyl substituents. The appearance of a common well-defined reversible maximum (Tmax) in the rate vs. temperature plots is reported and discussed. Reaction orders with respect to xylene partial pressures are plotted as a function of reaction temperature. The temperature dependence of the rate constants was fitted to an Arrhenius equation and generated positive (T ≤ Tmax) and negative (T ≥ Tmax) activation energies. The derivation of true activation energies and heats of adsorption from the kinetic data is presented. Turnover frequencies at a particular temperature decreased in the order p-xylene > m-xylene > o-xylene. The respective roles of steric and electronic effects in determining the strength of adsorption and surface reactivity are discussed. A compensation effect, which is established for the experimentally determined or apparent kinetic parameters, is attributed to variations in the temperature dependencies of the surface concentration of the reactive species.
Discrete Polyoxopalladates as Molecular Precursors for Supported Palladium Metal Nanoparticles as Hydrogenation Catalysts
Ayass, Wassim W.,Minambres, Juan F.,Yang, Peng,Ma, Tian,Lin, Zhengguo,Meyer, Randall,Jaensch, Helge,Bons, Anton-Jan,Kortz, Ulrich
, p. 5576 - 5582 (2019)
We have used discrete polyoxopalladates(II) (POPs) of the MPd12X8 nanocube- and Pd15X10 nanostar-types (M = central metal ion, X = capping group) as molecular precursors (diameter ca. 1 nm) for the formation of supported (SBA-15) metallic nanoparticles. These materials proved to be highly active in the hydrogenation of o-xylene. The characterization of such hydrogenation catalysts revealed that the average size of the resulting alloy particles is quite uniform with diameters ranging from 1 to 3 nm (indicating little to no agglomeration). The central transition-metal ion Mn+ (MnII, FeIII, CoII, NiII, CuII, ZnII, PdII) in the POP structure and also the nature of the capping group (AsO43-, SeO32-, PO43-, phenyl-AsO32-) influence the resulting catalytic performance.
Discovery of a Neutral 40-PdII-Oxo Molecular Disk, [Pd40O24(OH)16{(CH3)2AsO2}16]: Synthesis, Structural Characterization, and Catalytic Studies
Bhattacharya, Saurav,Bons, Anton-Jan,Cadot, Emmanuel,Espenship, Michael Forrester,Haouas, Mohamed,Jaensch, Helge,Kortz, Ulrich,Laskin, Julia,Ma, Xiang,Mougharbel, Ali S.,Stuerzer, Tobias,Su, Pei,Taffa, Dereje H.,Wark, Michael
, p. 17339 - 17347 (2021/11/17)
We report on the synthesis and structural characterization of a giant, discrete, and neutral molecular disk, [Pd40O24(OH)16{(CH3)2AsO2}16] (Pd40), comprising a 40-palladium-oxo core that is capped by 16 dimethylarsinate moieties, resulting in a palladium-oxo cluster (POC) with a diameter of μ2 nm. Pd40, which is the largest known neutral Pd-based oxo cluster, can be isolated either as a discrete species or constituting a 3D H-bonded organic-inorganic framework (HOIF) with a 12-tungstate Keggin ion, [SiW12O40]4- or [GeW12O40]4-. 1H and 13C NMR as well as 1H-DOSY NMR studies indicate that Pd40 is stable in aqueous solution, which is also confirmed by ESI-MS studies. Pd40 was also immobilized on a mesoporous support (SBA15) followed by the generation of size-controlled Pd nanoparticles (diameter μ2-6 nm, as based on HR-TEM), leading to an effective heterogeneous hydrogenation catalyst for the transformation of various arenes to saturated carbocycles.
Selective hydrothermal reductions using geomimicry
Bockisch, Christiana,Lorance, Edward D.,Shaver, Garrett,Williams, Lynda B.,Hartnett, Hilairy E.,Shock, Everett L.,Gould, Ian R.
, p. 4159 - 4168 (2019/08/07)
Reduction of carbon-carbon π-bonds has been demonstrated using iron powder as the reductant and simple powdered nickel as the catalyst in water as the solvent at 250 °C and the saturated water vapor pressure, 40 bars. Stereochemical, kinetic and electronic probes of the mechanism suggest reaction via a conventional Horiuti-Polyani process for hydrogenation at the nickel metal surface. Selective reduction of carbon-carbon π-bonds is observed in the presence of other functional groups. The reactions use benign and Earth-abundant reagents that are at low depletion risk and take place in water as the only solvent under conditions that are characteristic of many geochemical processes.
Polyoxometalates Comprising Noble Metals and Corresponding Metal Clusters
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Paragraph 0288-0292, (2019/02/13)
The invention relates to poly oxometalates represented by the formula (An)m+{M′s[M″M15X10OyRzHq]}m? or solvates thereof, corresponding supported poly-oxometalates, and processes for their preparation, as well as corresponding metal-clusters, optionally in the form of a dispersion in a liquid carrier medium or immobilized on a solid support, and processes for their preparation, as well as their use in reductive conversion of organic substrate.
Mesoporous Silica Doped with Dysprosium and Modified with Nickel: A Highly Efficient and Heterogeneous Catalyst for the Hydrogenation of Benzene, Ethylbenzene and Xylenes
Shafigulin,Filippova,Shmelev,Bulanova
, p. 916 - 928 (2019/02/14)
The catalytic activity of synthesized by the template method mesoporous silica doped with dysprosium and modified with nickel (Dy-Ni/MPS) in the hydrogenation of benzene, ethylbenzene and xylenes has been studied. The catalyst is characterized by various techniques such as TEM, SEM, BET, XRD, ICP, XRF analyses. It is shown that the presence of dysprosium in the MPS structure increases the activity of the catalyst. The catalytic activity of the catalyst (Dy-Ni/MPS) has been explored in hydrogenation reaction of benzene derivatives with excellent conversion (96–100%) at low pressure. Graphical Abstract: [Figure not available: see fulltext.].
Pyridine(diimine) Molybdenum-Catalyzed Hydrogenation of Arenes and Hindered Olefins: Insights into Precatalyst Activation and Deactivation Pathways
Joannou, Matthew V.,Bezdek, Máté J.,Chirik, Paul J.
, p. 5276 - 5285 (2018/05/15)
Pyridine(diimine) molybdenum bis(olefin) and bis(alkyl) complexes were synthesized, characterized, and examined for their catalytic activity in the hydrogenation of benzene and a selection of substituted arenes. The molybdenum bis(alkyl) complex (4-tBu-iPrPDI)Mo(CH2SiMe3)2 (iPrPDI = 2,6-(2,6-(C(CH3)2H)2C6H3N=CMe)2C5H3N) exhibited the highest activity for the hydrogenation of benzene, producing cyclohexane in >98% yield at 23 °C under 4 atm of hydrogen after 48 h. Toluene and o-xylene were similarly hydrogenated to their respective cycloalkanes, with the latter yielding predominantly (79:21 dr) cis-1,2-dimethylcyclohexane. The molybdenum-catalyzed hydrogenation of naphthalene yielded tetralin exclusively, and this selectivity was maintained at higher H2 pressure. At 32 atm of H2, more hindered arenes such as monosubstituted benzenes, biphenyl, and m- and p-xylenes underwent hydrogenation with yields ranging between 20 and >98%. (4-tBu-iPrPDI)Mo(CH2SiMe3)2 was also a competent alkene hydrogenation catalyst, supporting stepwise reduction of benzene to cyclohexadiene and cyclohexene during molybdenum-catalyzed arene hydrogenation. Deuterium labeling studies for the molybdenum-catalyzed hydrogenation of benzene produced numerous isotopologues and stereoisomers of cyclohexane, indicating reversible hydride (deuteride) insertion/β-H(D) elimination, diene/olefin binding, and allylic C-H(D) activation during the reaction. The resting state of the catalyst under neat conditions was established as the η6-benzene complex (iPrPDI)Mo(η6-benzene). Under catalytic conditions, pyridine underwent C-H activation of the 2-position and furan underwent formal C-O oxidative addition to yield a "metallapyran". Both reactions were identified as important catalyst deactivation pathways for the attempted molybdenum-catalyzed hydrogenation of heteroarenes.
