Unusually active sodium ions in NaY zeolite for the SO2-induced cis–trans isomerization of cis-but-2-ene

Abstract

The presence of very active sodium ions in NaY zeolite for the SO₂-induced cis-trans isomerization of cis-but-2-ene has been suggested. The sodium ions were removed by exchange with multivalent cations at a low level of exchange. It was inferred that a sodium ion in the six-membered rings (site II or II*) containing one (or zero) aluminium ion or a delocalized sodium ion somewhere in the supercages is responsible for the active site. The presence of active univalent cations has been also confirmed in K-L and Na-mordenite.