A distillation column is used to separate a mixture of benzene (A) and toluene (B) into two pure components. The feed to the column is a mixture of 80 mol% benzene and 20 mol% toluene. Design the distillation column to achieve 90 mol% purity of benzene in the overhead product. The following information is given:

1. The normal boiling points of benzene and toluene are 80.1°C and 110.6°C, respectively.
2. The relative volatility of the mixture is defined as the ratio of the vapor pressure of the more volatile component to the vapor pressure of the less volatile component. ? = P_A / P_B where P_A and P_B are the vapor pressures of benzene and toluene, respectively.
3. The relative volatility of the mixture at a given temperature is 2.2.