Butala, S
1997
Catalytic Effects of Mineral Matter on Natural Gas Formation During Coal Maturation
Butala, S.; Medina, J.C.; Bowerbank, C.R.; Lee, M.L.; Felt, S.A.; Taylor, T.Q.; Andrus, D.B.; Bartholomew, C.H.; Yin, P. and Surdam, R.C.
Gas Research Institute, GRI-97/0213, July 1997. Funded in part by ACERC.
Coal seam reservoirs are important commercial sources of natural gas in the U.S. It is commonly assumed that coals function as self-sourced reservoirs for hydrocarbon gases formed by temperature-controlled thermolysis (cracking) of the bulk coal organic matter. However, this geologic process model may be an unreliable exploration guide. Artificial maturation results indicate that raw coal generates more hydrocarbon gas than demineralized coal. This difference suggests that mineral catalysis merits evaluation as a critical variable affecting hydrocarbon gas formation during coal maturation.
Kinetic modeling of temperature-controlled hydrocarbon thermolysis reactions using coal maturation geologic times and temperatures indicate that thermolysis reaction rates would be too slow to generate large, self-sourced coal seam natural gas deposits. By contrast, acid mineral, transition metal, and metal oxide mineral catalyzed reactions would occur at rates sufficiently fast under geologic time and temperature conditions to generate large quantities of natural gas. The unavailability of suitable benchmark coal reactivity data preclude assessment of whether catalytic reactions actually control hydrocarbon gas formation during coal maturation.
1996
Determination of Volatile Hydrocarbons in Coals and Shales Using Supercritical Fluid Extraction and Chromatography
Li, W.; Lazar, I.M.; Wan, Y.J.; Butala, S.; Shen, Y.; Malik, A. and Lee, M.L
Energy & Fuels, 1996 (in press). Funded by ACERC and Gas Research Institute.
Conventional analytical techniques, such as headspace gas chromatography and Soxhlet extraction, can provide compositional information for the gaseous (C1-5) and heavy (C15+) hydrocarbon constituents, respectively. The volatile (C6-14) hydrocarbons, if present, usually go undetected because of volatility fractionation and loss. In this study supercritical CO2 was used to extract the C6-C14 volatile hydrocarbons from pulverized coal samples. Capillary column gas chromatography/mass spectrometry was used to identify the mixture components, and packed capillary column supercritical fluid chromatography was used to separate and quantify the aliphatic and aromatic hydrocarbon class fractions. It was found that the compositions of the light hydrocarbon fractions included several homologous series of normal and branched aliphatic hydrocarbons, cyclic and aromatic hydrocarbons, and alkyl-substituted benzenes and naphthalenes; the concentrations of these volatile hydrocarbons ranged between 0.01 to 0.2% (by weight) of the bulk material for the different coal and shale samples.
Analysis of Coal Structure Via Successive Catalytic Depolymerization and Supercritical Fluid/Enhanced Liquid Extraction
Wan, Y.J.; Butala, S.; Li, W. and Lee, M.L.
Proceedings of the Pittcon '96 (Pittsburgh Conference), Chicago, Illinois, March 6, 1996. Funded by ACERC.
To understand the original chemical features of the intact coal structure, a new method has been developed for depolymerization and extraction of coal. It involves successive catalyzed depolymerization reactions under mild and organic solvent free conditions, each immediately followed in in-situ supercritical fluid (carbon dioxide) extraction and enhanced solvent (methylene chloride) extraction of the reaction matrix. The procedure is simple and the system is easy to operate. The timely removal of coal products avoids any retrograde reactions that complicate the products. Compared with coal head distillation, supercritical fluid extraction and enhanced liquid extraction is fast and can be used to analyze a very small amount of coal for analytical purposes. Experimental detail, extraction yields, and GC and GC/MS characterization of the products associated with coal structure will be presented. From the comparison of the composition of products from different depolymerization steps, it appears that coal has a common macromolecular skeletal structure, despite the well-established heterogeneity of coal.
Butala, S
1997
Catalytic Effects of Mineral Matter on Natural Gas Formation During Coal Maturation
Butala, S.; Medina, J.C.; Bowerbank, C.R.; Lee, M.L.; Felt, S.A.; Taylor, T.Q.; Andrus, D.B.; Bartholomew, C.H.; Yin, P. and Surdam, R.C.
Gas Research Institute, GRI-97/0213, July 1997. Funded in part by ACERC.
Coal seam reservoirs are important commercial sources of natural gas in the U.S. It is commonly assumed that coals function as self-sourced reservoirs for hydrocarbon gases formed by temperature-controlled thermolysis (cracking) of the bulk coal organic matter. However, this geologic process model may be an unreliable exploration guide. Artificial maturation results indicate that raw coal generates more hydrocarbon gas than demineralized coal. This difference suggests that mineral catalysis merits evaluation as a critical variable affecting hydrocarbon gas formation during coal maturation.
Kinetic modeling of temperature-controlled hydrocarbon thermolysis reactions using coal maturation geologic times and temperatures indicate that thermolysis reaction rates would be too slow to generate large, self-sourced coal seam natural gas deposits. By contrast, acid mineral, transition metal, and metal oxide mineral catalyzed reactions would occur at rates sufficiently fast under geologic time and temperature conditions to generate large quantities of natural gas. The unavailability of suitable benchmark coal reactivity data preclude assessment of whether catalytic reactions actually control hydrocarbon gas formation during coal maturation.
1996
Determination of Volatile Hydrocarbons in Coals and Shales Using Supercritical Fluid Extraction and Chromatography
Li, W.; Lazar, I.M.; Wan, Y.J.; Butala, S.; Shen, Y.; Malik, A. and Lee, M.L
Energy & Fuels, 1996 (in press). Funded by ACERC and Gas Research Institute.
Conventional analytical techniques, such as headspace gas chromatography and Soxhlet extraction, can provide compositional information for the gaseous (C1-5) and heavy (C15+) hydrocarbon constituents, respectively. The volatile (C6-14) hydrocarbons, if present, usually go undetected because of volatility fractionation and loss. In this study supercritical CO2 was used to extract the C6-C14 volatile hydrocarbons from pulverized coal samples. Capillary column gas chromatography/mass spectrometry was used to identify the mixture components, and packed capillary column supercritical fluid chromatography was used to separate and quantify the aliphatic and aromatic hydrocarbon class fractions. It was found that the compositions of the light hydrocarbon fractions included several homologous series of normal and branched aliphatic hydrocarbons, cyclic and aromatic hydrocarbons, and alkyl-substituted benzenes and naphthalenes; the concentrations of these volatile hydrocarbons ranged between 0.01 to 0.2% (by weight) of the bulk material for the different coal and shale samples.
Analysis of Coal Structure Via Successive Catalytic Depolymerization and Supercritical Fluid/Enhanced Liquid Extraction
Wan, Y.J.; Butala, S.; Li, W. and Lee, M.L.
Proceedings of the Pittcon '96 (Pittsburgh Conference), Chicago, Illinois, March 6, 1996. Funded by ACERC.
To understand the original chemical features of the intact coal structure, a new method has been developed for depolymerization and extraction of coal. It involves successive catalyzed depolymerization reactions under mild and organic solvent free conditions, each immediately followed in in-situ supercritical fluid (carbon dioxide) extraction and enhanced solvent (methylene chloride) extraction of the reaction matrix. The procedure is simple and the system is easy to operate. The timely removal of coal products avoids any retrograde reactions that complicate the products. Compared with coal head distillation, supercritical fluid extraction and enhanced liquid extraction is fast and can be used to analyze a very small amount of coal for analytical purposes. Experimental detail, extraction yields, and GC and GC/MS characterization of the products associated with coal structure will be presented. From the comparison of the composition of products from different depolymerization steps, it appears that coal has a common macromolecular skeletal structure, despite the well-established heterogeneity of coal.