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Butenes manuscript SUBMIT.pdf (4.89 MB)
Thermodynamic Separation of 1-Butene from 2-Butene in Metal–Organic Frameworks with Open Metal Sites
Preprints are manuscripts made publicly available before they have been submitted for formal peer review and publication. They might contain new research findings or data. Preprints can be a draft or final version of an author's research but must not have been accepted for publication at the time of submission.
submitted on 13.09.2019 and posted on 17.09.2019by Brandon Barnett, Surya Parker, Maria
V. Paley, Miguel I. Gonzalez, Naomi Biggins, Julia Oktawiec, Jeffrey R. Long
Most C4 hydrocarbons are obtained as
byproducts of ethylene production or oil refining, and complex and
energy-intensive separation schemes are required for their isolation.
Substantial industrial and academic effort has been expended to develop more cost-effective adsorbent- or membrane-based approaches to purify
commodity chemicals such as 1,3-butadiene, isobutene, and 1-butene, but the
very similar physical properties of these C4 hydrocarbons makes this
a challenging task. Here, we examine the adsorption behavior of 1-butene, cis-2-butene and trans-2-butene in the metal–organic frameworks M2(dobdc)
(M = Mn, Fe, Co, Ni; dobdc2− =
M2(m-dobdc) (m-dobdc4− =
4,6-dioxido-1,3-benzenedicarboxylate), which all contain
a high density of coordinatively-unsaturated M2+ sites. We find that
both Co2(m-dobdc) and Ni2(m-dobdc) are able to separate 1-butene
from the 2-butene isomers, a critical industrial process that relies largely on
energetically demanding cryogenic distillation. The origin of 1-butene
selectivity is traced to the high charge density retained by the M2+
metal centers exposed within the M2(m-dobdc) structures, which results in a reversal of the cis-2-butene selectivity typically observed
at framework open metal sites. Selectivity for 1-butene adsorption under
multicomponent conditions is demonstrated for Ni2(m-dobdc) in both the gaseous and liquid phases via breakthrough and batch adsorption experiments.
The authors declare the following competing financial interest(s): J.R.L. has a financial interest in Mosaic Materials, Inc. and Flux Technology, Inc., which are developing metal–organic framework adsorbents and metal–organic framework membranes, respective-ly, for gas separations. The University of California, Berkeley has filed a provisional patent application on the work reported herein, on which B.R.B. and J.R.L. are listed as inventors.