Modern Alchemy: Catalysis by - Pire-Ecci...Modern Alchemy: Catalysis by Gold Nano-particles: Part 2...

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Transcript of Modern Alchemy: Catalysis by - Pire-Ecci...Modern Alchemy: Catalysis by Gold Nano-particles: Part 2...

  • Modern Alchemy: Catalysis by Gold Nano-particles: Part 2

    Masatake HarutaTokyo Metropolitan

    University

    PIRE-ECCI/ICMRSummer ConferenceSanta Barbara17 August, 2006

    1. Carbon and Gold in Nanotechnology2. Applications of Gold Catalysts

    Air Quality ControlPropylene EpoxidationLiquid Phase Aerobic Oxidation

    3. Clusters

  • Nano-Science & Technology

    1 nm = 1 x 10-3 μm= 1 x 10ー6 mm= 1 x 10-9 m

    1 mm = 1 x 10-9 x 1000 kmping pong ball the Earth

  • What elements are the major players in Nanotechnology?

    • It is a must for commercial applications that a material should be stable under ambient atmosphere.

    Carbon:2- and 3- dimensional structure sp2 → graphite,C60, nanotube, activated C sp3 → diamond

    Gold : Thermodynamically the most stable,Dramatic size effect, Recyclable.

  • Sp2 hybrid orbital:graphite,fullerrene,nanotube

  • Single and Multi Wall Carbon Nanotube

  • Buckminster fullerene : C60

    Presumed by Prof. Osawa(Kyoto Univ.)

    Discovered in 1985F, Curl Jr.,

    H. W. KrotoR. E. Smalley

    Diameter 1nm1x108 rotation/sec.

  • Gold Nano-wire:“7” is the magic number.

    High Resolution Transmission Electron Microscopy by Prof. Kunio Takayanagi,Tokyo Inst. Tech.

  • Gibbs Energy of Reaction

    Δr G = Δr H - TΔr S

    + : not naturally occurring

    Gibbs Energy Enthalpy EntropyAbsoluteTemp.

    heat of reaction under constant pressure

    regularity inmolecular array

    + : endothermic + : disordered

    - : naturally occurring

    - : exothermic - : ordered

    0 : equilibrium

  • Gibbs Energies for metal oxide formation : Yes or No ?

    ΔfGo(298K), kJ/molO24/3Au + O2 → 2/3Au2O3 +53.3 No

    4Ag + O2 → 2Ag2O -22.4 Yes

    Pt + O2 → PtO2 - 168 Yes

    2Fe + O2 → 2FeO - 493 Yes

  • Where are Gold Catalysts used?

    Air Purification: CO, HCHO, Odor

    Propylene Epoxidation

    H2 Production: H2O shift, CO oxid.

    Direct H2O2 Synthesis

    Aerobic Oxidation: alcohols, alkenes

  • 1

    10

    100

    1000

    104

    0 15 30 45 60

    CO濃

    度 / p

    pm

    反応時間 / min

    Au/TiO2

    1

    10

    100

    1000

    104

    0 15 30 45 60

    CO濃度 / ppm

    反応時間 / min

    Pt/TiO2

    ・ 0.1 g catalyst is used for 12L room air at room temp..・ Gold catalyst covers a wide range of CO concentration.

    CO removal from Ambient Air

  • Regeneration of Au/TiO2 Catalyst by

    Photo Irradiation

    Activity decreases due to theaccumulation of contaminants.

    Regeneration by photoirradiation?

  • • New Catalysts:Au-Ir/CeO2Au/CeO2-ZrO2

    Conventional Cat.:Au/Fe2O3 (AIST)Pt/CeO2(Toyota

    Central Lab.)

    20 40 60 80 100 1200

    20

    40

    60

    80

    100

    Conv

    ers

    ion,

    %

    Reaction Temperature, ℃

    Au/Ce0.5

    Zr0.5

    O2

    Au/CeO2-ZrO

    2(3:7)

    Au/CeO2-ZrO

    2(5:5)

    Au/CeO2-ZrO

    2(7:3)

    Au-Ir/CeO2

    Pt-Ir/CeO2

    Fixed bed Flow reactor, SV=40,000ml/h・g- cat., 50ppm HCHO in air, Cat. :100mg

    Oxidative Decomposition of HCHO

  • 0

    2 0

    4 0

    6 0

    8 0

    1 0 0

    5 0 1 0 0 1 5 0 2 0 0 2 5 0

    A u / N i F e 2 O 4

    P d / A l 2 O 3

    金 触 媒

    パ ラ ジ ウ ム触 媒

    ( P d 1 w t % )

    ( A u 1 w t % )

    反 応 温 度 / ℃

    トリメチル

    アミン

    除去

    率/

    (CH3)3N CO2, N2, H2Oトリメチルアミン

    (100ppm) 触媒

    空気中O2

    (SV=20,000h-1ml/g-触媒)

  • Gold Catalyst as an Odor Eater1992, “Beauty Toilet”, Matsushita Housing Products Co., Ltd.

  • E factors for Chemical Products

    RefineryRefinery

    Bulk chemiclas

    Medicine,Pepticide

    E factor = Product weightByproduct weight

    World Annual Production, 103 ton

    R.A.Sheldon(1992)

    0.1

    1

    10

    100E>25~100

    E=5~50

    E<1~5

    E=ca. 0.1

    10 102 103 104 105 106

    E f

    acto

    r

    Fine chemicals

  • Gold catalysts may become a major player in

    • Simple reactions consuming minimum process energies (gas phase)

    • Reactions without using solvents or using water as a solvent

    • New reactions with high atom efficiency

    Green Sustainable Chemistry!

  • Propylene Oxide

    • World Annual Production = 6 million tons

    → Polyurethane (60-60%) Propylene glycol (20-25%)

    • Annual Market Growth = above 5%

    • Market Share = Dow Chem. 30%, Lyondell 18%

  • Synthesis of Propylene Oxide

    Current Industrial Process Dow Chemical Co.

    A New Route Au/Ti-SiO2 Hayashi & Haruta, 1994

  • Three Major Factors Controlling

    the Activity and Selectivity

    Strong Contact with the Supports

    Size of Gold Particles

    Type of the Supports

  • Effect of Contact Structure in PO Synthesis

    Prod

    uct Y

    ield

    (%)

    Catalyst Temperature (K)

    T.Hayashi et al.,J.Catal. 178(1998)566.

  • Support Effect in PO Synthesis

    M. Haruta et al., Res. Chem. Intermed. 24(1998)329.

  • Au Size Effect in PO Synthesis

    Prod

    uct Y

    ield

    (%)

    Au Mean Diameter (nm)

    T.Hayashi et al.,J.Catal. 178(1998)566.

  • Product Selectivity Changes with Metals

    –1.72.4

    DAu(nm)

    1

    10.05

    1

    Load.(wt%)

    >990–3.1353

    9208712298Pt

    9809857298Pd

    0>99–0.63353Au

    C3H8POH2C3H6(K)Selec. (%)Conv. (%)Temp.Metal

    on TiO2

  • Step Density of Hemispherical Au

    Mavrikakis, Stoltze and Nørskov, Catal. Lett., 64 (2000) 101.

    NAu

    edge

    /NA

    utot

    al

    Au Cluster Size (nm)

  • STM & LBH Images of Model Au/TiO2

    Large

    Small

    LBH

    STM Local Barrier HeightY. Maeda et al., Appl. Surf. Sci. 222(2003)409.

  • -1.2

    -0.8

    -0.4

    0.0

    0.4

    0.8

    0 0.2 0.4 0.6 0.8 1Height(nm)

    ΔΦ (e

    V)

    0.0

    1.0

    2.0

    3.0

    4.0

    Eg (e

    V)

    Work Function and Energy Gap vs Thickness

    Au Cluster Height (nm)

    Ener

    gy G

    ap (e

    V)

    metallicnonmetallic

    Y. Maeda et al., Appl. Surf. Sci. 222(2003)409.

  • Liquid Phase Aerobic Oxidation

    • Activated carbons

    • Fine polymer particles

    • Nanocrystalline CeO2• MgAl2O3

    • Al2O3-SiO2

    Supports for Au

  • 353K,TBHP

    + ½ O2Au/a. c.

    cis-cyclooctene

    G.T. Hutchings et al., Nature 437, 1132(2005)

    Conv. 7.9%(24h)Sel. 81%

    Liquid alkene epoxidation with O2in the absence of a solvent

  • Liquid Phase Selective Oxidation

    Glucose to Gluconic Acid in Water

  • M. Rossi et al., Angew. Chem. Int. Ed.43(2004)5812.

    Au / Activated Carbon

    303K,React. period: 100 s,

    glucose 0.38M / H2O glucose : Au =12 000

    Conversion vs 1/DAu in Glucose Oxidation

  • Aerobic oxidation of 3-octanol: Support effect

    A. Corma et al., Angew. Chem. Int. Ed., 44, 4066(2005)

    5 nm CeO2

  • Aerobic alcohol oxidation over Au/CeO2

    A. Corma et al., Tetrahedron,2006, in press.

  • Bioethanol : CH3CH2OH +O2 → CH3COOH + H2O453K, 3Mpa

    0

    50

    100

    Pd/ Pt/

    Yie

    ld (

    %)

    Au/MgAl2O3C. H. Christensen et al., Angew. Chem. Int. Ed. 45, 4648(2006)

  • HOCH2 - CH2OH + CH3OH + O2

    HOCH2 - COCH3 + 2H2OO

    Pilot plant for the synthesis of methyl ester glycolate

    T. Hayashi, Nippon Shokubai Co.

    1~2x104 t/year( 3 years later)

    cleaner for semiconductors and liquid crystals, raw materials for cosmetics and biodegradable polymers

    Au / Al-SiO2

  • Reactivities of Au clusters dramatically change with size and

    structure.

    2nm

    <Au Clusters> <Au Nanoparticles>

    Number of Atoms 300

    Non-metallicQuantum Size Effect3D Structure

    No Surface PlasmonAbsorption

    MetallicEdges & Corners

    Contact Interfaces

    Surface PlasmonAbsorption

  • T. Tsukuda et al., J. Amer. Chem. Soc.127, 9374(2005).

    Gold clusters are more active!

  • XPS of Au after Exposure to Oxygen Atom

    Boyen et al., Science, 297 (2002) 1533

    Inte

    nsity

    (Arb

    .Uni

    t)

    Binding Energy (eV)

    Taken after radio frequency oxygen plasma

    Au55 is nobler than bulk gold!

    Au3+ Au3+Au0 Au0

  • Au13 Clusters Supported on Mg(OH)2 by DP

    4–6%100%CO OxidationEfficiency (200K)

    7:9358 : 42NIcosa. : NCubo-Octa.

    Icosahedron Cubo-Octahedron

    D.H.A.Cunninghamet al., J.Catal.177(1998)1.

  • Summary

    Gold catalysts are useful for air purificationowing to high oxidation activity at room temperature and to the activity enhancement by moisture.

    Thermodynamic stability and dramatic size effect of gold clusters smaller than 2nm is opening an exciting field of science.

    Gold catalysts have great potentials and capabilities in developing Green Sustainable Chemistry.

  • Thank you!