Narrow-range ethoxylation of fatty alcohols promoted by a zirconium alkoxide sulfate catalyst

Zirconium dodecanoxide sulfate is a very active catalyst in promoting fatty alcohol narrow-range ethoxylation. The catalytic activity is initially very high but rapidly decreases after the addition of one mole of ethylene oxide per mole of substrate. This peculiar behavior makes it possible to obtain narrow-range ethoxylated products containing not more than two or three ethylene oxide units. Because the catalyst shows a very feeble Brönsted acidity, it must be concluded that its activity originates from the Lewis acidity. This acidity is strongly enhanced from the introduction of the sulfate group in the catalyst molecule, because of the strong electron-withdrawing effect of this group. A kinetic model was developed for explaining experimental results