On the Nature and Formation of the Active Sites in Re2O7 Metathesis Catalysts Supported on Borated Alumina

Hydrodeoxygenation of 2-methoxyphenol over different Re active phases supported on SiO 2 catalysts

“…This finding is consistent with previous studies that have suggested that the presence of metal oxide facilitates the activation of the oxogroup on the substrate [35]. Furthermore, it has been reported that electron-deficient ReOx sites favour the adsorption of electron-rich carbon-carbon, as suggested by Sibeijn et al [36] during alkenes metathesis reaction [37][38][39]. Fig.…”

Characterization and catalytic performance of rhenium oxide-based catalysts supported on borated silica-alumina

“…In the case of boria-modified supports, the total acidity of the resulting rhenium-based catalyst seems to decrease, no matter the alumina loading. A decrease in Lewis and Brönsted acidity upon interaction with rhenium oxide has also been reported in the case of borated aluminas [20]. For the catalysts prepared with boria-modified silica-alumina described in this work, Lewis acid sites seem to be predominant (as judged by the intensity of the band at ca.…”

“…Both concentration and strength of acid sites in borated aluminas has been ascribed to BO 4 tetrahedral species [28]. Moreover, it has been reported that the main acidity of borated aluminas is of the Brönsted type [31] and it is known that borated alumina is a better support for rhenium oxide than non-modified ␥-alumina [20,32]. Although a ␥-alumina phase was not observed for the 75 wt.% alumina SiO 2 -Al 2 O 3 prepared in this work, its presence is suggested for the corresponding boria-modified support.…”

“…As it can be seen in Table 2, changes in catalytic activity cannot be directly related to the surface area of the catalysts. Keeping the best conditions (75 wt.% [20]). Therefore, they also suggest that the properties of alumino-silicates are strongly affected by the way they are prepared.…”

Ordered bimodal mesoporous boria–alumina composite: One-step synthesis, structural characterization, active catalysis for methanol dehydration

“…When the boria-alumina mixed oxides are used as active phase, they can catalyze reactions such as the Beckmann rearrangement of cyclohexanone [16], the condensation of alcohols [17], and the partial oxidation of alkanes such as ethane [18]. Furthermore, boria-alumina supported Re species has been used for metathesis reactions [19], supported Pt species has been used for cyclohexene hydrogenation [20], and supported Ru species has been used for CO hydrogenation [21]. However, little research was conducted on the preparation of ordered mesoporous boriaalumina materials.…”