Chang, H-C K
1991
Structural Comparison of Low-Molecular-Weight Extractable Compounds in Different Rank Coals Using Capillary Column Gas Chromatography
Chang, H.-C.K.; Bartle, K.D.; Markides, K.E. and Lee, M.L.
Advances in Coal Spectroscopy, 141-164, (H.L.C. Meuzelaar, ed.), Plenum Publishing Corp., New York, 1991. Funded by Gas Research Institute and ACERC.
In this chapter, results from the analysis of the low-molecular-weight organic constituents in six vitrinite-rich coals of ranks ranging from lignite to low volatile bituminous are reported. Aliphatics, neutral aromatics, nitrogen-containing aromatics, and sulfur-containing aromatics were first isolated from the coal extracts using column absorption and complexation chromatography, and then they were resolved and identified using capillary column gas chromatography coupled with sulfur- and nitrogen-selective detectors, and mass spectrometry.
1990
Determination of Sulfur-Containing Polycyclic Aromatic Compounds in Coal Extracts Using Capillary Column Gas Chromatography with Radio Frequency Plasma Detection
Chang, H.-C.K.; Skelton, R.J. Jr.; Markides, K.E. and Lee, M.L.
Polycyclic Aromatic Compounds, 1:251-264, 1990. Funded by Gas Research Institute and ACERC.
Detailed identification of sulfur-containing polycyclic aromatic compounds (S-PAC) was accomplished for solvent extracts of five different coals. The S-PAC were isolated by ligand-exchange chromatography. Due to the great complexities of these samples, capillary gas chromatography (GC) was employed for their analysis. An element selective radio frequency plasma detector was used to provide sulfur selective detections. Gas chromatography-mass spectrometry was used to identify individual compounds in isolated sulfur fractions. Condensed thiophenic compounds were found to be the major constituents in all five S-PAC fractions. Diaryl sulfides were also detected in the high volatile bituminous Illinois #6 coal. The prevalence of various S-PAC in different coal extracts was observed as a function of their rank.
1989
Radio Frequency Plasma Detector for Sulfur Selective Capillary Gas Chromatographic Analysis of Fossil Fuels
Skelton, R.J. Jr.; Chang, H.-C.K.; Farnsworth, P.B.; Markides, K.E. and Lee, M.L.
Anal. Chem., 61, 2292, 1989. Funded by Gas Research Institute and the Utah Centers of Excellence.
Polycyclic aromatic compounds (PAC) are known to be major constituents in coal and petroleum products. Polycyclic aromatic hydrocarbons (PAH) are by far the most common PAC in these materials. However, nitrogen-, oxygen- and sulfur-containing PAC are also often found in significant quantities. Because of the widespread interest in and use of fossil fuels, detailed study of their compositions has become an important task.
1988-1986
Identification and Comparison of Low-Molecular-Weight Neutral Constituents in Two Different Coal Extracts
Chang, H.-C.K.; Nishioka, M.; Bartle, K.D.; Wise, S.A.; Bayona, J.M.; Markides, K.E. and Lee, M.L.
Fuel, 67, 45-48, 1988. 4 pgs. Funded by Gas Research Institute.
Determination of the chemical structural features of coals is a continuing major goal of fuel science because of the vital energy source represented by this material. Coals are now perceived to be cross-linked macromolecular networks in which are trapped lower molecular weight materials either in sites readily accessible to solvent or in 'cages' analogous to clathrates. How representative this extractable material is of the multipolymeric macromolecular structure in which it is embedded in clearly open to question. However, the generally lower molecular weights of components in solvent extracts lead to much greater ease of analysis, and such extracts may provide insights into metamorphic changes undergone by the macromolecular structure during coal formation.
A two-step pyridine and then tetrahydrofuran solvent extraction procedure at room temperature under nitrogen gas flow was used to extract two different US coals, PSOC-592 (Illinois No. 5) and PSOC-521 (Rock Springs No. 7, Wyoming). Aliphatic and aromatic hydrocarbons were separated using neutral alumina column chromatography. The aromatics were then fractionated according to the number of aromatic carbons by high performance liquid chromatography. These neutral compounds were identified by gas chromatography (g.c.) and gas chromatography/mass spectrometry. n-Alkanes (C17-C31), pristane, phythane, hopanes (17aH, 21bH), and moretanes (17bH, 21aH) were found in aliphatic fractions of both coal extracts. Low-molecular-weight (2-4 rings) polycyclic aromatic hydrocarbons (PAH) were the major compounds in the aromatic fraction of the PSOC-592 coal extract. However, pentacyclic triterpenoid-like hydroaromatic hydrocarbons were the major components in the extract of the PSOC-521 coal. A number of new compounds were identified for the first time.
Structural Characteristics of Polycyclic Aromatic Hydrocarbon Isomers in Coal Tars and Combustion Products
Nishioka, M.; Chang, H.-C. K. and Lee, M.L.
Environ. Sci. Technol. 20, 1023-1027, 1986. 4 pgs. Funded by US Department of Energy.
Coal-derived products and thermally cracked petroleum oils are highly aromatic in nature and contain polycyclic aromatic hydrocarbons (PAH) as major components. Although average descriptive parameters are usually obtained for such materials (i.e., distillation curve, molecular weight range, aromaticity, etc.), it is oftentimes very important to obtain detailed compositional and structural information.
Isomeric polycyclic aromatic hydrocarbons (PAH) with two to six rings in coal-derived products and in a carbon black were separated, identified, and quantified by using capillary column gas chromatography and gas chromatography-mass spectrometry. A newly synthesized smectic liquid-crystalline polysiloxane and a conventional polymethylsiloxane were utilized as stationary phases. Many previously difficult-to-separate isomeric PAH (i.e., methylphenanthrenes/methylanthracenes, triphenylene/chrysene, methylchrysenes, benzofluoranthenes, and pentaphene/benzo [b] chrysene) were identified. The relative abundances of the PAH in these samples were compared and correlated to the reaction conditions during their production. The relationship between abundance and structure for the identified PAH was also discussed.
Chang, H-C K
1991
Structural Comparison of Low-Molecular-Weight Extractable Compounds in Different Rank Coals Using Capillary Column Gas Chromatography
Chang, H.-C.K.; Bartle, K.D.; Markides, K.E. and Lee, M.L.
Advances in Coal Spectroscopy, 141-164, (H.L.C. Meuzelaar, ed.), Plenum Publishing Corp., New York, 1991. Funded by Gas Research Institute and ACERC.
In this chapter, results from the analysis of the low-molecular-weight organic constituents in six vitrinite-rich coals of ranks ranging from lignite to low volatile bituminous are reported. Aliphatics, neutral aromatics, nitrogen-containing aromatics, and sulfur-containing aromatics were first isolated from the coal extracts using column absorption and complexation chromatography, and then they were resolved and identified using capillary column gas chromatography coupled with sulfur- and nitrogen-selective detectors, and mass spectrometry.
1990
Determination of Sulfur-Containing Polycyclic Aromatic Compounds in Coal Extracts Using Capillary Column Gas Chromatography with Radio Frequency Plasma Detection
Chang, H.-C.K.; Skelton, R.J. Jr.; Markides, K.E. and Lee, M.L.
Polycyclic Aromatic Compounds, 1:251-264, 1990. Funded by Gas Research Institute and ACERC.
Detailed identification of sulfur-containing polycyclic aromatic compounds (S-PAC) was accomplished for solvent extracts of five different coals. The S-PAC were isolated by ligand-exchange chromatography. Due to the great complexities of these samples, capillary gas chromatography (GC) was employed for their analysis. An element selective radio frequency plasma detector was used to provide sulfur selective detections. Gas chromatography-mass spectrometry was used to identify individual compounds in isolated sulfur fractions. Condensed thiophenic compounds were found to be the major constituents in all five S-PAC fractions. Diaryl sulfides were also detected in the high volatile bituminous Illinois #6 coal. The prevalence of various S-PAC in different coal extracts was observed as a function of their rank.
1989
Radio Frequency Plasma Detector for Sulfur Selective Capillary Gas Chromatographic Analysis of Fossil Fuels
Skelton, R.J. Jr.; Chang, H.-C.K.; Farnsworth, P.B.; Markides, K.E. and Lee, M.L.
Anal. Chem., 61, 2292, 1989. Funded by Gas Research Institute and the Utah Centers of Excellence.
Polycyclic aromatic compounds (PAC) are known to be major constituents in coal and petroleum products. Polycyclic aromatic hydrocarbons (PAH) are by far the most common PAC in these materials. However, nitrogen-, oxygen- and sulfur-containing PAC are also often found in significant quantities. Because of the widespread interest in and use of fossil fuels, detailed study of their compositions has become an important task.
1988-1986
Identification and Comparison of Low-Molecular-Weight Neutral Constituents in Two Different Coal Extracts
Chang, H.-C.K.; Nishioka, M.; Bartle, K.D.; Wise, S.A.; Bayona, J.M.; Markides, K.E. and Lee, M.L.
Fuel, 67, 45-48, 1988. 4 pgs. Funded by Gas Research Institute.
Determination of the chemical structural features of coals is a continuing major goal of fuel science because of the vital energy source represented by this material. Coals are now perceived to be cross-linked macromolecular networks in which are trapped lower molecular weight materials either in sites readily accessible to solvent or in 'cages' analogous to clathrates. How representative this extractable material is of the multipolymeric macromolecular structure in which it is embedded in clearly open to question. However, the generally lower molecular weights of components in solvent extracts lead to much greater ease of analysis, and such extracts may provide insights into metamorphic changes undergone by the macromolecular structure during coal formation.
A two-step pyridine and then tetrahydrofuran solvent extraction procedure at room temperature under nitrogen gas flow was used to extract two different US coals, PSOC-592 (Illinois No. 5) and PSOC-521 (Rock Springs No. 7, Wyoming). Aliphatic and aromatic hydrocarbons were separated using neutral alumina column chromatography. The aromatics were then fractionated according to the number of aromatic carbons by high performance liquid chromatography. These neutral compounds were identified by gas chromatography (g.c.) and gas chromatography/mass spectrometry. n-Alkanes (C17-C31), pristane, phythane, hopanes (17aH, 21bH), and moretanes (17bH, 21aH) were found in aliphatic fractions of both coal extracts. Low-molecular-weight (2-4 rings) polycyclic aromatic hydrocarbons (PAH) were the major compounds in the aromatic fraction of the PSOC-592 coal extract. However, pentacyclic triterpenoid-like hydroaromatic hydrocarbons were the major components in the extract of the PSOC-521 coal. A number of new compounds were identified for the first time.
Structural Characteristics of Polycyclic Aromatic Hydrocarbon Isomers in Coal Tars and Combustion Products
Nishioka, M.; Chang, H.-C. K. and Lee, M.L.
Environ. Sci. Technol. 20, 1023-1027, 1986. 4 pgs. Funded by US Department of Energy.
Coal-derived products and thermally cracked petroleum oils are highly aromatic in nature and contain polycyclic aromatic hydrocarbons (PAH) as major components. Although average descriptive parameters are usually obtained for such materials (i.e., distillation curve, molecular weight range, aromaticity, etc.), it is oftentimes very important to obtain detailed compositional and structural information.
Isomeric polycyclic aromatic hydrocarbons (PAH) with two to six rings in coal-derived products and in a carbon black were separated, identified, and quantified by using capillary column gas chromatography and gas chromatography-mass spectrometry. A newly synthesized smectic liquid-crystalline polysiloxane and a conventional polymethylsiloxane were utilized as stationary phases. Many previously difficult-to-separate isomeric PAH (i.e., methylphenanthrenes/methylanthracenes, triphenylene/chrysene, methylchrysenes, benzofluoranthenes, and pentaphene/benzo [b] chrysene) were identified. The relative abundances of the PAH in these samples were compared and correlated to the reaction conditions during their production. The relationship between abundance and structure for the identified PAH was also discussed.