Claude Moreau

Hydrogenation of substituted acrolein over alumina supported ruthenium catalysts

The gas phase hydrogenation of acrolein, 2-methyl-2-propenal, 2-butenal and 3-methyl-2-butenal was studied on Ru/Al2O3 and RuM/Al2O3 catalysts (M=Sn, Fe, Zn, Ge, Sb). The specific activity increases when the second element is added to the parent Ru/Al2O3 catalyst. This was ascribed to the activation of the C=O bond by Mδ+ species. Tin is the only additive which promotes the allyl alcohol selectivity. When methyl groups are tagged on the C=C bond the selectivity to the unsaturated alcohol increased sharply due to the steric hindrance against the adsorption of the substrate via the C=C double bond.

Search for surface brönsted acidity over sulphided Ni-W/Al2O3 hydrotreating catalysts

Abstract A series of catalysts containing tungsten and nickel on a γ-alumina carrier were examined with respect to surface acidity. The studies focused on the behaviour of sulphided samples to which various techniques were applied. In agreement with prior studies on Co-Mo catalysts, infrared spectroscopy of adsorbed pyridine showed that both Bronsted and Lewis acidic sites are present on the calcined Ni-W samples, but Bronsted acidity can no longer be detected after sulphiding. Other probes (ammonia or piperidine) substantiated these conclusions. Moreover, gravimetric adsorption-desorption studies on ammonia confirmed that Bronsted acidity is not a major characteristic of the sulphide catalysts. The lack of strong Bronsted acidity was also demonstrated by measuring the rates of cyclohexanol dehydration or cyclohexylamine coupling carried out on the series of sulphides Ni-W catalysts. Therefore, it was proved that acidic mechanisms do not play any major role in catalysis by sulphides. In contrast, the sulphide catalysts show a better aptitude than typical cracking catalysts for isomerizing and cracking 3-methylpentane under hydrodesulphurization conditions but the product selectivity is different. The occurrence of a metallic-type catalysis is suggested, which could also operate in hydrodenitrogenation.

Hydroxyalkylation of aromatic compounds over protonic zeolites

Hydroxyalkylation of activated carbocyclic aromatic compounds (phenol, anisole and toluene) by a deactivated carbonyl compound such as chloral has been performed in a batch mode in the presence of different dealuminated protonic zeolites (Y-FAU, MOR, MFI and BEA). A high selectivity to the corresponding carbinols is achieved in the presence of a HBEA zeolite with a Si/Al ratio of 12.5, at 293 K. Under these reaction conditions, a high selectivity to the para isomer is obtained. Other parameters, influencing both the course of the reaction and the selectivity to the para and ortho carbinols, such as temperature, catalyst weight, Si/Al ratio, zeolite structure and substituent effects are also discussed. Finally, a study of the relative reactivities of a series of substituted arylcarbinols in the etherification reaction shows a strong influence of the electronic properties of these substituents on their stabilities. Thus, it has been shown that the presence of electron-donating groups on the carbonyl compound has to be avoided to succeed in the hydroxyalkylation reaction.

Un chrysosporium nouveau isolé de dentine: C. keratinophilum (Frey) Carmichael var. denticolum nov. var. Remarques sur la genèse des aleuriospores.

LeChrysosporium keratinophilum var.denticolum diffère du type par ses spores caténées et son habitat. La formation des aleuriospores a été particulièrement étudiée. Chrysosporium keratinophilum var.denticolum is distinct from the type by its catenate spores and its substrate. The genesis of the aleuriospores has been specially studied.