1 Unité de catalyse et de chimie des matériaux divisés, Université catholique de Louvain

1. 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. Derré2and 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@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 STRATEGY INTRODUCTION Interest Chemical reactions demand metal-based catalysts with small, stable and tailored nanoparticles[2] industrial and fundamental 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 vesicles[3] 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 XPS surface analysis Chemical analysis (ICP-AES) 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 (320°C, air) Most of the surfactant is burned out at ~320°C 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 <300°C:less active (surfactant covering ; inaccessible surface 300-400°C: total conversion : no effect of Ag AgTV catalyst: Second run Accessible surface ; synergistic effect between V2O5 and Ag at 250°C TiO2 (T) = poorly active AgT 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 run Accessible surface ; (smaller) effect of Ag from 350°C. Activity measurements in benzene total oxidation (C6H6:O2 100ppm:20% in He ; 200 ml/min ; 200 mg of catalyst in fixed bed reactor Activity measurements in benzene total oxidation (C6H6:O2 100ppm:20% 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., A265 (2004) 207 [3] C. Faure, et al. J. Phys. Chem.107 (2003) 4738