Page - 118 - in Advanced Chemical Kinetics

educt concentrations, were varied to arrive at the kinetic regime. The commercial 0.9-wt% Au/γ-Al2O3(Aurolite TM)catalystwasusedtoestablishthemass transferregime.Thestirring ratewas fixedat1000rpmandtheamountofcatalystvariedasshowninFigure3. In theory, if the rate doubles with the doubling of the weight of the catalyst, then the reaction is controlledbykinetics; if this is not the case, then the reaction is controlledbymass transfer. The curve in Figure 3 indicates that, under the defined experimental conditions, the ideal amount of catalyst necessary to achieve kinetic control was between 0.5 and 1.2 g. This ‘reaction-limited’ situation was ideal for the determination of intrinsic reaction kinetic parameters. 3.2.3.The effect of temperature onactivation energy In thiswork, theactivationenergy for theoxidationof glycerol overAu/γ-Al2O3 catalystwas experimentallydetermined. For a zero-order reaction, it canbe shown that fractional conver- sion is linearlydependenton timeandtemperature throughtherelationshipsshowninEq. (1) andEq. (2): XA¼ kCAo � t (1) whereXA is the fractional conversionof reactantA, Figure2. Theeffect ofbase concentrationasa reaction initiatoronglyceroloxidationusing0.5gof0.9-wt%Au/γ-Al2O3 catalystat90�CandO2pressureof8.5bar. Advanced Chemical Kinetics118