Mass Transfer in Multiphase Reactions

Gas-liquid multiphase catalytic reactions require the reacting gas to be efficiently transferred to the liquid phase. This is then followed by the diffusion of the reacting species to the catalyst. These mass transfer processes depend on bubble hydrodynamics, temperature, catalyst activity, physical properties of the liquid phase like density, viscosity, solubility of the gas in the liquid phase and interfacial tension. 

In the case of a heterogeneous catalytic system consisting of gas, liquid, and solid catalyst, there are several factors that need to be considered for effective gas transfer (Fig. 3.4). These are  

Diffusion from bulk gas phase to gas-liquid interphase 

For homogeneous catalytic reactions the last two factors may be ignored. The rate of gas transfer into a liquid medium is given by Q = k,a(C f - C,), where ki is the mass transfer coefficient, a, the interfacial area between the gas and liquid, Cf and C are equilibrium concentrations of the gas in the liquid phase and the concentration of gas in the liquid, respectively. 

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