The Weisz-Prater criterion is given by the dimensionless number C_wp, expressed as:
C_wp = (r_obs * R^2) / (D_eff * C_s)
where:
r_obs is the observed reaction rate (mol/m3s) R is the characteristic length of the catalyst particle (m) D_eff is the effective diffusivity of the reactant in the catalyst (m2/s) C_s is the concentration of the reactant at the external surface of the catalyst (mol/m3)
