Compound-specific isotope analyses of products from carbonization of a fluid catalytic cracking decant oil doped with 13C-enriched 4-methyldibenzothiophene

Timothy R. Filley, Rose M. Filley, Semih Eser, Katherine Haines Freeman

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8 Citations (Scopus)

Abstract

This study presents the first combined application of 13C labeling and isotope-ratio-monitoring gas chromatography-mass spectrometry (irmGCMS) to analyze the thermochemical transformations of specific organic compounds within a complex heavy oil. Specifically, this technique was used to monitor the hydrocarbons produced during the carbonization of a fluid catalytic cracking decant oil (FCCDO). Structural GC/MS analysis of these products has previously shown that 4-methyldibenzothiophene, 13C-labeled at the methyl position (4- 13MDBT), undergoes methylation to form a number of polymethyldibenzothiophenes and cleavage of its aryl-methyl bond to give dibenzothiophene (Energy Fuels 1997, 11, 623, 631). The irmGCMS analysis of these products shows that the 4- 13MPBT is a source of 13C-enriched methyl that reacts with polyaromatic hydrocarbons (PAH) to produce a number of methylated PAHs. Precise measurement of 13C enrichment and concentration of specific compounds enables tracking of the labeled carbon within a complex mixture as a function of reaction time. There are large differences in apparent reactivities of mono- and dimethyl-substituted naphthalenes, phenanthrenes, and pyrenes. The differences in observed reactivities of methylnaphthalene, methylphenanthrene, and methylpyrene isomers are consistent with calculated free valence indices at specific positions. There is no significant 13C enrichment in unsubstituted PAH compounds, indicating that the labeled methyl group is not involved in producing GC-amenable unsubstituted PAH during early carbonization. This combined use of 13C-labeled reactants and irmGCMS analysis will have broad applications in oil processing and geochemical fields associated with the study of thermochemical transformations of organic compounds within complex mixtures.

Original languageEnglish (US)
Pages (from-to)637-644
Number of pages8
JournalEnergy and Fuels
Volume11
Issue number3
StatePublished - May 1997

Fingerprint

Fluid catalytic cracking
Carbonization
Hydrocarbons
Isotopes
Oils
Gas chromatography
Mass spectrometry
Complex Mixtures
Organic compounds
Monitoring
Pyrenes
Phenanthrenes
Naphthalenes
Methylation
Pyrene
Naphthalene
Polycyclic aromatic hydrocarbons
Isomers
Labeling
Carbon

All Science Journal Classification (ASJC) codes

  • Chemical Engineering(all)
  • Fuel Technology
  • Energy Engineering and Power Technology

Cite this

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title = "Compound-specific isotope analyses of products from carbonization of a fluid catalytic cracking decant oil doped with 13C-enriched 4-methyldibenzothiophene",
abstract = "This study presents the first combined application of 13C labeling and isotope-ratio-monitoring gas chromatography-mass spectrometry (irmGCMS) to analyze the thermochemical transformations of specific organic compounds within a complex heavy oil. Specifically, this technique was used to monitor the hydrocarbons produced during the carbonization of a fluid catalytic cracking decant oil (FCCDO). Structural GC/MS analysis of these products has previously shown that 4-methyldibenzothiophene, 13C-labeled at the methyl position (4- 13MDBT), undergoes methylation to form a number of polymethyldibenzothiophenes and cleavage of its aryl-methyl bond to give dibenzothiophene (Energy Fuels 1997, 11, 623, 631). The irmGCMS analysis of these products shows that the 4- 13MPBT is a source of 13C-enriched methyl that reacts with polyaromatic hydrocarbons (PAH) to produce a number of methylated PAHs. Precise measurement of 13C enrichment and concentration of specific compounds enables tracking of the labeled carbon within a complex mixture as a function of reaction time. There are large differences in apparent reactivities of mono- and dimethyl-substituted naphthalenes, phenanthrenes, and pyrenes. The differences in observed reactivities of methylnaphthalene, methylphenanthrene, and methylpyrene isomers are consistent with calculated free valence indices at specific positions. There is no significant 13C enrichment in unsubstituted PAH compounds, indicating that the labeled methyl group is not involved in producing GC-amenable unsubstituted PAH during early carbonization. This combined use of 13C-labeled reactants and irmGCMS analysis will have broad applications in oil processing and geochemical fields associated with the study of thermochemical transformations of organic compounds within complex mixtures.",
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AU - Filley, Rose M.

AU - Eser, Semih

AU - Freeman, Katherine Haines

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N2 - This study presents the first combined application of 13C labeling and isotope-ratio-monitoring gas chromatography-mass spectrometry (irmGCMS) to analyze the thermochemical transformations of specific organic compounds within a complex heavy oil. Specifically, this technique was used to monitor the hydrocarbons produced during the carbonization of a fluid catalytic cracking decant oil (FCCDO). Structural GC/MS analysis of these products has previously shown that 4-methyldibenzothiophene, 13C-labeled at the methyl position (4- 13MDBT), undergoes methylation to form a number of polymethyldibenzothiophenes and cleavage of its aryl-methyl bond to give dibenzothiophene (Energy Fuels 1997, 11, 623, 631). The irmGCMS analysis of these products shows that the 4- 13MPBT is a source of 13C-enriched methyl that reacts with polyaromatic hydrocarbons (PAH) to produce a number of methylated PAHs. Precise measurement of 13C enrichment and concentration of specific compounds enables tracking of the labeled carbon within a complex mixture as a function of reaction time. There are large differences in apparent reactivities of mono- and dimethyl-substituted naphthalenes, phenanthrenes, and pyrenes. The differences in observed reactivities of methylnaphthalene, methylphenanthrene, and methylpyrene isomers are consistent with calculated free valence indices at specific positions. There is no significant 13C enrichment in unsubstituted PAH compounds, indicating that the labeled methyl group is not involved in producing GC-amenable unsubstituted PAH during early carbonization. This combined use of 13C-labeled reactants and irmGCMS analysis will have broad applications in oil processing and geochemical fields associated with the study of thermochemical transformations of organic compounds within complex mixtures.

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