Laurence Vivier

Ceria‐Based Solid Catalysts for Organic Chemistry

Ceria has been the subject of thorough investigations, mainly because of its use as an active component of catalytic converters for the treatment of exhaust gases. However, ceria-based catalysts have also been developed for different applications in organic chemistry. The redox and acid-base properties of ceria, either alone or in the presence of transition metals, are important parameters that allow to activate complex organic molecules and to selectively orient their transformation. Pure ceria is used in several organic reactions, such as the dehydration of alcohols, the alkylation of aromatic compounds, ketone formation, and aldolization, and in redox reactions. Ceria-supported metal catalysts allow the hydrogenation of many unsaturated compounds. They can also be used for coupling or ring-opening reactions. Cerium atoms can be added as dopants to catalytic system or impregnated onto zeolites and mesoporous catalyst materials to improve their performances. This Review demonstrates that the exceptional surface (and sometimes bulk) properties of ceria make cerium-based catalysts very effective for a broad range of organic reactions.

Sustainable route to methyl-9-hydroxononanoate (polymer precursor) by oxidative cleavage of fatty acid methyl ester from rapeseed oil

Fatty acid methyl esters from rapeseed oil can be converted to monomers for polymer industries (85% methyl-9-hydroxynonanoate) by an oxydoreductive cleavage step in solvent free medium at room temperature, followed by a reduction step. All by-products are valuable and the reactions are performed under mild conditions.

Synthesis of ordered porous zirconia containing sulfate ions and evaluation of its surface acidic properties

The synthesis and characterization of sulfated ZrO2 with ordered pores as a solid acid catalyst were investigated. Ordered porous ZrO2 containing sulfate ions was synthesized by hydrolysis of zirconium n-propoxide in the presence of HCl, surfactant and (NH4)2SO4 dissolved in distilled water, when the SO4/Zr molar ratio was changed in the range of 0.8–1.4. BET surface area of sulfated ZrO2 thus synthesized was found to be 150–160xa0m2xa0g−1. The presence of sulfate ions in ZrO2 was confirmed by an appearance of IR band at ca. 1398xa0cm−1 in the IR spectra of sulfated ZrO2. Since two IR bands due to surface hydroxyl groups were still observed for sulfated ZrO2, the possibility that sulfate ions are highly dispersed on the surface of ordered porous ZrO2 was suggested. From the evaluation of surface acidity by NH3-TPD measurements, not only the amount of NH3 desorption but also the strength of acid sites related to NH3 desorption temperature were found to be increased with increasing the SO4/Zr ratio up to 1.2. On the other hand, FTIR spectroscopy following pyridine adsorption revealed that the maximum surface density of Brønsted acid sites was attained for sulfated ZrO2 with SO4/Zr ratio of 1.0. Sulfate species interacting strongly with nano-sized tetragonal ZrO2 was considered to be responsible for the creation of Brønsted acid sites. In accordance with the surface density of Brønsted acid sites, sulfated ZrO2 with SO4/Zr ratio of 1.0 showed the highest activity for the skeletal isomerization of 3,3-dimethylbut-1-ene, which predominantly occurs on Brønsted acid sites.

Characterization of the balance between metallic and acidic properties of Cu–MFI catalysts by using the transformation of haloaromatic compounds: effect of copper loading and Si/Al ratio

Abstract The transformation of equimolar mixtures of m -bromofluorobenzene and chlorobenzene was carried out over Cu–MFI catalysts at 400°C under atmospheric pressure in a fixed bed reactor. A reversible exchange of halogen atoms occurred between m -bromofluorobenzene and chlorobenzene leading to m -chlorofluorobenzene and bromobenzene. The isomerization of m -bromofluorobenzene into o - and p -bromofluorobenzene was also observed. It was found that the activity in halogen exchange increased linearly with increasing copper content up to a loading corresponding to the cationic exchange capacity of the zeolite, while the isomerization activity decreased symmetrically. It was concluded that the halogen exchange reaction between the aromatic compounds was catalyzed by the copper species located in the cationic exchange sites of the zeolite and that the isomerization reaction was catalyzed by the residual protonic acidity.