Enhancing action of SO2 on the carboniogenic isomerization of butene over La-X zeolite

Abstract

The SO₂-enhanced isomerization of cis-but-2-ene over La-X zeolite has been characterised. The effect of pretreatment temperature of the zeolite on its activity for the double-bond shift of the olefin has suggested that the SO₂ adsorbed on the dehydroxylated sites of the zeolite enhance the carboniogenic activity of the zeolite. Infrared spectroscopic studies have shown that no new acidic hydroxyl groups are formed by the adsorption of SO₂. The enhanced production of pyridinium ions on the zeolite after the addition of SO₂ suggests that the enhanced activity of the zeolite can be ascribed to an increase in activity of the acidic hydroxyl groups caused by the electron-withdrawing effect of SO₂.