title: Separation of C(5)-hydrocarbons on microporous materials: complementary performance of MOFs and zeolites.
abstract: This work studies the liquid-phase separation of the aliphatic C(5)-diolefins, mono-olefins, and paraffins, a typical feed produced by a steam cracker, with a focus on the seldomly studied separation of the C(5)-diolefin isomers isoprene, trans-piperylene, and cis-piperylene. Three adsorbents are compared: the metal-organic framework MIL-96, which is an aluminum 1,3,5-benzenetricarboxylate, and two zeolites with CHA and LTA topology. All three materials have spacious cages that are accessible via narrow cage windows with a diameter of less than 0.5 nm. The mechanisms determining adsorption selectivities on the various materials are investigated. Within the diolefin fraction, MIL-96 and chabazite preferentially adsorb trans-piperylene from a mixture containing all three C(5)-diolefin isomers with high separation factors and a higher capacity compared to the reference zeolite 5A due to a more efficient packing of the trans isomer in the pores. Additionally, chabazite is able to separate cis-piperylene and isoprene based on size exclusion of the branched isomer. This makes chabazite suitable for separating all three diolefin isomers. Its use in separating linear from branched mono-olefins and paraffins is addressed as well. Furthermore, MIL-96 is the only material capable of separating all three diolefin isomers from C(5)-mono-olefins and paraffins. Finally, the MOF [Cu(3)(BTC)(2)] (BTC = benzene-1,3,5-tricarboxylate) is shown to be able to separate C(5)-olefins from paraffins. On the basis of these observations, a flow scheme can be devised in which the C(5)-fraction can be completely separated using a combination of MOFs and zeolites.
authors.affiliation: Centre for Surface Chemistry and Catalysis, Katholieke Universiteit Leuven, Arenbergpark 23, B-3001 Leuven.
authors.forename: Michael
authors.initials: M
authors.lastname: Maes
authors.forename: Luc
authors.initials: L
authors.lastname: Alaerts
authors.forename: Frederik
authors.initials: F
authors.lastname: Vermoortele
authors.forename: Rob
authors.initials: R
authors.lastname: Ameloot
authors.forename: Sarah
authors.initials: S
authors.lastname: Couck
authors.forename: Vincent
authors.initials: V
authors.lastname: Finsy
authors.forename: Joeri F M
authors.initials: JF
authors.lastname: Denayer
authors.forename: Dirk E
authors.initials: DE
authors.lastname: De Vos