New Homogeneous-like Heterogeneous Catalysts For Fine Chemical Synthesis

(1)

New Homogeneous-like Heterogeneous Catalysts For Fine Chemical Synthesis

based on Metal Nanoparticles

Taeghwan Hyeon

National Creative Research Initiative Center for Oxide Nanocrystalline Materials,

and School of Chemical Engineering Seoul National University, Seoul, Korea

Theories and Applications of Chem. Eng., 2004, Vol. 10, No. 2 2700

화학공학의 이론과 응용 제10권 제2호 2004년

(2)

Synthesis of

Monodisperse Palladium Nanoparticles

Without a Size Selection Process

(3)

1 nm

20 nm

10 nm

Monodisperse 3.5 nm Pd nanoparticles

Pd(acac) ₂ +

trioctylphosphine (TOP) At 300 ^o C

S.-W. Kim et al. Nano Lett. 2003, 3, 1289

(4)

TEM Images of 5 nm sized Pd nanoparticles

S.-W. Kim et al. Nano Lett. 2003, 3, 1289

(5)

TEM Images of 7 nm sized Pd nanoparticles

S.-W. Kim et al. Nano Lett. 2003, 3, 1289

(6)

Designed Synthesis of

Atom Economical Pd/Ni Bimetallic Nanoparticle-based Catalysts

for Sonogashira Coupling Reactions

S. Son et al., J. Am. Chem. Soc. 2004, 126, 5026.

(7)

Model Structures of Pd-Ni Bimetallic Nanoparticles

Ni core

Pd Shell

Pd core

Ni Shell

Ni-rich core

Pd-rich Shell

(8)

5 nm

(a) (b)

(c)

S. Son et al., J. Am. Chem. Soc. 2004, 126, 5026.

(9)

Sonogashira Coupling Reactions

Ar X Ar Ar

Ar X Ph Ar Ph

+ TMS ^Ph ³ ^{P, DBU, H} ² ^O

cat. Toluene Ph ₃ P, CuI

+ cat. DIA A

B

3.9 nm

3.5 nm

* Equal amount of Pd used

(10)

Sonogashira Coupling Reactions

Ar X Ar Ar

Ar X Ph Ar Ph

+ TMS ^Ph

³

^{P, DBU, H}

²

^O cat. Toluene

Ph

₃

P, CuI

+ cat. DIA A

B

Entry X Substrate(Y) Reaction type Cat. Yield(%) ^b

1 Br 4-acetylbenzene A Pd-Ni NP 92

2 Br 4-acetylbenzene A recovered from entry1 95

3 Br 4-acetylbenzene A recovered from entry2 91

4 Br 4-acetylbenzene A recovered from entry3 92

5 Br 4-acetylbenzene A recovered from entry4 90

6 Br 2-thienyl A Pd-Ni NP 95

7 Cl 4-acetylbenzene A Pd-Ni NP n.r.

8 Br 4-acetylbenzene B Pd-Ni NP 86

9 Br 2-thienyl B Pd-Ni NP 86

S. Son et al., J. Am. Chem. Soc. 2004, 126, 5026.

(11)

Synthesis of Cu ₂ O Coated Cu Nanoparticles and

their Successful Applications to Ullmann-type Amination Coupling Reactions of Aryl Chlorides

Cl

N N

G

Cs ₂ CO ₃ , DMSO

EWG Cu ₂ O coated

Cu nanoparticles

+

EW

S. Son et al., Chem. Comm. 2004, 778.

(12)

Cu

Air Cu(acac) ₂

oleylamine

Cu ₂ O/ Cu

Cu

₂

O (111)

Cu (111)

Cu (220) Cu

₂

0 (220)

Cu (200)

30 40

2 θ

50 60 70 80

Cu

₂

O (111)

Cu (111)

Cu (220) Cu

₂

0 (220)

Cu (200)

30 40

2 θ

50 60 70 80

(d)

S. Son et al., Chem. Comm. 2004, 778.

(13)

entry reactant product yield(%)^b

1 95

2 91

3 90

4 85

5 97

6 69

7 86

8 88

9 n.r.

10 n.r.

Cl F

Cl

MeO Cl

O

N N

O₂N N

N

F N

N

N N

MeO N

N O

Cl

N N

N Cl N

N N

OHC

OHC Cl

Cl

CF₃ N

Cl Cl

Cl O₂N

N Cl

N

N N

Cl

Active catalysts

for Ullmann type amination coupling reactions

of aryl chlorides !!!

Bulk CuO powder works only for Aryl Bromides

S. Son et al., Chem. Comm. 2004, 778.

2712

(14)

Diameter-Controlled Synthesis of Discrete and Uniform-sized

Single-Walled Carbon Nanotubes

using Monodisperse Iron Oxide Nanoparticles

Embedded in Zirconia Nanoparticle Array as Catalysts

S. Han et. al. J. Phys. Chem. B 2004, in press.

(15)

CNT grown using CH ₄ CVD on spin-coated 2 nm sized monodisperse Fe ₂ O ₃ nanoparticles

Nanotube diameter (nm)

2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5

Frequency (%)

0 5 10 15 20 25

4.0 ± 1.3 nm

(16)

SiO₂

Si

1) LB deposition 2) Calcination

SiO₂

Si

3) CH

₄

CVD

SiO₂

Si

Iron oxide nanoparticle Zirconia nanoparticle Surfactant

(17)

particle size (nm)

1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0

Frequency (%)

0 20 40 60 80

3.3 ± 0.2 nm

particle size (nm)

1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0

Frequency (%)

0 20 40 60 80

3.3 ± 0.2 nm

1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0

Frequency (%)

0 10 20 30 40 50 60

3.0 ± 0.6 nm

1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0

Frequency (%)

0 10 20 30 40 50 60

3.0 ± 0.6 nm

(18)

SEM and HRTEM of 3.0 nm SWCNT

(19)

particle size (nm)

1.00 1.25 1.50 1.75 2.00 2.25 2.50

Frequency (%)

0 10 20 30 40 50 60

1.8 ± 0.2 nm

particle size (nm)

1.00 1.25 1.50 1.75 2.00 2.25 2.50

Frequency (%)

0 10 20 30 40 50 60

1.8 ± 0.2 nm

1.00 1.25 1.50 1.75 2.00 2.25 2.50

Frequency (%)

0 10 20 30 40 50

1.8 ± 0.3 nm

1.00 1.25 1.50 1.75 2.00 2.25 2.50

Frequency (%)

0 10 20 30 40 50

1.8 ± 0.3 nm

(20)

CONCLUSIONS

So Far,

We can synthesize

Monodisperse Nanocrystals of Fe, Fe ₂ O ₃ , Fe ₃ O ₄ , CoFe ₂ O ₄ ,

Co, Ni, Pd, Au, MnO, ZrO ₂ , PbS, CdS, MnS, ZnS, ZnO

(Most of Them,

without a size-selection) We can also synthesize Anisotorpic Nanocrystals of

These Materials.

(21)

Fabrication of hollow Pd spheres and their applications to

Suzuki coupling reactions

(22)

Silica sphere

Hollow Pd sphere

Fabrication of Pd Hollow Spheres

(23)

SEM image of Pd hollow spheres

(24)

TEM image of Pd hollow spheres

Surface area of > 60 m ² /g !!!

S.-W. Kim, M. Kim, W. Y. Lee, T. Hyeon J. Am. Chem. Soc. 2002, 124, 7642.

(25)

Suzuki coupling reactions using Pd hollow spheres Suzuki coupling reactions using Pd hollow spheres

s I B(OH)

₂

S

+

Usually catalyzed by homogeneous Pd(PPh ₃ ) ₄

S.-W. Kim, M. Kim, W. Y. Lee, T. Hyeon J. Am. Chem. Soc. 2002, 124, 7642.

(26)

Suzuki cross coupling for various substrates

S.-W. Kim, M. Kim, W. Y. Lee, T. Hyeon J. Am. Chem. Soc. 2002, 124, 7642.

(27)

27 Chem. & Eng. News

(28)

High Performance

Direct Methanol Fuel Cell Electrodes using

New Solid-phase Synthesized

Carbon Nanocoils (CNC)

(29)

What is Fuel Cell ?

A cell in which the reactants of an exoenergetic reaction are

continuously supplied, and the products continuously removed, so that electricity may be supplied indefinitely.

Brief History

- 1839 Discovery of fuel cell, William Grove

- 1960s Success as power during space flight, NASA

- 1984 Transportation technologies, U.S. Depart. of Energy - 2000s Portable power sources, Electric company

(30)

30 Comparison of Various Types of Fuel Cells

(31)

Fuel Cell vs. Lithium Battery

9 Chemical Energy → Electrical E.

9 Continuous generation of electricity.

9 No need for electrical charging.

9 Chemical Energy ↔ Electrical E.

9 Discontinuous generation of electricity.

9 Need for electrical charging.

(32)

Solid-phase Synthesis of Carbon Nanocoils

Mixing & Gelation of Resorcinol-Formaldehyde Gel in the Presence of Co(Ac) ₂ , Ni(Ac) ₂ , and Silica gel

Heating at 900 ^o C under N ₂

Formation of Carbon/Co,Ni/Silica Composite Removal of metals and silica

by Acid treatment

followed by NaOH treatment

Synthesis of Carbon Nanocoils

T. Hyeon et al., Angew. Chemi. Int. Ed. 2003, 42, 4352.

(33)

XRD and Raman revealed good crystallinity

wave number (cm^-1)

1000 1200 1400 1600 1800 2000

arbitrary unit

1345

1576

D-line G-line

2θ

15 20 25 30 35 40 45 50 55 60 65 70

arbitrary intensity

(002)

(100)

(004)

BET surface area of 320 m ² /g !!!

In our lab, we can make this carbon in 10s of grams scale in 1 synthesis.

The synthetic procedure is very cheap and easy to scale-up.

T. Hyeon et al., Angew. Chemi. Int. Ed. 2003, 42, 4352.

(34)

TEM showed that the particles are composed of 5 ~ 10 nm thick Graphitic coils

50 nm

BET surface area of 320 m ² /g !!!

T. Hyeon et al., Angew. Chemi. Int. Ed. 2003, 42, 4352.

(35)

HRTEM showed graphitic layers.

(36)

Specific Methanol Electrooxidation Current at Anode (Half-cell test)

4 and 6 times higher Oxidation current at 0.4 V !!!

Commercial E-Tek

60% Pt-Ru/Vulcan XC-72 60% Pt-Ru/Carbon Nanocoil

Real Fuel Cell:

60 wt. %

Catalyst loading

Vulcan XC-72 carbon: Cabot Co.

Standard & most-widely used

carbon support for fuel cell electrodes amorphous & surface area of 212 m

²

/g

0.0 0.2 0.4 0.6 0.8

0 100 200 300

Commercial Vulcan XC-72

CNR-CL7

Speci fi c cur re nt / A g

-1

Potential / V vs. NHE

Carbon Nanocoils

T. Hyeon et al., Angew. Chemi. Int. Ed. 2003, 42, 4352.

(37)

0 100 200 300 400 200

400 600

800

a)

Current density / mA cm

^-2

C el l v o lt age / m V

0 30 60 90

P o we r d en stiy / m W c m

-2

Commercial E-Tek

60% Pt-Ru/Vulcan XC-72 60% Pt-Ru/Carbon Nanocoil

Polarization curves of Direct Methanol Fuel Cell (MEA: Membrane-Electrode-Assembly, Real Fuel Cell ) at 30 ^o C

170 % and 230 % Higher Maximum Power Density!!!

T. Hyeon et al., Angew. Chemi. Int. Ed. 2003, 42, 4352.

(38)

New Homogeneous-like Heterogeneous Catalysts For Fine Chemical Synthesis