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It has been recently shown that (Ce, Zr)O2 mixed oxides provide improved catalytic performances compared to pure CeO2. Cerium oxide is the active Oxygen Storage Capacity (OSC) component in three way catalysts. However, higher performances, including OSC enhancement, can be achieved with thermally stable solid solutions of Ce and Zr oxides. In the present paper, we describe the structure and the advantages of Ce rich (Ce, Zr)O2 solid solutions and the improved catalytic properties of these materials when used in association with platinum. Various analytical techniques were used including thermo-reduction methods, OSC measurements, surface area measurements, XRD, HRTEM, XPS, and XANES/EXAFS.

Limited and non-regulated emissions of scooters were analysed during several annual research programs of the Swiss Federal Office of Environment (BAFU) *). Small scooters, which are very much used in the congested centers of several cities, are a remarkable source of air pollution. Therefore every effort to reduce the emissions is an important contribution to improve the air quality in urban centers. In the present work detailed investigations of particle emissions of different 2-stroke scooters with direct injection and with carburettor were performed. The nanoparticulate emissions were measured by means of SMPS, (CPC) and NanoMet. Also the particle mass emission (PM) was measured with the same method as for Diesel engines. Extensive analyses of PM-residuum for SOF/INSOF, PAH and toxicity equivalence (TEQ), were carried out in an international project network. Particle mass emission (PM) of 2-S Scooters consists mostly of SOF.