Adsorption and separation of β, β-dimethylnaphthalene isomers on various large-pore zeolites having 12-oxygen-member-ring structure

Different types of large-pore zeolites with 12-oxygen-member-ring structure were synthesized by a hydrothermal method and used for adsorbing and separating mixtures of β,β-DMN isomers. Among all the zeolites tested, zeolites Y and BEA which possess three-dimensional pore channels were found to adsorb β,β-DMN isomers effectively. On the other hand, SAPO-5, Mordenite and ZSM-12 scarcely adsorbed β,β-DMN molecules because of the large diffusional resistance offered by their one-dimensional pore channels. The adsorptive capacity of zeolite BEA was found to decrease while the adsorption selectivity increase by transition metals isomorphous substitution. Adsorption simulations by the Monte Carlo method indicate that the differences in the adsorption of β,β-DMN molecules on metal-incorporated zeolite BEAs may be attributed to their different adsorption energies.