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International audience; The acceleration of the development of ethylene oligomerization processes by homogeneous catalysis requires a complete characterization of the catalytic system. This work proposes to use segmented gas-liquid flow in microchannels to achieve high experimental throughput for catalyst testing. Gas-liquid flow was studied in order to validate the microreactor setup. Results showed that bubble and slug lengths vary linearly with the superficial velocities ratio following the Garstecki et al. model [21]. The impact of lateral feed in Taylor flow was explored to mimic the catalyst feed in an oligomerization test. The experiments showed that the volume of the liquid slugs increased proportionally to the additional flow rate, thereby suggesting that the majority of the liquid in the lateral feed is ultimately retained in the liquid slug. A study of mass transfer showed that the volumetric mass transfer coefficient is between 0.27 and 0.55 s−1. These values lead to a Hatta number < 0.5, thus confirming the possibility of conducting the ethylene oligomerization reaction in the chemical kinetic regime. Finally, an ethylene oligomerization test performed in the microreactor showed that the continuous microreactor system can be used for catalyst screening purpose.

This work presents the epoxidation of camphene employing methyltrioxorhenium(VII) (MTO) as catalyst. The effect of different factors on the formation of camphene oxide with respect to high yield and selectivity was investigated. First, the ratio camphene:MTO:pyrazole:H2O2 was studied in dichloromethane as solvent in order to determine the optimal condition. Moreover, the influence of the Lewis base adduct (tert-butylpyridine, 4,4'-dimethy1-2,2'-bypridine, imidazole or pyrazole) was investigated. The effect of an aqueous oxidant, namely H2O2 and a solid oxidant, namely urea hydrogen peroxide (UHP) was also examined. Finally, the solvent was varied from dichloromethane to chloroform, toluene and nitromethane. Based on the results the optimal conditions for the epoxidation of camphene using MTO as catalyst were determined. The molar ratio camphene:MTO:pyrazole: H2O2 of 100:0.5:10:110 in dichloromethane at room temperature leads after 3 h to 97

This report presents a study of the epoxidation of limonene employing methyltrioxorhenium (MTO) as catalyst. The influence of base ligands, namely t-butylpyridine, 4,4′-dimethyl-2,2′-bipyridine and pyrazole on the catalytic activity was investigated. The choice of the oxidant (H2O2 in water or H2O2 stabilized by urea) was also examined. The effect of the solvent has been studied in order to determine optimal conditions for the epoxidation of (+)-limonene. The best result was obtained when a molar ratio (+)-limonene:MTO:H2O2:t-butylpyridine of 100:0.5:10:150 was used at 25 °C in dichloromethane. 1,2-Limonene oxide was formed with 77% yield and 96% selectivity after 1 h with a TOF of ca. 900 h−1.

The epoxidation of α-pinene employing methyltrioxorhenium as catalyst is examined. The influence of mono- and bidentate Lewis basic additives (e.g. tbutylpyridine, 4,4′-dimethyl-2,2′-bipyridine, and Schiff-bases) is investigated. Additionally the impact of the oxidant (H2O2 in water or urea–hydrogen peroxide (UHP)) on the catalytic performance is studied. The effect of the solvent is also examined in order to determine the optimal conditions for the epoxidation of α-pinene. The best and straightforwardly applicable result is obtained when a ratio α-pinene:MTO:tbutylpyridine:UHP of 200:1:40:600 is applied at 0 °C in nitromethane. In this case, α-pinene oxide is formed with 95% yield after 3 h with a turnover frequency (TOF) of 610 h−1.