N.m.r. studies of ethylene adsorption by sodium and calcium forms of zeolite Y

Abstract

The n.m.r. spectrum of ethylene adsorbed on NaY, CaY-72, and CaY-87 is dependent on the coverage. At low coverages of ethylene, specific adsorption at the calcium ions gives rise to a broad resonance. As the coverage increases, non-specific adsorption becomes predominant and the line-width decreases markedly. At very high coverages ethylene adsorbed on the calcium zeolites under-goes catalytic oligomerization and polymerization, as evidenced by the growth of bands due to methyl groups and to polyethylene. Except at very low coverages, very little variation of linewidth is observed on the NaY zeolite (or on NaX).