Olefin hydrogenation catalysis of platinum nanocrystals with different shapes

Bai, Xingzhen; Miyabayashi, Keiko; Shen, Zhongrong; Ebitani, Kohki; Miyake, Mikio

doi:10.1007/s11051-011-0497-6

Cited by 24 publications

(24 citation statements)

References 43 publications

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“…For instance, the rate of hydrogenation of 2-methyl-3-butyn-2-ol with monodispersed surfactant-stabilized Pd nanospheres with sizes between 6 and 13 nm, prepared by a reverse microemulsion procedure, was reported to scale with the number of atoms on their (111) terraces; this suggests that those are the active sites for that reaction (Figure 1). [45,46] This type of correlation between nanoparticle size and activity that leads to the identification of the active catalytic sites is, however, often not valid because other factors may also contribute to the catalytic performance. [44] Shown in the main panel are the turnover frequencies (TOFs) for the reaction, calculated both per total number of surface atoms (*, left axis) and per number of atoms in (111) facets (~, right axis).…”

Section: Catalysis In Solutionmentioning

confidence: 99%

Shape‐Controlled Nanostructures in Heterogeneous Catalysis

2013

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Nanotechnologies have provided new methods for the preparation of nanomaterials with well-defined sizes and shapes, and many of those procedures have been recently implemented for applications in heterogeneous catalysis. The control of nanoparticle shape in particular offers the promise of a better definition of catalytic activity and selectivity through the optimization of the structure of the catalytic active site. This extension of new nanoparticle synthetic procedures to catalysis is in its early stages, but has shown some promising leads already. Here, we survey the major issues associated with this nanotechnology-catalysis synergy. First, we discuss new possibilities associated with distinguishing between the effects originating from nanoparticle size versus those originating from nanoparticle shape. Next, we survey the information available to date on the use of well-shaped metal and non-metal nanoparticles as active phases to control the surface atom ensembles that define the catalytic site in different catalytic applications. We follow with a brief review of the use of well-defined porous materials for the control of the shape of the space around that catalytic site. A specific example is provided to illustrate how new selective catalysts based on shape-defined nanoparticles can be designed from first principles by using fundamental mechanistic information on the reaction of interest obtained from surface-science experiments and quantum-mechanics calculations. Finally, we conclude with some thoughts on the state of the field in terms of the advances already made, the future potentials, and the possible limitations to be overcome.

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Section: Catalysis In Solutionmentioning

confidence: 99%

Shape‐Controlled Nanostructures in Heterogeneous Catalysis

2013

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“…In addition, the growth evolution of the particles into nanowires on Mo and W substrates is shown in Fig.3. It was reported that the size and shape of the nanocrystals can be controlled by the reaction temperature, the type of reducer, ligand and shape directing agent, and not only nanoparticles, but also nanowires can be grown [32]. The nanowire formation is important as one of the nano structural evolution.…”

Section: Morphological and Structural Controls Of Ag Nanostructuresmentioning

confidence: 99%

Growth of Ag Nanostructures on Various Metallic Substrates

Meng

Nakane

Matsushita

et al. 2013

Trans. Mat. Res. Soc. Japan

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Various kinds of Ag nanostructures were grown on various metallic substrates using hexakisphosphate (IP6) as a silver carrier agent. The Ag nanostructures with three-dimensional dendritic structure, the two-dimensional dendritic structure, the two-dimensional fractal structure, particles and nanowire structures were controllably obtained. The morphological control by IP6 using additional metallic materials is proposed. The structural properties of the Ag nanostructures were examined, and the growth evolution of the nanostructures was discussed. It is considered that the IP6 plays an important role as a silver carrier agent for the structural and morphological control of the Ag nanostructures.

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“…Then the flask was filled with H 2 and the solution was stirred for 15 h at 25, 40, 50 or 60°C. The Pt cuboctahedron and Pt tetrahedron were prepared essentially in a similar manner to that of Pt cube in the absence of NaI [49]. For the Pt tetrahedron preparation, we used H 2 PtCl 6 and PAA (MW = 2,100).…”

Section: Hydrogenation Of Olefins Over Structure Controlled Pt Ncs Asmentioning

confidence: 99%

“…The hydrogenation of cis-and trans-stilbene was conducted in a stainless-steel autoclave equipped with a glass reactor (50 mL) at 60°C under 0.2 MPa of hydrogen [49].…”

Section: Hydrogenation Of Olefins Over Structure Controlled Pt Ncs Asmentioning

confidence: 99%

“…The reactor was filled with H 2 at 0.2 MPa and heated to 60°C whilst stirring (800 rpm). For the hydrogenation of cyclohexene and 1-hexene [49], Pt cube (1 mg), substrate (1 mmol) and ethanol (5 mL) were loaded into the glass flask (50 mL). The system was filled with hydrogen, which was added continuously from the balloon throughout the course of the reaction.…”

Section: Hydrogenation Of Olefins Over Structure Controlled Pt Ncs Asmentioning

confidence: 99%

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Shape and Size Controlled Pt Nanocrystals as Novel Model Catalysts

Miyake

Miyabayashi

2011

Catal Surv Asia

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A tremendous development of nanotechnology enabled us to prepare precisely structure-controlled nanocrystals (NCs). Recently, such structure controlled NCs have been applied as model catalysts with controlled active sites to evaluate reaction mechanisms. Here, we review our recent works on preparation of shape controlled Pt NCs, such as cube and wire, and on application as model catalysts for olefin hydrogenation to assess active Pt sites. A hydrogen reduction method of Pt(II) ion was adopted in an aqueous phase to prepare Pt cube in the presence of shape forming agent (NaI) and organic protective agent (sodium polyacrylate or sodium succinate). We succeed to prepare Pt cube with high size and shape selectivity, followed by very small Pt cube of less than 3 nm. Such simultaneous control of both size and shape of Pt NCs has been successfully achieved by the sophisticated tuning of multiple conditions for the growth kinetics of Pt nuclei during hydrogen reduction of PtCl 4 2-in aq. N-, N-dimethylformamide (DMF) solution. The key strategy is to produce small Pt nuclei and to avoid the excessive growth of Pt nuclei, in conjunction with face selective adsorption of anionic protective and shape-forming agents by the control of solvent system. For the preparation of Pt nanowires with high anisotropy, template-assisted methods have been usually used. We have developed facile liquid phase preparation method at room temperature in air without any template. The key factors of the method are: firstly, to use aqueous organic solvent system to control solvent polarity; secondly, to use co-solvent DMF as shape forming agent; thirdly, to use excess NaBH 4 as a stabilizer of Pt nuclei to prevent formation of conventional particles. Single-crystalline Pt nanowires of 2 nm diameter and more than micron length were easily obtained by the reduction of Pt(IV) with excess NaBH 4 in water-DMF-toluene solution (1:8:5 volume ratio) in a short reaction period of 3 h. Then, we have applied shape-controlled Pt NCs protected with PAA prepared by our original methods, such as cube, tetrahedron and wire, as model catalysts for olefin (cis-and trans-stilbenes) hydrogenation in ethanol to evaluate the active facet of Pt catalysts; e.g., Pt(111) or Pt(100). The estimated TOF values for the hydrogenation of cis-and trans-stilbene decreased in the order: cube [ cuboctahedron [ tetrahedron * nanowire. This tendency indicates that Pt(100) show high activity compared with Pt(111). The result is compatible with measurement of XPS and Raman spectra, suggesting strong adsorption of reactant on Pt(100). Hydrogenation of olefins (1-hexene and cyclohexene) has been carried out over Pt cubes with different sizes (8.2-10.1 nm) as catalysts to get information about active sites of Pt catalysts, e.g., flat facet or edge/corner atoms. The results of similar TOF values among Pt cubes with different sizes imply that the active sites are flat facets.

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Olefin hydrogenation catalysis of platinum nanocrystals with different shapes

Cited by 24 publications

References 43 publications

Shape‐Controlled Nanostructures in Heterogeneous Catalysis

Shape‐Controlled Nanostructures in Heterogeneous Catalysis

Growth of Ag Nanostructures on Various Metallic Substrates

Shape and Size Controlled Pt Nanocrystals as Novel Model Catalysts

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