In this work, we have derived a general dynamic model for a fixed-bed reactor involving combined reaction kinetics and deactivation kinetics. Catalyst deactivation was treated as a surface reaction among the other reactions. The evolved system of partial differential equations (PDEs) was solved numerically by the method of lines. Several rival deactivation mechanisms for ferrierite catalyst in skeletal isomerization of I-pentene were investigated. The model assuming two adsorbed n-pentene molecules as surface species forming coke explained the experimental results best.