Solid, Porous Material for Improved Efficiency of Gasoline Production
and Low-Cost and Non-Toxic Enhancement of Gasoline Quality
Starting feedstock with
varied percentages of
hexane isomers
Reactor generates
a mixture of 10-30 %
of each isomer
Gasoline with a higher
octane number than if only
the linear isomer (octane
number 30) were removed
Octane number
Octane number
Top: Schematic of the proposed hexane isomer separation. The
numbers next to the hexane isomers are octane numbers.
Bottom Right: The crystal structure of Fe2(BDP)3 showing
Fe(orange), N(blue), and C(gray) atoms, viewing along the c-axis.
Bottom Left: Results of a breakthrough experiment in which a
mixture of hexane isomers were moved through a bed of
Fe2(BDP)3. The more valuable dimethylbutane isomers elute first
and are therefore possible to separate.
Herm, Z. R.; Wiers, B, M.; Mason, J. A.; van Baten, J. M.;
Hudson, M. R.; Zajdel, P.; Brown, C. M.; Masciocchi, N.;
Krishna, R.; Long, J. R. Science 2013, 340, 960-964.
Work was performed at University of California and supported by the Center
for Gas Separations Relevant to Clean Energy Technologies EFRC.
Scientific Achievement
A metal-organic framework (MOF) material was prepared
that shows excellent performance for separation of
isomers of pentane, hexane, and heptane. These
hydrocarbons are components of gasoline and have
drastically varying value in the petroleum industry due to
their wide-ranging octane numbers. Currently, some lowquality isomers end up in gasoline because they cannot
be removed efficiently.
Significance and Impact
The discovery could render the refining of petroleum
more efficient and, as a result, save substantial energy
worldwide. Further, if fewer low octane number
hydrocarbons were added to gasoline, fewer toxic
additives would be required to boost quality – benefiting
both human health and the environment.
Research Details
In petroleum refineries, hydrocarbons with 5-7 carbons
are generated as a mixture of their isomers. The linear
isomers are removed via sieving, and monobranched
isomers are added to gasoline despite their low octane
numbers compared to dibranched isomers.
A solid iron based adsorbent featuring triangular channels
can separate the dibranched isomers from the
monobranched and linear, without energetically costly
temperature or pressure constraints.