Thermal stability and water effect on ion-exchange resins in ethyl octyl ether production at high temperature

Thermal stability and water inhibition effects were studied at 150 and 190 degrees C on the chlorinated acidic polystyrene-divinylbenzene resins Amberlyst 70, Amberlyst XE804 and Purolite CT482, and the non-chlorinated one Dowex 50Wx2. Catalytic activity in the reaction between ethanol and 1-octanol to form ethyl octyl ether (EOE) was monitored for 70 h in a continuous fixed-bed reactor. Leaching of sulfonic groups at 190 degrees C was found to be negligible for Purolite CT482 and Amberlyst 70, but it was significant for Amberlyst XE804 and Dowex 50Wx2. The activity decay to a steady EOE reaction rate on Purolite CT482 and Amberlyst 70 has been ascribed to the reaction rate inhibition by the formed water. However, water adsorption on the catalyst also modified the resin morphology during the course of the reaction. Adsorbed water swelled the gel-phase and more acid sites became accessible for 1-octanol molecules. As a result, the activity decay of EOE and the longer byproduct di-n-octyl ether syntheses was smaller than that of the shorter one diethyl ether. (C) 2013 Elsevier B.V. All rights reserved.