Browsing by Author "Sewell, G"

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    Effect of activation procedure and support on the reductive amination of ethanol using supported cobalt catalysts.
    (Elsevier, 1997) Sewell, G; O'Connor, C T; van Steen, E
    The reductive amination of alcohols using ammonia catalyzed by supported cobalt catalysts has been studied. The catalytic activity for ethanol conversion is shown to be directly proportional to the exposed metal surface area, indicating that the activation of ethanol is metal-catalyzed and no metal-support effects were detected. The selectivity to the mono-, di-, and triethylamine varies with temperature, reactant partial pressures, and extent of reactant conversion generally as expected for a series-type reaction scheme. Both the activation procedure and the type of support also influence selectivity. Increasing the acidity of the support favors the formation of monoethylamine, probably due to disproportionation of diethylamine on the acid sites of the support indicating the bifunctionality of the catalyst.
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    Use of TPR/TPO for characterization of supported cobalt catalysts.
    (Springer, 1996) Sewell, G; van Steen, E; O'Connor, C
    The extent of reduction of supported cobalt catalysts is difficult to determine using TPR due to the unknown stoichiometry of reduction and due to the dynamic nature of the measurement. A method is described where, by using a combined TPR/TPO technique, it is possible to determine the extent of cobalt reduction and obtain an estimate of the extent of cobalt-support species formation. The results showed that the extent of metal reduction following hydrogen reduction at 500°C is affected considerably by the type of metal carrier. In particular, the extent of metal reduction decreased with increasing aluminium content of the support material. Decreasing extents of metal reduction could be correlated with an increase in the temperature required for reduction of the nitrate ion during TPR. Increasing the time and temperature of hydrogen reduction results in increased extents of metal reduction.