Influence of the isobutene/methanol ratio and of the methyl tert-butyl ether content on the reaction rate of the synthesis of methyl tert-butyl ether

The forward reaction rate constant of the MtBE synthesis was determined for different reaction mixture compositions. The forward rate constant decreases continuously with increasing isobutene/methanol ratio, while an increase in reaction rate constant is observed with an increasing amount of MtBE in the reaction mixture. This effect has not been reported before. These so-called solvent effects could be explained by using a pseudo-homogeneous reaction rate model in combination with the transition state theory. Not only changes in activity of the initial state (reactants and ion exchange resin) but also changes in the activity of the activated complex turned out to contribute to the solvent effects observed. Changes in the rate caused by changes in the activity of the activated complex are not accounted for in the existing homogeneous and heterogeneous models such as the Langmuir-Hinshelwood model.