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TitleCyclopentanones and 2-cyclopenten-1-ones as major products of hydrous pyrolysis of immature organic-rich shales
AuthorJiang, CORCID logo; Reyes, JORCID logo; Snowdon, L RORCID logo; Milovic, M; Robinson, R; Zhang, S; Armstrong, D; Lavoie, DORCID logo
SourceOrganic Geochemistry vol. 122, 2018 p. 126-139,
Alt SeriesNatural Resources Canada, Contribution Series 20180059
PublisherElsevier BV
Mediapaper; on-line; digital
File formatpdf; html
Subjectsfossil fuels; geochemistry; petroleum resources; hydrocarbons; energy resources; sedimentary rocks; shales; pyrolysis; gas chromatography; mass spectrometer analysis; thermal analyses; thermal maturation; temperature; source rocks; Water; Biomass; Phanerozoic; Paleozoic; Devonian; Ordovician
Illustrationstables; chromatograms; schematic representations
ProgramGEM2: Geo-mapping for Energy and Minerals Hudson/Ungava Hydrocarbon source rocks
Released2018 05 30
AbstractCyclopentanone is an important platform chemical for various industrial syntheses. It has been recently reported as a major product in biomass cellulose-derived biofuels but has rarely been reported in geochemical research. We report here the abundant occurrence of cyclopentanone, 2-cyclopenten-1-one and their alkyl derivatives in pyrolysates of organic-rich shales. Closed system pyrolyses at temperatures from 290 ºC to 350 ºC have been carried out on thermally immature organic-rich shale samples of Ordovician and Devonian age from Canada. GC-MS analyses of the pyrolysates show that cyclopentanones, 2-cyclopenten-1-ones and phenols dominate over hydrocarbons in the low temperature hydrous pyrolysates, and their abundance relative to hydrocarbons decreases with increasing thermal maturation. However, these low molecular weight cyclic ketones are only minor components compared with hydrocarbons in anhydrous pyrolysates, indicating that water has played an important role in the formation of these oxygen-containing compounds. In addition, n-alkan-2-ones in the range of C6-C35 are also detected in the hydrous pyrolysates, but they are at much reduced concentrations compared with the cyclic ketones. The potential precursors in the shale and the likely chemical reaction mechanism for the formation of these cyclic ketones are discussed in detail in the paper.
Summary(Plain Language Summary, not published)
We report here the abundant occurrence of Cyclopentanones and 2-cyclopenten-1-ones in the pyrolysis products of organic-rich Ordovician and Devonian shale samples. To the best of our knowledge, there was no previous report on the occurrence of these low molecular weight cyclic ketones at such high abundances in geological samples. Based on current findings on the compositions of cellulose derived biofuels, the detection of these compounds may indicate partial preservation of polysaccharides in the Paleozoic shales. Upon confirmation by further characterization of the sedimentary organic matter, this may shed some light on the studies of early life evolution. Results from this study also indicates that hydrous pyrolysis of oil shale before retorting may be an efficient alternative to biofuel upgrading for the synthesis of cyclopentanone related platform chemicals necessary for industrial synthesis.

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