EFFECT OF LITHIUM ADDITION UPON GAMMA-AL2O3 FOR ISOPROPANOL DEHYDRATION

The effect of lithium addition to gamma-Al2O3 on the acidity and on th e catalytic behaviour in the isopropanol dehydration reaction is studi ed. Results show that there is an important blocking or poisoning effe ct of lithium on the Lewis Al3+ sites of the alumina surface; these si tes play an important role in the isopropanol dehydration reaction to di-isopropylether and propylene. The diisopropylether formation is dra stically reduced by lithium addition, while the propylene formation ca n be maintained, even at a high lithium content, by increasing the rea ction temperature. Results are interpreted by considering that the eth er would be produced by a concerted mechanism (E(2)), and the olefin f ormation could be carried out by both E(2) or E(1) mechanisms.