Huai, H
1996
On-Line GC/MS Techniques for Monitoring High-Pressure Conversion Reactions
Jakab, E.; Huai, H.; Nie, H. and Meuzelaar, H.L.C.
Process Control & Quality, 8:55-67, 1996. Funded by Consortium for Fossil Fuel Liquefaction Science, ACERC and Rocketdyne.
Gas chromatography-mass spectrometry instruments were interfaced to high-pressure flow-through microreactors to monitor the product formation on-line. Three types of instrumental setup are described illustrating the versatility of this kind of coupling. The first example shows the thermal and catalytic conversion of dibenzyl ether in solution under 155 bar hydrogen atmosphere. In the second application, thermal decomposition of JP-7 jet fuel was carried out under supercritical conditions to study the gaseous product evolution. This system features the application of a microbalance to monitor the weight of the total liquid sample plus products. The third system was designed to perform conversion of solid sample (wood) in liquid/vapor environment. This reactor can be applied to model two-step liquefaction processes with catalytic conversion of the primary product. All three systems provide information on the product distribution and kinetic profiles of the conversion processes.
1992
Spectroscopic Studies of Coal Maceral Depolymerization Effected by an Iron-Based Catalyst
Wang, H.P.; Lo, R.; Sommerfeld, D.A.; Huai, H.; Pugmire, R.J.; Shabtai, J.S. and Eyring, E.M.
Fuel, 71(7):723-729, 1992. Funded by US Department of Energy.
Demineralized Hiawatha (Utah) coal was divided into narrow density fractions of resinite and vitrinite macerals using a density gradient centrifugation technique. The distribution of an iron-based catalyst in the coal maceral matrix was studied using an electron probe microanalyser. The data indicate that the iron catalyst is evenly dispersed inside the vitrinite. This uniform dispersion is preserved upon mild (275ºC) hydrotreatment and attendant partial depolymerization of the vitrinite maceral. However, the iron catalyst does not completely penetrate into the resinite maceral matrix due to a lack of microporosity. The small amount of dispersed iron catalyst in the resinite causes some depolymerization of maceral components, e.g. dimers, trimers, or higher polymers, into monomers. Due to the insufficient dispersion of the iron catalyst in the resinite a competing thermal breakdown of the maceral occurs. This apparently involved a partial dehydrogenation reaction that may be favored during the hydrotreatment of resinite.
Determining Molecular Weight Distributions of Polar Coal Derived Liquids by Means of Combined GC/MS and Vacuum TG Techniques
Huai, H. and Meuzelaar, H.L.C.
ACS Division of Fuel Chemistry Preprints, 37(1):424-431, 1992 (203rd ACS National Meeting, San Francisco, CA, April 1992). Funded by Pittsburgh Energy Technology Center/Consortium for Fossil Fuel Liquefaction and ACERC.
A novel, low temperature (<300 C) coal liquefaction method described by Shabtai et al., consisting of a mild hydrotreatment (HT) step followed by base-catalyzed depolymerization (BCD) is thought to proceed by selective scission of C-C and C-O type bonds in the bridges connecting the aromatic and hydroaromatic clusters making up the bulk of the coal matrix, while minimizing secondary condensation reactions. Consequently, the resulting liquid products are expected to consist primarily of "monomeric" building blocks of the type and size inferred from solid state NMR measurements, i.e., corresponding to (hydro)aromatic structures with 10-15 aromatic carbons, 2-3 aliphatic carbons and 1-2 substituted oxygens (in addition to more sporadic sulfur, nitrogen or metal substituents) depending on coal rank, maceral composition, depositional environment and weathering status. In agreement with these expectations, the cyclohexane soluble "oil" fractions of the HT-BCD product, comprising up to 70% of the daf coal, were found to be completely vacuum distillable and to contain significant quantities of volatile, low MW components when analyzed by combined gas chromatography/mass spectrometry (GC/MS).
In order to further verify the mechanistic assumptions underlying the HT-BCD method as well as to obtain valuable information regarding type and size of the monomeric building blocks in coals, we decided to determine the precise molecular weight distribution (MWD) of HT-BCD oil fractions. The term MWD will be used interchangeably here with MMD (molecular or molar mass distribution). In view of the relatively low molecular weight and high polarity of the HT-BCD oil fractions, the use of gel permeation chromatography (GPC), also referred to as size exclusion chromatography, techniques was rejected in favor of mass spectrometry (MS) using "soft ionization" methods, such as field ionization (FI) and chemical ionization (CI), which tend to produce little or no fragmentation of molecular ions. Direct probe FIMS measurements were performed by Dr. H.R. Schulten (Fresenius Institute, Wiesbaden, GFR) whereas CIMS analyses were carried out in our laboratory using on-line preseparation by short column capillary gas chromatography (GC) and sample injection by means of Curie point flash evaporation. Well-known shortcomings of MS techniques include: possible loss of volatile components during sample introduction (in particular during direct probe MS); incomplete transport of low volatile components into the ion source (especially when using GC/MA); compound dependent response differences; and inability to analyze nonvolatile residues. Therefore, vacuum thermogravimetry (VTG) was selected as a tool for quantitative calibration, similar to its well-established use for calibrating simulated distillation (SIMDIS) methods. The results of these DP-FIS, GC/CIMS and VTG experiments with a mixture of coal liquid like model compounds as well as with HT-BCD oil fractions from three ANL-PCSP (Argonne National Laboratory - Premium Coal Sample Program) coals, viz. Beulah Zap lignite, Illinois #6 hvCb and Blind Canyon hvBb coals, will be reported here.
On-Line GC/MS Analysis of High Pressure Reactions
Dworzanski, J.P.; Huai, H.; Arnold, N.S. and Meuzelaar, H.L.C.
Proceedings of the Fortieth ASMS Conference on Mass Spectrometry and Allied Topics, 762-767, Washington, DC, 1992. Funded by Consortium for Fossil Fuel Liquefaction, Rocketdyne and ACERC.
The growing demand for real-time monitoring of industrial processes performed in reactors under conditions of high pressure and temperature indicates that MS technology, especially in combination with GC preseparation potential could fulfill many current requirements. To achieve these goals we have expanded the application of our valveless vapor sampling inlet for on-line analysis of atmospheric gases and vapors by "transfer line" GC/MS to monitor chemical processes at high pressures (1000-2000 psi) through the construction of a special capillary restrictor to reduce the pressure to near ambient conditions. The restrictor effluent is coupled to the automatic vapor-sampling inlet via a dilution chamber. This allows repetitive GC/MS analyses to be obtained at 1-15 minute intervals.
Kinetic parameters and yields of primary and secondary decomposition products of jet fuels as well as model compounds in coal liquefaction processes have been obtained in a fraction of time needed for conventional off-line measurements and indicate that the proposed approach may be easily applied to a broad range of existing reactor types and potential processing environments.
On-Line GC/MS Analysis of High Pressure Conversion Reactions of Model Compounds for Coal-Derived Liquids
Huai, H.; Tsai, C.H.; Shabtai, J.S. and Meuzelaar, H.L.C.
ACS Division of Fuel Chemistry Preprints, 37(2):925-932, 1992 (203rd ACS National Meeting, San Francisco, CA, April 1992). Funded by Consortium for Fossil Fuel Liquefaction.
Direct coal liquefaction involves complex and insufficiently defined chemical reactions. In order to improve direct coal liquefaction processes, it is necessary to improve our understanding of key chemical reactions. Unfortunately, due to the high pressure and high temperature requirements of most coal liquefaction processes, real-time on-line reaction monitoring by advanced spectroscopic and/or chromatographic techniques has generally been impossible until now. Thus, relatively little is known about the precise reaction pathways as well as the intermediate reaction products involved. This is particularly true for conversion reactions carried out in batch reactors such as autoclaves. Due to the relatively long residence times primary reaction products formed in batch type autoclaves are quite susceptible to secondary, or even tertiary reactions. Consequently, real-time on-line monitoring experiments are needed to elucidate reaction pathways in autoclaves.
Although several on-line systems have been developed for coal conversion at near-ambient pressure or high vacuum conditions, there are no repots of on-line chromatography/spectroscopy based systems built for monitoring high-pressure conversion reactions. Therefore, the development of a direct GC/MS interface for near-real time analysis of high-pressure reaction products, while minimally disturbing the reaction process, has been undertaken in our laboratory.
It is well established that coal contains fused aromatic and hydroaromatic ring clusters, composed of an average of two to tour condensed ring units, connected by various alkylene, ether, sulfide and direct (Ar)C-C(Ar) bridges. Liquefaction reactions are primarily thought to involve these connecting bridges, especially ether linkages and alkylene linkages. In recent years, a number of workers have subjected coal-model compounds to various coal conversion conditions in order to confirm that certain coal structures are reactive during coal conversion and to infer the conversion mechanisms of real coals from mechanisms determined for such compounds.
The present paper reports the design and testing of a newly developed on-line GC/MS monitoring system for high pressure reactions and its application to the investigation of hydrogenation and hydrodeoxygenation (HDO) of model compounds, such as diphenyl methane and dibenzyl ether, under both catalytic and thermal conditions.
1991
Canonical Correlation Analysis of Multisource Fossil Fuel Data
Meuzelaar, H.L.C.; Statheropoulos, M.; Huai, H. and Yun, Y.
Computer-Enhanced Analytical Spectroscopy, 3:185-214, (P.C. Jurs, ed.), Plenum Publishing Co., New York, 1991. Funded by ACERC and US Department of Energy.
The following sections of this chapter will demonstrate the application of Canonical Correlation Analysis (CCA) to multisource fossil fuel data generated by the application of three different spectroscopic methods: Pyrolysis Low Voltage Electron Ionization Mass Spectrometry (LVMS); Pyrolysis Field Ionization Mass Spectrometry (FIMS); and Photo-acoustic Fourier Transform Infrared Spectroscopy (FTIR) to a single suite of eight U.S. coals obtained from the Argonne National Laboratory Premium Coal Sample Program (ANL-PCSP). Consequently, the three data sets obtained describe the same suite of samples but are markedly different with respect to number as well as type of variables.
The Chemical Structure and Petrology of Resinite from the Hiawatha "B" Coal Seam
Crelling, J.C.; Pugmire, R.J.; Meuzelaar, H.L.C.; McClennen, W.H.; Huai, H. and Karas, J.
Energy & Fuels, 5:688-694, 1991. Funded by US Department of Energy and ACERC.
The objective of the present study is to examine the chemical structure and composition of Utah Wasatch Plateau coal resinite. Macerals were separated from the coal matrix by hand picking, sink-float treatments, and/or density gradient centrifugation (DGC). DGC separation was found to produce highly purified resinite fractions. Resinite-rich Wattis Seam coal samples were collected from fresh mine faces and, after varying degrees of concentration, subjected to C-13 magic angle spinning NMR, Curie-point pyrolysis MS, and Curie-point pyrolysis GC/MS in addition to petrographic analysis and fluorescence microscopy as well as conventional (e.g., ultimate analysis) characterization methods. The data obtained confirm recent findings indicating that the abundant blue/green fluorescing resinite component is a polymeric substance composed of sesquiterpenoid repeat units with a median size of 204 Da, corresponding to the empirical formula C15H24. The monomeric sesquiterpenoid units obtained during pyrolysis appear to represent different degrees of unsaturatization ranging from C15H26 sesquiterpenes to the aromatic C15H18 cadalene. Clearly, sesquiterpenoids constitute the bulk of extractable resinite in Wasatch Plateau field coal and are likely to be important precursors of the abundant extractable alkynaphthalene moieties in such coal.
Chemical Composition and Origin of Fossil Resins from Utah Wasatch Plateau Coal
Meuzelaar, H.L.C.; Huai, H.; Lo, R. and Dworzanski, J.P.
Fuel Processing Technology, 28:119-134, 1991. Funded by Pittsburgh Energy Technology Center/Consortium for Fossil Fuel Liquefaction, ACERC and Advanced Coal Technology Center.
In order to arrive at a more detailed chemical description of fossil coal associated resins we need to distinguish between micropetrographic, organic geochemical and process technological definitions, each of which may encompass varying quantities of constituents unrelated to fossil tree resins. New information on composition and origin of Utah Wasatch Plateau coal resins obtained by Curie-point pyrolysis/evaporation in combination with iso-butane chemical ionization mass spectrometry, as presented in this paper, points to the presence of four more or less distinct resin components: (1) a sesquiterpenoid polymer; (2) sesqui- and triterpenoid monomers and dimers; (3) a suite of triterpenoid alcohols, ketones and acids; and (4) a series of increasingly aromatized hydrocarbons with naphthalene and picene type skeletons. Moreover, a strong similarity is found between the composition of recent dammar resin and fossil. Wasatch Plateau coal resins indicating a possible Angiosperm (fam. Dipterocarpaceae) origin of these Upper Cretaceous coal resins. Some of the technological implications of these findings and the consequent need for a more precise chemical definition and nomenclature are discussed.
Laser Pyrolysis Gas Chromatography/Mass Spectrometry of Single Spherocarb Particles Impregnated with Bituminous and Polymeric Substances
Maswadeh, W.; Huai, H. and Meuzelaar, H.L.C.
ASC Preprints, Division of Fuel Chemistry, 36(2):733-740, 1991 (201st ACS National Meeting, Atlanta, GA, April 1991). Funded by ACERC.
A major bottleneck in the development of novel coal characterization methods, such as laser pyrolysis GC/MS, capable of analyzing individual coal particles, is the unavailability of suitable standard samples. Although carefully homogenized and characterized standard coals are now available through the Argonne National Laboratory Premium Coal Sample Program (ANL-PCSP) such "statistically homogenous" coal powders are of limited value as reference materials for single particle analysis methods. Even if it would be feasible to prepare particles of closely similar chemical composition and size, e.g., by using highly concentrated coal maceral fractions and careful sieving, remaining variations in shape, density, porosity or thermal conductivity could still introduce an unacceptably high level of uncertainty for most optimization and calibration purposes.
In an attempt to find model coal char particles with well-defined chemical and physical properties, e.g., for the purpose of modeling char oxidation reactions, several authors have used Spherocarb® particles. Flagan et al have even prepared spherical char particles spiked with mineral matter components in order to more closely mimic actual coal char particles. Although Spherocarb particles still show considerable variability with regard to size (rel. s.d. ~20% on a volume basis), other characteristics such as shape, density, porosity, thermal conductivity and chemical composition are assumed to be quite constant.
Unfortunately, Spherocarb particles are of little value for modeling coal devolatilization reactions due to their very low volatile matter yields. This prompted us to think of ways to increase volatile matter yields by introducing a variety of model compounds, ranging from low molecular weight, bitumen-like components to polymeric materials such as soluble lignins or resins. To the best of our knowledge this article represents the first reported use of bitumen and polymer impregnated Spherocarb particles for modeling devolatilization processes in individual coal particles.
Analysis of Peru Margin Surface Sediments by PY-MS
Eglinton, T.I.; McCaffrey, M.A.; Huai, H. and Meuzelaar, H.L.C.
ACS Preprints, Division of Fuel Chemistry, 36(2):781-789 (201st ACS National Meeting, Atlanta, GA, April 1991).
In offshore Peru high sedimentary organic carbon contents are a direct consequence of the extremely high primary productivity (ca. 1000g Carbon m²/yr) which, in turn, is supported by the upwelling of nutrient-rich waters near the coast. Diatoms represent the major phytoplankton type and give rise to sediments dominated by biogenic silica and planktonic organic matter. The remineralization of this large flux of organic matter to the bottom waters and sediments results in oxygen depletion over large areas of the shelf that, in turn, promotes organic carbon preservation in the underlying sediments. Sulfide from sulfate reduction is prevalent in the bottom waters and with a limited availability of iron (due to the dominant biogenic input coupled with a very low influx of detrital sediments) the excess sulfide is available for reaction with the organic matter. As a result high organic sulfur concentrations are found in the sediments.
The coastal Peru upwelling region is believed to be a modern analogue to the depositional environments of petroleum source rocks such as the Miocene Monterey Formation of the California Borderland. Because organic matter alteration pathways in surface sediments ultimately influence kerogen type and eventual petroleum yield, there has been interest in characterizing surface sediments such as those offshore Peru. Lipid, carotenoid and amino acid constituents as well as general biogeochemistry have been studied previously. However, studies of the macromolecular components of the sediments have been less extensive. This paper describes results from Py-MS analyses of sediment samples obtained from discrete intervals in a 1-meter core obtained from the upper continental shelf of the Peru Upwelling region. Factor and discriminant analysis of the Py-MS data revealed several distinct changes within this 1-meter section.
1990
The Chemical Structure and Petrology of Resinite from the Hiawatha "B" Coal Seam
Crelling, J.C.; Pugmire, R.J.; Meuzelaar, H.L.C.; McClennen, W.H.; Huai, H. and Karas, J.
Energy & Fuels, 1990 (In press). Funded by ACERC and US Department of Energy.
Although the maceral resinite occurs in most U.S. coals, it is particularly abundant in the coal seams of the Wasatch Plateau coalfield in central Utah. The high resinite content of the coals of central Utah has long been known and commercially exploited but little work has been reported on the elucidation of the chemical composition of this material. Details of the chemical structure of the micropetrographically defined maceral resinite have generally been lacking because it is noncrystalline and is only partially soluble in organic solvents. In contrast with the abundance of spectroscopic and chromatographic data available on some of the better known fossil resin types, e.g., Baltic amber, Utah coal resins appear to have generated relatively little interest among coal scientists. The overall objective of the present study was to examine the structure of Utah Wasatch Plateau coal resinite macerals that have been separated from the coal matrix, purified, and most important, carefully characterized by fluorescence spectral analysis. The samples were then analyzed by means of CP/MAS C NMR and by Curie-point pyrolysis in direct combination with mass spectrometry (Py-MS) or via preseparation by gas chromatography (Py-GC/MS).
A Comparative Study of Eight U.S. Coals by Several Different Pyrolysis Mass Spectrometry Techniques
Huai, H.; Lo, R.; Yun, Y. and Meuzelaar, H.L.C.
ACS Division of Chemistry, 35 (3), Washington, D.C., 1990. (Also Proc. of the 38th ASMS Conference on Mass Spectrometry and Allied Topics, Tucson, AZ, 601-602, 1990). Funded by Consortium for Fossil Fuel Liquefaction Science.
Eight U.S. coals of different rank and/or composition, obtained through the Argonne National Laboratory Premium Coal Sample Program, were analyzed by means of several different pyrolysis-MS (Py-MS) techniques, namely: direct Curie-Point Py-MS, Curie-point Py-GC/MS (including GC/EIMS, GC/CIMS and "short column" GC/CIMS), and vacuum thermogravimetry/MS (TG/MS). The data obtained were compared to Pyrolysis-Field Ionization MS (Py-FIMS) data.
The results show a very good agreement between all techniques used in spite of the marked differences in pyrolysis techniques (Curie-point, furnace, direct probe), "soft" ionization methods (low voltage EI, CI FI) and mass spectrometer types (quadrupole, ion trap, magnetic sector) used. As might be expected, the most pronounced variations between techniques appear to be due to mass dependent differences in ion transmissivity and detector response, with the type of soft ionization method taking second place and the type of pyrolysis technique showing least effect on the results. Whereas Py-FIMS provides the most complete and detailed overview of the coal pyrolysis tars, Cuire-point Py-MS and TG/MS methods provide more reliable information on relatively light gaseous products, and Curie-point Py-GC/MS shows the detail composition of the 2/3 of the total pyrolysis tars.
Huai, H
1996
On-Line GC/MS Techniques for Monitoring High-Pressure Conversion Reactions
Jakab, E.; Huai, H.; Nie, H. and Meuzelaar, H.L.C.
Process Control & Quality, 8:55-67, 1996. Funded by Consortium for Fossil Fuel Liquefaction Science, ACERC and Rocketdyne.
Gas chromatography-mass spectrometry instruments were interfaced to high-pressure flow-through microreactors to monitor the product formation on-line. Three types of instrumental setup are described illustrating the versatility of this kind of coupling. The first example shows the thermal and catalytic conversion of dibenzyl ether in solution under 155 bar hydrogen atmosphere. In the second application, thermal decomposition of JP-7 jet fuel was carried out under supercritical conditions to study the gaseous product evolution. This system features the application of a microbalance to monitor the weight of the total liquid sample plus products. The third system was designed to perform conversion of solid sample (wood) in liquid/vapor environment. This reactor can be applied to model two-step liquefaction processes with catalytic conversion of the primary product. All three systems provide information on the product distribution and kinetic profiles of the conversion processes.
1992
Spectroscopic Studies of Coal Maceral Depolymerization Effected by an Iron-Based Catalyst
Wang, H.P.; Lo, R.; Sommerfeld, D.A.; Huai, H.; Pugmire, R.J.; Shabtai, J.S. and Eyring, E.M.
Fuel, 71(7):723-729, 1992. Funded by US Department of Energy.
Demineralized Hiawatha (Utah) coal was divided into narrow density fractions of resinite and vitrinite macerals using a density gradient centrifugation technique. The distribution of an iron-based catalyst in the coal maceral matrix was studied using an electron probe microanalyser. The data indicate that the iron catalyst is evenly dispersed inside the vitrinite. This uniform dispersion is preserved upon mild (275ºC) hydrotreatment and attendant partial depolymerization of the vitrinite maceral. However, the iron catalyst does not completely penetrate into the resinite maceral matrix due to a lack of microporosity. The small amount of dispersed iron catalyst in the resinite causes some depolymerization of maceral components, e.g. dimers, trimers, or higher polymers, into monomers. Due to the insufficient dispersion of the iron catalyst in the resinite a competing thermal breakdown of the maceral occurs. This apparently involved a partial dehydrogenation reaction that may be favored during the hydrotreatment of resinite.
Determining Molecular Weight Distributions of Polar Coal Derived Liquids by Means of Combined GC/MS and Vacuum TG Techniques
Huai, H. and Meuzelaar, H.L.C.
ACS Division of Fuel Chemistry Preprints, 37(1):424-431, 1992 (203rd ACS National Meeting, San Francisco, CA, April 1992). Funded by Pittsburgh Energy Technology Center/Consortium for Fossil Fuel Liquefaction and ACERC.
A novel, low temperature (<300 C) coal liquefaction method described by Shabtai et al., consisting of a mild hydrotreatment (HT) step followed by base-catalyzed depolymerization (BCD) is thought to proceed by selective scission of C-C and C-O type bonds in the bridges connecting the aromatic and hydroaromatic clusters making up the bulk of the coal matrix, while minimizing secondary condensation reactions. Consequently, the resulting liquid products are expected to consist primarily of "monomeric" building blocks of the type and size inferred from solid state NMR measurements, i.e., corresponding to (hydro)aromatic structures with 10-15 aromatic carbons, 2-3 aliphatic carbons and 1-2 substituted oxygens (in addition to more sporadic sulfur, nitrogen or metal substituents) depending on coal rank, maceral composition, depositional environment and weathering status. In agreement with these expectations, the cyclohexane soluble "oil" fractions of the HT-BCD product, comprising up to 70% of the daf coal, were found to be completely vacuum distillable and to contain significant quantities of volatile, low MW components when analyzed by combined gas chromatography/mass spectrometry (GC/MS).
In order to further verify the mechanistic assumptions underlying the HT-BCD method as well as to obtain valuable information regarding type and size of the monomeric building blocks in coals, we decided to determine the precise molecular weight distribution (MWD) of HT-BCD oil fractions. The term MWD will be used interchangeably here with MMD (molecular or molar mass distribution). In view of the relatively low molecular weight and high polarity of the HT-BCD oil fractions, the use of gel permeation chromatography (GPC), also referred to as size exclusion chromatography, techniques was rejected in favor of mass spectrometry (MS) using "soft ionization" methods, such as field ionization (FI) and chemical ionization (CI), which tend to produce little or no fragmentation of molecular ions. Direct probe FIMS measurements were performed by Dr. H.R. Schulten (Fresenius Institute, Wiesbaden, GFR) whereas CIMS analyses were carried out in our laboratory using on-line preseparation by short column capillary gas chromatography (GC) and sample injection by means of Curie point flash evaporation. Well-known shortcomings of MS techniques include: possible loss of volatile components during sample introduction (in particular during direct probe MS); incomplete transport of low volatile components into the ion source (especially when using GC/MA); compound dependent response differences; and inability to analyze nonvolatile residues. Therefore, vacuum thermogravimetry (VTG) was selected as a tool for quantitative calibration, similar to its well-established use for calibrating simulated distillation (SIMDIS) methods. The results of these DP-FIS, GC/CIMS and VTG experiments with a mixture of coal liquid like model compounds as well as with HT-BCD oil fractions from three ANL-PCSP (Argonne National Laboratory - Premium Coal Sample Program) coals, viz. Beulah Zap lignite, Illinois #6 hvCb and Blind Canyon hvBb coals, will be reported here.
On-Line GC/MS Analysis of High Pressure Reactions
Dworzanski, J.P.; Huai, H.; Arnold, N.S. and Meuzelaar, H.L.C.
Proceedings of the Fortieth ASMS Conference on Mass Spectrometry and Allied Topics, 762-767, Washington, DC, 1992. Funded by Consortium for Fossil Fuel Liquefaction, Rocketdyne and ACERC.
The growing demand for real-time monitoring of industrial processes performed in reactors under conditions of high pressure and temperature indicates that MS technology, especially in combination with GC preseparation potential could fulfill many current requirements. To achieve these goals we have expanded the application of our valveless vapor sampling inlet for on-line analysis of atmospheric gases and vapors by "transfer line" GC/MS to monitor chemical processes at high pressures (1000-2000 psi) through the construction of a special capillary restrictor to reduce the pressure to near ambient conditions. The restrictor effluent is coupled to the automatic vapor-sampling inlet via a dilution chamber. This allows repetitive GC/MS analyses to be obtained at 1-15 minute intervals.
Kinetic parameters and yields of primary and secondary decomposition products of jet fuels as well as model compounds in coal liquefaction processes have been obtained in a fraction of time needed for conventional off-line measurements and indicate that the proposed approach may be easily applied to a broad range of existing reactor types and potential processing environments.
On-Line GC/MS Analysis of High Pressure Conversion Reactions of Model Compounds for Coal-Derived Liquids
Huai, H.; Tsai, C.H.; Shabtai, J.S. and Meuzelaar, H.L.C.
ACS Division of Fuel Chemistry Preprints, 37(2):925-932, 1992 (203rd ACS National Meeting, San Francisco, CA, April 1992). Funded by Consortium for Fossil Fuel Liquefaction.
Direct coal liquefaction involves complex and insufficiently defined chemical reactions. In order to improve direct coal liquefaction processes, it is necessary to improve our understanding of key chemical reactions. Unfortunately, due to the high pressure and high temperature requirements of most coal liquefaction processes, real-time on-line reaction monitoring by advanced spectroscopic and/or chromatographic techniques has generally been impossible until now. Thus, relatively little is known about the precise reaction pathways as well as the intermediate reaction products involved. This is particularly true for conversion reactions carried out in batch reactors such as autoclaves. Due to the relatively long residence times primary reaction products formed in batch type autoclaves are quite susceptible to secondary, or even tertiary reactions. Consequently, real-time on-line monitoring experiments are needed to elucidate reaction pathways in autoclaves.
Although several on-line systems have been developed for coal conversion at near-ambient pressure or high vacuum conditions, there are no repots of on-line chromatography/spectroscopy based systems built for monitoring high-pressure conversion reactions. Therefore, the development of a direct GC/MS interface for near-real time analysis of high-pressure reaction products, while minimally disturbing the reaction process, has been undertaken in our laboratory.
It is well established that coal contains fused aromatic and hydroaromatic ring clusters, composed of an average of two to tour condensed ring units, connected by various alkylene, ether, sulfide and direct (Ar)C-C(Ar) bridges. Liquefaction reactions are primarily thought to involve these connecting bridges, especially ether linkages and alkylene linkages. In recent years, a number of workers have subjected coal-model compounds to various coal conversion conditions in order to confirm that certain coal structures are reactive during coal conversion and to infer the conversion mechanisms of real coals from mechanisms determined for such compounds.
The present paper reports the design and testing of a newly developed on-line GC/MS monitoring system for high pressure reactions and its application to the investigation of hydrogenation and hydrodeoxygenation (HDO) of model compounds, such as diphenyl methane and dibenzyl ether, under both catalytic and thermal conditions.
1991
Canonical Correlation Analysis of Multisource Fossil Fuel Data
Meuzelaar, H.L.C.; Statheropoulos, M.; Huai, H. and Yun, Y.
Computer-Enhanced Analytical Spectroscopy, 3:185-214, (P.C. Jurs, ed.), Plenum Publishing Co., New York, 1991. Funded by ACERC and US Department of Energy.
The following sections of this chapter will demonstrate the application of Canonical Correlation Analysis (CCA) to multisource fossil fuel data generated by the application of three different spectroscopic methods: Pyrolysis Low Voltage Electron Ionization Mass Spectrometry (LVMS); Pyrolysis Field Ionization Mass Spectrometry (FIMS); and Photo-acoustic Fourier Transform Infrared Spectroscopy (FTIR) to a single suite of eight U.S. coals obtained from the Argonne National Laboratory Premium Coal Sample Program (ANL-PCSP). Consequently, the three data sets obtained describe the same suite of samples but are markedly different with respect to number as well as type of variables.
The Chemical Structure and Petrology of Resinite from the Hiawatha "B" Coal Seam
Crelling, J.C.; Pugmire, R.J.; Meuzelaar, H.L.C.; McClennen, W.H.; Huai, H. and Karas, J.
Energy & Fuels, 5:688-694, 1991. Funded by US Department of Energy and ACERC.
The objective of the present study is to examine the chemical structure and composition of Utah Wasatch Plateau coal resinite. Macerals were separated from the coal matrix by hand picking, sink-float treatments, and/or density gradient centrifugation (DGC). DGC separation was found to produce highly purified resinite fractions. Resinite-rich Wattis Seam coal samples were collected from fresh mine faces and, after varying degrees of concentration, subjected to C-13 magic angle spinning NMR, Curie-point pyrolysis MS, and Curie-point pyrolysis GC/MS in addition to petrographic analysis and fluorescence microscopy as well as conventional (e.g., ultimate analysis) characterization methods. The data obtained confirm recent findings indicating that the abundant blue/green fluorescing resinite component is a polymeric substance composed of sesquiterpenoid repeat units with a median size of 204 Da, corresponding to the empirical formula C15H24. The monomeric sesquiterpenoid units obtained during pyrolysis appear to represent different degrees of unsaturatization ranging from C15H26 sesquiterpenes to the aromatic C15H18 cadalene. Clearly, sesquiterpenoids constitute the bulk of extractable resinite in Wasatch Plateau field coal and are likely to be important precursors of the abundant extractable alkynaphthalene moieties in such coal.
Chemical Composition and Origin of Fossil Resins from Utah Wasatch Plateau Coal
Meuzelaar, H.L.C.; Huai, H.; Lo, R. and Dworzanski, J.P.
Fuel Processing Technology, 28:119-134, 1991. Funded by Pittsburgh Energy Technology Center/Consortium for Fossil Fuel Liquefaction, ACERC and Advanced Coal Technology Center.
In order to arrive at a more detailed chemical description of fossil coal associated resins we need to distinguish between micropetrographic, organic geochemical and process technological definitions, each of which may encompass varying quantities of constituents unrelated to fossil tree resins. New information on composition and origin of Utah Wasatch Plateau coal resins obtained by Curie-point pyrolysis/evaporation in combination with iso-butane chemical ionization mass spectrometry, as presented in this paper, points to the presence of four more or less distinct resin components: (1) a sesquiterpenoid polymer; (2) sesqui- and triterpenoid monomers and dimers; (3) a suite of triterpenoid alcohols, ketones and acids; and (4) a series of increasingly aromatized hydrocarbons with naphthalene and picene type skeletons. Moreover, a strong similarity is found between the composition of recent dammar resin and fossil. Wasatch Plateau coal resins indicating a possible Angiosperm (fam. Dipterocarpaceae) origin of these Upper Cretaceous coal resins. Some of the technological implications of these findings and the consequent need for a more precise chemical definition and nomenclature are discussed.
Laser Pyrolysis Gas Chromatography/Mass Spectrometry of Single Spherocarb Particles Impregnated with Bituminous and Polymeric Substances
Maswadeh, W.; Huai, H. and Meuzelaar, H.L.C.
ASC Preprints, Division of Fuel Chemistry, 36(2):733-740, 1991 (201st ACS National Meeting, Atlanta, GA, April 1991). Funded by ACERC.
A major bottleneck in the development of novel coal characterization methods, such as laser pyrolysis GC/MS, capable of analyzing individual coal particles, is the unavailability of suitable standard samples. Although carefully homogenized and characterized standard coals are now available through the Argonne National Laboratory Premium Coal Sample Program (ANL-PCSP) such "statistically homogenous" coal powders are of limited value as reference materials for single particle analysis methods. Even if it would be feasible to prepare particles of closely similar chemical composition and size, e.g., by using highly concentrated coal maceral fractions and careful sieving, remaining variations in shape, density, porosity or thermal conductivity could still introduce an unacceptably high level of uncertainty for most optimization and calibration purposes.
In an attempt to find model coal char particles with well-defined chemical and physical properties, e.g., for the purpose of modeling char oxidation reactions, several authors have used Spherocarb® particles. Flagan et al have even prepared spherical char particles spiked with mineral matter components in order to more closely mimic actual coal char particles. Although Spherocarb particles still show considerable variability with regard to size (rel. s.d. ~20% on a volume basis), other characteristics such as shape, density, porosity, thermal conductivity and chemical composition are assumed to be quite constant.
Unfortunately, Spherocarb particles are of little value for modeling coal devolatilization reactions due to their very low volatile matter yields. This prompted us to think of ways to increase volatile matter yields by introducing a variety of model compounds, ranging from low molecular weight, bitumen-like components to polymeric materials such as soluble lignins or resins. To the best of our knowledge this article represents the first reported use of bitumen and polymer impregnated Spherocarb particles for modeling devolatilization processes in individual coal particles.
Analysis of Peru Margin Surface Sediments by PY-MS
Eglinton, T.I.; McCaffrey, M.A.; Huai, H. and Meuzelaar, H.L.C.
ACS Preprints, Division of Fuel Chemistry, 36(2):781-789 (201st ACS National Meeting, Atlanta, GA, April 1991).
In offshore Peru high sedimentary organic carbon contents are a direct consequence of the extremely high primary productivity (ca. 1000g Carbon m²/yr) which, in turn, is supported by the upwelling of nutrient-rich waters near the coast. Diatoms represent the major phytoplankton type and give rise to sediments dominated by biogenic silica and planktonic organic matter. The remineralization of this large flux of organic matter to the bottom waters and sediments results in oxygen depletion over large areas of the shelf that, in turn, promotes organic carbon preservation in the underlying sediments. Sulfide from sulfate reduction is prevalent in the bottom waters and with a limited availability of iron (due to the dominant biogenic input coupled with a very low influx of detrital sediments) the excess sulfide is available for reaction with the organic matter. As a result high organic sulfur concentrations are found in the sediments.
The coastal Peru upwelling region is believed to be a modern analogue to the depositional environments of petroleum source rocks such as the Miocene Monterey Formation of the California Borderland. Because organic matter alteration pathways in surface sediments ultimately influence kerogen type and eventual petroleum yield, there has been interest in characterizing surface sediments such as those offshore Peru. Lipid, carotenoid and amino acid constituents as well as general biogeochemistry have been studied previously. However, studies of the macromolecular components of the sediments have been less extensive. This paper describes results from Py-MS analyses of sediment samples obtained from discrete intervals in a 1-meter core obtained from the upper continental shelf of the Peru Upwelling region. Factor and discriminant analysis of the Py-MS data revealed several distinct changes within this 1-meter section.
1990
The Chemical Structure and Petrology of Resinite from the Hiawatha "B" Coal Seam
Crelling, J.C.; Pugmire, R.J.; Meuzelaar, H.L.C.; McClennen, W.H.; Huai, H. and Karas, J.
Energy & Fuels, 1990 (In press). Funded by ACERC and US Department of Energy.
Although the maceral resinite occurs in most U.S. coals, it is particularly abundant in the coal seams of the Wasatch Plateau coalfield in central Utah. The high resinite content of the coals of central Utah has long been known and commercially exploited but little work has been reported on the elucidation of the chemical composition of this material. Details of the chemical structure of the micropetrographically defined maceral resinite have generally been lacking because it is noncrystalline and is only partially soluble in organic solvents. In contrast with the abundance of spectroscopic and chromatographic data available on some of the better known fossil resin types, e.g., Baltic amber, Utah coal resins appear to have generated relatively little interest among coal scientists. The overall objective of the present study was to examine the structure of Utah Wasatch Plateau coal resinite macerals that have been separated from the coal matrix, purified, and most important, carefully characterized by fluorescence spectral analysis. The samples were then analyzed by means of CP/MAS C NMR and by Curie-point pyrolysis in direct combination with mass spectrometry (Py-MS) or via preseparation by gas chromatography (Py-GC/MS).
A Comparative Study of Eight U.S. Coals by Several Different Pyrolysis Mass Spectrometry Techniques
Huai, H.; Lo, R.; Yun, Y. and Meuzelaar, H.L.C.
ACS Division of Chemistry, 35 (3), Washington, D.C., 1990. (Also Proc. of the 38th ASMS Conference on Mass Spectrometry and Allied Topics, Tucson, AZ, 601-602, 1990). Funded by Consortium for Fossil Fuel Liquefaction Science.
Eight U.S. coals of different rank and/or composition, obtained through the Argonne National Laboratory Premium Coal Sample Program, were analyzed by means of several different pyrolysis-MS (Py-MS) techniques, namely: direct Curie-Point Py-MS, Curie-point Py-GC/MS (including GC/EIMS, GC/CIMS and "short column" GC/CIMS), and vacuum thermogravimetry/MS (TG/MS). The data obtained were compared to Pyrolysis-Field Ionization MS (Py-FIMS) data.
The results show a very good agreement between all techniques used in spite of the marked differences in pyrolysis techniques (Curie-point, furnace, direct probe), "soft" ionization methods (low voltage EI, CI FI) and mass spectrometer types (quadrupole, ion trap, magnetic sector) used. As might be expected, the most pronounced variations between techniques appear to be due to mass dependent differences in ion transmissivity and detector response, with the type of soft ionization method taking second place and the type of pyrolysis technique showing least effect on the results. Whereas Py-FIMS provides the most complete and detailed overview of the coal pyrolysis tars, Cuire-point Py-MS and TG/MS methods provide more reliable information on relatively light gaseous products, and Curie-point Py-GC/MS shows the detail composition of the 2/3 of the total pyrolysis tars.