Catalyst Preparation

  • December 2019
  • PDF

This document was uploaded by user and they confirmed that they have the permission to share it. If you are author or own the copyright of this book, please report to us by using this DMCA report form. Report DMCA


Overview

Download & View Catalyst Preparation as PDF for free.

More details

  • Words: 2,017
  • Pages: 36
How to make catalysts

WS 07 Cat React Eng Prof. Dr. Wendelin J. Stark

Catalyst Preparation

Agenda ƒ Use of suported catalysts ƒ

What are weak points

ƒ Traditional catalyst preparation methods ƒ

Why can that be made better?

ƒ Novel functionalization methods ƒ One-step methods 27. April 2005

Institute of Chemical and Bioengineering ETH Hönggerberg, HCI E 107 8093 Zürich Prof. Dr. Wendelin J. Stark

Institute of Chemical and Bioengineering ETH Hönggerberg, HCI E 107 8093 Zürich Prof. Dr. Wendelin J. Stark

Catalyst Preparation

Criteria for a good catalyst Chemistry related

Non-chemical

activity

stability

selectivity

morphology

thermal characteristics

mechanical strength originality cost

27. April 2005

Catalyst Preparation

Why supported catalysts? ƒ Most active materials are NOT: ƒ

Mechanically or thermally stable

ƒ

of a open morphology

ƒ

of low cost

Æ Good for making rings Æ Useless Catalysts

27. April 2005

Institute of Chemical and Bioengineering ETH Hönggerberg, HCI E 107 8093 Zürich Prof. Dr. Wendelin J. Stark

Catalyst Preparation

Institute of Chemical and Bioengineering ETH Hönggerberg, HCI E 107 8093 Zürich Prof. Dr. Wendelin J. Stark

Catalyst preparation

Æ Good and stable dispersion necessary 27. April 2005

Catalyst Preparation

Institute of Chemical and Bioengineering ETH Hönggerberg, HCI E 107 8093 Zürich Prof. Dr. Wendelin J. Stark

Traditional ƒ (1) Produce a support with a high surface area ƒ (2) Functionalize support using large range of surface methods ƒ

Classical: Grafting, Precipitation, Impregnation

ƒ

Modern techniques: Vapor deposition, layer deposition

27. April 2005

Catalyst Preparation

Institute of Chemical and Bioengineering ETH Hönggerberg, HCI E 107 8093 Zürich Prof. Dr. Wendelin J. Stark

Supports – keeping activity at the right place ƒ Goal: optimal dispersion for active component and stabilisation against sintering

ƒ How: Using ultra hard and chemically unreactive materials with high melting points (SiO2, TiO2, Al2O3, Carbon….)

ƒ With a large surface area (10-? m2/g) ƒ

27. April 2005

How big is the SSA of a single carbon graphene sheet?

Graphite STM Image

ρ ~ 2160 kg m-3 Interlayer distance = 0.335 nm

Catalyst Preparation

Institute of Chemical and Bioengineering ETH Hönggerberg, HCI E 107 8093 Zürich Prof. Dr. Wendelin J. Stark

Methods for preparation of supports “anorganic materials at large scale” ƒ Solid state reactions (precipitation, drying, coagulation) ƒ Reduction, carbonization, leaching ƒ Sol – gel (reactive chemistry) ƒ Flame hydrolysis of chloride (high temp + gas phase)

27. April 2005

Institute of Chemical and Bioengineering ETH Hönggerberg, HCI E 107 8093 Zürich Prof. Dr. Wendelin J. Stark

Catalyst Preparation

Reduction, carbonization: metallic phases ƒ Temperature controlled reaction Bed of precursor material (usually oxide MOx) Recative gases (H2, CH4, NH3…)

ΔT (500- 1500°C) ~ 4-12 h

Preparation of Catalytic bed (e.g. M, MNx, MCx)

27. April 2005

WC, MoC, W, Fe, CoN …

Institute of Chemical and Bioengineering ETH Hönggerberg, HCI E 107 8093 Zürich Prof. Dr. Wendelin J. Stark

Catalyst Preparation

Alloy leaching, larger surfaces: Raney nickel! Ni Alloy (e.g. AlNi) Solid solution

Quenching Precipitation Al

Digestion of less noble metal using NaOH

Porous Ni with low particle size (Raney Nickel) 27. April 2005

Catalyst Preparation

Sol-Gel: mostly oxides

27. April 2005

Institute of Chemical and Bioengineering ETH Hönggerberg, HCI E 107 8093 Zürich Prof. Dr. Wendelin J. Stark

Catalyst Preparation

Zeolites ƒ Aluminiumsilicates ƒ

> 600 m2/gr

ƒ

Solid acids

ƒ

Trapping of Ions and metal complexes (ship in a bottle)

ƒ

27. April 2005

Isomer selective synthesis

Institute of Chemical and Bioengineering ETH Hönggerberg, HCI E 107 8093 Zürich Prof. Dr. Wendelin J. Stark

Catalyst Preparation

Flame hydrolysis ƒ 2 H2 + O2 Æ H2O SiCl4 + H2O Æ SiO2 + 4 HCl

ƒ TiCl4, SnCl4, AlCl3, Fe(CO)5…

27. April 2005

Institute of Chemical and Bioengineering ETH Hönggerberg, HCI E 107 8093 Zürich Prof. Dr. Wendelin J. Stark

Catalyst Preparation

Institute of Chemical and Bioengineering ETH Hönggerberg, HCI E 107 8093 Zürich Prof. Dr. Wendelin J. Stark

Functionalization ƒ Traditional Chemical methods ƒ

Grafting

ƒ

Precipitation

ƒ

Impregnation

ƒ Modern methods (mostly from electronics industry) ƒ

Chemical and Physical Vapor Deposition

ƒ

Atomic Layer Deposition

27. April 2005

Institute of Chemical and Bioengineering ETH Hönggerberg, HCI E 107 8093 Zürich Prof. Dr. Wendelin J. Stark

Catalyst Preparation

Anchoring and Grafting ƒ Stable covalent bonds between homogeneous transition metal complex and inorganic support O

O M OH silica

+

MoCl5

473 K -HCl

OMoCl4 silica anchored species

27. April 2005

473 K -HCl

O O silica grafted species

Institute of Chemical and Bioengineering ETH Hönggerberg, HCI E 107 8093 Zürich Prof. Dr. Wendelin J. Stark

Catalyst Preparation

Impregnation Æ low loading Support, often porous grains

Dipping Drying, Reduction

calcination T circa 400°C Metal salt solution

Impregnated support

Active Catalyst 27. April 2005

Catalyst Preparation

Institute of Chemical and Bioengineering ETH Hönggerberg, HCI E 107 8093 Zürich Prof. Dr. Wendelin J. Stark

Precipitation Æ high loading

Change of T, pH or concentration Metal salt solution

ÆDecrease solubility of metal

Particle size of active species determined by solubility + supersolubility (see TVT) 27. April 2005

Catalyst Preparation

Institute of Chemical and Bioengineering ETH Hönggerberg, HCI E 107 8093 Zürich Prof. Dr. Wendelin J. Stark

Physical Vapor deposition (PVD) or “how to transfer metals from A to B”

27. April 2005

Catalyst Preparation

What is flame spray synthesis? Flame spray as a one step method to functionalized catalysts

Æ Flame spray •Use of an organic liquid precursor •Dispersing precursor with oxygen •Igniting the spray using a premix flame L. Madler, H. K. Kammler, R. Mueller, S. E. Pratsinis, J. Aerosol Sci., 2002, 33, 369. 27. April 2005

Institute of Chemical and Bioengineering ETH Hönggerberg, HCI E 107 8093 Zürich Prof. Dr. Wendelin J. Stark

Catalyst Preparation

Institute of Chemical and Bioengineering ETH Hönggerberg, HCI E 107 8093 Zürich Prof. Dr. Wendelin J. Stark

Gas phase synthesis of nanomaterials

© Reto Strobel Stark, W.J., Mädler L., Pratsinis S. E., WO 2004005184 27. April 2005

Catalyst Preparation

How useful is it?

27. April 2005

Institute of Chemical and Bioengineering ETH Hönggerberg, HCI E 107 8093 Zürich Prof. Dr. Wendelin J. Stark

Catalyst Preparation

How useful is it?

27. April 2005

Institute of Chemical and Bioengineering ETH Hönggerberg, HCI E 107 8093 Zürich Prof. Dr. Wendelin J. Stark

Institute of Chemical and Bioengineering ETH Hönggerberg, HCI E 107 8093 Zürich Prof. Dr. Wendelin J. Stark

Catalyst Preparation

Products ƒ Complex systems ƒ

Mixed oxides (e.g YAG)

ƒ

Composites (e.g. Pt/CeO2/ZrO2)

ƒ Excellent product dispersion CeO2/ZrO2 transmission electron micrograph

J. Marchal, T. John, R. Baranwal, T. Hinklin, R. M. Laine, Chem. Mater., 2004, 16, 822. W.J. Stark, 27. April 2005 L. Madler, M. Maciejewski, S.E. Pratsinis, and A. Baiker, Chem. Commun., 2003, 588-9.

Institute of Chemical and Bioengineering ETH Hönggerberg, HCI E 107 8093 Zürich Prof. Dr. Wendelin J. Stark

Catalyst Preparation

VOx / titania for DeNOx O2

NO + NH3

NOx removed / %

100

N2 + H2O

V/TiO2 flame synthesis

50

commercial material 0

100

150

200

250

Process temperature / °C

W. J. Stark, K. Wegner, S. E. Pratsinis, A. Baiker, J. Catal., 197, 182 (2001) W. J. Stark, A. Baiker, S. E. Pratsinis, Part. Part. Sys. Charact., 19, 306-311 (2002). 27. April 2005

Institute of Chemical and Bioengineering ETH Hönggerberg, HCI E 107 8093 Zürich Prof. Dr. Wendelin J. Stark

Catalyst Preparation

Fine chemistry OH

OH OOH O

Ti/silica 1

2

Selectivity / %

100 90

Peroxid Olefin 1

80 70 60 50

Shell- Aerogel patent wet-phase

TS-1 6 g/h 150 g/h

500 g/h

flame-made Ti/SiO2

W. J. Stark, S. E. Pratsinis, A. Baiker, A., J. Catal., 203, 516 (2001). W. J. Stark, H. K. Kammler, R. Strobel, D. Günther, A. Baiker, S. E. Pratsinis, Ind. Eng. Chem. Res., 41, 4921 (2002). 27. April 2005

Institute of Chemical and Bioengineering ETH Hönggerberg, HCI E 107 8093 Zürich Prof. Dr. Wendelin J. Stark

Catalyst Preparation

Highest purity catalysts result better selectivity OH

OH

TBHP (5)

100

O

60

40

2

OH

80

Co Cr Mn Fe

1

OH

20 10

100

1000

80

60

40

20

1

O

Lewis acid

(b)

Fe, Ti

TBHP (5)

Co Cr Mn Fe

O

OH

3 O

(c)

Cr, Co

10

Heavy metal content / ppm

4

100

1000

heavy metal content / ppm 0.5 O2 + H O

Cr, Mn, Fe, Co

5

W. J. Stark, R. Strobel. D. Günther, S. E. Pratsinis, A. Baiker, J. Mater. Chem. 12, 3620 (2002) 27. April 2005

(a)

Ti

1

olefin usage / %

peroxid usage / %

100

6

(d)

Institute of Chemical and Bioengineering ETH Hönggerberg, HCI E 107 8093 Zürich Prof. Dr. Wendelin J. Stark

Catalyst Preparation

flame

100 75

commercial

50 25

0.8

1000

ee / %

75 50 E4759 (reference)

25

5Pt3/3 (this work)

0 0

50

100

time / min

150

200

dV/dlog(D) / cm3 nm-1 g-1

Conversion / %

Pt/alumina: 50 % less Pt required for enantioselective hydrogenations

0.6 0.4 0.2 0 1

10

Pore diameter / nm

R. Strobel, W. J. Stark, L. Mädler, S. E. Pratsinis, A. Baiker, J. Catal., 294-304, 213 (2002). 27. April 2005

5Pt3/3

E4759

100

Institute of Chemical and Bioengineering ETH Hönggerberg, HCI E 107 8093 Zürich Prof. Dr. Wendelin J. Stark

Catalyst Preparation

High temperature stability ceramic materials

Ceria/zirconia for automotive exhaust gas cleaning

Composite materials Excellent cold-start less Pt/Pd/Rh

27. April 2005

Institute of Chemical and Bioengineering ETH Hönggerberg, HCI E 107 8093 Zürich Prof. Dr. Wendelin J. Stark

Catalyst Preparation

Dyn. oxygen /mol kg

-1

0.5 Pt/ceria/zirconia Flame Wet phase

1.2 1.0 0.8 0.6

2 CeO2

0.4

CO H2

0.2 0.0 0

200

400

600

Ce2O3 + "O" CO2 H2O 800

1000

Temperature / °C 27. April 2005

1200

Reference powder prepared from precipitation and impregnation

Institute of Chemical and Bioengineering ETH Hönggerberg, HCI E 107 8093 Zürich Prof. Dr. Wendelin J. Stark

Catalyst Preparation

Dyn. oxygen /mol kg

-1

0.5 Pt/ceria/zirconia: Thermal stability 1.2 1.0 0.8 0.6

st

Flame, 1 nd Flame, 2 st Wet phase, 1 nd Wet phase, 2

0.4 0.2 0.0 0

200

400

600

800

1000

Temperature / °C

27. April 2005

1200

Catalyst Preparation

Institute of Chemical and Bioengineering ETH Hönggerberg, HCI E 107 8093 Zürich Prof. Dr. Wendelin J. Stark

Morphology and particles size strongly influence the sintering stability ƒ Rhodia, 2004: fractal like structures of ceria based oxides: ƒ

Highest thermal stability.

ƒ

14 m2/g for Ce/ZrOx after 1100 °C, 4h

ƒ

23 m2/g for Pr-doped Ce/ZrOx after 1100 °C, 4h

Rohart et al, Rhodia Electronics & Catalysis, Top. Catal. 30/31, 2004. Engelhard WO 02/30546, OMG-DMC2 EP 1181970; Daihatsu EP 1174174; Delphi US 6378338; Engelhard WO 02/22242; Toyota EP 1172139 27. April 2005

Catalyst Preparation

Institute of Chemical and Bioengineering ETH Hönggerberg, HCI E 107 8093 Zürich Prof. Dr. Wendelin J. Stark

Larger flame spray burners

Pilot scale flame spray synthesis at 750 g / h

only 45 m2/g as prep. 27. April 2005

Institute of Chemical and Bioengineering ETH Hönggerberg, HCI E 107 8093 Zürich Prof. Dr. Wendelin J. Stark

Catalyst Preparation

Large vs. small starting powders as prep.

1100 °C, 4 h, air

Lab scale,

120-160 m2/g for

4.5 m2/g

res. time 5-10 μsec

0.5 wt% Pt / CeZrO4

Pilot scale,

40-45 m2/g

26-29 m2/g

res. time >30 μsec

0.5 wt% Pt / CeZrO4

14 m2/g*

Rohart et al, Rhodia Electronics & Catalysis, Top. Catal. 30/31, 2004. Engelhard WO 02/30546, OMG-DMC2 EP 1181970; Daihatsu EP 1174174; Delphi US 6378338; Engelhard WO 02/22242; Toyota EP 1172139 27. April 2005

Institute of Chemical and Bioengineering ETH Hönggerberg, HCI E 107 8093 Zürich Prof. Dr. Wendelin J. Stark

Catalyst Preparation

Large vs. small starting powders

Neck formation, local equilibrium

Rapid sintering

Rohart et al, Rhodia Electronics & Catalysis, Top. Catal. 30/31, 2004. Engelhard WO 02/30546, OMG-DMC2 EP 1181970; Daihatsu EP 1174174; Delphi US 6378338; Engelhard WO 02/22242; Toyota EP 1172139 27. April 2005

Catalyst Preparation

Institute of Chemical and Bioengineering ETH Hönggerberg, HCI E 107 8093 Zürich Prof. Dr. Wendelin J. Stark

Large vs. small starting powders

Rohart et al, Rhodia Electronics & Catalysis, Top. Catal. 30/31, 2004. Engelhard WO 02/30546, OMG-DMC2 EP 1181970; Daihatsu EP 1174174; Delphi US 6378338; Engelhard WO 02/22242; Toyota EP 1172139 27. April 2005

Related Documents

Catalyst Preparation
December 2019 11
Catalyst
May 2020 21
Preparation
June 2020 23
Preparation
June 2020 16
Cisco Catalyst
April 2020 17
Hoa Catalyst
August 2019 24