Dispersing palladium nanoparticles using a water-in-oil microemulsion—homogenization of heterogeneous catalysis

Yoon, Byunghoon; Kim, Hakwon; Wai, Chien M.

doi:10.1039/b211836j

Cited by 63 publications

(49 citation statements)

References 12 publications

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“…2 nm [38]. The intricated problem of equilibrium between Pd(0) as colloidal nanoparticles and Pd(0) or Pd(II) as monomolecular soluble forms was also discussed for carbonylation [39,40] and hydrogenation using water-in-oil-microemulsion [41].…”

Section: Introductionmentioning

confidence: 99%

Homogeneous/heterogeneous palladium based catalytic system for Heck reaction. The reversible transfer of palladium between solution and support

et al. 2006

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Pd(II)/Al 2 O 3 and Pd(0)/Al 2 O 3 , containing 0.6% of palladium were characterized by EDX, SEM and XRD methods and used as catalysts of the Heck coupling of bromobenzene with butyl acrylate at 140°C in molten [Bu 4 N]Br salt. Monoarylated (transPhCH = CHC(O)OBu) (1) and diarylated (Ph 2 C = CHC(O)OBu) (2) products were obtained in amounts dependent on kind of base present in the system (Scheme 1). During the reaction palladium was partially leached from the support forming [Bu 4 N][PdBr 4 ] complex that catalyze Heck reaction or undergo readsorption on Al 2 O 3 . These soluble palladium complexes are partially reduced to Pd soluble nanoparticles which can also be anchored on Al 2 O 3 giving active catalyst of Pd(0)/Al 2 O 3 type. Reduction of Pd(II) to Pd(0) during catalytic process at the presence of bases (NaHCO 2 , NaHCO 3 , NaOAc, Cs 2 CO 3 ) was studied by XPS method and the total reduction was observed in reactions of PdCl 2 (PhCN) 2 with NaHCO 2 or with NaHCO 3 and [Bu 4 N]Br. It was experimentally proved that heterogenized catalyst, Pd(0)/Al 2 O 3 , after oxidative addition of aryl halides, serve as a source of soluble palladium species and colloidal nanoparticles that are active as homogeneous catalysts.

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Section: Introductionmentioning

confidence: 99%

Homogeneous/heterogeneous palladium based catalytic system for Heck reaction. The reversible transfer of palladium between solution and support

et al. 2006

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“…ME-derived nanoparticles are widely used in catalytic reactions, mainly as a nanoparticle-containing MEs per se or deposited onto supports. The use of ME itself [18][19][20][21][22][23][24][25] implies the addition of extra components to the catalytic reaction mixture (hydrocarbon, water, surfactant, excess of a metal re-ducing agent). This leads to an increase of the reaction volume, and a catalytic reaction may be affected through "medium" and "solubilization" effects [26,27].…”

Section: Introductionmentioning

confidence: 99%

Synthesis of monodispersed palladium nanoparticles to study structure sensitivity of solvent-free selective hydrogenation of 2-methyl-3-butyn-2-ol

Semagina

Renken

Laub

et al. 2007

Journal of Catalysis

111

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A novel method for isolation of monodispersed Pd nanoparticles from a reverse microemulsion was developed using hydrocarbon evaporation and methanol-assisted particle purification from a surfactant. Fcc Pd nanoparticles of 6, 8, 11, and 13 nm in diameter were isolated from water/ AOT/isooctane mixture and used to study a size effect during solvent-free hydrogenation of 2-methyl-3-butyn-2-ol to 2-methyl-3-buten-2-ol. The initial TOF calculated per mole of surface palladium atoms was duplicated when particle size was increased from 6 to 13 nm but remained constant when accounted per number of specific Pd atoms on Pd(111) facets. Selectivity to olefinic alcohol was not size-dependent, but an increase in particle size decreased the byproduct ratio of dimers to saturated alcohol. Acetylenic alcohol hydrogenation is shown to be a structure-sensitive but size-independent reaction for Pd particles with size of 6-13 nm. The work shows also that the Pd size controlled the reaction rate and the byproduct distribution.

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“…The same authors also reported the dispersion of palladium nanoparticles in a water/AOT/n-hexane microemulsion by hydrogen gas reduction of PdCl 4 2-and its efficiency for hydrogenation of alkenes in organic solvents [79]. UV-visible spectroscopy and TEM analysis revealed the formation of Pd nanoparticles with diameters in the range of 4 to 10 nm.…”

Section: Supercritical Microemulsions Used As Templates For the Stabimentioning

confidence: 84%

“…(Reprinted with the permission of the American Chemical Society[79]) Molar ratio of alkene/AOT/Na 2 PdCl 4 = 1/1/0.01 and 10 mL of n-hexane used as solvent (W = 15) at 30 8C. b) 1.7 mg Pd/C (0.17 mg or 1.6 lmol Pd) in 10 mL n-hexane.…”

mentioning

confidence: 99%

Homogeneous Hydrogenation: Colloids – Hydrogenation with Noble Metal Nanoparticles

Roucoux¹,

Philippot²

2006

The Handbook of Homogeneous Hydrogenation

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Dispersing palladium nanoparticles using a water-in-oil microemulsion—homogenization of heterogeneous catalysis

Abstract: Palladium nanoparticles dispersed by a water-in-oil microemulsion are very effective catalysts for hydrogenation of olefins in an organic solvent.

Cited by 63 publications

References 12 publications

Homogeneous/heterogeneous palladium based catalytic system for Heck reaction. The reversible transfer of palladium between solution and support

Homogeneous/heterogeneous palladium based catalytic system for Heck reaction. The reversible transfer of palladium between solution and support

Synthesis of monodispersed palladium nanoparticles to study structure sensitivity of solvent-free selective hydrogenation of 2-methyl-3-butyn-2-ol

Homogeneous Hydrogenation: Colloids – Hydrogenation with Noble Metal Nanoparticles

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