摘要：

Mssbauer and solid-state NMR spectroscopic studies have been carried out on Re2O7/SiO2–Al2O3/SnR4 metathesis catalysts (R = Me, Et or n-Bu). The effects of both the rhenium loading and the SnR4 alkyl group are presented. The amounts of gas released upon the interaction between Re2O7/SiO2–Al2O3 and SnR4 do not correspond to a simple stoichiometry while chemical reactivity suggests the presence of minor amounts of a rhenium–alkylidene species. Mssbauer and NMR data suggest two kinds of tin sites, with the tin atom linked to the surface by one or two Sn—O bonds. The effects of exposure to air and catalyst regeneration on the tin environment have also been investigated. The nature of the tin-containing surface species is discussed.

展开