Unlike the amine catalyst data of Figure 2-6, the experimental data in Figure 2-8 shows a non-direct proportional relationship between reaction rate and amount of catalyst loading. Low concentration tin catalysts have little catalysis effect and the increment in high concentration area doesn’t make a significant difference since the reaction is already over catalyzed. Therefore, a catalyst poisoning mechanism was introduced into this model. Equation 2-5 was used to calculate the effective catalyst amount based on different initial catalyst loadings. Table 2-4 presents the actual effective catalyst content respect to different initial catalyst loadings. An objective function (OF) was introduced to minimize the difference of equilibrium constants between the left side and the right side in Equation 2-5. Figure 2-9 shows the relationship between catalyst loading and reaction rate constant at the beginning of the reaction under tin catalyzed condition (Fomrez®UL-22)