Pr

1
An innovative preparation of heterogeneous metal
nanoparticles catalysts for VOC abatement the
onion-type multilamellar vesicles route1
D.P. Debecker1, C. Faure2, M.-E. Meyre2, A.
Derré2 and E.M. Gaigneaux1
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_at_uclouvain.be FNRS Research
Fellow
2 Centre de Recherche Paul Pacal (CNRS),
Université de Bordeau 1 Avenue du Dr. Albert
Schweitzer, 33600 Pessac, France
www.emmimaterials.eu
INTRODUCTION
STRATEGY
Chemical reactions demand metal-based catalysts
with small, stable and tailored nanoparticles2
industrial and fundamental interest
Interest
Constraint
Limitation of classical preparation method need
of thermal treatment during which sintering is
hardly controlled deactivation, loss of
selectivity, etc.2
New idea
Production of tailored metal nanoparticle at
ambient t inside organic onion-type vesicles3
used in the preparation of solid
catalysts !
CONCLUSION
1. Transfer of onion-grown Ag nanoparticles onto
an inorganic support easy and quantitative 2.
In situ burning of the surfactant leads
to accessible catalyst surface and active
catalyst 3. Relative stability vs. sintering 4.
Potential application with nanoparticles of
various nature, form, size, density, etc
RESULTS
Quantitative transfer of Onion-grown Ag
nanoparticles onto TiO2 support (T) and
V2O5/TiO2 (TV) catalyst.
Left diffusion (D) 10 nm Right encapsulation
(E) 5 nm
After incubation
After impregnation
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
TEM Ag nanoparticles grown in onions and
impregnated on TiO2 particles
Chemical analysis (ICP-AES)
XPS surface analysis
  Ti Ag C V
?AgT_D 15.3 2.1 46.7 na
?AgT_E 19.1 0.1 39.1 na
?AgTV_E 15.8 0.2 38.0 3.1
  TiO2 () Ag () V2O5 () Mass balance ()
?AgT_D measured 90.4 5.1 - 4.5
Expected 91.1 4.3 - 4.6
?AgT_E Measured 96.4 0.3 - 3.4
Expected 95.0 0.2 - 4.8
?AgTV_E Measured 90.7 0.3 4.0 4.9
Expected 90.0 0.3 4.3 5.4
Experimental composition closely fits the
expected values The surfactant account for less
than 5 of the total dry weight
High carbon surface concentration Excess of Ag in
D preparation Low Ag load in E preparation
XPS Ag 3d peak
Adherence, accessibility, activity and stability
of supported Ag nanoparticles
XPS surface analysis
After calcination (320C, air)
  Ti () Ag () C () O () N () Ag/Ti C/Ti N/Ti
?AgT_D 15.3 2.1 47 34 2.0 0.14 3.0 0.13
?AgT_D Calcined 21.6 5.1 26 47 0.4 0.24 1.2 0.02
Most of the surfactant is burned out at
320C Small particles still adhere on TiO2 after
calcination
Surface C and N (from the surfactant)
concentrations drop Ti, O, Ag concentrations
increase (accessibility of inorganic surface)
TEM calcined catalyst
TG analysis of Ag nanoparticle loaded onion
V2O5/TiO2 (TV) very active VOC catalyst AgTV
catalyst First run lt300C less active
(surfactant covering inaccessible
surface 300-400C total conversion no effect
of Ag AgTV catalyst Second run Accessible
surface synergistic effect between V2O5 and Ag
at 250C
TiO2 (T) poorly active AgT catalyst First run
lt350C less active (surfactant covering
inaccessible surface gt300C increase of activity
(Ag nanoparticles work in the reaction) AgT
catalyst Second run Accessible surface
(smaller) effect of Ag from 350C.
Activity measurements in benzene total oxidation
(C6H6O2 100ppm20 in He 200 ml/min 200 mg
of catalyst in fixed bed reactor
Activity measurements in benzene total oxidation
(C6H6O2 100ppm20 in He 200 ml/min 200 mg
of catalyst in fixed bed reactor
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