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CoMo additive-impregnated dried catalysts are studied, exploring the ''CoMoS'' active phase features by combining X-ray Photoelectron Spectroscopy (XPS), Transmission Electron Microscopy (TEM) and catalytic tests. Starting from different polyoxomolybdate precursors, additive-impregnated dried, additive-free dried and calcined catalyst performances are compared. TEM reveals that the mean particle sizes are about 3.1 nm and do not depend on the catalytic precursors except for the additivefree dried catalysts exhibiting higher lengths: 3.7 nm. XPS quantification of the Mo species shows that 75 mol% of the Mo species are present in the MoS 2 phase whatever the preparation route. This value is slightly enhanced (ca. 85%) with additive impregnation. The molybdenum to aluminium surface coverage ratio (Mo/Al) ranking is found to be as follows: additive-free dried o additive-impregnated dried o calcined. However, this ranking is not significantly modified by the impregnating solution used, and the behaviour is similar for the cobalt to aluminium ratio (Co/Al). A geometrical model combining XPS quantification of the crystallite's Co/Mo ratio and DFT calculations is used to establish a correlation with the catalytic results obtained in toluene hydrogenation. It is shown that the catalytic performances of additive-free dried, additive-impregnated dried and calcined catalysts directly correlate the number of mixed Co-Mo sites present at the MoS 2 edges. DFT calculations highlight that the adsorption step of toluene is thermodynamically favored on the mixed Co-Mo site located at the M-edge. As a consequence, this study suggests that the various routes of preparation leading to different catalytic performances would not lead to new types of active sites or morphology but rather to a different number of mixed sites present at the edges.

Heavy oil fractions can be upgraded through various processes, such as catalytic residue hydrotreatments. Mass transfer of macromolecules present in the heavy oil fraction, so-called asphaltenes, from feedstock to catalytic active sites is limited during hydroprocesses. Mechanisms of the diffusion of asphaltenes through pore network, adsorption, and pore plugging are no well-known under process conditions. A new method has been developed to characterize and investigate asphaltene diffusion phenomenon in catalysts under a high temperature and pressure. Alumina supports immersed in asphaltene solution are left to evolve at 250 °C and 5.0 MPa. Solutions and supports are analyzed to quantify the mass transfer, penetration depth, and change in support porosity of asphaltenes. This procedure was evaluated in terms of reproducibility and sensitivity. The impact of several parameters, such as pressure, was appraised. With this powerful procedure, for the first time, asphaltene diffusion without conversion into the pore network of a catalyst at a high temperature and pressure has been monitored over time. In accordance with analytical results, we proposed a primary model for the asphaltene adsorption and pore network cluttering mechanism under hydroprocessing conditions.

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Two copolyethers were prepared by chemical modification of poly[3,3-bis(chloromethyl)oxetane] with sodium 4-cyano-4'-biphenyl oxide, employing the concept of having the cyanobiphenyl species serve concomitantly as both the nonlinear optical chromophore and the mesogenic moiety in the polymer. Their thermal behavior was established by means of DSC and optical microscopy. Some preliminary Corona poling experiments were performed, and the second harmonic generation coefficients d31 and d3, were measured by Maker fringe analysis. The results showed that liquid crystallinity enhances field-induced polar ordering. The ratio d33 /d31 was found to be much larger than 3, in agreement with the theoretical models for electric field poling of liquid crystalline polymers where hyperpolarizable chromophores are attached as side groups to a polymer backbone.

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