Continuous-flow alkene metathesis: the model reaction of 1-octene catalyzed by Re2O7/γ-Al2O3 with supercritical CO2 as a carrierElectronic supplementary information (ESI) available: Details of TEM analysis and EDX spectra are reported for Re/AlWI2 catalyst. Also, representative GC-MS spectra of some components of the oil recovered after catalyst recycling, are shown. See DOI: 10.1039/c2gc35983a

In the presence of Re 2 O 7 supported on γ-Al 2 O 3 , the self-metathesis of 1-octene was conveniently carried out under continuous-flow (CF) conditions using supercritical CO 2 (scCO 2 ) as a carrier. This investigation allowed optimization of reaction parameters, the best values of which were found to be 100 °C and 90 bar, operating at flow rates of 0.05 and 1 mL min −1 for 1-octene and scCO 2 , respectively, the reaction proceeded with very good self-metathesis selectivity (>90%) and an average productivity of ∼0.24 mL tetradecene g Re −1 min −1 . Although the catalyst was completely deactivated after the first 100-150 min of reaction, it could be recycled for (at least) five subsequent reactions without any loss of performance. The results provided incontrovertible evidence that for the investigated reaction, scCO 2 was a superior carrier with respect to conventional liquids, such as toluene or n -hexane. The continuous-flow metathesis of 1-octene occurs selectively on 7-tetradecene (>90%) in the presence of CO 2 as a carrier and Re 2 O 7 /γ-Al 2 O 3 as a catalyst.