INTERFACIAL STATES IN FIXED-BED REACTORS

Realistic analysis of fixed-bed reactor experiments requires calculation of interfacial states. Laboratory reactors are typically much shorter than full-scale units and operate with smaller axial velocities, producing significant departures of the iiiterfacial states from the measurable values in the mainstream fluid and consequent difficulties in establishing catalytic reaction models. Interfacial temperatures and partial pressures were calculated with jn and jo- and used in estimating reaction model parameters, in a landmark paper by Yoshida. Ramaswami. and Hougen (1962). Here we give an updated analysis of interfacial states in fixed-bed reactor operations for improved treatment of catalytic reaction data. 

For a single chemical reaction in a catalyst particle at steady state, mass balances give the expressions 

The preceding five equations may be solved by successive substitution, beginning with the assumption Tq = Tb to initiate a rapidly convergent iteration process. 

we predict the interfacial gas composition on the chosen particle, using a detailed multicomponent diffusion law. For this calculation we use the array 

Kinetic theory (Maxwell 1860. 1868 Stefan 1871. 1872 Curtiss and Hirschfelder 1949) gives the elements of [A] as follows in the moderate-density gas region  

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