Separation of branched hexane isomers using zeolite BEA for the octane improvement of gasoline pool

Abstract

A sorption study of single, binary, ternary and quaternary mixtures of hexane (C 6 ) isomers n-hexane (nHEX), 3-methylpentane (3MP), 2,3-dimethylbutane (23DMB) and 2,2-dimethylbutane (22DMB) was performed in commercial pellets of zeolite BETA (BEA structure), covering the temperature range between 423 K and 523 K and partial pressures up to 0.3 bar. From these data, single and multicomponent adsorption equilibrium isotherms were collected. An extended tri-site Langmuir model (TSL) was developed to interpret accurately the equilibrium data, and a dynamic adsorption model was developed and tested predicting with a good accuracy the behaviour of multicomponent fixed bed experiments. At the partial pressures studied, the sorption hierarchy in the zeolite BETA is: nHEX>3MP>23DMB>22DMB. BEA structure demonstrates a significant selectivity between C 6 isomers, especially at low coverage, giving a good perspective regarding future work.