Methanol to dimethyl ether conversion over a ZSM-5 catalyst: Intrinsic kinetic study on an external recycle reactor

The kinetic measurements were performed at a total pressure of 1 bar, partial pressure of methanol (pm) from 0.3 bar to 1 bar, temperatures from 140 °C to 190 °C, weight hourly space velocities (WHSV) from 15 h−1 to 100 h−1, and two different amounts of water content (0 and 30 wt%). Experiments at different methanol concentrations in the feed revealed a weak dependence of the rate on pm. It could be determined to our knowledge for the first time that the reaction order with respect to water is negative, in the range of −0.80 to 0, thus providing quantitative proof of the inhibition effect of water on the methanol dehydration reaction rate over ZSM-5 catalysts, while DME showed no effect.