The authors acknowledge Fundação para a Ciência e Tecnologia
(FCT, Portugal) and ERDF under Programme PT2020 to 1) José A.
C. Silva under Project ref. POCI01-0145-FEDER-016517 (PTDC/QEQPRS/
3599/2014), 2) CIMO (UID/AGR/00690/2020), (3) LSRE-LCM
(POCI-01-0145-FEDER006984), and (4) Adriano Henrique from the individual
research grant SFRH/BD/148525/2019. The authors also acknowledge
Ivan M. C. Pinto for the measurement of the single component
isotherms shown in Figure S20 in the Supporting Information, Kristin Gleichmann
and Chemiewerk Bad Koestritz GmbH for kindly providing the
binder-free beads of zeolite 5A used in this work, Ben Slater from IMAP for
the proofreading of the manuscript, and Dr. Jong San Chang from KRICT
for his helpful discussions.The computational work was performed using
HPC resources from GENCI-CINES (Grant A0100907613).
Zeolites and metal-organic frameworks (MOFs) are considered as
“competitors” for new separation processes. The production of high-quality
gasoline is currently achieved through the total isomerization process that
separates pentane and hexane isomers while not reaching the ultimate goal of
a research octane number (RON) higher than 92. This work demonstrates
how a synergistic action of the zeolite 5A and the MIL-160(Al) MOF leads to a
novel adsorptive process for octane upgrading of gasoline through an efficient
separation of isomers. This innovative mixed-bed adsorbent strategy
encompasses a thermodynamically driven separation of hexane isomers
according to the degree of branching by MIL-160(Al) coupled to a steric
rejection of linear isomers by the molecular sieve zeolite 5A. Their adsorptive
separation ability is further evaluated under real conditions by sorption
breakthrough and continuous cyclic experiments with a mixed bed of shaped
adsorbents. Remarkably, at the industrially relevant temperature of 423 K, an
ideal sorption hierarchy of low RON over high RON alkanes is achieved, i.e.,
n-hexane ≫n-pentane ≫2-methylpentane > 3-methylpentane⋙
2,3-dimethylbutane > isopentane ≈ 2,2-dimethylbutane, together with a
productivity of 1.14 mol dm−3 and a high RON of 92, which is a leap-forward
compared with existing processes.
