design of pt-sn catalysts on mesoporous titania films for ... · synthesis of pt-sn carbonyl...

1

Design of Pt-Sn catalysts on mesoporous

titania films for microreactor application

Ismagilov Z.R.1, Matus E.V.1, Yakutova A.M.1, Ismagilov I.Z.1

Kerzhentsev M.A.1, Protasova L.N.1,2, Rebrov E.V.2, Schouten J.C2

September 27-30, 2009 Ischia, Naples Italy

1Boreskov Institute of Catalysis SB RAS, Novosibirsk, Russia2Eindhoven University of Technology, Eindhoven, The Netherlands

3 rd International Conference on

STRUCTURED CATALYSTS

AND REACTORS

2

Target

Catalyst and Reactor design to

achieve the higher selectivity of

unsaturated alcohols formation

Selective hydrogenation of ,-unsaturated

aldehydes to unsaturated alcohols

Unsaturated alcohols – products for

pharmaceutical, food and perfume

industry.

O

OH

O

OH

O

O

O

O

OH

H

ГЕРАНИОЛ/НЕРОЛЦИТРАЛЬcitral Geraniol/nerol

3



β-(цис-3,7-dimethyl-2,6-octadien-1-ol)

NEROL

CITRAL

Z-isomer

neral

E-isomer

geranial

3,7-dimethyl-2,6-octadienal

GERANIOL

β-(trans-3,7-dimethyl-2,6-octadien-1-ol)

4

Approach to solve the problem

• Microchannel reactorreactor, which contains channels with diameter less than 500 μm and high ratio surface/volume (105 m2/m3)

• Increase of selectivity of desired product formation:

• 1. High coefficient of heat transmissionprovides isothermal conditions

• 2. The contact time is controlled precisely.

• Mesoporous TiO2 support

• Pt-Sn active component

• Bimetallic cluster adsorption

2.24Å

2.36 Å

2.31Å

2.34Å

2.32Å

Pt-Sn/TiO2 catalyst

5

Selection of reactor: microchannel reactor

Chemical microreactor – reactor, which contains channels with diameter

less than 500 μm and high ratio surface/volume (105 m2/m3)

Increase of selectivity of desired product

formation:

1. High coefficient of heat transmission provides

isothermal conditions

2. The contact time is controlled precisely.

6

Development of Pt-Sn nanosized bimetallic catalysts on

mesoporous TiO2 coatings for the microreactors of the selective

hydrogenation of ,-unsaturated aldehydes.

Nanoclusters, nanopores of coating, mesoporous highly organized

coating, channel structure of microreactor, microstructured plate

Reactor plate

Microchannel

10-310-8 10-5 10-410-9 10-610-7

Mesoporous

coating

Nanoclusters

m

Levels of catalyst development –

from «nano-» to «micro-»:

7

• SiO2

• TiO2• Al2O3

• С

TiO2-supported catalysts show the higher selectivity to unsaturated

alcohols in comparison with others.

Mesoporous TiO2 is appropriate support with uniform mesoporous

structure, which is accessible for big molecules of organic

compounds-reagents.

Support:

Active component:

• Au

• Pt

• Rh

• Pt-Sn• Pt-Ru

Noble metals (Pt, Rh) are known to be active catalysts in this

reaction. Increasing of selectivity of C=O bond hydrogenation

occurs after modification of the noble metal catalysts with more

electropositive metals (Sn, Ru).

Synthesis technique:

• successive impregnation

• combined impregnation

• bimetallic complexes adsorption

• Uniform distribution of

bimetallic particles with a

size 1-2 nm.

• Mild activation conditions.

Materials and methods selection

8

Target:Catalyst and Reactor design to achieve the higher

selectivity of unsaturated alcohols formation

Tasks:

• Preparation of Pt and Pt-Sn complexes, study influence of synthesis

conditions (solvent, concentrations) on their composition;

• preparation and choice of bulk TiO2 and mesoporous film;

• Investigation of adsorption kinetics of Pt-Sn complexes on mesoporous

TiO2;

• Preparation of Pt-Sn/TiO2 catalyst on b; influence of synthesis conditions

on physicochemical properties and activity in citral hydrogenation reaction.

9

• uniform composition of bimetallic

particles

• particles size of 1-2 nm

• mild activation conditions

(180-200оC, vacuum)

Composition of Pt carbonyl anion depends on the

preparation conditions:

• solvent type

• water concentration

• composition of gas atmosphere.

[PtCl6]2- → [Pt(CO)Cl3]

- → [Pt3(CO)6]102- → [Pt3(CO)6]6

2- → [Pt3(CO)6]52- →

[Pt3(CO)6]42-→ [Pt3(CO)6]3

2- → [Pt3(CO)6]22- → [Pt3(CO)6]

2-.

Reducing carbonilation of Pt (IV):

Platinum

Carbon

Oxygen

1.5

nm

0.5 nm

Synthesis and investigation of Pt-Sn carbonyl clusters

– precursor of active component

10

+ solvent,

H2O

H2[Pt3(CO)6]10

+ SnCl2·2H2O

+ СО

Platinum

Carbon

Oxygen

1.5

nm

0.5 nm(1)

(2)

(3)

• t = 2-24 ч

• CPt = 0,5; 2; 10 mg/ml

• Solvent nature: acetone,

tetrahydrofuran, ethanol, isopropanol

• gas atmosphere (CO, Ar)

• CSn = 0,3; 1,2; 6,0 mg/ml (Pt:Snmolar=1:1)

H2PtCl6·6H2O

H2[Pt3(CO)6]n

H2n[Pt3(CO)3(SnCl3)2(SnCl2H2O)]n

Synthesis of Pt-Sn carbonyl clusters

H2[Pt3(CO)6]n,

n - quantity of

triangular units

0 5 10 15 20 25

0

500

1000

1500

2000

Pt

con

centr

atio

n in

solu

tion

, g

/ml

Reaction time, h

Synthesis of high-nuclearity cluster H2[Pt3(CO)6]10

11

Terminal СО

1945-2065 cm-1

Bridging СО

1740-1900 cm-1

solvent, H2O

H2PtCl6*6H2O H2[Pt3(CO)6]10 H2[Pt3(CO)6]n, n = 5, 6СО

(1) (2)

FTIR study of Pt carbonyl clusters composition

1800 2000 2200 24000

10

20

30 Pt concentration:

0 mg/ml;

2 mg/ml;

10 mg/ml.

1887 cm-1

1880 cm-1

2065 cm-1

Wavenumber, cm-1

T, %

2056 cm-1

(С2Н5OH)

n=5

n=6

Position of terminal CO ligand absorbance band

indicate quantity of platinum triangular units.

H2[Pt3(CO)6]n,

n - quantity of

triangular units

12

Synthesis of carbonyl clusters H2[Pt3(CO)6]n: effect of solvent

H2[Pt3(CO)6]10 2H+ + 2[Pt3(CO)6]2-

5

solvent

С2H5OH С4H8O

1800 2000 2200 24000

10

20

30

1886 cm-1

1882 cm-1

2057 cm-1

2058 cm-1

Pt concentration:

0 mg/ml;

2 mg/ml;

10 mg/ml.

T,

%

Wavenumber, cm-1

(С2H5OH)

n=5

n=5

solvent, Н2O

СO + H2O = CO2 + 2H+ + 2e

presipitate solution

1800 2000 2200 24000

10

20

30 Pt concentration:

0 mg/ml;

2 mg/ml;

10 mg/ml.

1887 cm-1

1880 cm-1

2065 cm-1

Wavenumber, cm-1

T, %

2056 cm-1

(С2Н5OH)

n=5

n=6

13

0.52

10

4

5

6

Triangular

units, n

Acetone

Tetrahydrofuran

Ethanol

Isopropanol

Synthesis conditions (solvent nature, Pt concentration) providing cluster [Pt3(CO)6]n2-

formation with number of triangular units equal to 5 and 6 have been determined.

Synthesis of carbonyl clusters H2[Pt3(CO)6]n: effect of

solvent and Pt concentration

14

Bridging СО

1740-1900 cm-1

Synthesis of Pt-Sn carbonyl clusters

Absorbance band of bridging CO ligands

disappears from spectra, that is evidence of

substitution of bridging СO ligands by Sn-

containing ligands.

10 mgPt /ml

n=5

n=3-6

1800 2000 2200 2400

0

10

20

30

2042 cm-1

2025 cm-1

C2H5OH;

Pt-CO;

Pt-Sn-CO.

1880 cm-1

2056 cm-1

Wavenumber, cm-1

T, %

2068 cm-1

[Pt3(CO)6]n2- + 2SnCl3

-+ SnCl2·H2O → [Pt3(CO)3(SnCl3-)2SnCl2·H2O]n

-2nHCl

(3)

15

1800 2000 2200 2400

0

10

20

30

2045 cm-1

2025 cm-1

C2H

5OH;

Pt-CO;

Pt-Sn-CO.

1880 cm-1

2056 cm-1

Wavenumber, cm-1T

, %

2068 cm-1

2 mgPt /ml 10 mgPt /ml

n=6n=3-6

n=5n=6

Structure of Pt carbonyl cluster is not damaged under interaction with SnCl2 at 0.5-2

mgPt/ml. At higher concentration 10 mgPt/ml complex formation with n= 3-6 occurs.

Pt-Sn carbonyl clusters synthesis

1800 2000 2200 24000

10

20

30 C2H

5OH;

Pt-CO;

Pt-Sn-CO.

1887 cm-1

2065 cm-1

Wavenumber, cm-1

T,

%

2058 cm-1

16

Support: mesoporous TiO2

10065100 EOPOEO

Pluronic F127

2 Ti[OiPr]4-x(OH)x

[OiPr]4x(OH)x-1Ti-O-Ti[OiPr]4x(OH)x-1

+H2O

• uniform porous structure (2-6 nm)

• specific surface area (~ 200 m2/g)

• thermal stubility (~ 600oC)

• acid properties of surface (~3-7 LAS/nm2)

Po

re v

olu

me

, cm

3/g

(б)

Sol-gel synthesis TiO2 with using surfactant:

~10 nm

hydrophilic

«head»

hydrophobic

«head»

Ti atomformation of

Ti-O-Ti bond

atom of

oxygen

hydrogen

bond

17

Aging

Initial sol

• pH 1.5-2.0

• Ti(OiPr)4 : F127 : C2H5OH

= 1 : 0.005-0.009 : 40

• speed

• time

RH 80%

Drying

Surfactant

removing

(300 оС)

Mesoporous TiO2-film

Substrat – glass,

silicic or titanic

plates 1x1x0.05 cm

Precursor solution Surfactant solution

Precursor Ti(OiPr)4 H+ C2H5OHSurfactant Pluronic F127

(EO)100(PO)65(EO)100

Gel formation

Mesoporous bulk

TiO2

Spin-coating

Synthesis of mesoporous TiO2

Surfactant

removing

550°С/4h

Drying

100°C/1h

18

Influence of surfactant content

Hexagonal pore

structure

Mesoporous films

have a hexagonal

pore structure.

Parameter of unit

cell decrease with

increasing of

surfactant content.

S/P 0.009 S/P 0.007

1.6 2.4 3.2 4.0 4.8

200

S/P=0.009, a0 = 7.0 nm

S/P=0.007, a0 = 8.5 nm

S/P=0.006, a0 = 9.3 nm

Inte

nsity

2Theta,o

19

Synthesis of Pt-Sn/TiO2 catalysts

H2PtCl6·6H2O

H2n[Pt3(CO)3(SnCl3)2(SnCl2H2O)]n

H2[Pt3(CO)6]10

H2[Pt3(CO)6]n

+ SnCl2·2H2O

+ solvent

+ СО

Pt-Sn/TiO2

drying

activationTiO2 powder

TiO2-film

+ TiO2 • method of Pt-Sn cluster loading

(adsorption, impregnation)

•duration of adsorption (0.3-24 h)

• condition of activation (vacuum/

190оС-220oC, H2/400oC)

• CPt = 0.5; 2; 10 mg/ml

• CSn = 0.3; 1.2; 6.0 mg/ml (Pt:Snmolar=1:1)

• Solvent nature: acetone, ethanol,

tetrahydrofuran (THF), isopropanol

20

Synthesis conditions of Pt-Sn/TiO2 catalystsSample name Synthesis conditions ( molar ratio Pt : Sn = 1)

Metal concentration in solution, mg/ml Duration of support

exposition in the

solution, hrs

Thermal treatment

Pt Sn

Adsorption from solution of carbonyl Pt-Sn cluster

AA-OR-2 2 1.2 24 H2/400oC/2 hrs

AE-OR-2 2 1.2 24 H2/400oC/2 hrs

AT-OR-2 2 1.2 24 H2/400oC/2 hrs

AE-OR-10 10 6 24 H2/400oC/2 hrs

AE-V-2 2 1.2 24 vacuum /190oC/2 hrs

Impregnation by solution of carbonyl Pt-Sn cluster

IE-OR-2 2 1.2 72 H2/400oC/2 hrs

Impregnation by solution of inorganic metal salts precursor (H2PtCl6+SnCl2)

IA-OR-33 33 20 0.25 H2/400oC/2 hrs

IE-OR-33 33 20 0.25 H2/400oC/2 hrs

AA-OR-2method of deposition

Adsorption (A), Impregnation (I)

Pt concentration in solution

2, 10, 33 mg/mlsolvent thermal treatment

Ox-Red (OR), Vacuum (V)Acetone (A), Ethanol (E), THF (T)

21

0,00

0,10

0,20

0,30

0 2 4 6Pt equilibrium concentration in solution,

mg/ml

Pla

tin

um

co

nte

nt,

mg

/m2

Adsorbed cluster quantity

increases with an increase of

adsorption duration from 0.3 to 24

hours and then remains practically

constant.

Adsorbed cluster quantity increases

from 0.035 to 0.22 mgPt/m2 at an

increase of Pt equilibrium

concentration from 0.5 to 4.6 mgPt/ml.

Adsorption kinetics and isotherm of Pt-Sn carbonyl

cluster on TiO2

0 1 2 3 4 20 30 40 50 600.00

0.04

0.08

0.12

0.16

Pla

tin

um

co

nte

nt,

mg

/m2

Time, h

22

0 1 2 3 4 5 6 7 8 9 100

10

20

30

40

50

Na / N

s , %

Particle size, nm

0 1 2 3 4 5 6 7 8 9 100

10

20

30

40

50

Na

/ N

s,

%

Particle size, nm

average particle

size 1.5 nm

max 2.9 nm

Adsorption of Pt-Sn carbonyl cluster

from ethanol solution

2 mg/ml

average particle

size 3.2 nm

max 11.3 nm

Influence of solution concentration

on particle size distributionAdsorption of Pt-Sn carbonyl cluster


10 mg/ml

Pt3Sn

d200= 2.03 ÅPt3Sn

d111= 2.37 Å

The increase of solution concentration leads to the increase of metals content,

average particle size and boarding of particle size distribution.

23

Adsorption of Pt-Sn carbonyl

cluster from solution of

ethanol

0 1 2 3 4 5 6 7 8 9 100

10

20

30

40

50

Na

/ N

s,

%Particle size, nm

average particle

size 2.2 nm

max 11.4 nm


from solution of

tetrahydrofurane

Pt3Sn

d111= 2.34 ÅPt3Sn

d111= 2.37 Å

Influence of solvent nature on particle size distribution

0 1 2 3 4 5 6 7 8 9 100

10

20

30

40

50

Na

/ N

s,

%

Particle size, nm

average particle

size 1.5 nm

max 2.9 nm

Using of tetrahydrofurane as a solvent instead ethanol during adsorption lead

to the increase of metals content, average particle size and boarding of

particle size distribution.

24

Influence of acid site concentration of TiO2 support

Synthesis

conditions of

TiO2

Acid site concentration

of TiO2 support

Pt and Sn content in

Pt-Sn/TiO2*

Pt :Sn

molar ratio

Surfactant/Ti pH C(BAS)**,

μmol/g

C(LAS)***,

μmol/g

Pt, wt.% Sn, wt.%

0.008 1.5 37 110 0.59 0.33 1.09

0.008 1.8 110 170 0.65 0.37 1.07

The concentration of acid sites of TiO2 support does not influence on

adsorption of Pt-Sn anion carbonyl cluster and, consequently, on metals

content in the Pt-Sn/TiO2 catalysts.

*adsorption from ethanol solution of Pt-Sn cluster

(CPt = 2 mg/ml, CSn=1.2 mg/ml) during 24 hrs

**BAS - Broensted acid sites

***LAS - Lewis acid sites

25

average particle

size 1.5 nm

max 2.9 nm

Comparison of catalysts activated in vacuum and H2

average particle

size 1.1 nm

max 5.1 nm



Activation: H2 400оC/2h



Activation: vacuum 190оC/2h

Activation of dried Pt-Sn/TiO2 samples in vacuum at 190оС/2h gives smaller particle size

and narrow distribution.

Activation in H2/400оС/2h -- increase maximum particle size and wider distribution

0 1 2 3 4 5 6 7 8 9 100

10

20

30

40

50

Na

/ N

s,

%

Particle size, nm0 1 2 3 4 5 6 7 8 9 10

0

10

20

30

40

50

N / N

s , %

Particle size, nm

26

2.31A (111) Pt3Sn

0 1 2 3 4 5 6 7 8 9 100

10

20

30

40

50

Na / N

s, %

Particle size, nm

average particle

size 2.3 nm

max 5.4 nm

2.30A (111) Pt3Sn

2.32A (111) Pt3Sn

0 1 2 3 4 5 6 7 8 9 100

10

20

30

40

50

Na / N

s, %

Particle size, nm

average particle

size 2.6 nm

max 5.6 nm

The increase of activation temperature in vacuum of dried Pt-Sn/TiO2 catalysts

from 190оС to 220оС does not lead to change of average and maximum Pt-Sn

particle size.

Influence of temperature activation in vacuum







27

Deposition of Pt-Sn carbonyl

cluster onto ТiO2


cluster

Impregnation by solution,

contained Pt-Sn carbonyl cluster

concentration of cluster

in the solution

solvent nature ratio

solution/support

duration of adsorption solvent nature

acetone ethanol THF2 mgPt/ml 2 h20 24 h10010 mgPt/mlacetone ethanol THF

• increase of metals content

• increase of average particle size

• broadening of particle size distribution

Regulation of metals content and particle size

distribution in Pt-Sn/TiO2 catalysts

28

СPt in

solution

t

adsorption

average

particle

size, nm

Min and Max

particle size, nm

0.5 24 3.3 1.1-7.4

2 0.3 1.8 0.7-5.7

2 2 2.3 0.8-3.9

2 24 2.3 1.2-3.6

3 24 2.5 1.3-4.5

0 1 2 3 4 5 6 7 8 9 100

10

20

30

40

50

Na / N

s , %

Particle size, nmSolvent: ethanol

Duration of adsorption: 24 h.

2.24Å

2.36 Å

2.31Å

2.34Å

2.32Å

Particle size distribution and composition of Pt-Sn

active component supported on TiO2 film

Adsorption of Pt-Sn complex on

mesoporous TiO2-film provides narrow

particle size distribution of bimetallic

particles on titania surface.

29

XRD bands for Pt-Sn system

2.24Å

2.36 Å

2.31Å

2.34Å

2.32Å

Composition Interplanar spacing, Å

Pt d111 =2,2650 d200=1,9616

Sn d101 =2,5710 d200 =1,9060

PtSn d102 =2,1570 d111 =2,0500

Pt3Sn d111 =2,3107 d200 =2,0015

Pt2Sn3 d110=2,1680 d105 =2,1320

Solvent: ethanol

Duration of adsorption: 24 h.

Pt-Sn/TiO2

3.00E+02

5.00E+02

7.00E+02

9.00E+02

66 68 70 72 74 76 78 80 82

BE, eV

I, c

ps

Pt4f

70.7

Pt4f7/2

74.072.5

75.873.2

76.5

Pt4f5/2

XPS Pt4f region: effect of metal loading

on chemical state

Spectra show presence of both Pt metal and PtOx. Pt metal prevailing for the Pt-

Sn/TiO2 catalysts prepared via Pt-Sn carbonyl cluster precursor, PtOx – for

catalysts prepared via inorganic metal salts precursors.

TiO2

AE-OR-2

AE-V-2

IE-OR-2

IE-OR-33H2PtCl6+ SnCl2

Precursor

Pt-Sn

carbonyl

XPS Sn3d region: effect of metal loading

on chemical state

2.00E+03

2.40E+03

2.80E+03

3.20E+03

3.60E+03

474 478 482 486 490 494 498 502

BE, eV

I, c

ps

Sn3d Sn3d5/2

Sn3d3/2

486.1

488.0

493.2484.8

494.5

496.4

Spectra show presence of both Sn metal and SnOx. Sn metal prevailing for the Pt-

Sn/TiO2 catalysts prepared via Pt-Sn carbonyl cluster precursor, SnOx – for

catalysts prepared via inorganic metal salts precursors.

Precursor

IE-OR-33

IE-OR-2

AE-V-2

AE-OR-2

TiO2

H2PtCl6+ SnCl2

Pt-Sn

carbonyl

320 50 100 150 200 250 300

0,00

0,25

0,50

0,75

1,00

Pro

du

cts

(re

ag

en

ts)/

DH

N, m

ol/m

ol

Reaction duration, min.

Citral

Geraniol

+nerol

Citronellal

Citronellol

Activity of Pt-Sn/TiO2 catalysts

in the reaction of citral hydrogenation

Main products of citral

hydrogenation are geraniol and

nerol.

Reaction conditions: 150 ml of

0.01 М solution of citral in

2-propanol (+ 0.01 М

decahydronaphthalene (DHN)

as an internal standart),

temperature 343 К,

Н2 pressure 12 bar,

mixing rate 1500 rpm,

catalyst mass ~ 0,1 g

33

Activity of Pt-Sn/TiO2 catalysts in citral hydrogenation

Selectivity of Pt-Sn/TiO2 catalysts in citral hydrogenation increases from

40 to 90% with an increase of metal particle size from 1.5 to 3.2 nm.

N Metal content, wt.

%

Average

particle

size, nm

Initial TOF,

s-1

Selectivity, %

(at 96-98% citral conversion)

Pt Sn Geraniol

+nerol

Citronellal Citronellol 3.7-dimethil-1-

octanol

Adsorption of Pt carbonyl complex

1 1.98 - - 5.6 3 11 21 65

Adsorption of Pt-Sn carbonyl complex

2 0.61 0.25 1.5 0.18 39 35 26 0

3 4.04 1.75 2.2 0.20 82 7 10 1

4 3.55 2.8 3.2 0.54 90 6 4 0

Selectivity of geraniol+nerol formation increases from 3 to 40-90%

after modification of Pt/TiO2 catalyst with Sn.

34

Sn+d

Sn+d

Sn+d

Pt-Sn catalyst for selective hydrogenation of citral

Number of Atoms

25 60 160 300

5 10 15 20 25 30 35 40 45

Particle Diameter (Ǻ)

12

10

8

6

4

2

Ave

rag

e F

irs

t C

oo

rdin

ati

on

Nu

mb

er

35

Conclusions:

1.Adsorption kinetics of Pt-Sn carbonyl complex on mesoporous bulk TiO2 has been

investigated. Adsorbed complex quantity increases with an increase of adsorption

duration from 0.3 to 24 hours and then remains constant.

2. The metal content, average particle size, and particle size distribution can be

regulated by variation of solvent nature and metal concentration. The average particle

size increases from ~1.5 to ~3.5 nm at an increase of Pt and Sn content from 0.6 to~3

wt. %.

3. Pt and Sn contents in Pt-Sn/TiO2 catalysts, prepared by adsorption, depend on

solvent nature and increase in the row : acetone < ethanol < tetrahydrofuran.

4. Activation of dried Pt-Sn/TiO2 samples in vacuum at 190оС/2h gives smaller

particle size and narrow distribution.

Activation in H2/400оС/2h -- increase maximum particle size and wider distribution

5. The selectivity of geraniol+nerol formation increases from 3 to 40-90% after

modification of Pt/TiO2 catalyst with Sn.

The selectivity of Pt-Sn/TiO2 catalysts in citral hydrogenation increases from 40 to 90%

with an increase of metal particle size from 1.5 to 3.2 nm.

36

Authors express thanks to:

Kuznetsov Vadim

Ischenko Arkadiy

Ushakov Vladimir

Efimenko Tatyana

F.Garin

P.Bernhardt

NWO-RFBR 047.015.012.

3737

THANK YOU FOR YOUR ATTENTION

First Snow in Novosibirsk. 17 September 2008

38

Publications:

1. Z.R. Ismagilov, E.V. Matus, A.M. Yakutova, L.N. Protasova, I.Z. Ismagilov, M.A. Kerzhentsev, E.V. Rebrov,

J.C. Schouten, Design of Pt-Sn catalysts on mesoporous titania films for microreactor application // Сatalysis

Today, 2009, doi:10.1016/j.cattod2009.07.046.

2. L.N. Protasova, E.V. Rebrov, E.V. Matus, Z.R. Ismagilov, J.C. Schouten. Highly dispersed bimetallic catalysts

supported on mesoporous titania films for applications in gas-liquid microstructured reactor. // Abstr. of 14

International Congress on Catalysis. Seoul, Korea, 2008. P. 395.

3. L.N. Protasova, E.V. Rebrov, E.V. Matus, Z.R. Ismagilov, J.C. Schouten, Highly dispersed supported Pt-Sn/TiO2

catalysts derived from mixed metal cluster precursors for selective hydrogenation of α,β-unsaturated aldehydes //

Xth Netherlands Catalysis and Chemistry Conference. Noordwijkerhout, The Netherlands, 2009.

4. A.M. Yakutova, E.V. Matus, L.N. Protasova, I.Z. Ismagilov, E.V. Rebrov, M.A. Kerzhentsev, Z.R. Ismagilov, J.C.

Schouten, Development of bimetallic Pt-Sn/TiO2 catalysts for selective hydrogenation of citral // Abstr. of 3nd

International School-Conference on Catalysis for Young Scientists. Ekaterinburg, Russia, 2009.

5. E.V. Matus, I.Z. Ismagilov, L.N. Protasova, M.A. Kerzhentsev, E.V. Rebrov, Z.R. Ismagilov, J.C. Schouten,

Development of highly selective Pt-Sn catalysts on mesoporous titania for hydrogenation of citral to unsaturated

alcohols // Abstr. of EuropaCat-IX, Salamanca, Spain, 2009.

6. Z.R. Ismagilov, E.V. Matus, A.M. Yakutova, I.Z. Ismagilov I.Z., M.A. Kerzhentsev, L.N. Protasova, E.V. Rebrov, J.C.

Schouten, Preparation of high-nuclearity Pt-Sn carbonyl clusters and nanosized bimetallic Pt-Sn catalysts on

mesoporous titania // VI All-Russian conference on chemistry of high-nuclearity compounds and clusters, Kazan,

Russia, 2009

7. Z.R. Ismagilov, E.V. Matus, I.Z. Ismagilov, L.N. Protasova, A.M. Yakutova, M.A. Kerzhentsev, E.V. Rebrov,

J.C. Schouten, Design of Pt-Sn catalysts on mesoporous titania films for microreactor application // Abstr. of

ICOSCAR-2. Ischia, Italy, 2009.

8. I.Z. Ismagilov, E.V. Matus, A.M. Yakutova, L.N. Protasova, Rebrov E.V., M.A. Kerzhentsev, Z.R. Ismagilov, J.C.

Schouten, P. Bernhardt, F. Garin, Study of electronic and structural properties nanosized bimetallic catalysts on

mesoporous supports by XPS and FTIR // 1-st All-Russian scientific conference “Methods of investigation of

composition and structure of functional materials“ MICSFM, Novosibirsk, Russia, 2009.

40



α-(cis-3,7-dimethyl-2,7-octadien-1-ol)

β-(цис-3,7-dimethyl-2,6-octadien-1-ol)

NEROL

α-(trans-3,7-dimethyl-2,7-octadien-1-ol)

β-(trans-3,7-dimethyl-2,6-octadien-1-ol)

GERANIOL

CITRAL

Z-isomer

neral

E-isomer

geranial

3,7-dimethyl-2,6-octadienal

41

Synthesis of high-nuclearity cluster H2[Pt3(CO)6]10

0 5 10 15 20 25

0

500

1000

1500

2000

Pt concentr

ation in s

olu

tion, g/m

l

Reaction time, h

Optimal duration of the reaction of reducing carbonilation is t > 6 h.

СО

H2PtCl6*6H2O H2[Pt3(CO)6]10

solution precipitate

30H2PtCl6*6H2O +121СO + 6H2O = H2[Pt3(CO)6]10 + 61CO2 +180HCl

(1)

42

FTIR: literature data for [Pt3(CO)6]2-

n (n = 1- 6) clusters

Composition of

solution

Position of maximum of

absorbance band, νСО, cm-1

Quantity of

triangular

units, n

Reference

[Pt3(CO)6]n2-

THF

1945, 1740 1 G. Longoni, P.Chini //

J. Am. Chem. Soc.

98:23 (1976) 7225.1995, 1818, 1795 2

2030, 1855, 1840, 1830, 1810 3

2040, 2030, 1880, 1860, 1825 4

2055, 1890, 1870, 1840, 1830 5

2065, 1900, 1875, 1855, 1840 6

[Pt3(CO)6]n2-

acetone

2055, 1870 5 N.B.Shitova,

Y.D.Perfil’ev, L.Y.Al’t,

G.G.Savel’eva //

Russ. J. Inorg. Chem.

46 №3 (2001) 376.

43

Solvent Pt concentration,

mg/ml

νСО, cm-1 Quantity of

triangular

units, n

Ethanol 0.5 2067 6

2 2065, 1887 6

10 2056, 1880 5

Acetone 0.5 2058 5

2 2057, 1872 5

10 2057, 1882 5

Tetrahydrofurane 0.5 2062 6

2 2058, 1886 5

10 2057, 1882 5

Isopropanol 2 2065, 1890 6

H2PtCl6*6H2O H2[Pt3(CO)6]10 H2[Pt3(CO)6]n, n = 5, 6СО

(1) (2)

solvent, H2O

Synthesis of carbonyl clusters H2[Pt3(CO)6]n: effect of

solvent and Pt concentration

44

Solvent nature influence on Pt content in

Pt-Sn/TiO2 catalyst

Pt and Sn contents in Pt-Sn/TiO2 catalysts, prepared by adsorption,

depend on solvent nature and increase in the row :

acetone < ethanol < tetrahydrofuran.

0

1

2

3

4

5

1 2 3acetone tetrahydrofuranSolvent: ethanol

Pt content

in catalyst,

mass. %

(CPt = 2 mg/ml, CSn=1.2 mg/ml)

45

Synthesis conditions influence on Pt content in

Pt-Sn/TiO2 catalyst

0

0.5

1

1.5

2

2.5

3

3.5

4

1 2 30.5 2 10

Pt content in

catalyst, wt. %

Pt concentration in ethanol solution, mg/ml

Pt and Sn content in Pt-Sn/TiO2 catalysts, prepared by adsorption of Pt-Sn carbonyl

cluster, increase with solution concentration.

46

Influence of precursor nature on particle size distribution

Pt3Sn

d111= 2.36 Å

Pt3Sn

d111= 2.33 Å

0 5 10 15 20 250

10

20

30

40

50

60

Na / N

s, %

Particle size, nm

0 5 10 15 20 250

10

20

30

40

50

60

N / N

s , %

Particle size, nm

average particle

size 1.8 nm

max 20.8 nm

average particle

size 2.2 nm

max 5.4 nm


cluster from ethanol solution


Co-impregnation of H2PtCl6*6H2O +

SnCl2*2H2O from ethanol solution

Activation: H2 400оC/2h

Under using of Pt-Sn carbonyl cluster as a active component precursor

instead inorganic metal salts during Pt-Sn/TiO2 preparation the mild activation

condition provides the formation of Pt3Sn particles ~ 2 nm in size.

XPS Ti2p region: effect of Pt-Sn active component

interaction with TiO2 support

Spectra show strong effect of differential electrical charging of catalyst surface

depending on synthesis condition. This mean different schemes of Pt-Sn active

component interaction with TiO2 support, which important for catalysis.

Precursor

H2PtCl6+ SnCl2

Pt-Sn

carbonyl

5.00E+02

4.50E+03

8.50E+03

452 454 456 458 460 462 464 466 468 470

BE, eV

I, c

ps

Ti2p Ti2p3/2

458.4

459.4

460.2

460.9464.2

466.0

465.2

466.7

Ti2p1/2

IE-OR-33

IE-OR-2

AE-V-2

AE-OR-2

TiO2

1.50E+03

5.50E+03

9.50E+03

1.35E+04

524 526 528 530 532 534 536 538

BE, eV

I, c

ps

O1s

529.6

532.0

531.0

XPS O1s region: effect of Pt-Sn active component

interaction with TiO2 support

Spectra include main contribution from TiO2, as well as from PtOx, SnOx, and O-

containing carbon groups. Spectra show correlation with effect of differential

electrical charging in Ti2p region.

Precursor

H2PtCl6+ SnCl2

Pt-Sn

carbonyl

IE-OR-33

IE-OR-2

AE-V-2

AE-OR-2TiO2

XPS: effect of Pt-Sn particle growth

0

5000

10000

15000

20000

25000

0 1 2 3 4 5 6 7

Peak surface ratio "Sn3d5/2 (3 alternative measures) : residual Ti2p"

Sn

3d

5/2

pe

ak

su

rfa

ce

(3

alt

ern

ati

ve

me

as

ure

s)

S(Sn3d5/2) from all

S(Sn3d5/2) actual

S(Sn3d5/2) from 3d3/2

PST1

PST2

PST3

PST4 PST5

PST6

Increase of 3D character in growth of Sn-containing

particles with higher Sn contents (obtained from salt

compared to carbonyl precursors): possibly from

Frank van der Merwe (2D, island mode)

to

Volmer-Weber (3D, cluster mode)

or to

Stranski-Krastanov (2D/3D mode)

The three thin film growing modes. In the two-

dimensional Frank van der Merwe mode, layers

of material grow on top of each other, atoms or

molecules grow layer-by-layer in a sequential

fashion. In the Volmer-Weber mode, separate

three-dimensional islands form on the substrate.

And in the Stranski-Krastanov mode, the critical

mechanism for forming quantum dots, one or

two monolayers form first, followed by

individual islands.

Similar evaluation can be done for Pt4f

spectral region, and so overall trend in

Pt-Sn particle morphology, comple-

mentary to results of qualitative and

quantitative analysis, can be obtained.

Pt-Sn carbonyl precursor

H2PtCl6+ SnCl2

precursor

50

Selective hydrogenation of citral

0 5 10 15 20 25 300.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14 Pt/TiO

2

Ru/KL-zeolite

TO

F,

s-1

Particle diameter, nm

0 5 10 15 20 25 30 35 400

10

20

30

40

50

60

70

80 d = 1.1 nm

d = 5.1 nm

d = 2.8 nm

d = 20 nm

Se

lec

tiv

ity

to

un

sa

tura

ted

alc

oh

ols

, %

Citral conversion, %

d = 16 nm

Pt content, % Particle size, nm Selectivity, %

0,77 1,1 70

1,44 2,8 70

2,65 5,1 74

6,65 16 57

3,59 28 48

Utpal K. Singh, M. Albert Vannice, The

influence of metal-support interactions

during liquid-phase hydrogenation of an

α, β-unsaturated aldehyde over Pt //

Studies in Surface Science and Catalysis,

Volume 130, Part 1, 2000, Pages 497-502

51

Target: development of Pt-Sn nanosized bimetallic catalysts on

mesoporous TiO2 coatings for the microreactors of the selective

hydrogenation of ,-unsaturated aldehydes.

Nanoclusters, nanopores of coating, mesoporous highly organized

coating, channel structure of microreactor, microstructured plate

Reactor plate

Microchannel

10-310-8 10-5 10-410-9 10-610-7

Mesoporous

coating

Nanoclusters

m

Levels of catalyst development –

from «nano-» to «micro-»:

52

Conclusions on Pt-Sn carbonyl clusters synthesis :

1. For H2[Pt3(CO)6]n (n = 5, 6) cluster formation following synthesis

conditions are necessary: absence of precipitate H2[Pt3(CO)6]10

washing stage; СО gas atmosphere during of dissolution of

H2[Pt3CO6]10. The variation of water content in range 0.5-4 vol.% in the

solvent does not influences on Pt carbonyl cluster composition.

2. It have been established, that solvent type and Pt concentration

influence on Pt carbonyl cluster composition. Synthesis conditions

(solvent nature, Pt concentration) providing cluster [Pt3(CO)6]n2-

formation with number of triangular units n equal to 5 and 6 have been

determined.

3. Structure of Pt carbonyl cluster does not damaged under interaction

with SnCl2 at 0.5-2 mgPt/ml. At higher concentration 10 mgPt/ml

complex formation with n = 3-6 occurs.

design of pt-sn catalysts on mesoporous titania films for ... · synthesis of pt-sn carbonyl...

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