Kinetic study of the esterification of acetic acid and n-amyl alcohol catalyzed by H3PW6Mo6O_(40) immobilized on silylated palygorskite

摘要

Modified palygorskite with 3-aminopropyltriethoxysilane (KH550) was used as the carrier to immobilize a 12-heteropolyacid of molybdenum and tungsten. The prepared catalyst was characterized by FT-IR, XRD, XPS, BET and TG. The kinetic behavior of heterogeneous esterification of acetic acid with n-amyl alcohol over the catalyst was investigated. The nonideality of the liquid phase was considered by using activities instead of molar fractions. The activity coefficients have been calculated by using the group contribution method UNIFAC. The experimental results showed that the reaction is controlled by chemical steps rather than external and internal mass transfer steps. Experimental data fitted well to the pseudo-homogeneous (PH) model. The temperature dependency of the equilibrium constant and the reaction rate constant were found. It indicated that the heat of reaction is 7.33 kJ mol~(-1). The new rate equation gave a good fit to the data and was able to describe the behavior of the system.