Download or read book Analyzing Organic Sulfur in Coal written by and published by . This book was released on 1994 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Analyzing Organic Sulfur in Coal written by and published by . This book was released on 1994 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt: The cost effective removal of sulfur from coal has been very difficult to accomplish. Perhaps the single most important reason for this is the fact that the organic sulfur in coal remains very poorly characterized. The overall goal of this study is to improve our understanding of sulfur in coals/chars via the use of combined advanced non-destructive and advanced destructive methods of sulfur analysis. This study combines selective oxidation, analytical pyrolysis, and sulfur X-ray Absorption Near Edge Structure Spectroscopy (XANES) analysis. Examination of samples that were oxidized with peroxyacetic acid using the analytical pyrolysis technique showed that the level of simple thiophene structures observed in the pyrolysis products declines with increasing levels of oxidation. Sulfur XANES spectra of treated samples showed various effects depending on the treatment severity. For the less severely treated samples (demineralization and solvent extraction), the XANES spectra were similar, although not identical, to the untreated coal spectra, whereas the more severe treatments (steam at 450°C; peroxyacetic acid at 25°C) showed preferential oxidation of one or more sulfur-bearing phases in the original coal.
Download or read book Analyzing Organic Sulfur in Coal written by and published by . This book was released on 1993 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: To address the acid rain problem effort has been expended on finding methods for the removal of sulfur from coal. Despite these efforts organic sulfur has proven very difficult to remove. Perhaps the single most important reason for this is the fact that the organic sulfur in coal remains very poorly characterized. Thus, objective of this study is to combine advanced nondestructive and advanced destructive methods of sulfur analysis for characterization of the organic sulfur in Illinois Basin coals and mild gasification chars derived from them. Thus, the study combines selective oxidation strategies, analytical pyrolysis, and sulfur X-ray Absorption Near Edge Structure Spectroscopy (XANES) analysis. In, addition identical samples are to be provided for W-Band EPR spectroscopy. During the previous quarter ten coal derived samples have been prepared with the sulfur content varing from 0.77 to 4.4%. Each sample has been submitted for XANES analysis, W-Band EPR analysis, and analytical pyrolysis. A mild gasification reactor has been designed and is undergoing final assembly.
Download or read book A Review of Organic Sulfur Analysis in Coal and a New Procedure written by Robert Raymond and published by . This book was released on 1978 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Analyzing Organic Sulfur in Coal written by and published by . This book was released on 1994 with total page 33 pages. Available in PDF, EPUB and Kindle. Book excerpt: The overall goal of this study is to improve the understanding of sulfur in coals/chars via the use of combined advanced nondestructive and advanced destructive methods of sulfur analysis. This study combines selective oxidation, analytical pyrolysis, and sulfur X-ray Absorption Near Edge Structure Spectroscopy (XANES) analysis. Samples with a wide variety of sulfur contents, (0.63%--4.40%) have been prepared for use in this study. This includes steam gasification chars, oxidized coals and desulfurized coals as well of the original unaltered coals. Mild pyrolysis and XANES data shows that the sulfur chemistry of gasification chars is significantly different from that of the original coals. Mild pyrolysis of the samples that were oxidized with peroxyacetic acid showed that the level of simple thiophene structures observed in the pyrolysis products declines with increasing levels of oxidation. Sulfur XANES spectra of treated samples showed various effects depending on the treatment severity. The XANES spectra of less severely treated samples were similar, although not identical, to the untreated coal spectra. XANES of gasification chars indicated conversion of pyrite to pyrrhotite, removal of organic sulfide sulfur and dissolution of soluble inorganic sulfur species during gasification. Mild oxidation with peroxyacetic acid results in preferential oxidation of sulfide forms before thiophene forms but increasing oxidation severity leads to virtually all sulfur species being oxidized. Good agreement between W-band EPR and XANES data for aromatic sulfur contents were obtained. The TPR analysis of coal indicated that organic sulfur was present as alkyl-aryl sulfide, aryl-aryl sulfides, simple thiophenes and condensed thiophenes. TPR shows that non-thiophenic compounds are removed by PAA oxidation, and that the longer the oxidation is performed the greater is the removal of non-thiophenic sulfur structures.
Download or read book Analyzing Organic Sulfur in Coal written by and published by . This book was released on 1994 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: The overall goal of this study is to improve the understanding of sulfur in coals/chars via the use of combined advanced non-destructive and advanced destructive methods of sulfur analysis. This study combines selective oxidation, analytical pyrolysis, and sulfur X-ray Absorption Near Edge Structure Spectroscopy (XANES) analysis. Samples with a wide variety of sulfur contents, (0.63% to 4.40%) have been prepared for use in this study. This includes steam gasification chars, oxidized coals and desulfurized coals as well of the original unaltered coals. Mild pyrolysis and preliminary XANES data shows that the sulfur chemistry of gasification chars is significantly different from that of the original coals. Mild pyrolysis of the samples that were oxidized with peroxyacetic acid showed that the level of simple thiophene structures observed in the pyrolysis products declines with increasing levels of oxidation. Sulfur XANES spectra of treated samples showed various effects depending on the treatment severity. For the less severely treated samples (demineralization and solvent extraction), the XANES spectra were similar, although not identical, to the untreated coal spectra, whereas the more severe treatments (steam at 450 C; peroxyacetic acid at 25 C) showed preferential oxidation of one or more sulfur-bearing phases in the original coal. Additional samples have recently been examined by XANES and W-band EPR and the data is currently being processed and evaluated.
Download or read book VHF EPR Analysis of Organic Sulfur in Coal written by and published by . This book was released on 1991 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report covers progress made in the first yearly quarter of a two year investigation using novel, very high frequency electron paramagnetic resonance (VHF EPR) spectroscopy techniques and instrumentation (one of only two W-band spectrometers in existence) developed earlier by these authors, to conduct further qualitative and quantitative studies of heteroatomic organic molecules in coal with particular emphasis on sulfur. Previous W-band (96 GHz) work is being extended to studies of new model compounds as well as coal and desulfurized coal samples. Typically, the model compounds under investigation and their analogues are found in coals as stable free radicals which give rise to an EPR signal. The preparation of radicals from compounds having widely varying structures and physical properties in a stable environment has long been a very difficult task. To address this problem, the refinement of several new and very useful methods of preparing of these stable free radicals in various glasses, at catalytic surfaces, and in solution, are presented in this first report. Free radical generation was accomplished by both UV photolysis as well as chemical oxidation/reduction techniques. By these methods, over 25 new compounds, often commercially derived from coal extracts, have been prepared and studied by conventional X-band EPR (9 GHz). Several representative W-band spectra are also presented.
Download or read book Analyzing Organic Sulfur in Coal written by and published by . This book was released on 1994 with total page 33 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Analysis of Organic Sulfur and Nitrogen in Coal Via Tandem Degradation Methods written by and published by . This book was released on 1991 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: With the recent increase in concern for environmental issues and the implication of sulfur and nitrogen in coal combustion products as prime causes of acid rain, it has become clear that there is an urgent need for alternative methods for determining the nature of organic sulfur and nitrogen compounds in coal. The present study couples mold oxidative and reductive procedures to enhance the depolymerization of coal and its constituent macerals and the quantities of produces amenable to analysis. The study also seeks to apply the degradative techniques to coal asphaltenes, since they are believed to be polymeric structures similar to the whole coal, but smaller and more readily analyzed. While the research effort will focus on Illinois coal, additional samples with even higher sulfur contents will also used, allowing for much easier detection and characterization of organic sulfur structures. A preliminary tests of this hypothesis indicates that many of the same sulfur compounds are present in both the Illinois and in an extremely sulfur-rich coal and that the more complex sulfur compounds are indeed more concentrated in the sulfur-rich sample.
Download or read book The Analysis of Sulphur Forms in Coal written by Alfred Richard Powell and published by . This book was released on 1921 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book VHF EPR Analysis of Organic Sulfur in Coal Final Technical Report September 1 1992 August 31 1993 written by and published by . This book was released on 1993 with total page 29 pages. Available in PDF, EPUB and Kindle. Book excerpt: A direct and non-destructive technique called very High Frequency Electron Paramagnetic Resonance (VHF EPR) utilizing instrumentation and application techniques developed in this laboratory, is proving to be a practical and sensitive analytical method for the organic sulfur in coal. Research during this past year (1992--1993) was very successful in terms of obtaining spectrochemical information on organic sulfur in coal both quantitatively (amount of organic sulfur) and qualitatively (form and distribution of organic sulfur). Starting in this funding year, the authors have begun to develop and use a two-species model (non-exchanging and axially symmetric) for the simulation of VHF EPR coal spectra. Such a model provides quantitative information on the total concentration of sulfur species that can be directly related to the organic sulfur content as measured by conventional chemical methods. Utilizing the newly developed method, they have analyzed the VHF EPR spectra from some sub-bituminous coals containing organic sulfur in the range from 2% to 12% and a number of maceral blends. Excellent quantitative agreement is achieved between VHF EPR results and chemical analyses. In addition, the modelling of VHF EPR spectra of coal provides detailed spectral parameters. These parameters can be related to the molecular structures of the paramagnetic species giving rise to the EPR signals, as demonstrated by our study of the model compounds. The foundation of VHF EPR analysis of aromatic sulfur radicals has been firmly established based on careful investigations of the molecular and electronic structures of the thiophenic model compounds. The results validate the theoretical soundness of the method and carry important practical implications.
Download or read book VHF EPR Analysis of Organic Sulfur in Coal Quarterly Technical Report March 1 1993 May 31 1993 written by and published by . This book was released on 1993 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: One important goal of this project is the development of methods to analyze the Very High Frequency Electron Paramagnetic Resonance (VHF EPR) spectra from Illinois coals in order to determine the concentration of organic sulfur in them. In this third Quarter, the axially symmetric model for the simulation of VHF EPR coal spectra was refined for routine quantitative percent sulfur determination. The computer modeling technique which we have developed makes use of a sophisticated multi-dimensional simplex strategy for optimization. The percent sulfur determined from VHF-EPR of sporinite, vitrinite, and two blends of these macerals (from Illinois Herrin No. 6) show excellent linear correlation with far less reliable, time consuming, and difficult techniques.
Download or read book Analysis of Organic Sulfur and Nitrogen in Coal Via Tandem Degradation Methods Final Technical Report 1 September 1991 31 October 1992 written by and published by . This book was released on 1992 with total page 33 pages. Available in PDF, EPUB and Kindle. Book excerpt: With the recent increase in concern for environmental issues and the implication of sulfur and nitrogen in coal combustion preducts as prime causes of acid rain, it has become clear that there is an urgent need for alternative methods for determining the nature of organic sulfur and nitrogen compounds in coal. The principal impediment to the molecular characterization of organic sulfur and nitrogen forms in coal is the polymeric nature of coal's molecular structure, rendering coal insoluble and impossible to analyze by the necessary gas chromatographic (GC) methods. In our research, we apply mild chemical degradation techniques in order to render coal soluble in common organic solvents and thus amenable to standard GC characterization. The study also seeks to apply the degradative techniques to coal asphaltenes, since they are believed to be polymeric structures similar to the whole coal, but smaller and more readily analyzed. Of the degradation techniques used to date, oxidation by sodium dichromate provides the best chemical structure information. A variety of major sulfur compounds were detected in the dichromate oxidation products of demineralized IBC101 coal, including thiazoles (compounds which contains both sulfur and nitrogen) and a series of isomers of C2-, C3- and C4-alkylthiophene derivatives. Precise agreement between GC-MS and sulfur-selective GC-FPD data was obtained for these compounds, which probably originated as short alkyl chains on exterior portions of the original peat macromolecular structure that were sulfurized shortly after burial by H2S. The results were further confirmed by the analysis of a non-Illinois Basin coal with nearly twice the organic sulfur content of IBC101.
Download or read book Organic and Pyritic Sulfur in Coal written by R. W. Stanton and published by . This book was released on 1981 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A New Standard for Electron Microanalysis of Organic Sulfur in Coal written by Robert Raymond and published by . This book was released on 1977* with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Analysis of Organic Sulfur and Nitrogen in Coal Via Tandem Degradation Methods Quarterly Technical Report March 1 May 31 1993 written by and published by . This book was released on 1993 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt: There is need for alternative methods for determining the nature of organic sulfur and nitrogen compounds in coal. In our research, we apply chemical and thermal degradation techniques to render coal amenable to standard gas chromatography characterization. Standard density gradient centrifugation successfully isolated vitrinite from the IBC101 coal, whereas the multi-step high resolution method was required to isolate liptinite and inertinite macerals, which are minority constituents. Analytical pyrolysis-gas chromatography, operating with either the sulfur selective flame photometric detector (py-GC-PFD) or a mass spectrometer (py-GC/MS), provides distinctive organosulfur ''fingerprints'' for all coal, asphaltene and maceral samples analyzed to date. PY-GC/MS permits ready differentiation of asphaltenes from low and high rank coals. Of the two pyrolysis techniques, py-GC-FPD is simpler and less expensive, and is the recommended method for situations in which sulfur content is the prime concern. Both py-GC methods are superior to oxidative degradation techniques in that they are permit direct, one-step micro-scale analysis, requiring only a minimum of sample preparation. Distinctive chromatographic profiles are also achieved using the methylated dichromate oxidation products of coals, asphaltenes and macerals, but the extensive wet chemical preparation required is a serious disadvantage. Reasonable matches for the expected masses of alkylthiophene carboxylic acid derivatives have been found in the direct probe, low voltage, high resolution mass spectral data set collected on the methylated dichromate oxidation products of the sulfur-rich Spanish lignite sample, providing an additional line of evidence confirming the presence of such compounds.
