Partial hydrogenation of benzene to cyclohexene on a Ru–Zn/m-ZrO2 nanocomposite catalyst

Wang, Jianqiang; Wang, Youzhen; Xie, Songhai; Qiao, Minghua; Li, Hexing; Fan, Kangnian

doi:10.1016/j.apcata.2004.04.038

Cited by 94 publications

(51 citation statements)

References 24 publications

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“…Recent studies have suggested that Zn͑II͒ can be reduced by chemisorbed hydrogen to form Ru-Zn 2+ / Ru-Zn distribution on the catalyst surface. 19 This is confirmed by theoretical study focused on effect of Zn 2+ / Zn layer on dissociation of H 2 on Ru͑0001͒. 20 They found that Zn 2+ has a dramatic influence on the electron delocalization between molecular orbit on H 2 and valence orbits of atop Ru atom increasing H 2 dissociation barrier and resulting in zones of sparse chemisorbed H around Zn 2+ .…”

Section: Introductionsupporting

confidence: 57%

Hydrogen mediated transport of Sn to Ru film surface

Faradzhev

Sidorkin

2009

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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The authors report on the interaction of atomic hydrogen with Sn and thin Ru film at room temperature. The study is done using a combination of photoelectron and low energy ion scattering spectroscopies as well as scanning electron microscopy. The adsorption of hydrogen on a Sn surface leads to the formation of stannane ͑SnH 4 ͒, which dissociatively adsorbs on the surface of polycrystalline Ru film. In the range of effective Sn coverages studied ͑up to 1 ML͒, the resulting overlayer consists of randomly distributed three-dimensional islands with average size below 40 nm occupying up to several percent of the surface area. Nucleation of Sn is observed presumably at defect sites ͑e.g., grain boundaries͒. Ion scattering data are found consistent with Volmer-Weber growth mode: no initial transition wetting layer formation is detected. Oxidation of Sn islands on a Ru surface at room temperature results in the formation of SnO. Neither metallic nor oxidation states of Sn higher than Sn 2+ are observed by photoelectron spectroscopy.

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Section: Introductionsupporting

confidence: 57%

Hydrogen mediated transport of Sn to Ru film surface

Faradzhev

Sidorkin

2009

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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“…The variation in the BE values indicates that the Ru clusters that are anchored onto the MSN-Zr support are positively charged and induce the Zr in the supports to adopt a new chemical environment. [16] The H 2 -TPR profiles of RuCl 3 salt on different supports further confirm that there is a strong interaction between the Ru cluster and the MSN-Zr support (see the Supporting Information, Figure S7). [17] From these results, we concluded that Ru d+ species and a new chemical environment around the Zr species were formed on the Ru/MSN-Zr-20 catalysts.…”

supporting

confidence: 49%

Immobilized Ru Clusters in Nanosized Mesoporous Zirconium Silica for the Aqueous Hydrogenation of Furan Derivatives at Room Temperature

Chen

Zhang

et al. 2013

ChemCatChem

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Noble-metal clusters are important catalysts because of their unique structures and activities, which are associated with their metalÀmetal bonds.[1] Numerous methods have been developed to encapsulate metal clusters within porous materials or polymers to protect the clusters against sintering.[2] A common porous support is zeolite, owing to its intrinsic subnanometer pore diameters, which are similar to the size of the metal clusters and can confine and prevent the clusters from growing into big particles. This confinement allows metal clusters to activate reactants with small molecular sizes that are accessible to the pores. [3] Mesoporous silica provides an ideal support, owing to its large pore diameters, which are suitable for large-sized organic substrates and biomass derivatives.[4] Ligand-stabilized metal precursors are usually used to anchor the clusters within the mesoporous channel with a low loading of the metal.[5] Uniform mesoporous-silica-supported noble-metal clusters cannot be achieved by impregnation of the support in an aqueous solution of the metal salts because the pore diameter of mesoporous silica (> 2 nm) is larger than the size of the metal clusters. The metal clusters are easily grown into big particles with a broad size distribution.[6] The incorporation of heteroelements (Zr, Ti, Al, etc.) into mesoporous silica has been developed to disperse metal species.[7] However, some metal particles still migrate towards the outside of the support during the reduction step with hydrogen, which causes their aggregation into big particles and, hence, the blocking of the entrance to the pore channels. Therefore, substantial challenges remain towards the goal of synthesizing uniform metal clusters that are immobilized within mesoporous silica from the corresponding metal salts.Biomass becomes an increasingly important feedstock to produce fuels and chemicals for a sustainable future.[8] Furan derivatives have been identified as the key building blocks to synthesize valuable chemicals.[9] Besides its nontoxic and nonflammable properties, water is a desirable solvent because the furan derivatives are soluble under aqueous conditions.[10] Several catalysts have been developed for the hydrogenation of furan derivatives in water, but high reaction temperatures or high hydrogen pressures are required to achieve high activities because of the low aqueous solubility of hydrogen. [11] Herein, immobilized ruthenium clusters (50 Ru atoms) in nanosized mesoporous zirconium silica (MSN-Zr) were synthesized by using an impregnation method, starting from an aqueous solution of RuCl 3 . The Ru cluster catalyst showed remarkable activity for hydrogenation of furan derivatives in water at room temperature under 5 bar hydrogen pressure.MSN-Zr-x, which has a uniform hexagonal pore structure, was synthesized by modification of our previously reported two-step procedure, [12] in which x denotes the Si/Zr molar ratio (for the detailed preparation, see the Supporting Information). The morphology and pore structure are sim...

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“…The perhaps surprisingly large influence that the stirring speed exerts on the outcome of these hydrogenations [45] can be interpreted as a classic example of mass-transfer limitation, as hydrogen contained in the top part of the reaction vial (headspace) needs to diffuse to the liquid phase in the bottom part in which the catalytic process occurs and hydrogen is consumed. [46] Increased stirring influences the gas-liquid interfacial area and thus effects the hydrogenation rate, which is a known phenomenon in hydrogenation chemistry. [46] From a chemical engineering standpoint it is apparent, that the 10 mL cylindrical tube used for most microwave experiments in single-mode reactors today, in particular, in combination with a comparatively ineffective magnetic stirring system, is not an ideal reactor for gaseous transformations of this type.…”

Section: Resultsmentioning

confidence: 99%

“…[46] Increased stirring influences the gas-liquid interfacial area and thus effects the hydrogenation rate, which is a known phenomenon in hydrogenation chemistry. [46] From a chemical engineering standpoint it is apparent, that the 10 mL cylindrical tube used for most microwave experiments in single-mode reactors today, in particular, in combination with a comparatively ineffective magnetic stirring system, is not an ideal reactor for gaseous transformations of this type.…”

Section: Resultsmentioning

confidence: 99%

Microwave‐Assisted Cross‐Coupling and Hydrogenation Chemistry by Using Heterogeneous Transition‐Metal Catalysts: An Evaluation of the Role of Selective Catalyst Heating

Irfan

Fuchs

Glasnov

et al. 2009

Chemistry A European J

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The concept of specific microwave effects in solid/liquid catalytic processes resulting from the selective heating of a microwave-absorbing heterogeneous transition-metal catalyst by using 2.45 GHz microwave irradiation was evaluated. As model transformations Ni/C-, Cu/C-, Pd/C-, and Pd/Al2O3-catalyzed carbon-carbon/carbon-heteroatom cross-couplings and hydrogenation reactions were investigated. To probe the existence of specific microwave effects by means of selective catalyst heating in these transformations, control experiments comparing microwave dielectric heating and conventional thermal heating at the same reaction temperature were performed. Although the supported metal catalysts were experimentally found to be strongly microwave absorbing, for all chemistry examples investigated herein no differences in reaction rate or selectivity between microwave and conventional heating experiments under carefully controlled conditions were observed. This was true also for reactions that use low-absorbing or microwave transparent solvents, and was independent of the microwave absorbtivity of the catalyst support material. In the case of hydrogenation reactions, the stirring speed was found to be a critical factor on the mass transfer between gas and liquid phase, influencing the rate of the hydrogenation in both microwave and conventionally heated experiments.

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Partial hydrogenation of benzene to cyclohexene on a Ru–Zn/m-ZrO2 nanocomposite catalyst

Cited by 94 publications

References 24 publications

Hydrogen mediated transport of Sn to Ru film surface

Hydrogen mediated transport of Sn to Ru film surface

Immobilized Ru Clusters in Nanosized Mesoporous Zirconium Silica for the Aqueous Hydrogenation of Furan Derivatives at Room Temperature

Microwave‐Assisted Cross‐Coupling and Hydrogenation Chemistry by Using Heterogeneous Transition‐Metal Catalysts: An Evaluation of the Role of Selective Catalyst Heating

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