TERNARY DIFFUSION AND FLOW IN STEAM REFORMING CATALYSTS

The steady-state diffusion and flow of ternary mixtures of non-adsorbe d gases through porous substrates cut from commercial pellets of nicke l-based catalysts have been studied in a Wicke-Kallenbach cell. The ra tes of transport were obtained from the rates of flow of pure gases an d composition measurements were obtained by gas chromatography. In sev eral experiments a predetermined pressure difference across the cell w as applied so that the measured rates of transport reflected the effec t of transition-range diffusion and superimposed viscous flow, The eff ective binary diffusivities, Knudsen diffusivities, and the Darcy cons tant for viscous flow were estimated from the experimental measurement s. A knowledge of these parameters is a prerequisite for modelling of the reactive catalyst.