Sodalite ion exchange in polyethylene oxide oligomer solvents

Abstract

Traditional aqueous methods of cation exchange in zeolites present complications for the exchange of catalytically important transition metal and rare earth ions. Ethylene oxide-based oligomers (polyethylene glycol, polyethylene glycol methyl ether, diglyme, tetraglyme, and polypropylene glycol) are being investigated as alternative media for zeolite ion exchange. Reactions using lithium as the exchanging species indicate that these solvents can be used successfully for ion exchange in hydrosodalite and dehydrated sodalite zeolites, enabling these reactions to be carried out in the absence of water. The oligomer solutions allow for the exchange of 88% to 99% of sodium ions for lithium ions after 3–5 exchange cycles at 100 °C in both hydrosodalite and dehydrated sodalite as determined by unit cell parameters and elemental analysis.