Hill, GR
1988-1986
Time-Resolved Pyrolysis Mass Spectrometry of Coal: A New Tool for Mechanistic and Kinetic Studies
Chakravarty, T.; Meuzelaar, H.L.C.; Windig, W. and Hill, G.R.
Energy & Fuel, 2, 400-405, 1988. 5 pgs. Funded by ACERC (National Science Foundation and Associates and Affiliates).
Most coal devolatilization studies so far have focused on the determination of reaction rates for reactions occurring under widely different conditions encountered in liquefaction, gasification, coking or combustion processes. Published rates on more or less comparable coals may differ by several orders of magnitude, especially when obtained at high temperatures (>1000 K) and/or high heating rates (10²-105 K/s).
At the present state-of-the-art in coal devolatilization research, more emphasis should perhaps be placed on elucidating the mechanisms of the chemical reactions underlying the observed phenomena. When studying thermal conversion reactions in coal it seems correct to concentrate first on the so-called "primary" reactions before attempting to elucidate the many possible secondary reaction pathways. This is especially true since most secondary reaction pathways are strongly influenced by reactor design and experimental conditions.
The devolatilization behavior of coal will be determined primarily by the chemical composition of coal and secondly by the experimental conditions. Under properly designed vacuum micropyrolysis experiments working with sufficiently small particles (<50 mm diameter), it is possible to avoid mass and heat transport limitations and minimize the secondary reactions. Using unoxidized or well preserved coal samples, the chemical composition can be well defined and possibly characterized by major factors such as rank and depositional environment. Recent advances in pyrolysis mass spectrometry (Py-MS), viz, time-resolved Py-MS (TR Py-MS), along with multivariate analysis techniques enable extraction of underlying chemical components from a single experiment, thus reducing the uncertainty due to varying reactions conditions in different experiments. This paper demonstrates the feasibility of obtaining valuable mechanistic and kinetic data using microgram amounts of carefully selected coal samples under properly designed reaction conditions using TR Py-MS techniques in combination with advanced multivariate data analysis methods.
Prediction and Modeling of Coal Conversion Reactions by Pyrolysis Mass Spectrometry and Multivariate Statistical Analysis
Meuzelaar, H.L.C.; Hoesterey, B.L.; Windig, W. and Hill, G.R.
Fuel Processing Technology, l5, 59-70, 1987. 11 pgs. Funded by Electric Power Research Institute and US Department of Energy.
Report on the use of Curie-point pyrolysis MS as a microscale modeling technique for the conversion of four Western US coals into pyrolytic tars and for the production of SO2 during the combustion of l6 Gulf Province lignites.
Attempted Development of a "Weathering Index" for Argonne PCSP Coals
Yun, Y.; Hoesterey, B.L.; Meuzelaar, H.L.C. and Hill, G.R.
ACS Preprints, 32, 4, 1987, New Orleans. Funded by US Department of Energy.
In order to develop a reliable, simple procedure for determining the oxidation status ("weathering index") of a coal sample, several candidate methods were tested with all eight coals from the Argonne Premium Coal Sample Program after air oxidation under relatively mild, controlled environmental conditions. Twenty-five gram aliquots of all eight PCSP coals were exposed to a 10-ml/min dry airflow at 100ºC in all-glass reactors for eight days. Weight changes and O2, CO2, and H2O exchange rates were recorded. Among the various characterization methods tested were FSI, slurry pH, Zeta potential and thermogravimetry. Pyrolysis mass spectrometry and Fourier transform IR spectroscopy were used to monitor structural changes. Results obtained to data show that FSI is a good indicator of oxidation state for low-to-medium caking coals of bituminous rank whereas slurry pH appeared to be less useful for most coals. Although Zeta potential and thermogravimetry tests are still underway, it is becoming quite clear that a reliable, generally useful "weathering index" may have to be based on a fairly comprehensive battery of tests rather than on a single technique.
The Role of Aliphatic and Aromatic Coal Structures and Macerals in Low-Temperature Oxidation Processes
Yun, Y.; Jakab, E.; McClennen, W.H.; Hill, G.R. and Meuzelaar, H.L.C.
ACS Preprints, 32, (1), 1987, Denver, CO. Funded by US Department of Energy.
Low temperature (<100ºC) coal oxidation processes are known to have a pronounced effect on important coal properties such as coking and caking behavior, heat of combustion, floatability, slurry pH, tar yield and extractability. However, the mechanisms and kinetics of the chemical reactions underlying such weathering processes in coal are far from well understood. In this article new Py-MS data on low temperature oxidation effects in several US coals of different rank and origin will be discussed with special emphasis on the role of different coal macerals.
Differential Coal Liquefaction, An Economically Viable Way of Producing Liquid, Solid, and Gaseous Fuels
Hill, G.R. and Meuzelaar, H.L.C.
Proc. New Fuels Forms Workshop, 1986. Funded by US Department of Energy, Electric Power Research Institute, Utah Power and Light, and State of Utah.
Although liquefaction yields in the 80-100% range have been regularly reported, it is becoming increasingly clear than an economically viable approach to the production of liquid fuels from coals should seek to optimize rather than maximize liquid yields. These considerations have prompted us to pursue new, "differential" liquefaction avenues characterized by disproportionation of the feedstock coal into two or more valuable end products.
Hill, GR
1988-1986
Time-Resolved Pyrolysis Mass Spectrometry of Coal: A New Tool for Mechanistic and Kinetic Studies
Chakravarty, T.; Meuzelaar, H.L.C.; Windig, W. and Hill, G.R.
Energy & Fuel, 2, 400-405, 1988. 5 pgs. Funded by ACERC (National Science Foundation and Associates and Affiliates).
Most coal devolatilization studies so far have focused on the determination of reaction rates for reactions occurring under widely different conditions encountered in liquefaction, gasification, coking or combustion processes. Published rates on more or less comparable coals may differ by several orders of magnitude, especially when obtained at high temperatures (>1000 K) and/or high heating rates (10²-105 K/s).
At the present state-of-the-art in coal devolatilization research, more emphasis should perhaps be placed on elucidating the mechanisms of the chemical reactions underlying the observed phenomena. When studying thermal conversion reactions in coal it seems correct to concentrate first on the so-called "primary" reactions before attempting to elucidate the many possible secondary reaction pathways. This is especially true since most secondary reaction pathways are strongly influenced by reactor design and experimental conditions.
The devolatilization behavior of coal will be determined primarily by the chemical composition of coal and secondly by the experimental conditions. Under properly designed vacuum micropyrolysis experiments working with sufficiently small particles (<50 mm diameter), it is possible to avoid mass and heat transport limitations and minimize the secondary reactions. Using unoxidized or well preserved coal samples, the chemical composition can be well defined and possibly characterized by major factors such as rank and depositional environment. Recent advances in pyrolysis mass spectrometry (Py-MS), viz, time-resolved Py-MS (TR Py-MS), along with multivariate analysis techniques enable extraction of underlying chemical components from a single experiment, thus reducing the uncertainty due to varying reactions conditions in different experiments. This paper demonstrates the feasibility of obtaining valuable mechanistic and kinetic data using microgram amounts of carefully selected coal samples under properly designed reaction conditions using TR Py-MS techniques in combination with advanced multivariate data analysis methods.
Prediction and Modeling of Coal Conversion Reactions by Pyrolysis Mass Spectrometry and Multivariate Statistical Analysis
Meuzelaar, H.L.C.; Hoesterey, B.L.; Windig, W. and Hill, G.R.
Fuel Processing Technology, l5, 59-70, 1987. 11 pgs. Funded by Electric Power Research Institute and US Department of Energy.
Report on the use of Curie-point pyrolysis MS as a microscale modeling technique for the conversion of four Western US coals into pyrolytic tars and for the production of SO2 during the combustion of l6 Gulf Province lignites.
Attempted Development of a "Weathering Index" for Argonne PCSP Coals
Yun, Y.; Hoesterey, B.L.; Meuzelaar, H.L.C. and Hill, G.R.
ACS Preprints, 32, 4, 1987, New Orleans. Funded by US Department of Energy.
In order to develop a reliable, simple procedure for determining the oxidation status ("weathering index") of a coal sample, several candidate methods were tested with all eight coals from the Argonne Premium Coal Sample Program after air oxidation under relatively mild, controlled environmental conditions. Twenty-five gram aliquots of all eight PCSP coals were exposed to a 10-ml/min dry airflow at 100ºC in all-glass reactors for eight days. Weight changes and O2, CO2, and H2O exchange rates were recorded. Among the various characterization methods tested were FSI, slurry pH, Zeta potential and thermogravimetry. Pyrolysis mass spectrometry and Fourier transform IR spectroscopy were used to monitor structural changes. Results obtained to data show that FSI is a good indicator of oxidation state for low-to-medium caking coals of bituminous rank whereas slurry pH appeared to be less useful for most coals. Although Zeta potential and thermogravimetry tests are still underway, it is becoming quite clear that a reliable, generally useful "weathering index" may have to be based on a fairly comprehensive battery of tests rather than on a single technique.
The Role of Aliphatic and Aromatic Coal Structures and Macerals in Low-Temperature Oxidation Processes
Yun, Y.; Jakab, E.; McClennen, W.H.; Hill, G.R. and Meuzelaar, H.L.C.
ACS Preprints, 32, (1), 1987, Denver, CO. Funded by US Department of Energy.
Low temperature (<100ºC) coal oxidation processes are known to have a pronounced effect on important coal properties such as coking and caking behavior, heat of combustion, floatability, slurry pH, tar yield and extractability. However, the mechanisms and kinetics of the chemical reactions underlying such weathering processes in coal are far from well understood. In this article new Py-MS data on low temperature oxidation effects in several US coals of different rank and origin will be discussed with special emphasis on the role of different coal macerals.
Differential Coal Liquefaction, An Economically Viable Way of Producing Liquid, Solid, and Gaseous Fuels
Hill, G.R. and Meuzelaar, H.L.C.
Proc. New Fuels Forms Workshop, 1986. Funded by US Department of Energy, Electric Power Research Institute, Utah Power and Light, and State of Utah.
Although liquefaction yields in the 80-100% range have been regularly reported, it is becoming increasingly clear than an economically viable approach to the production of liquid fuels from coals should seek to optimize rather than maximize liquid yields. These considerations have prompted us to pursue new, "differential" liquefaction avenues characterized by disproportionation of the feedstock coal into two or more valuable end products.