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Title: Electronic Structure of Naturally Occurring Aromatic Carbon

Abstract

Aromatic carbon in fused-ring systems can be classified into two forms of electronic structure: aromatic sextets, which have large highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) gaps and resemble benzene; and isolated double bonds, which have small HOMO–LUMO gaps and resemble olefins. The relative abundance of aromatic sextets versus isolated double bonds in mixtures can be probed by carbon X-ray Raman spectroscopy. Here, we report the carbon X-ray Raman spectra of a wide variety of forms of naturally occurring aromatic carbon: kerogen (insoluble organic carbon in sedimentary rocks, which is the most abundant form of naturally occurring organic carbon in the Earth’s crust) over a range of types and thermal maturities, fresh materials of a variety of forms, and coal and petroleum asphaltenes (toluene soluble and heptane insoluble materials, which represent organic carbon resulting from extensive thermal processing). It is observed that all these materials are dominated by aromatic sextets over isolated double bonds. On the basis of the diversity of materials analyzed, it is concluded that naturally occurring organic carbon is generally dominated by aromatic sextets over isolated double bonds. This conclusion is rationalized in terms of statistical and thermodynamic effects.

Authors:
ORCiD logo [1];  [1];  [1];  [2];  [3];  [4];  [4]
  1. Schlumberger-Doll Research, Cambridge, MA (United States)
  2. Stanford Univ., Stanford, CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)
  3. SLAC National Accelerator Lab., Menlo Park, CA (United States); Center for High Pressure Science & Technology Advanced Research, Shanghai (China)
  4. SLAC National Accelerator Lab., Menlo Park, CA (United States)
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1498540
Grant/Contract Number:  
AC02-76SF00515
Resource Type:
Accepted Manuscript
Journal Name:
Energy and Fuels
Additional Journal Information:
Journal Name: Energy and Fuels; Journal ID: ISSN 0887-0624
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Pomerantz, Andrew E., Bostrom, Neil W., Kleinberg, Robert L., Crace, Ethan, Weng, Tsu-Chien, Sokaras, Dimosthenis, and Nordlund, Dennis. Electronic Structure of Naturally Occurring Aromatic Carbon. United States: N. p., 2019. Web. doi:10.1021/acs.energyfuels.8b04366.
Pomerantz, Andrew E., Bostrom, Neil W., Kleinberg, Robert L., Crace, Ethan, Weng, Tsu-Chien, Sokaras, Dimosthenis, & Nordlund, Dennis. Electronic Structure of Naturally Occurring Aromatic Carbon. United States. doi:10.1021/acs.energyfuels.8b04366.
Pomerantz, Andrew E., Bostrom, Neil W., Kleinberg, Robert L., Crace, Ethan, Weng, Tsu-Chien, Sokaras, Dimosthenis, and Nordlund, Dennis. Tue . "Electronic Structure of Naturally Occurring Aromatic Carbon". United States. doi:10.1021/acs.energyfuels.8b04366.
@article{osti_1498540,
title = {Electronic Structure of Naturally Occurring Aromatic Carbon},
author = {Pomerantz, Andrew E. and Bostrom, Neil W. and Kleinberg, Robert L. and Crace, Ethan and Weng, Tsu-Chien and Sokaras, Dimosthenis and Nordlund, Dennis},
abstractNote = {Aromatic carbon in fused-ring systems can be classified into two forms of electronic structure: aromatic sextets, which have large highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) gaps and resemble benzene; and isolated double bonds, which have small HOMO–LUMO gaps and resemble olefins. The relative abundance of aromatic sextets versus isolated double bonds in mixtures can be probed by carbon X-ray Raman spectroscopy. Here, we report the carbon X-ray Raman spectra of a wide variety of forms of naturally occurring aromatic carbon: kerogen (insoluble organic carbon in sedimentary rocks, which is the most abundant form of naturally occurring organic carbon in the Earth’s crust) over a range of types and thermal maturities, fresh materials of a variety of forms, and coal and petroleum asphaltenes (toluene soluble and heptane insoluble materials, which represent organic carbon resulting from extensive thermal processing). It is observed that all these materials are dominated by aromatic sextets over isolated double bonds. On the basis of the diversity of materials analyzed, it is concluded that naturally occurring organic carbon is generally dominated by aromatic sextets over isolated double bonds. This conclusion is rationalized in terms of statistical and thermodynamic effects.},
doi = {10.1021/acs.energyfuels.8b04366},
journal = {Energy and Fuels},
number = ,
volume = ,
place = {United States},
year = {2019},
month = {2}
}

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