Permeation of Hexane Isomers through an MFI Membrane

The pervaporation tests for n -hexane, 2-methylpentane (2-MP), and 2,3-dimethylbutane (2,3-DMB) were performed using an MFI-type zeolitic membrane at 303 K. In the unary systems, those fluxes followed the order n -hexane ≫ monobranched hexane (2-MP), > dibranched hexane (2,3-DMB). The ideal selectivities of n -hexane/2-MP and n -hexane/2,3-DMB were 37 and 50, respectively. n -Hexane preferentially permeated in the measurements of a binary mixture of n -hexane/2-MP and n -hexane/2,3-DMB. The feed composition dependence in separating n -hexane/2,3-DMB binary mixtures was studied. The separation factor for the 50/50 n -hexane/2,3-DMB mixture exceeded 120, which was much greater than 54 in the 50/50 n -hexane/2-MP system. When the feed concentration of n -hexane was 10 mol %, the separation factor α( n -hexane/2,3-DMB) at the steady state was as high as 270. n -Hexane effectively inhibited the permeation of 2,3-DMB, even when the concentration of n -hexane was very small.