A. Deluzarche

Application of chemical trapping to the determination of surface species and to the study of their evolution under reaction conditions in heterogeneous catalysis

Abstract The detection of surface species by chemical trapping is described and discussed. The results obtained by scavenging intermediates in CO-H 2 and CO 2 -H 2 reactions show the relevance of this method to the study of reaction mechanisms in heterogeneous catalysis. Quantitative detection of some species (carboxylate, formyi, methoxy) is achieved and a correlation has been found between activity and surface species on a Pd/MgO-SiO 2 catalyst. A reaction scheme is proposed for the CO-H 2 and CO 2 -H 2 reactions.

Contribution a L'étude des condensations de composés dihydroxylés avec des dialcoyldialcoxygermanes I. Condensations avec des diols

Abstract On condensation of dialkyldialkoxygermanes, in the pure state or in benzene solution, with diols, cyclic compounds of the type [-GeR 2 -O-(CH 2 ) x -O-] n were obtained. For dibutyldiethyoxygermane (R = C 4 H 9 ) with propane-1,3-diol a cyclic compound with n = 1 was obtained. For dimethyldiethoxygermane (R = CH 3 ) or dibutyldiethoxygermane (R = C 4 H 9 ) with hexane-1,6-diol ( x = 6) a mixture of cyclic compounds was obtained with a mean value of n = 3.

Oxidizing properties of alumina towards alcohols. Possible reaction scheme

By chemical trapping, an acyl species has been evidenced in the oxidation of alcohols to carboxylate on an alumina surface. A possible reacton scheme is discussed.AbstractС помощью химического захвата удалось доказать образование ациловых частиц при окислении спиртов до карбоксилатов на поверхности окиси алюминия. Обсуждается вероятная схема реакции.

Liquid phase CO+H2 reactions in presence of ruthenium catalysts

Several effects on the hydrogenation of carbon monoxide in propanol in presence of ruthenium catalysts are examined. The homologation reaction is not observed, only propyl formate and propyl acetate are produced with any ruthenium catalyst. The pH-value is an important parameter: in acid media, the yield of propyl formate is noticeably increased indicating different catalytic active species. The addition of cesium salts is also benefitial for formate formation. This is not the case when water is associated with propanol as solvent. Finally, no ethylene glycol is detected. The process is found to be homogeneous and methanol seems to be the precursor of methyl formate.AbstractИзучены различные зффекты, влияющие на гидрирование окиси углерода в пропаноле в присутствии рутениевых катализаторов. Реакция гомологирования не наблюдается, в присутствии рутениевого катализатора образуются лишь формиат и ацетат пропила. Важным параметром является значение рН: в кислой среде выход формиата пропила значительно увеличивается, что указывает на различные типы каталитически активных частиц. Добавки солей цезия благоприятствуют образованию формиата. В этом случае вода не ассоциирована с пропанолом, как растворителем. В конечиом итоге этиленгликоль не обнаружен. Процесс оказался гомогенным и метанол, по-видимому, является источником метилформиата.

Especes multiliees dans la chimisorption de co (Ni/Si O2, Ni/Al2O3, Co/Al2O3, Co, Pd/SiO2)

Abstract The application of chemical trapping to chemisorbed CO has led to the characterization of multibonded species on Ni/SiO 2 , Ni/Al 2 O 3 , Co, Co/Al 2 O 3 and of a bridged form on Pd/SiO 2 . A structure like [proposed by Muetterties) is in good agreement with infrared and magnetic studies of CO chemisorption on Ni/SiO 2 .

Reactions CO, H2. Intervention de formiates de surface portes par le support dans la reaction de methanation (catalyseur Al2O3/Ni)

Abstract Surface formates supported on alumina are active species in the methanation of CO on Al 2 O 3 /Ni catalysts. Their reduction occurs concurrently with the hydrogenation of surface carbon. Hydrogen spillover could explain the formate transformation.

Reaction of carbon monoxide and hydrogen on rare earth metal oxide catalysts

Isobutane, 2-methylprop-1-ene, and aromatic compounds are formed from CO–H2 on rare earth metal oxides (La2O3 and Dy2O3) under severe conditions (P 400 bar and T 410–475 °C).

Contribution a l'étude des condensations de composés dihydroxylés avec des dialcoyldialcoxygermanes II. Condensation du diméthyldiéthoxygermane avec l'hydroquinone

Abstract On condensation of pure dimethyldiethoxygermane with hydroquinone a cyclic compound was obtained with the structure This structure was confirmed by mass spectrometry.