A nonequilibrium model (MECRES equations) for the simulation of catalytic distillation (CD) processes developed by Huang et al. (Chem. Eng. Sci. 1998, 53, 3489; 2000, 55, 5919) was improved so as to provide a more generalized three-phase model for the simulation and optimal design of a CD process. Instead of using the overall mass transfer coefficients for the reaction zone determined for our column, the vapor and liquid mass transfer equations in the MECRES model were modified to take into account the effect of multicomponent mass transfer according to multicomponent mass transfer theory. In addition, temperature gradients among the vapor, liquid, and solid (catalyst) phases were considered. The heat transfer rates in the heat balances were calculated according to multicomponent heat transfer theory. The CD process for the aldol condensation of acetone to diacetone alcohol was simulated using this improved model. The model predictions for the product yield and selectivity are in excellent agreement with experimental CD data. The simulation profiles of the temperature along the column and the composition in the reboiler are in better agreement with the experimental data than those simulated by the MECRES model. This improved model is more generalized and will be used to simulate the new CD process for the oligomerization of butenes developed in our laboratory.