Title: Tandem Aromatization of Oxygenated Furans by Framework Zinc In Zeolites. A Computational Study

Abstract

We have performed electronic structure calculations to characterize the active site of the zeolite CIT-6 (isomorphically substituted Zn-Beta) and to study the Diels–Alder dehydrative aromatization of methyl-5-(methoxymethyl)-furoate (MMFC) and of the dimethyl ester of 2,5-furan-dicarboxylic acid (DMFDC) with ethylene. Three types of active sites have been investigated: a site where the framework charge was balanced by two protons (Z0); a site with an H⁺ and a Li⁺ as counter-cations (Z₁); and an active site with two Li⁺ counter-cations (Z₂). Using NBO and Bader analysis, we conclude that Zn incorporation into the zeolite framework is not through covalent bonding to framework oxygen atoms but rather is through ionic bonding. Despite the ionic character of the active site and the generally strong Lewis acidic nature of Zn(II) cations, we find no catalysis of the Diels–Alder reaction for the two furans tested. On the other hand, the dehydration of the Diels–Alder cycloadduct can be either Brønsted or Lewis acid catalyzed depending on the active site type. The Z₀-type sites are found to be more active than the Z₁- and Z₂-type sites. Furthermore, the Z₀-type sites exhibit both Lewis and Brønsted acid characters with similar catalytic activities. In full agreement with experiment, we findmore » that the conversion of MMFC to (4-methoxymethyl) benzenecarboxylate via Diels–Alder dehydrative aromatization is easier than the conversion of DMFDC to dimethyl terephthalate as the two electron withdrawing groups in DMFDC stabilize the corresponding cycloadduct against dehydration.« less

Authors:

Patet, Ryan E.  ^[1];

• Search DOE PAGES for author "Patet, Ryan E."
• Search DOE PAGES for ORCID "0000-0001-6066-2995"

Caratzoulas, Stavros  ^[2];

• Search DOE PAGES for author "Caratzoulas, Stavros"
• Search DOE PAGES for ORCID "0000-0001-9599-4199"

Vlachos, Dionisios G.  ^[1]

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• Search DOE PAGES for ORCID "0000-0002-6795-8403"

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+ Show Author Affiliations

1. Univ. of Delaware, Newark, DE (United States). Dept. of Chemical and Biomolecular Engineering, and Catalysis Center for Energy Innovation (CCEI)
2. Univ. of Delaware, Newark, DE (United States). Catalysis Center for Energy Innovation (CCEI)

Publication Date:

Fri Sep 29 00:00:00 EDT 2017

Research Org.:

Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). National Energy Research Scientific Computing Center (NERSC); Energy Frontier Research Centers (EFRC) (United States). Catalysis Center for Energy Innovation (CCEI)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1482393

Grant/Contract Number:  

SC0001004; AC02-05CH11231

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Physical Chemistry. C

Additional Journal Information:

Journal Volume: 121; Journal Issue: 40; Journal ID: ISSN 1932-7447

Publisher:

American Chemical Society

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY