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Mechanism of selective benzene hydroxylation catalyzed by iron-containing zeolites

Snyder, Benjamin E. R. and Bols, Max L. and Rhoda, Hannah M. and Vanelderen, Pieter and Böttger, Lars H. and Braun, Augustin and Yan, James J. and Hadt, Ryan G. and Babicz, Jeffrey T. and Hu, Michael Y. and Zhao, Jiyong and Alp, E. Ercan and Hedman, Britt and Hodgson, Keith O. and Schoonheydt, Robert A. and Sels, Bert F. and Solomon, Edward I. (2018) Mechanism of selective benzene hydroxylation catalyzed by iron-containing zeolites. Proceedings of the National Academy of Sciences of the United States of America, 115 (48). pp. 12124-12129. ISSN 0027-8424. PMCID PMC6275498. doi:10.1073/pnas.1813849115.

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A direct, catalytic conversion of benzene to phenol would have wide-reaching economic impacts. Fe zeolites exhibit a remarkable combination of high activity and selectivity in this conversion, leading to their past implementation at the pilot plant level. There were, however, issues related to catalyst deactivation for this process. Mechanistic insight could resolve these issues, and also provide a blueprint for achieving high performance in selective oxidation catalysis. Recently, we demonstrated that the active site of selective hydrocarbon oxidation in Fe zeolites, named α-O, is an unusually reactive Fe(IV)=O species. Here, we apply advanced spectroscopic techniques to determine that the reaction of this Fe(IV)=O intermediate with benzene in fact regenerates the reduced Fe(II) active site, enabling catalytic turnover. At the same time, a small fraction of Fe(III)-phenolate poisoned active sites form, defining a mechanism for catalyst deactivation. Density-functional theory calculations provide further insight into the experimentally defined mechanism. The extreme reactivity of α-O significantly tunes down (eliminates) the rate-limiting barrier for aromatic hydroxylation, leading to a diffusion-limited reaction coordinate. This favors hydroxylation of the rapidly diffusing benzene substrate over the slowly diffusing (but more reactive) oxygenated product, thereby enhancing selectivity. This defines a mechanism to simultaneously attain high activity (conversion) and selectivity, enabling the efficient oxidative upgrading of inert hydrocarbon substrates.

Item Type:Article
Related URLs:
URLURL TypeDescription Information CentralArticle
Bols, Max L.0000-0002-4576-5969
Yan, James J.0000-0001-5516-3446
Hadt, Ryan G.0000-0001-6026-1358
Hu, Michael Y.0000-0002-3718-7169
Zhao, Jiyong0000-0002-0777-3626
Alp, E. Ercan0000-0002-4803-8863
Solomon, Edward I.0000-0003-0291-3199
Additional Information:© 2018 National Academy of Sciences. Published under the PNAS license. Edited by Alexis T. Bell, University of California, Berkeley, CA, and approved October 18, 2018 (received for review August 22, 2018). PNAS published ahead of print November 14, 2018. B.E.R.S. acknowledges support from National Science Foundation Graduate Research Fellowship Program Grant DGE-11474 and from the Munger, Pollock, Reynolds, Robinson, Smith & Yoedicke Stanford Graduate Fellowship. M.L.B. acknowledges the Research Foundation – Flanders for funding of his stay at Stanford University (Grant V417018N). R.G.H. acknowledges a Gerhard Casper Stanford Graduate Fellowship. P.V. acknowledges Research Foundation – Flanders (Grant 12L0715N) and Katholieke Universiteit Leuven for his postdoctoral fellowships and travel grants during his stay at Stanford University. Funding for this work was provided by National Science Foundation Grant CHE-1660611 (to E.I.S.) and Research Foundation – Flanders Grant G0A2216N (to B.F.S.). Use of the Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, is supported by the US Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences under Contract DE-AC02-76SF00515. The SSRL Structural Molecular Biology Program is supported by the DOE Office of Biological and Environmental Research and by National Institutes of Health, National Institute of General Medical Sciences Grant P41GM103393 (to K.O.H.). This research used resources of the APS, a US DOE Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract DE-AC02-06CH11357. Author contributions: B.E.R.S., R.A.S., B.F.S., and E.I.S. designed research; B.E.R.S., M.L.B., H.M.R., P.V., L.H.B., A.B., J.J.Y., R.G.H., J.T.B., M.Y.H., J.Z., and E.E.A. performed research; B.E.R.S., B.H., K.O.H., R.A.S., B.F.S., and E.I.S. analyzed data; and B.E.R.S., R.A.S., B.F.S., and E.I.S. wrote the paper. The authors declare no conflict of interest. This article is a PNAS Direct Submission. This article contains supporting information online at
Funding AgencyGrant Number
NSF Graduate Research FellowshipDGE-114747
Stanford UniversityUNSPECIFIED
Fonds Wetenschappelijk Onderzoek (FWO)V417018N
Fonds Wetenschappelijk Onderzoek (FWO)12L0715N
Katholieke Universiteit LeuvenUNSPECIFIED
Fonds Wetenschappelijk Onderzoek (FWO)G0A2216N
Department of Energy (DOE)DE-AC02-76SF00515
Department of Energy (DOE)DE-AC02-06CH11357
Subject Keywords:zeolites; spectroscopy; catalysis
Issue or Number:48
PubMed Central ID:PMC6275498
Record Number:CaltechAUTHORS:20181115-101001408
Persistent URL:
Official Citation:Mechanism of selective benzene hydroxylation catalyzed by iron-containing zeolites. Benjamin E. R. Snyder, Max L. Bols, Hannah M. Rhoda, Pieter Vanelderen, Lars H. Böttger, Augustin Braun, James J. Yan, Ryan G. Hadt, Jeffrey T. Babicz, Michael Y. Hu, Jiyong Zhao, E. Ercan Alp, Britt Hedman, Keith O. Hodgson, Robert A. Schoonheydt, Bert F. Sels, Edward I. Solomon. Proceedings of the National Academy of Sciences Nov 2018, 115 (48) 12124-12129; DOI: 10.1073/pnas.1813849115
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:90913
Deposited By: Tony Diaz
Deposited On:15 Nov 2018 19:00
Last Modified:16 Nov 2021 03:36

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