Packed-bed reactor experimentation is a key tool used in order to formulate chemical kinetics. The chemical species equation and overall methodology are described for a one-dimensional pseudo-homogeneous packed-bed reactor model useful for experimental calibration of chemical kinetics. Over the history of simulation development for this equation there exist numerous different effective diffusivity correlations. The included historical review and parametric study of these correlations help to determine the correct choice based on numerical simplicity and model outcomes. A subsequent review paper describes the energy equation and effective thermal conductivity correlations while coming to a generalized conclusion regarding modeling efforts.