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Thermodynamics And Surface Structure Of Coals Quarterly Report April 1 1991 June 31 1991
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Book Synopsis Thermodynamics and Surface Structure of Coals. Quarterly Report, April 1, 1991--June 31, 1991 by :
Download or read book Thermodynamics and Surface Structure of Coals. Quarterly Report, April 1, 1991--June 31, 1991 written by and published by . This book was released on 1991 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: Review of previous use of Gas-Solid Chromatography to the determine thermodynamics of coal adsorption revealed several problems with data acquisition, as discussed previously (quarterly report 6, January 1, 1991 to March 31, 1991). In addition, in previous studies, the effect of diffusion of the adsorbate into the coal was not correctly taken into account. The goal of the present work is to obtain a more complete characterization and understanding of the adsorbate/coal interaction from both a physical and chemical viewpoint. These studies should contribute much to the fundamental understanding of the interaction of technologically important molecules with the complex structure that is coal. In addition, this work has profound implications for modelling of various industrial processes, including: extraction of fuel from coal and from carbonaceous/inorganic matter in general, reaction of solvents with coal during production of clean coal and during production of organic chemicals from coal, effects of solvent swelling on coal structure and chemistry, and characterization of coal thermodynamics for efficient burning of coal.
Book Synopsis Thermodynamics and Surface Structure of Coals. Quarterly Report, July 1, 1991--September 31, 1991 by :
Download or read book Thermodynamics and Surface Structure of Coals. Quarterly Report, July 1, 1991--September 31, 1991 written by and published by . This book was released on 1991 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: Our work this month has been determining the effect of added surface dysprosium(III) ions on the NMR spectra of coal. We have also been examining the effect of this relaxation agent on our model system, an aryl sulfonate silica gel. To the best of our knowledge, NMR has not previously been. applied to surface studies of coal. It is a powerful technique because line positions and intensities are indicative of geometry, bonding hybridization and population of distinct functionalities as well as local environment effects. The NMR spectrum can be influenced by many factors including dipolar through-space coupling between an unpaired electron spin and the spin of the carbon atom. The unpaired electron can act as a relaxation sink, significantly shortening the spin-lattice relaxation time (T1) of the coupled carbon-13 atom. This shortening of the T1 can broaden the signal to the point where it disappears into the baseline noise. The effective range of interaction is proportional to the inverse sixth power of the separation of the two spins (r−6). In this system, the effective range is a relatively short distance on the order of 1 nanometer.
Download or read book Energy Research Abstracts written by and published by . This book was released on 1995 with total page 782 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Thermodynamics and Surface Structure of Coals. Quarterly Report, January 1, 1991--March 31, 1991 by :
Download or read book Thermodynamics and Surface Structure of Coals. Quarterly Report, January 1, 1991--March 31, 1991 written by and published by . This book was released on 1991 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: We have reported the determination of the average micropore diameter of an Argonne Illinois No. 6 coal (77% C, daf) and a standard 15 A diameter Spherocarb sample by 129Xe NMR spectroscopy. We have successfully applied this technique to determine the average micropore diameter of the full series of Argonne coals. We have recently developed a computer program (Appendix A) which correlates the 129 Xe NMR spectrum of Coals directly to the micropore size distribution of each Argonne coal. The micropore size distribution of Argonne: Pocahontas No. 3 (91.8% C, dmmf); Pittsburgh No. 8 (85.0% C, dmmf); and Blind Canyon (81.3% C, dmmf) coals, determined by 129 Xe NMR spectroscopy are shown in Figures 2, 4, and 6, respectively.
Book Synopsis Thermodynamics and Surface Structure of Coals. Quarterly Report, October 1, 1991--December 31, 1991 by :
Download or read book Thermodynamics and Surface Structure of Coals. Quarterly Report, October 1, 1991--December 31, 1991 written by and published by . This book was released on 1991 with total page 35 pages. Available in PDF, EPUB and Kindle. Book excerpt: NMR relaxation and shift reagents are being deposited on the surface of coals. The dipolar coupling of the unpaired electron spin of the relaxation agent and the carbon atom should significantly shorten the carbon T, which should broaden it away. We propose to record the NMR spectrum of a coal before and after deposition and subtract the spectra. The difference spectra will arise from the functionalities within approximately one nanometer of the surface and reveal the surface composition of the coal. In order to determine the surface concentration of the dysprosium in the coal, we are using x-ray photoelectron spectroscopy (XPS) also known as electron spectroscopy for chemical analysis (ESCA). XPS is a surface technique that can be used for the elucidation of chemical structure. The binding energy for each electron in each element is unique. The measurement of the binding energy in XPS allows the identification of the element and its oxidation state. The relative atomic concentrations of each element can also be determined using XPS spectra.
Book Synopsis Thermodynamics and Surface Structure of Coals by :
Download or read book Thermodynamics and Surface Structure of Coals written by and published by . This book was released on 1991 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: Review of previous use of Gas-Solid Chromatography to the determine thermodynamics of coal adsorption revealed several problems with data acquisition, as discussed previously (quarterly report 6, January 1, 1991 to March 31, 1991). In addition, in previous studies, the effect of diffusion of the adsorbate into the coal was not correctly taken into account. The goal of the present work is to obtain a more complete characterization and understanding of the adsorbate/coal interaction from both a physical and chemical viewpoint. These studies should contribute much to the fundamental understanding of the interaction of technologically important molecules with the complex structure that is coal. In addition, this work has profound implications for modelling of various industrial processes, including: extraction of fuel from coal and from carbonaceous/inorganic matter in general, reaction of solvents with coal during production of clean coal and during production of organic chemicals from coal, effects of solvent swelling on coal structure and chemistry, and characterization of coal thermodynamics for efficient burning of coal.
Book Synopsis Government Reports Annual Index by :
Download or read book Government Reports Annual Index written by and published by . This book was released on 1993 with total page 1198 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Thermodynamics and Surface Structure of Coals. Quarterly Report, April 1, 1990--July 1, 1990 by :
Download or read book Thermodynamics and Surface Structure of Coals. Quarterly Report, April 1, 1990--July 1, 1990 written by and published by . This book was released on 1990 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: Our work this quarter has been the determination of: (1) the average micropore diameter of three Argonne coal samples by 129Xe NMR spectroscopy; (2) the cyclohexane BET surface areas for the full series of Argonne coals. For a detailed discussion of the relationship between the 129Xe NMR chemical shift and the pore diameter, see DE-AC22-89PC89757-1. The 129Xe NMR chemical shift was measured as a function of Xe pressure.
Book Synopsis Thermodynamics and Surface Structure of Coals by : John W. Larsen
Download or read book Thermodynamics and Surface Structure of Coals written by John W. Larsen and published by . This book was released on 1990* with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Government Reports Announcements & Index by :
Download or read book Government Reports Announcements & Index written by and published by . This book was released on 1995-04 with total page 848 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Thermodynamics and Surface Structure of Coals. Quarterly Report, January 1, 1990--April 1, 1990 by :
Download or read book Thermodynamics and Surface Structure of Coals. Quarterly Report, January 1, 1990--April 1, 1990 written by and published by . This book was released on 1990 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: We have previously observed and reported a steep BET surface area dependence on adsorbate size for an Argonne Illinois No. 6 coal. During this quarter, the cyclopentane BET surface areas were determined for the entire set of Argonne coals and are presented in Table 1. All surface areas were determined on a Micromeritics stainless steel surface area instrument. The 5-point cyclopentane surface areas were measured at an adsorption temperature of 0°C, allowing 24 hours equilibration time for the first point and 6 hours equilibration time for each subsequent BET adsorption point.
Book Synopsis Thermodynamics and Surface Structure of Coals. Quarterly Report, July 1, 1990--September 30, 1990 by :
Download or read book Thermodynamics and Surface Structure of Coals. Quarterly Report, July 1, 1990--September 30, 1990 written by and published by . This book was released on 1990 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt: We measured the surface areas of the Argonne coals using standard multipoint volumetric BET techniques, a series of aliphatic alkanes, N2, and CO2. All samples were dried by evacuation at 10−6 torr overnight on a Micromeritics Digisorb 2500 stainless steel adsorption rig. Twenty four hours equilibration for the first adsorption point and six hours equilibration for each subsequent point was allowed for the cyclic hydrocarbon gases, except where otherwise noted. Six hours equilibration between adsorption points was used for all the other gases except N2·1°. The data and measurement conditions for Argonne: Pocahontas No. 3, Upper Freeport, and Pittsburgh No. 8 coals are presented in figures 1--3 respectively. The coal surface areas obtained using CO2, ethane and cyclopropane, all of similar cross sectional area, cannot be rationalized using a constricted pore model. Ethane (cylindrical) and cyclopropane (planar) have different shapes and slit like or cylindrical pores would discriminate between them.
Book Synopsis Thermodynamics and Surface Structure of Coals. Quarterly Report, October 1, 1990--December 31, 1990 by :
Download or read book Thermodynamics and Surface Structure of Coals. Quarterly Report, October 1, 1990--December 31, 1990 written by and published by . This book was released on 1990 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: We propose that most pores in coals are closed. They cannot be reached by diffusion through a pore network but can only be reached by diffusion through solid coal. Co2 gives accurate total surface areas because it dissolves in and rapidly diffuses through solid coals, reaching all the pores. This surface area is irrelevant to materials which are only slightly soluble or insoluble in coals for these can only reach a small portion of the pores. Thus, the diffusion rate controls the determined pore size. For the large molecules involved in direct-liquefaction and most organic reactions, the effective surface areas of these coals are very small, only a few m2/g. The consequences of this structure model for coal processing and reaction are significant. These coals cannot be considered high (hundreds of m2/g) surface area materials which are easily accessible. They are low surface area solids only slightly permeable to hydrocarbons. The advantages of fine grinding are obvious. Using solvents which will cause coal to become rubbery rather than glassy will enhance diffusion and thus reactivity.
Book Synopsis Surface Structure and Thermodynamics of Coals. Quarterly Report, October 1, 1989--December 31, 1989 by :
Download or read book Surface Structure and Thermodynamics of Coals. Quarterly Report, October 1, 1989--December 31, 1989 written by and published by . This book was released on 1989 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: Our work has been the determination of the average micropore diameter of an Argonne Illinois No. 6 coal and a spherocarb sample by 129Xe NMR. 129Xe NMR spectroscopy has been used to determine pore sizes and surface characteristics in zeolites. The chemical shift of 129Xe was measured as a function of pressure and the average micropore diameter was calculated using established techniques. For the spherocarb, the calculated pore diameter of 15.4 CA agrees well with the 0 manufacturer's reported value of 15Å. The Illinois No. 6 coal gave two 129Xe peaks. Extrapolation of the pressure dependent peak gave a micropore diameter of 5.2Å. The other peak was not pressure dependent and is tentatively assigned to Xe dissolved in the coal. The NMR chemical shift of 129Xe is a useful probe of micropore (
Book Synopsis Winter Waterfront : Year-round Use in Metropolitan Toronto by : Xenia Klinger
Download or read book Winter Waterfront : Year-round Use in Metropolitan Toronto written by Xenia Klinger and published by . This book was released on 1991 with total page 79 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Coal Surface Structure and Thermodynamics. Final Report by :
Download or read book Coal Surface Structure and Thermodynamics. Final Report written by and published by . This book was released on 1994 with total page 413 pages. Available in PDF, EPUB and Kindle. Book excerpt: Coals surfaces were studied using static surface adsorption measurements, low angle x-ray scattering (LAXS), inverse gas chromatography (IGC) and a new 13C NMR relaxation technique. A comparison of surface areas determined by hydrocarbon gas adsorption and LAXS led to the twin conclusions that the hydrocarbons had to diffuse through the solid to reach isolated pores and that the coal pores do not form interconnected networks, but are largely isolated. This conclusion was confirmed when IGC data for small hydrocarbons showed no discontinuities in their size dependence as usually observed with porous solids. IGC is capable of providing adsorption thermodynamics of gases on coal surfaces. The interactions of non-polar molecules and coal surfaces are directly proportioned to the gas molecular polarizability. For bases, the adsorption enthalpy is equal to the polarizability interaction plus the heat of hydrogen bond formation with phenol. Amphoteric molecules have more complex interactions. Mineral matter can have highly specific effects on surface interactions, but with most of the molecules studied is not an important factor.
Book Synopsis Monthly Catalogue, United States Public Documents by :
Download or read book Monthly Catalogue, United States Public Documents written by and published by . This book was released on 1994 with total page 1592 pages. Available in PDF, EPUB and Kindle. Book excerpt:
