Thiele modulus cylindrical catalyst pellets

No practical catalyst pellet can be described by the geometry of the wafer, yet it will be shown that eqn. (6), albeit with a slightly different interpretation of the Thiele modulus, 0, is of practical value. For a cylindrical catalyst pellet (a shape often used in practice) of radius r and sealed at its flat ends... 

N.B. For a cylindrical pellet, L (i.e., Le) in the Thiele modulus is RI2> where R is the radius. 8-20 Suppose experiments were conducted to characterize the performance of a catalyst for a certain reaction (A - products) that is first-order. The following data refer to experiments with... 

The parameter ag= 1, 2, 3, for flat plate, cylindrical, or spherical geometry respectively. In the Thiele modulus, the character distance L = L (a half of thickness of catalyst pellet) for flat plate, L = r<, (the radius of catalyst pellet) for cylindrical, or spherical geometry. 

Metal deposition occurs with sharp gradients within a catalyst pellet, usually concentrated on the outside of catalyst pellets forming a U-shaped distribution. Sato et at [3] related this metal deposition with simultaneous diffusion and reaction, and suggested a value of 8 for the Thiele modulus in a slab geometry. Tamm [4] suggested that this distribution can be characterized by a theta factor defined in a cylindrical geometry as... 

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