1 unité de catalyse et de chimie des matériaux divisés, université catholique de louvain croix...
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1 Unité de catalyse et de chimie des matériaux divisés, Université catholique de Louvain Croix du Sud 2/17, 1348 Louvain-la-Neuve (Belgium) – * [email protected] ; 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