Nie, X
1994
Investigation of Physical Control Mechanisms in the Thermal Decomposition of Coal by Means of On-Line Mass Spectrometric Techniques
Nie, X.; Liu, K.; Maswadeh, W.; Tripathi, A. and Meuzelaar, H.L.C.
ACS Preprints, Division of Fuel Chemistry, 39(2):558-563, 1994. (Also presented at the 17th Annual Symposium of the Rocky Mountain Fuels Society, Golden, CO, March 1994, and at the ACS Meeting, San Diego, CA, March 1994.) Funded by ACERC and the Consortium for Fossil Fuel Liquefaction Science.
During the past decade marked progress has been made with regard to our understanding of the chemical processes occurring during the thermal degradation ("devolatilization," "desorption + pyrolysis") of coal and several advanced mechanistic models offering a qualitative and quantitative description of these processes, e.g., FG-DVC and CPD models, are now available. By contrast, there appears to be a comparative lack of progress in the description and understanding of the physical processes involved. It is becoming increasingly clear that the frequent lack of interlaboratory reproducibility almost invariably originates within the physical parameters of the experiment. Although heating rate, particle size and reactor pressure have long been recognized as the dominant physical parameters influencing the rates and product yields of coal devolatilization processes, current models pay little or no attention to heat and mass transport limitations. In fact, particle size is not an input parameter in these models. Furthermore, although most industrial scale coal devolatilization processes occur at near ambient pressures, current renewed interest in high pressure coal conversion processes would seem to dictate a more detailed look at the effects of pressure.
The objective of the research reported here is to exploit the capabilities of two novel experimental techniques, based on the on-line coupling of microscale, TG-type reactors to mass spectrometry and combined gas chromatography/mass spectrometry systems. The TG/GC/MS technique has high-pressure TG capabilities and will be described separately at this meeting. The direct TG/MS instrument is characterized by a heated, all quartz interface and will be discussed here. The complementary nature of both systems enables us to investigate the nature and extent of physical control mechanisms over a broad range of experimental conditions.
1993
Investigation of Physical Control Mechanisms in the Thermal Decomposition of Coal by Means of On-Line Mass Spectrometric Techniques
Nie, X.; Lui, K.; Maswadeh, W.; Tripathi, A. and Meuzelaar, H.L.C.
Proceedings ACS Conference Fuel Chem. Division, ACS Preprints, Fuel Chem. Div., 1993 (in press). Funded by ACERC.
During the past decade marked progress has been made with regard to our understanding of the chemical processes occurring during the thermal degradation ("devolatilization," "desorption + pyrolysis") of coal and several advanced mechanistic models offering a qualitative and quantitative description of these processes, e.g., FG-DVC and CPD models, are now available. By contrast, there appears to be a comparative lack of progress in the description and understanding of the physical processes involved. It is becoming increasingly clear that the frequent lack of interlaboratory reproducibility almost invariably originates within the physical parameters of the experiment. Although heating rate, particle size and reactor pressure have long been recognized as the dominant physical parameters influencing the rates and product yields of coal devolatilization processes, current models pay little or no attention to heat and mass transport limitations. In fact, particle size is not an input parameter in these models. Furthermore, although most industrial scale coal devolatilization processes occur at near ambient pressures, current renewed interest in high pressure coal conversion processes would seem to dictate a more detailed look at the effects of pressure. The objective of the research reported here is to exploit the capabilities of two novel experimental techniques, based on the on-line coupling of microscale, TG-type reactors to mass spectrometry and combined gas chromatography/mass spectrometry systems. The TG/GC/MS technique has high-pressure TG capabilities and will be described separately at this meeting. The direct TG/MS instrument is characterized by a heated, all quartz interface and will be discussed here. The complementary nature of both systems enables us to investigate the nature and extent of physical control mechanisms over a broad range of experimental conditions.
Development of On-Line GC/MS Monitoring Techniques for High-Pressure Fuel Conversion Processes
Nie, X.; McClennen, W.H.; Liu, K. and Meuzelaar, H.L.C.
Proceedings of the 206th American Chemical Society National Meeting, ACS Preprints, Fuel Chem. Div., 38 (4), Chicago, IL, August 1993. Funded by US Department of Energy.
It is well known that on-line analytical methods offer considerable advantages over conventional off-line procedures for fuel conversion processes. Although many on-line spectroscopic detection systems for thermal process reactors have been reported, they have had only very little application to high-pressure reactors. Therefore, relatively little is known about the precise pathways and intermediate products involved in high-pressure reactions. The application of real time, on-line chromatographic and/or spectroscopic techniques capable of throwing light on these processes is hampered by the high temperatures and pressures inside the reactor which complicate direct interfacing to standard analytical instruments.
Thermogravimetry (TG) can provide detailed information on thermally driven conversion reactions, especially when combined with on-line detection and identification techniques such as Fourier transform infrared spectroscopy (FTIR) and mass spectrometry (MS). However, high pressure TG systems have only recently become available for studying the basic pyrolysis and especially hydropyrolysis reactions involved in coal liquefaction, thus, the combined chromatographic/spectroscopic interfaces for such high pressure systems are only now producing results. Other high-pressure reactors of interest include those used to study the thermal processes in liquid fuels or in solvent-based coal conversion. Thus there have been recent reports of on-line GC/MS monitoring of a high pressure recirculating autoclave used to study coal derived liquid model compounds. Other work in our laboratory has examined the supercritical pyrolytic degradation of jet fuels with on-line GC/IR/MS. Several of these systems have involved the use of a patented automated vapor sampling (AVS) inlet with short column or so-called "transfer line" gas chromatography (TLGC) with MS or FTIR.
This paper presents the experimental descriptions and results from three high-pressure systems using a variety of components. The first is a high pressure TG/GC/MS system used to study coal hydropyrolysis. The other two use quartz-tubing reactors to examine the liquid and gaseous products from the thermal decomposition of jet fuels.
Development of Field-Portable Mass Spectrometric Techniques for Particulate Organic Matter in PM-10
Dworzanski, J.P.; Meuzelaar, H.L.C.; Maswadeh, W.; Nie, X.; Cole, P.A. and Arnold, N.S.
Proceedings of the International Symposium on Field Screenings Methods for Hazardous Wastes and Toxic Chemicals, Las Vegas, NV, February 1993. Funded by Southwest Center for Environmental Research and Policy, and the Environmental Protection Agency.
The chemical composition and structure of particulate organic matter can provide important information regarding origin, distribution and fate of respirable aerosols (PM-10) in the environment. Nevertheless, because of a lack of fast and reliable methods for chemical characterization of the organic components of the PM-10 fraction, most source apportionment studies focus exclusively on specification of inorganic components. In view of its inherent sensitivity, specificity and quantitative response, mass spectrometry (MS) offers obvious promise for characterization of the organic fraction. Consequently, special collection and sampling modules suitable for MS analysis of PM-10 have been developed in our laboratory and field-tested. The modules consist of a sampling unit and a low-dead volume Curie-point thermal desorption/pyrolysis inlet interfaced to a temperature programmable "transfer line" capillary column which is coupled to a ruggedized, miniaturized Finnigan MAT ion trap mass spectrometer (ITMS).
From among the PM-10 collection methods for MS investigated in our laboratory quartz fiber filters were selected because of inherent simplicity and high collection efficiency. After PM-10 collection, quartz filters underwent thermal desorption or pyrolysis followed by on-line GC/MS analysis. This approach was used to characterize the organic matter in particulate samples collected at 3-hour intervals at the US/Mexican border. Subsequent principal component analysis of selected mass profiles together with particle density and size distribution data as well as meteorological parameters allowed tentative identification of several PM-10 sources, including automotive emissions, food preparation and wood burning.
Nie, X
1994
Investigation of Physical Control Mechanisms in the Thermal Decomposition of Coal by Means of On-Line Mass Spectrometric Techniques
Nie, X.; Liu, K.; Maswadeh, W.; Tripathi, A. and Meuzelaar, H.L.C.
ACS Preprints, Division of Fuel Chemistry, 39(2):558-563, 1994. (Also presented at the 17th Annual Symposium of the Rocky Mountain Fuels Society, Golden, CO, March 1994, and at the ACS Meeting, San Diego, CA, March 1994.) Funded by ACERC and the Consortium for Fossil Fuel Liquefaction Science.
During the past decade marked progress has been made with regard to our understanding of the chemical processes occurring during the thermal degradation ("devolatilization," "desorption + pyrolysis") of coal and several advanced mechanistic models offering a qualitative and quantitative description of these processes, e.g., FG-DVC and CPD models, are now available. By contrast, there appears to be a comparative lack of progress in the description and understanding of the physical processes involved. It is becoming increasingly clear that the frequent lack of interlaboratory reproducibility almost invariably originates within the physical parameters of the experiment. Although heating rate, particle size and reactor pressure have long been recognized as the dominant physical parameters influencing the rates and product yields of coal devolatilization processes, current models pay little or no attention to heat and mass transport limitations. In fact, particle size is not an input parameter in these models. Furthermore, although most industrial scale coal devolatilization processes occur at near ambient pressures, current renewed interest in high pressure coal conversion processes would seem to dictate a more detailed look at the effects of pressure.
The objective of the research reported here is to exploit the capabilities of two novel experimental techniques, based on the on-line coupling of microscale, TG-type reactors to mass spectrometry and combined gas chromatography/mass spectrometry systems. The TG/GC/MS technique has high-pressure TG capabilities and will be described separately at this meeting. The direct TG/MS instrument is characterized by a heated, all quartz interface and will be discussed here. The complementary nature of both systems enables us to investigate the nature and extent of physical control mechanisms over a broad range of experimental conditions.
1993
Investigation of Physical Control Mechanisms in the Thermal Decomposition of Coal by Means of On-Line Mass Spectrometric Techniques
Nie, X.; Lui, K.; Maswadeh, W.; Tripathi, A. and Meuzelaar, H.L.C.
Proceedings ACS Conference Fuel Chem. Division, ACS Preprints, Fuel Chem. Div., 1993 (in press). Funded by ACERC.
During the past decade marked progress has been made with regard to our understanding of the chemical processes occurring during the thermal degradation ("devolatilization," "desorption + pyrolysis") of coal and several advanced mechanistic models offering a qualitative and quantitative description of these processes, e.g., FG-DVC and CPD models, are now available. By contrast, there appears to be a comparative lack of progress in the description and understanding of the physical processes involved. It is becoming increasingly clear that the frequent lack of interlaboratory reproducibility almost invariably originates within the physical parameters of the experiment. Although heating rate, particle size and reactor pressure have long been recognized as the dominant physical parameters influencing the rates and product yields of coal devolatilization processes, current models pay little or no attention to heat and mass transport limitations. In fact, particle size is not an input parameter in these models. Furthermore, although most industrial scale coal devolatilization processes occur at near ambient pressures, current renewed interest in high pressure coal conversion processes would seem to dictate a more detailed look at the effects of pressure. The objective of the research reported here is to exploit the capabilities of two novel experimental techniques, based on the on-line coupling of microscale, TG-type reactors to mass spectrometry and combined gas chromatography/mass spectrometry systems. The TG/GC/MS technique has high-pressure TG capabilities and will be described separately at this meeting. The direct TG/MS instrument is characterized by a heated, all quartz interface and will be discussed here. The complementary nature of both systems enables us to investigate the nature and extent of physical control mechanisms over a broad range of experimental conditions.
Development of On-Line GC/MS Monitoring Techniques for High-Pressure Fuel Conversion Processes
Nie, X.; McClennen, W.H.; Liu, K. and Meuzelaar, H.L.C.
Proceedings of the 206th American Chemical Society National Meeting, ACS Preprints, Fuel Chem. Div., 38 (4), Chicago, IL, August 1993. Funded by US Department of Energy.
It is well known that on-line analytical methods offer considerable advantages over conventional off-line procedures for fuel conversion processes. Although many on-line spectroscopic detection systems for thermal process reactors have been reported, they have had only very little application to high-pressure reactors. Therefore, relatively little is known about the precise pathways and intermediate products involved in high-pressure reactions. The application of real time, on-line chromatographic and/or spectroscopic techniques capable of throwing light on these processes is hampered by the high temperatures and pressures inside the reactor which complicate direct interfacing to standard analytical instruments.
Thermogravimetry (TG) can provide detailed information on thermally driven conversion reactions, especially when combined with on-line detection and identification techniques such as Fourier transform infrared spectroscopy (FTIR) and mass spectrometry (MS). However, high pressure TG systems have only recently become available for studying the basic pyrolysis and especially hydropyrolysis reactions involved in coal liquefaction, thus, the combined chromatographic/spectroscopic interfaces for such high pressure systems are only now producing results. Other high-pressure reactors of interest include those used to study the thermal processes in liquid fuels or in solvent-based coal conversion. Thus there have been recent reports of on-line GC/MS monitoring of a high pressure recirculating autoclave used to study coal derived liquid model compounds. Other work in our laboratory has examined the supercritical pyrolytic degradation of jet fuels with on-line GC/IR/MS. Several of these systems have involved the use of a patented automated vapor sampling (AVS) inlet with short column or so-called "transfer line" gas chromatography (TLGC) with MS or FTIR.
This paper presents the experimental descriptions and results from three high-pressure systems using a variety of components. The first is a high pressure TG/GC/MS system used to study coal hydropyrolysis. The other two use quartz-tubing reactors to examine the liquid and gaseous products from the thermal decomposition of jet fuels.
Development of Field-Portable Mass Spectrometric Techniques for Particulate Organic Matter in PM-10
Dworzanski, J.P.; Meuzelaar, H.L.C.; Maswadeh, W.; Nie, X.; Cole, P.A. and Arnold, N.S.
Proceedings of the International Symposium on Field Screenings Methods for Hazardous Wastes and Toxic Chemicals, Las Vegas, NV, February 1993. Funded by Southwest Center for Environmental Research and Policy, and the Environmental Protection Agency.
The chemical composition and structure of particulate organic matter can provide important information regarding origin, distribution and fate of respirable aerosols (PM-10) in the environment. Nevertheless, because of a lack of fast and reliable methods for chemical characterization of the organic components of the PM-10 fraction, most source apportionment studies focus exclusively on specification of inorganic components. In view of its inherent sensitivity, specificity and quantitative response, mass spectrometry (MS) offers obvious promise for characterization of the organic fraction. Consequently, special collection and sampling modules suitable for MS analysis of PM-10 have been developed in our laboratory and field-tested. The modules consist of a sampling unit and a low-dead volume Curie-point thermal desorption/pyrolysis inlet interfaced to a temperature programmable "transfer line" capillary column which is coupled to a ruggedized, miniaturized Finnigan MAT ion trap mass spectrometer (ITMS).
From among the PM-10 collection methods for MS investigated in our laboratory quartz fiber filters were selected because of inherent simplicity and high collection efficiency. After PM-10 collection, quartz filters underwent thermal desorption or pyrolysis followed by on-line GC/MS analysis. This approach was used to characterize the organic matter in particulate samples collected at 3-hour intervals at the US/Mexican border. Subsequent principal component analysis of selected mass profiles together with particle density and size distribution data as well as meteorological parameters allowed tentative identification of several PM-10 sources, including automotive emissions, food preparation and wood burning.