Synthesis of propyl acetate by sulfated zirconia: kinetics and mechanism modeling

In this study, the kinetics of the esterification of acetic acid and n-propanol catalyzed by sulfated zirconia was investigated for the first time. The effect of different temperatures (60–80 °C), n-propanol to acetic acid molar ratios (1:1–3:1), catalyst loadings (5–10 wt%), and external and internal mass transfers on the acetic acid conversions was evaluated in a batch reactor. The pseudo-homogeneous, Langmuir–Hinshelwood, and Eley–Rideal models were adjusted to the experimental data to determine the reaction mechanism. The reusability and performance of the catalyst were also reported. The results demonstrated that increasing temperature, reactants molar ratio, and catalyst loadings positively affected the formation of propyl acetate. The Eley–Rideal with acetic acid adsorbed model presented the most suitable fit, suggesting that the surface reaction at the catalyst acid sites was the limiting step in the reaction mechanism. The estimated enthalpy of the reaction indicated a slightly endothermic process. The reusability of the catalyst showed a loss of activity after successive reaction cycles. The sulfated zirconia catalyst was effective for the studied esterification reaction.