SEPARATION OF 2,6-DIMETHYLNAPHTHALENE FROM A MIXTURE OF ITS ISOMERS USING LITHIUM-INCORPORATED ZEOLITE-Y SYNTHESIZED BY RAPID CRYSTALLIZATION METHOD

Lithium-incorporated zeolite Ys (Li-NaYs) were directly synthesized un der a hydrothermal condition from a gel mixture of Li2O . Na2O . SiO2 . Al2O3 . H2O. It was confirmed by XRD, NMR and elementary analysis, t hat lithium ions could be introduced onto the ion sites of zeolite Y d uring the course of crystallization. Usage of lithium citrate as the l ithium source is the indispensable factor to achieve the synthesis. In adsorption of mixtures of 2,6-dimethylnaphthalene and its isomers, Li -NaYs exhibited greater adsorptive capacities and higher adsorption se lectivities to 2,6-dimethylnaphthalene than NaY. Direct hydrothermal s ynthesis of Li-incorporated zeolite Y prevents the blockage of pore op enings and/or channels during lithium ion-exchange. Furthermore, the d ifference in adsorptive properties between Li-NaY and Li ion-exchanged NaY is due to Li ions being introduced onto the S-1 ion sites, which can hardly be ion-exchanged, during the hydrothermal synthesis.