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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

preprint
submitted on 13.09.2019, 22:19 and posted on 17.09.2019, 12:04 by 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 = 2,5-dioxidobenzene-1,4-dicarboxylate) and 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.

Funding

U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Award DE-SC0019992

History

Email Address of Submitting Author

brbarnett@berkeley.edu

Institution

University of California, Berkeley

Country

USA

ORCID For Submitting Author

0000-0002-3113-7347

Declaration of Conflict of Interest

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.

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