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In this work, CO 2 methanation reaction was studied on Ni-based zeolite catalysts, which were prepared by incipient wetness impregnation of USY zeolite with 5 wt% Ni. The effects of the drying method after impregnation, the calcination temperature and the pre-reduction temperature on the catalysts performances were evaluated. The catalysts were characterized by N 2 adsorption, hydrogen temperature programmed reduction, diffuse reflectance UV-Vis spectroscopy (DRS UV-Vis), transmission electron microscopy and X-ray diffraction. Drying under microwaves irradiation induced remarkable changes on the type, location and reducibility of Ni species at the same time that leaded to effects in the structural and textural properties of the support and in the average nickel particle size. As a result, changes in the catalytic performances were observed. The calcination temperature changed the location and reducibility of the Ni species being concluded that calcining at 300°C leads to higher conversions and selectivities. At high reduction temperatures the amount of reduced Ni species (active sites) was greater, but the impact of sintering processes was also stronger. For catalysts with 5 % Ni, the reduction at 550°C was observed as the most favourable. However for 14 % Ni sample no remarkable effects were observed by reducing at higher temperatures. Thus, it was proved that CO 2 conversion and CH 4 selectivity can be maximised through the proper choice of both preparation and pre-reduction conditions.

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International audienceThis paper is a comprehensive study dealing with the parameters that influence the response of a resistive soot sensor which was developed for Diesel Particulate Filter (DPF) failure detection in a past project. From the conductance measurement between two Pt electrodes, and a regeneration strategy, this kind of sensor can provide the weight concentration of particulate matter (PM). In this study, we have characterized and determined the key parameters such as the PM distribution size and the polarization voltage between the electrodes that could influence the sensor response. First results show that the sensor response strongly depends on the polarization voltage applied between the two electrodes

International audienceAdsorption behavior of a hydrocarbon mixture (propene, toluene, decane) mimicking Diesel cold-start was investigated under dry and wet conditions for commercial HY zeolites with a Si/Al ratio ranging from 2.5 to 100. Textural and structural characterizations were carried out using N-2 adsorption at 77 K and X-ray diffraction. In situ FTIR spectroscopy of adsorbed pyridine was exploited to probe acidic sites. The methodology used in this study consisted of adsorption phase at 35 degrees C with several kinds of mixtures followed by a Temperature-Programmed Desorption (TPD) at 10 degrees C/min. At high Si/Al ratio, a competitive thermodynamic adsorption between toluene and decane was demonstrated. To the opposite, propene is substantially not adsorbed whatever the Si/Al ratio of the zeolite. By decreasing the Si/Al ratio, the presence of large amounts of acidic sites enhances adsorption of unsaturated hydrocarbons. Water adsorption was found to be detrimental for HC storage due to hydrophilic nature

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