Reactions at solid surfaces: From atoms to complexity · 2018. 6. 22. · ng step in ammonia synt...

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Reactions at solid surfaces: Gerhard Ertl Fritz Haber Institut der Max Planck-Gesellschaft Berlin, Germany From atoms to complexity

Transcript of Reactions at solid surfaces: From atoms to complexity · 2018. 6. 22. · ng step in ammonia synt...

Page 1: Reactions at solid surfaces: From atoms to complexity · 2018. 6. 22. · ng step in ammonia synt hesis over iron catalysts is the ogen. The ques tion as to whether the nitrogen species

Reactions at solid surfaces:

Gerhard ErtlFritz Haber Institut der Max Planck-Gesellschaft

Berlin, Germany

From atoms to complexity

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Jöns Jakob Berzelius1779 – 1848

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Wilhelm Ostwald1853 – 1932

Nobel Prize 1909

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A + B → C

d[A]dt

r = – –––– = k[A][B]

k = k0e–E*/RT

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Progress of a chemical reaction

withoutcatalyst

with catalyst

Energy

E

ΔE

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Steady-state reaction rate:

= r = f (pi, pj, T, catalyst)dnjdt

Reactor

dnidt

dnidt

dnjdt

i: reactants

j: products

Heterogeneous catalysis

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Fritz Haber1868 - 1934

Nobel Prize 1918

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N2 + 3 H2 → 2 NH3

Haber & LeRossignol, 1909

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Carl Bosch1874 - 1940

Nobel Prize 1931

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World population and ammonia production

Population

Production

0

1

2

3

4

5

6

7 140

120

100

80

60

40

20

01920 1940 1960 1980 2000

Pop

ulat

ion

/ 10

9

Pro

duct

ion

/ 10

6t/a

N

Year

M. Appl, “Ammonia”, Wiley–VCH (1999)

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P.H. Emmett (1974):

„ The experimental work of the past 50 years leads to the conclusion that the rate-limiting step in ammonia synthesis over iron catalysts is the chemisorption of nitrogen. The question as to whether the nitrogen species involved is molecular or atomic is still not conclusively resolved, though, in my opinion, the direct participation of nitrogen in an atomic form seems more likely than in molecular form.“

The physical basis of heterogeneous catalysis (E. Drauglis & R.I. Jaffee, eds.), Plenum Press, New York, 1975, p. 3

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100 nm

talyticCCatalytic synthesis of ammonia am

((Haber--Bosch process)process)

Technical conditions: T ≈ 400°C, p ≈ 300 barpromoted iron catalyst

BASF S6-10 catalyst (at. %)

Bulk composition 40.5 0.35 2.0 1.7 53.2Surface –

unreduced 8.6 36.2 10.7 4.7 40.0reduced 11.0 27.0 17.0 4.0 41.0cat. active spot 30.1 29.0 6.7 1.0 33.2

Fe K Al Ca O

G. Ertl, D. Prigge, R. Schlögl & D. Weiss, J.Catal. 79 (1983), 359

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Irving Langmuir1881 – 1957

Nobel Prize 1932

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“Most finely divided catalysts must have structures of

great complexity. In order to simplify our theoretical

consideration of reactions at surfaces, let us confine

our attention to reactions on plane surfaces. If the

principles in this case are well understood, it should

then be possible to extend the theory to the case of

porous bodies. In general, we should look upon the

surface as consisting of a checkerboard ...”

I. Langmuir, Trans. Faraday Soc. 17 (1922), 607

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AlAl (111)(111)

1.3 nm × 0.9 nm

4.6 nm × 7.1 nm

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Page 18: Reactions at solid surfaces: From atoms to complexity · 2018. 6. 22. · ng step in ammonia synt hesis over iron catalysts is the ogen. The ques tion as to whether the nitrogen species

O / Pt (111)

J. Wintterlin, R. Schuster, and G. Ertl, Phys.Rev.Lett. 77 (1996), 123.

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QuickTime™ and a decompressor

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O/Ru (0001) T = 300 K

J. Wintterlin & R. Schuster

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N / Fe (100)

R. Imbihl, R.J. Behm, G. Ertl, W. Moritz, Surface Sci. 123 (1982), 129.

Å

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Fe (111)

Fe (100)

Fe (110)

0 .1 .2 .3 .4 .5 .6 .7 .8 .9 × 107 [L ]

N2 exposure

y

0

.1

.2

.3

.4

.5

.6

.7

Fe (111) Fe (100), T = 693K

Fe (110)

F. Bozso, G. Ertl, M. Grunze & M. Weiss, J. Catal. 49 (1977), 18; 50 (1977), 519

Dissociative nitrogen adsorption on Fe single crystal surfaces

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N + 3H

NH + 2H

NH2 + H

NH3NH3 ad

NH2 ad+

Had

NHad+

2HadNad + 3Had

1/2 N2

ad+

3/2 H2

1/2 N2+

3/2 H2

1129 kJ/mol1400

~960

543460ΔH = 46 kJ/mol

17 50~41~33

259106

~21

314

Mechanism of catalytic ammonia synthesis

389

N2 N2 ad 2Nad←→

H2 2Had

Nad + Had NHad

NHad + Had NH2 ad

NH2 ad + Had NH3 ad NH3

←→

←→

←→

←→

←→ ←→

G. Ertl, Catal.Rev.Sci.Eng. 21 (1980), 201

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Experimental exit NH3 mole fraction

Cal

cula

ted

exit

NH

3m

ole

frac

tion

10-3

10-2

10-1

1

10-3 10-2 10-1 1

300 atm150 atm

1 atm

Catalytic synthesis of ammonia: Microkinetics Cammonia

N2 + 3 H2 2NH3→←

P. Stoltze and J.K. Nørskov,

Phys. Rev. Lett. 55 (1985), 2502

J. Catal. 110 (1988), 1

promoted iron catalyst

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CO

NOx

HC

mg/mile

150

100

50

01970 1975 1980 1985 1990 year

Car exhaust emission(USA)

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Page 26: Reactions at solid surfaces: From atoms to complexity · 2018. 6. 22. · ng step in ammonia synt hesis over iron catalysts is the ogen. The ques tion as to whether the nitrogen species

Rh(111)-(2×2)-ORh(111)-(√3×√3)R30°-CO⎫⎭ Rh(111)-(2×2)-(O+1 CO)⎫⎭

0.08

1.201.87

2.170.06 0.05

2.194

2.25

2.194

2.28

2.194

2.061.20

1.83

S. Schwegmann, H. Over, V. De Renzi, G. Ertl, Surf Sci. 375 (1997), 91

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OC

260

~ 21

ΔH = 283 kJ/mol

ELH = 100∗

CO + 2O21

CO2ad

COad + Oad CO2

2CO + O2 2CO2

Oad + COad CO2 + 2* O2 + 2* O2,ad 2Oad

CO + * COad

I––

Pt

Catalytic oxidation of CO

Pt at low coverages( )

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CO + 2O2 → CO2 / Pt(110)1

RCO2300

250

200

150

100

50

2 4 6 8 10 12 14 16 18 20 22t [100sec]

T = 470K; pCO = 3×10-5 mbar; pO2 = 2.0→2.7×10-4mbar

M. Eiswirth and G. Ertl, Surface Sci. 177 (1986), 90

Page 29: Reactions at solid surfaces: From atoms to complexity · 2018. 6. 22. · ng step in ammonia synt hesis over iron catalysts is the ogen. The ques tion as to whether the nitrogen species

1845 1855 18751865 1885 1895 1905 1915 1925 1935

160

140

120

100

80

60

20

40

Year

Num

ber

(th

ousa

nds)

Hares

Lynxes

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Lotka-Volterra Model

x,y

t

x

y

dxdt = α1x – α2xy

dydt = β1xy – β2y

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CO / Pt(110)

0.2ML ≤ θCO ≤ 0.5ML

θCO ≤ 0.5ML

1×11×2 missing row

Page 32: Reactions at solid surfaces: From atoms to complexity · 2018. 6. 22. · ng step in ammonia synt hesis over iron catalysts is the ogen. The ques tion as to whether the nitrogen species

CO + 2O2 → CO2 / Pt(110)1

0.7

0.6

0.5

0.4rate

[M

L·s–

1 ]

1×1

CO

O

706050403020100

0.6

0.4

0.2

0

cove

rage

[M

L]

t [s]

T = 540K; pO2 = 6.7×10-5 mbar; pCO = 3×10-5 mbar

K. Krischer, M.Eiswirth & G. Ertl, J.Chem.Phys. 96 (1992), 9161 (Theory)

Page 33: Reactions at solid surfaces: From atoms to complexity · 2018. 6. 22. · ng step in ammonia synt hesis over iron catalysts is the ogen. The ques tion as to whether the nitrogen species

Heartbeats of ultra thin catalyst

Ultra thin (200 nm thick) Pt(110) catalyst during CO oxidation, 5 mm sample diameter, T = 528 K, pO2 = 1 x 10-2 mbar, pCO = 1.85 x 10-3 mbar

F. Cirak, J.E. Cisternas, A.M. Cuitino, G. Ertl, P.Holmes, I. Kevrekidis, M.Ortiz, H.H. Rotermund, M.Schunack, J. Wolff,

Science 300 (2003), 1932

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2 CO + O2 ⇒ 2 CO2 / Pt(110)Target patterns

[110]

[001]

[110]--

Ø = 500 μm

pO2 = 3.2 x 10-4 mbar

pCO = 3 x 10 -5 mbar

T = 427 K

Page 35: Reactions at solid surfaces: From atoms to complexity · 2018. 6. 22. · ng step in ammonia synt hesis over iron catalysts is the ogen. The ques tion as to whether the nitrogen species

PEEM images with 500 µm diameter,steady-state conditions: pO2

= 4 x 10-4 mbar, pCO = 4.3 x 10-5 mbar, T = 448 K

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Spiral waves during CO-oxidation on Pt(110)

S. Nettesheim, A. von Oertzen, H.H. Rotermund, G. Ertl, J.Chem.Phys. 98 (1993), 9977

Page 36: Reactions at solid surfaces: From atoms to complexity · 2018. 6. 22. · ng step in ammonia synt hesis over iron catalysts is the ogen. The ques tion as to whether the nitrogen species

Chemical turbulence

Photoemission electron microscope (PEEM) imaging. Dark regions are predominantly oxygen covered, bright regions are mainly CO covered.

Real time, image size 360 x 360 μm

Temperature T = 548 K, oxygen partialpressure po2 = 4 x 10-4 mbar, CO partial pressure pco = 1.2 x10-4 mbar.

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Global delayed feedback

O2 CO

UHVChamber

PEEM

Delay

Amplifier

Integrator

sample

M. Kim, M. Bertram, M. Pollmann, A. von Oertzen;A.S. Mikhailov, H.H. Rotermund, and G. Ertl,

Science 292 2001 , 1357( )

Page 38: Reactions at solid surfaces: From atoms to complexity · 2018. 6. 22. · ng step in ammonia synt hesis over iron catalysts is the ogen. The ques tion as to whether the nitrogen species

CO oxidation reaction on Pt(110)

• Suppression of spiral-wave turbulence and development of intermittent turbulence with cascades of reproducing bubbles

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Retina

10μm

Page 40: Reactions at solid surfaces: From atoms to complexity · 2018. 6. 22. · ng step in ammonia synt hesis over iron catalysts is the ogen. The ques tion as to whether the nitrogen species