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We demonstrated the surface composite character down to the nanometer scale of SiO(2)-CeO(2) composite high surface area materials, prepared using 5 nm colloidal CeO(2) nanoparticle building blocks. These materials are made of a homogeneous distribution of CeO(2) nanoparticles in thin layers of SiO(2), arranged in a hexagonal symmetry as shown by small-angle X-ray scattering and transmission electron microscopy. Since the preparation route of these composite materials was selected in order to produce SiO(2) wall thickness in the range of the CeO(2) nanoparticle diameter, these materials display surface nanorugosity as shown by inverse chromatography. Accessibility through the porous volume to the functional CeO(2) nanoparticle surfaces was evidenced through an organic acid chemisorption technique allowing quantitative determination of CeO(2) surface ratio. This surface composite nanostructure down to the nanometer scale does not affect the fundamental properties of the functional CeO(2) nanodomains, such as their oxygen storage capacity, but modifies the acid-base properties of the CeO(2) surface nanodomains as evidenced by Fourier transform IR technique. These arrays of accessible CeO(2) nanoparticles displaying high surface area and high thermal stability, along with the possibility of tuning their acid base properties, will exhibit potentialities for catalysis, sensors, etc.

Purpose -Because domestic heating appliances have the advantage of reducing emissions of greenhouse gas, their use is greatly increased and is largely recommended by European governments. However, some recent studies revealed that residential wood stoves and inserts are the source of many chemicals in the form of gases (CO 2 , CO, SO 2 , NO x ), volatile organic compounds (alkane, alkenes, benzene, etc. . . .) and tars (mainly constituting poly-aromatic hydrocarbons). The most important of them in terms of the emission factor and impact on environment and human health are carbon monoxide and fine particles. The aim of this study is to test the activity of a Pd-based catalyst on the reduction of gas and particles during wood combustion in a domestic fireplace. Design/methodology/approach -A catalytic system, placed at the exit of the fireplace, was developed to reduce pollutants. Pollutant characterization of a domestic fireplace from FONDIS SA, according to two paces of functioning (nominal and low-charge), was performed with and without the presence of the catalyst. Fine and ultrafine particle distributions were characterized using an Electrical Low Pressure Impactor. Findings -The presence of a catalyst drastically decreases the emission factors of CO. Though performing efficiently with respect to the total suspended particles emission factor, it does not significantly affect the emission factors of aerosols. Nevertheless, in the presence of the catalyst, air supply conditions slightly modify size distributions of PM0.1 to PM10. Practical implications -A purification assembly, having catalysts for gases and combustion fumes from solid fuel heating apparatus, was patented and fireplaces are now commercially available from FONDIS SA. Originality/value -This work was an adaptation of the catalytic system present in the automotive Diesel exhaust engines. It was not necessary to consult previous laboratory experiments in order to perform its activity because it was directly tested at the duct fireplace.

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