Conversion, stirring speed effect

Effect of agitation on the rate of 2-propanol dehydrogenation to acetone at 355 K over Ni catalysts. [Rates are calculated at constant conversion level from the data in D. E. Mears and M. Boudart, AIChE J., 12 (1966) 313.] In this case, increasing the stirring speed increased the rate of acetone diffusion away from the catalyst pellet and decreased product inhibition. 

Heat transfer effects were minimized by agitating the gas past the catalyst pellets. At stirring speeds of 2200 r.p.m., temperature gradients between catalyst and gas ranged from 0° to 11 °F., depending on the feed gas rate, the feed gas CO content, and the CO conversion. 

Reactor Conditions for Experimental Runs. Operating conditions for the continuous, stirred tank reactor runs were chosen to study the effects of mixing speed on the monomer conversion and molecular weight distribution at different values for the number average degree of polymerization of the product polymer. 

The importance of incorporating a rigorous treatmentT of the film heat and mass transfer processes is that interfacial conditions are determined whilst conversion and colour development are being predicted. Fig. 6(a) shows the predicted variation of interface temperature T with time for conditions corresponding to ] ig. 4(a)(variation in gas composition at N=400 rpm and G=2.3 mol s ). Substantial interface temperatures appear to accompany the absorption. For 9-8 SO, the initial temperature is 120°C above the bulk of 60°C. T then rails as complete conversion is approached. Even for 2.7 SO, the initial temperature increase is 25°C. A similar effect is observed in Fig. 6(b) with the highest T occurring for the lowest stirrer speed of 100 rpm. Absorption in the stirred cell is evidently quite exothermic. 

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