Effects of the addition of Nb2O5 to rhenium-based olefin metathesis catalysts

✍ Scribed by Regina Buffon; Marcelo JoséD.M Jannini; Anuar Abras

• Publisher: Elsevier Science
• Year: 1997
• Tongue: English
• Weight: 813 KB
• Volume: 115
• Category: Article
• ISSN: 1381-1169
• DOI: 10.1016/s1381-1169(96)00099-4

✦ Synopsis

The effects of the addition of Nb,O, to 6 wt.% Re,0,/A1203 metathesis catalysts were investigated. At least until 9 wt.% Nb,O, loadings both tetrahedral and octahedral aluminum sites are evenly involved in the reaction between alumina and niobium oxide. Up to 12 wt.% Nb,O, no significative influence was observed in the catalytic activity of the resulting systems. For higher niobia loadings, however, the catalytic activity decreased quickly. In such conditions a second rhenium species, probably [Nb]--0Re0, was detected by TPR. "9Sn MSssbauer analyses showed that the reaction between the niobia-modified systems and SnBu, ([Sn]:[Re] = 0.55) led to the formation of only one kind of rhenium-tin site, with the tin atom attached to the surface by two Sn-0 bonds. In contrast to what happens with the unmodified system, no physisorbed SnBu, was observed.