1 Unité de catalyse et de chimie des matériaux divisés, Université catholique de Louvain Croix du Sud 2/17, 1348 Louvain-la-Neuve (Belgium) – * damien.debecker@uclouvain.be ; FNRS Research Fellow

An innovative preparation of heterogeneous metal nanoparticles catalysts for VOC abatement: the onion-type multilamellar vesicles route[1]

D.P. Debecker1*, C. Faure2, M.-E. Meyre2, A. Derré2 and E.M. Gaigneaux1

2 Centre de Recherche Paul Pacal (CNRS), Université de Bordeau 1 Avenue du Dr. Albert Schweitzer, 33600 Pessac, France www.emmimaterials.eu

CONCLUSION1. Transfer of onion-grown Ag nanoparticles onto an inorganic support:

easy and quantitative2. In situ burning of the surfactant leads to:

accessible catalyst surface and active catalyst3. Relative stability vs. sintering4. Potential application with nanoparticles of

various nature, form, size, density, etc

  Ti Ag C V

ӨAgT_D 15.3 2.1 46.7 na

ӨAgT_E 19.1 0.1 39.1 na

ӨAgTV_E 15.8 0.2 38.0 3.1

Université c atholique de Louvain (Belgium) - Té l +32 (0)10 47 36 64 - P rinted using Ca saXPS

376 374 372 370 368 366 364

Binding Energy (eV)

  TiO2 (%) Ag (%) V2O5 (%) Mass balance (%)

ӨAgT_D measured 90.4 5.1 - 4.5

Expected 91.1 4.3 - 4.6

ӨAgT_E Measured 96.4 0.3 - 3.4

Expected 95.0 0.2 - 4.8

ӨAgTV_E Measured 90.7 0.3 4.0 4.9

Expected 90.0 0.3 4.3 5.4

50 150 250 350 450

Temperature (°C)

We

igh

t lo

ss d

eri

vativ

e (

a.u

.) -

  Ti (%) Ag (%) C (%) O (%) N (%) Ag/Ti C/Ti N/Ti

ӨAgT_D 15.3 2.1 47 34 2.0 0.14 3.0 0.13

ӨAgT_D Calcined 21.6 5.1 26 47 0.4 0.24 1.2 0.02

[1] D.P. Debecker et al., Small, In Press [2] S. Eriksson et al. Appl. Catal., A 265 (2004) 207 [3] C. Faure, et al. J. Phys. Chem.107 (2003) 4738

Adherence, accessibility, activity and stability of supported Ag nanoparticles

Quantitative transfer of Onion-grown Ag nanoparticles onto TiO2 support (‘T’) and V2O5/TiO2 (‘TV’) catalyst.

surfactant + water is sheared in vials with a spatula to form onions.AgNO3 is introduced by encapsulation (at the shearing step, denoted ‘E’) or by diffusion into preformed onions (denoted ‘D’)

TEM: aggregate of Ag nanoparticles-loaded onions

Chemical analysis (ICP-AES)

XPS surface analysis

Most of the surfactant is burned out at ~320°CSmall particles still adhere on TiO2 after calcination

Surface C and N (from the surfactant) concentrations dropTi, O, Ag concentrations increase (accessibility of inorganic surface)

0

10

20

30

40

50

250 300 350 400

Temperature (°C)

Ben

zene

con

vers

ion

(%)

-

T

OAgT H40m (1)

OAgT H40m (2)

0

20

40

60

80

100

250 300 350 400

Temperature (°C)

Be

nze

ne

co

nve

rsio

n (

%)

-

TV

OAgTV (1)

OAgTV (2)

TG analysis of Ag nanoparticle loaded onion

TEM: Ag nanoparticles grown in onions and impregnated on TiO2 particles

After incubation After impregnation Left: diffusion (D)~10 nmRight: encapsulation (E)~5 nm

XPS surface analysis

High carbon surface concentrationExcess of Ag in ‘D’ preparationLow Ag load in ‘E’’ preparation

XPS: Ag 3d peak

Experimental composition closely fits the expected valuesThe surfactant account for less than 5% of the total dry weight

After calcination (320°C, air)

TEM: calcined catalyst

Activity measurements in benzene total oxidation (C6H6:O2 100ppm:20% in He ; 200 ml/min ; 200 mg of catalyst in fixed bed reactor

TiO2 (T) = poorly activeAgT catalyst: First run <350°C: less active (surfactant covering ; inaccessible surface>300°C: increase of activity (Ag nanoparticles work in the reaction) AgT catalyst: Second runAccessible surface ; (smaller) effect of Ag from 350°C.

V2O5/TiO2 (TV) = very active VOC catalystAgTV catalyst: First run <300°C: less active (surfactant covering ; inaccessible surface300-400°C: total conversion : no effect of Ag AgTV catalyst: Second runAccessible surface ; synergistic effect between V2O5 and Ag at 250°C Activity measurements in benzene total oxidation

(C6H6:O2 100ppm:20% in He ; 200 ml/min ; 200 mg of catalyst in fixed bed reactor

RESULTS

INTRODUCTION

Chemical reactions demand metal-based catalysts with small, stable and tailored nanoparticles[2]

industrial and fundamental interest

Limitation of classical preparation method: need of thermal treatment during which sintering is hardly controlled

deactivation, loss of selectivity, etc.[2]

Production of tailored metal nanoparticle at ambient t° inside organic onion-type vesicles[3]

used in the preparation of solid catalysts !

Interest

Constraint

New idea

STRATEGY