A new heterogeneous olefin metathesis catalyst composed of rhenium oxide and mesoporous alumina

Rhenium Nanochemistry for Catalyst Preparation

“…Re 2 O 7 dispersed on mesoporous alumina (abbreviated as meso-Al 2 O 3 ) with a narrow pore-size distribution centered at 3 nm in the metathesis of internal as well as terminal olefins without functional groups has shown higher catalytic activity than Re 2 O 7 on common γ-Al 2 O 3 in liquid phase [21,22]. Rhenium oxide supported on ordered mesoporous alumina has even been claimed as a more active and selective catalyst than Re 2 O 7 /γ-Al 2 O 3 for alkenes metathesis [23].…”

Self-Metathesis of 1-Octene Using Alumina-Supported Re2O7 in Supercritical CO2

“…As far as the mesoporous alumina as support is concerned, the higher activity reported for mesoporous Al 2 O 3 was obtained with high-surface area supports (560 m 2 /g) [26,27]. In our case the mesoporous Re-A 4 catalyst (entry 4, Table 1) is not as active, and is comparable to that of Re-A 2 , probably due to the surface area being not sufficiently large.…”

“…The TEM analysis of Re-A 1 and Re-A 2 shows the c-phase in the shape of grains of 5-6 nm, while the Re-oxide particles are not clearly distinguishable, their size being less than 1 nm. Oikawa et al have reported a similar result [26,27].…”

“…The reaction of 1-octene (1a) was carried out in scCO 2 as well as in the presence of conventional liquid solvents (nheptane and toluene: procedure adapted from ref. [27]). …”

“…It is generally agreed that a monomeric tetrahedral structure of ReO 4 -species, is stabilized over the alumina surface: the metal centre forms three equivalent Re=O moieties and a Re-OAl bond with an acidic OH group on the support [26,27] [35]. Although the nature of this last interaction is not fully understood, a high surface area (A s ) of the solid alumina is crucial to increase the dispersion of the active phase and to improve the catalytic performance [6].…”