Catalytic Stefan-Maxwell equation

At present two models are available for description of pore-transport of multicomponent gas mixtures the Mean Transport-Pore Model (MTPM)[4,5] and the Dusty Gas Model (DGM)[6,7]. Both models permit combination of multicomponent transport steps with other rate processes, which proceed simultaneously (catalytic reaction, gas-solid reaction, adsorption, etc). These models are based on the modified Maxwell-Stefan constitutive equation for multicomponent diffusion in pores. One of the experimentally performed transport processes, which can be used for evaluation of transport parameters, is diffusion of simple gases through porous particles packed in a chromatographic column. 

Equations (10.9)-(10.12) can also be written for the vapor phase, for which [Fg ] is usually taken as unit matrix. The binary mass-transfer coefficients can be extracted from suitable binary mass-transfer correlations, using the appropriate Maxwell-Stefan diffusion coefficients - j. A number of mass-transfer correlations for both catalytic and noncatalytic column internals are available in the literature (see, e.g., [42, 50, 57, 70, 72-74]). 

In catalytic cracking the gas oil feed reacts to much lighter compounds, which causes a high convective flux from the catalyst surface to the bulk of the fluid. Therefore Fick s diffusion law is not applicable (assumes equimolar counter-diffusion) in the mass transfer calculations and as a result rigorous Maxwell-Stefan equations must be used. Due to the... 

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