Abstract

Autoxidation chemistry catalyzed by cobalt(II) acetate is an industrial pathway for converting hydrocarbons into oxygenated compounds and has promising potential applications in plastic waste deconstruction. However, the chemical properties of the Co acetate-based catalysts and their roles in the reaction mechanism are poorly understood, and as a result, attempts to redesign the autoxidation chemical process for novel applications lack clear direction. In this work, we investigate the structure and electronic properties of a series of multinuclear Co(III) compounds that have been proposed as active participants in catalytic autoxidation. Through a combination of X-ray spectroscopic measurements [Co K-edge X-ray absorption spectroscopy (XAS), extended X-ray absorption fine structure (EXAFS), Kβ X-ray emission spectroscopy (XES), and high-energy resolution fluorescence detection (HERFD) XAS] and theoretical methods, we characterize the interactions of Co with acetate and hydroxyl ligands in these compounds. Here we show that the substitution of acetate ligands with hydroxyls in these compounds causes an increase in the electron density on Co, driven by the loss of a π back-bonding interaction between Co and acetate and an increase in electron donation to Co from the hydroxyl ligands. We further classify the bonding between Co and acetate based on the orbital overlap and showmore » that the experimental absorption and emission spectra are well-described by the resulting molecular orbitals. Finally, we predict the impacts of acetate/hydroxyl ligand exchange on autoxidation catalytic properties, showing that the reaction free energies for key Co oxidation and reduction steps are extremely sensitive to metal-ligand bonding interactions and thus have meaningful impacts on overall reactivity. The results of this study constitute an important set of design criteria for developing novel homogeneous autoxidation catalysts.« less

Authors:

Asundi, Arun S.  ^[1];

• Search DOE PAGES for author "Asundi, Arun S."
• Search DOE PAGES for ORCID "0000-0003-0333-6784"

Ebrahim, Amani M. ^[1]; Maurya, Anjani K. ^[1]; Palumbo, Chad T. ^[2]; Sullivan, Kevin P. ^[2]; Beckham, Gregg T.  ^[2];

• Search DOE PAGES for author "Beckham, Gregg T."
• Search DOE PAGES for ORCID "0000-0002-3480-212X"

Sarangi, Ritimukta  ^[1]

• Search DOE PAGES for author "Sarangi, Ritimukta"
• Search DOE PAGES for ORCID "0000-0002-2764-2279"

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+ Show Author Affiliations

1. SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States). Stanford Synchrotron Radiation Lightsource (SSRL)
2. National Renewable Energy Laboratory (NREL), Golden, CO (United States). Renewable Resources and Enabling Science Center

Publication Date:

Wed Aug 02 00:00:00 EDT 2023

Research Org.:

SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)

Sponsoring Org.:

USDOE Office of Energy Efficiency and Renewable Energy (EERE), Office of Sustainable Transportation. Bioenergy Technologies Office (BETO); USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE Office of Science (SC), Biological and Environmental Research (BER); National Institutes of Health (NIH)

OSTI Identifier:

1993277

Grant/Contract Number:  

AC02-76SF00515; P30GM133894

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Physical Chemistry. C

Additional Journal Information:

Journal Volume: 127; Journal Issue: 32; Journal ID: ISSN 1932-7447

Publisher:

American Chemical Society

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; autoxidation, cobalt acetate, x-ray spectroscopy