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Title: Mechanism of selective benzene hydroxylation catalyzed by iron-containing zeolites

Abstract

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) andmore » selectivity, enabling the efficient oxidative upgrading of inert hydrocarbon substrates.« less

Authors:
; ; ; ; ; ; ORCiD logo; ; ; ORCiD logo; ; ; ; ; ; ; ORCiD logo
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1482162
Grant/Contract Number:  
AC02-06CH11357
Resource Type:
Journal Article: Published Article
Journal Name:
Proceedings of the National Academy of Sciences of the United States of America
Additional Journal Information:
Journal Name: Proceedings of the National Academy of Sciences of the United States of America Journal Volume: 115 Journal Issue: 48; Journal ID: ISSN 0027-8424
Publisher:
Proceedings of the National Academy of Sciences
Country of Publication:
United States
Language:
English

Citation Formats

Snyder, Benjamin E. R., Bols, Max L., Rhoda, Hannah M., Vanelderen, Pieter, Böttger, Lars H., Braun, Augustin, Yan, James J., Hadt, Ryan G., Babicz, Jr., Jeffrey T., Hu, Michael Y., Zhao, Jiyong, Alp, E. Ercan, Hedman, Britt, Hodgson, Keith O., Schoonheydt, Robert A., Sels, Bert F., and Solomon, Edward I. Mechanism of selective benzene hydroxylation catalyzed by iron-containing zeolites. United States: N. p., 2018. Web. doi:10.1073/pnas.1813849115.
Snyder, Benjamin E. R., Bols, Max L., Rhoda, Hannah M., Vanelderen, Pieter, Böttger, Lars H., Braun, Augustin, Yan, James J., Hadt, Ryan G., Babicz, Jr., Jeffrey T., Hu, Michael Y., Zhao, Jiyong, Alp, E. Ercan, Hedman, Britt, Hodgson, Keith O., Schoonheydt, Robert A., Sels, Bert F., & Solomon, Edward I. Mechanism of selective benzene hydroxylation catalyzed by iron-containing zeolites. United States. doi:10.1073/pnas.1813849115.
Snyder, Benjamin E. R., Bols, Max L., Rhoda, Hannah M., Vanelderen, Pieter, Böttger, Lars H., Braun, Augustin, Yan, James J., Hadt, Ryan G., Babicz, Jr., Jeffrey T., Hu, Michael Y., Zhao, Jiyong, Alp, E. Ercan, Hedman, Britt, Hodgson, Keith O., Schoonheydt, Robert A., Sels, Bert F., and Solomon, Edward I. Wed . "Mechanism of selective benzene hydroxylation catalyzed by iron-containing zeolites". United States. doi:10.1073/pnas.1813849115.
@article{osti_1482162,
title = {Mechanism of selective benzene hydroxylation catalyzed by iron-containing zeolites},
author = {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, Jr., 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.},
abstractNote = {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.},
doi = {10.1073/pnas.1813849115},
journal = {Proceedings of the National Academy of Sciences of the United States of America},
number = 48,
volume = 115,
place = {United States},
year = {Wed Nov 14 00:00:00 EST 2018},
month = {Wed Nov 14 00:00:00 EST 2018}
}

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