Sulfur species in source rock bitumen before and after hydrous pyrolysis determined by X-ray absorption near-edge structure

Energy & Fuels
By: , and 

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Abstract

The sulfur speciation of source rock bitumen (chloroform-extractable organic matter in sedimentary rocks) was examined using sulfur K-edge X-ray absorption near-edge structure (XANES) spectroscopy for a suite of 11 source rocks from around the world. Sulfur speciation was determined for both the native bitumen in thermally immature rocks and the bitumen produced by thermal maturation of kerogen via hydrous pyrolysis (360 °C for 72 h) and retained within the rock matrix. In this study, the immature bitumens had higher sulfur concentrations than those extracted from samples after hydrous pyrolysis. In addition, dramatic and systematic evolution of the bitumen sulfur moiety distributions following artificial thermal maturation was observed consistently for all samples. Specifically, sulfoxide sulfur (sulfur double bonded to oxygen) is abundant in all immature bitumen samples but decreases substantially following hydrous pyrolysis. The loss in sulfoxide sulfur is associated with a relative increase in the fraction of thiophene sulfur (sulfur bonded to aromatic carbon) to the extent that thiophene is the dominant sulfur form in all post-pyrolysis bitumen samples. This suggests that sulfur moiety distributions might be used for estimating thermal maturity in source rocks based on the character of the extractable organic matter.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Sulfur species in source rock bitumen before and after hydrous pyrolysis determined by X-ray absorption near-edge structure
Series title Energy & Fuels
DOI 10.1021/acs.energyfuels.6b00744
Volume 30
Issue 8
Year Published 2016
Language English
Publisher ACS publications
Contributing office(s) Central Energy Resources Science Center
Description 7 p.
First page 6264
Last page 6270
Online Only (Y/N) N
Additional Online Files (Y/N) N