Kinetics of Catalyzed Gas-Liquid Reaction in a Stirred Reactor

Abstract

The rate of isotopic exchange between heavy hydrogen and normal water, catalyzed by suspended platinum-active carbon catalyst, was measured in a stirred reactor at atmospheric pressure, and the total rate of exchange, R, was calculated by the use of Equation (15). The rate of strring, the bubbling velocity and the diameter of the catalyst particle exhibited remarkable effects upon the total rate of exchange as shown in Figures 4 to 8 and by Equation (21). It may be concluded that the chemical reaction at the catalyst surface is extremely rapid and the mass transfer of hydrogen through the liquid is the rate-controlling step in this reaction.Since the total rate of exchange controlled by mass transfer may be related to the over-all mass transfer coefficient by Equation (8), the experimental data on the exchange are to be correlated in the similar way as given in the previous paper(10)) under the assumption that the resistance to the mass transfer consists of two separate parts: namely, the resistance in the liquid surrounding the bubbles and that in the liquid surrounding the suspended solid particles.The general equation derived from the above assumption:(22)was in a satisfactory agreement with the experimental data as shown in Figures 12 to 14. Equation (22) was also compared with the previous one, Equation (23), which had been derived from the experimental data on the hydrogenation of alpha-methylstyrene carried out by using a palladium-alumina catalyst. A fairly good agreement was obtained in the order of the magnitude of the total rate of exchange calculated by means of the two equations that were based upon entirely different chamical reactions which took place in different reactors having different sizes and different mechanical constructions and for which different kinds of catalysts were employed. In order to explore the possibility of employing a single or series of continuous stirred reactors for the commercial production of heavy water, the reactor volume required for obtaining some conversion was estimated for the operation at 100 atmospheres, assuming that the mass transfer remained the controlling step even at such a high pressure.