Dong, JZ
1993
Origin of Long-Chain Alkylcyclohexanes and Alkylbenzenes in a Coal-Bed Wax
Dong, J.-Z.; Vorkink, W.P. and Lee, M.L.
Geochimica et Cosmochimica Acta, 57:837-849, 1993. Funded by Gas Research Institute.
A coal-bed wax was fractionated and analyzed using capillary column GC and combined GC/MS. It was found that the major components in the wax were n-alkanes (55.6%), cyclic/branched alkanes (26.0%), and several homologous series of alkylbenzenes (5.7%). All alkylbenzene isomers (except 6-n-alky-m-xylene) were positively identified by comparison with the retention times and mass spectra of newly synthesized authenic standards. 5-n-Alkyl-m-xylene, 2-n-alkyl-p-xylene, 4-n-alkyl-m-xylene, 4-n-alkyl-o-xylene, 2-n-alkyl-m-xylene, and 3-n-alkyl-o-xylene were identified for the first time from geological sources. All of these long-chain alkyl compounds (e.g., n-alkylcyclohexanes, n-alkylbenzenes, n-alkyl-o-toluenes, n-alkyl-p-toluenes, and 5-n-alkyl-m-xylenes) have similar total carbon number distributions and maxima with a slight even over odd carbon number preference between C28-C30. Moreover, the carbon number distributions of these compounds resembled those of the n-alkanes found in the same wax with slight odd over even carbon preference between C-C27class="sub">31. This indicates that the alkylcyclohexanes and alkylbenzenes may have the same fatty acid precursors as the n-alkanes. The alkylcyclohexanes and alkylbenzenes could have been formed by direct cyclization and aromatization, while the n-alkanes could have been formed by decarboxylation of the straight chain fatty acids. This explanation is further supported by the identification of homologous series of tetramethyl-n-alkylbenzenes and pentamethyl-n-alkylbenzenes with relatively high abundances at C15, C16, and C18, and a fatty acid distribution with maxima at C16 and C18. Based on these findings, mechanisms for the conversion of fatty acids or alcohols to alkylcyclohexanes and alkylbenzenes are proposed.
1992
High-Resolution Chromatographic Characterization of Depolymerized Coals of Different Rank: Aliphatic and Aromatic Hydrocarbons
Carlson, R.E.; Critchfield, S.; Vorkink, W.P.; Dong, J.-Z.; Pugmire, R.J.; Bartle, K.D.; Lee, M.L.; Zhang, Y. and Shabtai, J.S.
Fuel, 71(1):1-29, 1992. Funded by US Department of Energy, Gas Research Institute and ACERC.
A selective, low temperature depolymerization procedure has been applied to four Argonne coals of different rank to produce products that are representative of the original coal macromolecular structure, and that are amenable to chromatographic analysis. The products of this depolymerization procedure retained most of the original aromatic and functional group structures of the original coals. A comparison of liquid C-13 NMR spectra of the products and solid-state C-13 NMR spectra of the original coals showed only minor changes in the aromaticities of two of the coals, and some loss of the carbonyl carbons in all of the coals.
Tetrahydrofuran pre-extracts of the four coals and their depolymerized products were separated into chemical classes by adsorption chromatography. Two of these fractions, which contained aliphatic hydrocarbons and polycyclic aromatic hydrocarbons were analyzed using gas chromatography/mass spectrometry. Structural identifications were based on a combination of chromatographic retention and mass spectral fragmentation data. For the lower rank coals, the compositions of the pre-extracts were quite different from the corresponding depolymerized products, and they contained an abundance of molecular biological markers. The compositions of the pre-extracts became more similar to the depolymerized products as rank increased.
1990
High Resolution Chromatographic Characterization of Depolymerized Coals of Different Rank: Aliphatic and Aromatic Hydrocarbons
Carlson, R.E.; Critchfield, S.; Vorkink, W.P.; Dong, J.-Z.; Pugmire, R.J.; Bartle, K.D. and Lee, M.L.
Fuel, 1990 (In Press). Funded by US Department of Energy, Gas Research Institute and ACERC.
A selective, low temperature depolymerization procedure has been applied to four Argonne coals of different rank to produce products that are representative of the original coal macromolecular structure, and that are amenable to chromatographic analysis. The products of this depolymerization procedure retained most of the original aromatic and functional group structures of the original coals. A comparison of liquid C-13 NMR spectra of the products and solid-state C-13 NMR spectra of the original coals showed only minor changes in the aromaticities of two of the coals, and some loss of the carbonyl carbons in all of the coals.
Tetrahydrofuran pre-extracts of the four coals and their depolymerized products were separated into chemical classes by adsorption chromatography. Two of these fractions, which contained aliphatic hydrocarbons and polycyclic aromatic hydrocarbons were analyzed using gas chromatography/mass spectrometry. Structural identifications were based on a combination of chromatographic retention and mass spectral fragmentation data. For the lower rank coals, the compositions of the pre-extracts were quite different from the corresponding depolymerized products, and they contained an abundance of molecular biological markers. The compositions of the pre-extracts became more similar to the depolymerized products as rank increased.
Dong, JZ
1993
Origin of Long-Chain Alkylcyclohexanes and Alkylbenzenes in a Coal-Bed Wax
Dong, J.-Z.; Vorkink, W.P. and Lee, M.L.
Geochimica et Cosmochimica Acta, 57:837-849, 1993. Funded by Gas Research Institute.
A coal-bed wax was fractionated and analyzed using capillary column GC and combined GC/MS. It was found that the major components in the wax were n-alkanes (55.6%), cyclic/branched alkanes (26.0%), and several homologous series of alkylbenzenes (5.7%). All alkylbenzene isomers (except 6-n-alky-m-xylene) were positively identified by comparison with the retention times and mass spectra of newly synthesized authenic standards. 5-n-Alkyl-m-xylene, 2-n-alkyl-p-xylene, 4-n-alkyl-m-xylene, 4-n-alkyl-o-xylene, 2-n-alkyl-m-xylene, and 3-n-alkyl-o-xylene were identified for the first time from geological sources. All of these long-chain alkyl compounds (e.g., n-alkylcyclohexanes, n-alkylbenzenes, n-alkyl-o-toluenes, n-alkyl-p-toluenes, and 5-n-alkyl-m-xylenes) have similar total carbon number distributions and maxima with a slight even over odd carbon number preference between C28-C30. Moreover, the carbon number distributions of these compounds resembled those of the n-alkanes found in the same wax with slight odd over even carbon preference between C-C27class="sub">31. This indicates that the alkylcyclohexanes and alkylbenzenes may have the same fatty acid precursors as the n-alkanes. The alkylcyclohexanes and alkylbenzenes could have been formed by direct cyclization and aromatization, while the n-alkanes could have been formed by decarboxylation of the straight chain fatty acids. This explanation is further supported by the identification of homologous series of tetramethyl-n-alkylbenzenes and pentamethyl-n-alkylbenzenes with relatively high abundances at C15, C16, and C18, and a fatty acid distribution with maxima at C16 and C18. Based on these findings, mechanisms for the conversion of fatty acids or alcohols to alkylcyclohexanes and alkylbenzenes are proposed.
1992
High-Resolution Chromatographic Characterization of Depolymerized Coals of Different Rank: Aliphatic and Aromatic Hydrocarbons
Carlson, R.E.; Critchfield, S.; Vorkink, W.P.; Dong, J.-Z.; Pugmire, R.J.; Bartle, K.D.; Lee, M.L.; Zhang, Y. and Shabtai, J.S.
Fuel, 71(1):1-29, 1992. Funded by US Department of Energy, Gas Research Institute and ACERC.
A selective, low temperature depolymerization procedure has been applied to four Argonne coals of different rank to produce products that are representative of the original coal macromolecular structure, and that are amenable to chromatographic analysis. The products of this depolymerization procedure retained most of the original aromatic and functional group structures of the original coals. A comparison of liquid C-13 NMR spectra of the products and solid-state C-13 NMR spectra of the original coals showed only minor changes in the aromaticities of two of the coals, and some loss of the carbonyl carbons in all of the coals.
Tetrahydrofuran pre-extracts of the four coals and their depolymerized products were separated into chemical classes by adsorption chromatography. Two of these fractions, which contained aliphatic hydrocarbons and polycyclic aromatic hydrocarbons were analyzed using gas chromatography/mass spectrometry. Structural identifications were based on a combination of chromatographic retention and mass spectral fragmentation data. For the lower rank coals, the compositions of the pre-extracts were quite different from the corresponding depolymerized products, and they contained an abundance of molecular biological markers. The compositions of the pre-extracts became more similar to the depolymerized products as rank increased.
1990
High Resolution Chromatographic Characterization of Depolymerized Coals of Different Rank: Aliphatic and Aromatic Hydrocarbons
Carlson, R.E.; Critchfield, S.; Vorkink, W.P.; Dong, J.-Z.; Pugmire, R.J.; Bartle, K.D. and Lee, M.L.
Fuel, 1990 (In Press). Funded by US Department of Energy, Gas Research Institute and ACERC.
A selective, low temperature depolymerization procedure has been applied to four Argonne coals of different rank to produce products that are representative of the original coal macromolecular structure, and that are amenable to chromatographic analysis. The products of this depolymerization procedure retained most of the original aromatic and functional group structures of the original coals. A comparison of liquid C-13 NMR spectra of the products and solid-state C-13 NMR spectra of the original coals showed only minor changes in the aromaticities of two of the coals, and some loss of the carbonyl carbons in all of the coals.
Tetrahydrofuran pre-extracts of the four coals and their depolymerized products were separated into chemical classes by adsorption chromatography. Two of these fractions, which contained aliphatic hydrocarbons and polycyclic aromatic hydrocarbons were analyzed using gas chromatography/mass spectrometry. Structural identifications were based on a combination of chromatographic retention and mass spectral fragmentation data. For the lower rank coals, the compositions of the pre-extracts were quite different from the corresponding depolymerized products, and they contained an abundance of molecular biological markers. The compositions of the pre-extracts became more similar to the depolymerized products as rank increased.