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Title: Two dimensional and zero field NMR studies of coal structure: Final progress report, including the period July 1, 1987 to September 30, 1987

Abstract

This report covers the progress made on the title project during the last quarter and summarizes the accomplishments for the project period. During the last three months we have completed a full analysis of the limitations of our ADIPSHIFT 2D NMR experiment that we have developed to determine the distribution of functional types of carbon in coals. This is an extensive piece of work and will provide a firm foundation for the application of the method to complex organic solids in the future. A particularly useful graphical analysis is described for use with unknowns such as coals. 17 refs.

Authors:
Publication Date:
Research Org.:
Yale Univ., New Haven, CT (USA). Dept. of Chemistry
OSTI Identifier:
6887775
Report Number(s):
DOE/PC/80508-8
ON: DE88013575
DOE Contract Number:
FG22-85PC80508
Resource Type:
Technical Report
Resource Relation:
Other Information: Portions of this document are illegible in microfiche products
Country of Publication:
United States
Language:
English
Subject:
01 COAL, LIGNITE, AND PEAT; COAL; STRUCTURAL CHEMICAL ANALYSIS; CARBON 13; IMPURITIES; NMR SPECTRA; NUCLEAR MAGNETIC RESONANCE; PROGRESS REPORT; CARBON ISOTOPES; CARBONACEOUS MATERIALS; DOCUMENT TYPES; ENERGY SOURCES; EVEN-ODD NUCLEI; FOSSIL FUELS; FUELS; ISOTOPES; LIGHT NUCLEI; MAGNETIC RESONANCE; MATERIALS; NUCLEI; RESONANCE; SPECTRA; STABLE ISOTOPES 010600* -- Coal, Lignite, & Peat-- Properties & Composition

Citation Formats

Zilm, K.W.. Two dimensional and zero field NMR studies of coal structure: Final progress report, including the period July 1, 1987 to September 30, 1987. United States: N. p., 1987. Web.
Zilm, K.W.. Two dimensional and zero field NMR studies of coal structure: Final progress report, including the period July 1, 1987 to September 30, 1987. United States.
Zilm, K.W.. 1987. "Two dimensional and zero field NMR studies of coal structure: Final progress report, including the period July 1, 1987 to September 30, 1987". United States. doi:.
@article{osti_6887775,
title = {Two dimensional and zero field NMR studies of coal structure: Final progress report, including the period July 1, 1987 to September 30, 1987},
author = {Zilm, K.W.},
abstractNote = {This report covers the progress made on the title project during the last quarter and summarizes the accomplishments for the project period. During the last three months we have completed a full analysis of the limitations of our ADIPSHIFT 2D NMR experiment that we have developed to determine the distribution of functional types of carbon in coals. This is an extensive piece of work and will provide a firm foundation for the application of the method to complex organic solids in the future. A particularly useful graphical analysis is described for use with unknowns such as coals. 17 refs.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 1987,
month =
}

Technical Report:
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  • This report covers the progress made on the use of our unique low temperature CPMAS probe for more quantitative structural analysis of coals by /sub 13/C CPMAS spectroscopy. We have found that by degassing whole coals and taking their CPMAS spectrum at 77K that a much more quantitative response is obtained. 1 fig
  • This report covers the progress made on exploring some of the limitations of our ADIPSHIFT 2D NMR experiment that we have developed to determine the distribution of functional types of carbon in coals. One of the assumptions made in this methods is that molecular motion in minimal so that the C-H dipolar couplings are not partially averaged out. To investigate this aspect we have measured ADIPSHIFT patterns for paraformaldehyde at room temperature and at 77K and for 2-methyltetrahydrofuran at 77K. The same homonuclear scaling factor is found to fit both room temperature and 77K spectra indicating that motional correction formore » lattice modes are minimal. Furthermore we find that at 77K we can stop the methyl rotation in 2-methyltetrahydrofuran on the NMR timescale. For coals this implies that nearly any possible motional narrowing problems in the ADIPSHIFT method can be handled by going to 77K operation. 1 fig.« less
  • This report covers the progress made on exploring a new set of 2D NMR experiments which could potentially be used to determine the connectivity of the various groups in coals. The idea is to use through bond or through space measures of connectivity in solid state NMR analogues of the COSY and NOESY experiments popular in solution NMR. We have investigated a /sup 13/C methylated coal and find that /sup 13/C-/sup 13/C NOESY experiments in the solid can be used to establish connectivity between groups in chemically modified coals. 2 figs
  • This report covers the progress made on the title project during the last quarter. During the last three months we have concentrated on further developing zero field NMR methods so that they can be applied to coal structure problems. Designs for both shuttling and pulsed field ZFNMR systems have been finalized and construction about halfway completed. Circuits for driving the fast pulsed field and bucking field coils are completed and described herein. Test results for the piston shuttle and ZFNMR probe are also described. For the pulsed field system we have set up the power supplies neccesary to drive themore » pulsed magnet. The final configuration of this system is also described in this report. 5 figs.« less
  • This report covers the progress made on the title project during the last quarter. During the last three months we have concentrated on further developing zero field NMR methods so that they can be applied to coal structure problems. Considerations of the short proton relaxation times for the protons in coals have lead us to redesign the basic zero field NMR setup. Two new implementations are being constructed to allow us to lengthen the proton T/sub 1/'s by using cryogenic temperatures and by excluding molecular oxygen from the samples. In one design being investigated a double action piston is usedmore » to permit temperatures as low as 77K. The second design uses a field cycling magnet and will eventually accomodate temperatures as low as 4K. The latter design will also allow us to combine the zerofield experiment with magic angle spinning /sup 13/C spectroscopy in the future. We have also recently added a low temperature MAS capability to our laboratory. Preliminary data on model systems are quite encouraging and indicate that 77K operation should be routine. With this system sealed 5mm NMR tubes can be spun at rates of up to 2200Hz allowing us to evacuate our samples. This feature and the use of low temperatures should allow us to significantly lengthen proton T/sub 1p/'s to obtain better sensitivity and quantitation in coal CP/MAS spectra.« less