Catalytic activity, stirring speed

Note, however, that rehydration of Mg-Al hydrotalcites in the liquid phase using ultrasound or a high stirring speed [267] leads to nanoplatelets with surface areas of400 m g , displaying catalytic activities in aldol condensations up to eight-times higher than the best catalytic system reported in the literature. There are thus alternative methods to increase the performances of HT materials. 

The hydrogenation of cinnatnaldehyde in liquid phase was performed in a stirred autoclave. In a typical experiment, 3 tmnol of cinnatnaldehyde (99%) was dissolved into 150 ml of 2-propanol arid purged with N2 twice. The Pd catalysts (Pd 0.47-0.9 mg) were then introduced itrto the autoclave before a next N2 purge. The reaction was performed at 50°C under 10 bars H2 pressure at a stirring speed of 500 rpm. The duration of each test was 6 h. A small amount (0.3pl) of the reacting medium was withdrawn at tegular times (every 30 min) and analyzed by gas chromatography (Varian 3380). Catalytic activity was measured in terms of initial rates and calculated from the slope of the curves conversion versus time (t) at t=0. 

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