Avoiding rhenium loss in non-hydrolytic synthesis of highly active Re–Si–Al olefin metathesis catalysts

• Re2O7–SiO2–Al2O3 mixed oxide catalysts are prepared by non-hydrolytic sol–gel.
• If handled and calcined in anhydrous conditions no rhenium loss is observed.
• A range of composition is explored including high Re content and low Al content.
• Good textures are obtained with high specific surface area and large mesopores.
• Catalysts perform outstandingly in the metathesis of ethene and butene to propene.

Rhenium oxide-based catalysts are highly active olefin metathesis catalysts. However, sublimation of rhenium heptoxide during the calcination step can lead to the loss of rhenium. We show that rhenium losses in Re–Si–Al mixed oxide catalysts synthesized by non-hydrolytic sol–gel can be avoided providing that strictly anhydrous conditions are kept in all the preparation steps and during storage. Re–Si–Al mixed oxides with various Re2O7 loadings and SiO2/Al2O3 ratios were prepared, without any loss of rhenium. Catalysts were amorphous, exhibited good mesoporous textures and acidity and performed outstandingly in the metathesis of ethene and trans-2-butene to propene.

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