Two dimensional NMR and NMR relaxation studies of coal structure
This report covers the progress made on the title project and summarizes the accomplishments for the project period. Four major areas of inquiry have been pursued. Advanced solid state NMR methods are being developed to assay the distribution of the various important functional groups in coals that determine the reactivity of coals. Other methods are being developed which will also determine how these functional groups are linked together. A third area of investigation concern how molecular mobility in coals impacts NMR relaxation times, which is important for interpretation of such data in terms of the mobile phase in coals model. Along the same lines we are also using these studies to establish protocols for obtaining the best quantitative response from coals in solid state C-13 NMR spectra. The effects of very high MAS rates (>10 kHz) on cross polarization dynamics are also being investigated for similar reasons. During the last quarter the authors have concentrated on improvements in cross polarization (CP) sequences with a goal of making the CP process insensitive to experimental conditions such as the magic angle spinning (MAS) rate. In order to be able to use fields the order of 7.0 T or higher, CP efficiency must be maintained at MAS rates of over 10 kHz. The standard sequences have severe limitations at these rates which lead to intensity distortions in {sup 13}C CPMAS spectra. Thus in order to be able to take advantage of the increases in sensitivity and resolution that accompany high field operation, improvements in the NMR methods are required. The new sequences the authors are developing will be especially important for quantitative analysis of coal structure by {sup 13}C solid state NMR at high field strengths. 13 refs., 7 figs., 2 tabs.
- Research Organization:
- Yale Univ., New Haven, CT (USA). Dept. of Chemistry
- Sponsoring Organization:
- USDOE; USDOE, Washington, DC (USA)
- DOE Contract Number:
- FG22-87PC79910
- OSTI ID:
- 5859069
- Report Number(s):
- DOE/PC/79910-9; ON: DE91011283
- Country of Publication:
- United States
- Language:
- English
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Two dimensional NMR and NMR relaxation studies of coal structure
Two dimensional NMR and NMR relaxation studies of coal structure
Related Subjects
COAL
STRUCTURAL CHEMICAL ANALYSIS
ACTIVATION ENERGY
AROMATICS
CARBON
CARBON 13
DISTRIBUTION
HYDROGEN 1
MEASURING METHODS
MOLECULAR STRUCTURE
NUCLEAR MAGNETIC RESONANCE
OPTIMIZATION
PROGRESS REPORT
RELAXATION TIME
RESOLUTION
SENSITIVITY
SPIN-SPIN RELAXATION
CARBON ISOTOPES
CARBONACEOUS MATERIALS
DOCUMENT TYPES
ELEMENTS
ENERGY
ENERGY SOURCES
EVEN-ODD NUCLEI
FOSSIL FUELS
FUELS
HYDROGEN ISOTOPES
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
MATERIALS
NONMETALS
NUCLEI
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
RELAXATION
RESONANCE
STABLE ISOTOPES
010600* - Coal
Lignite
& Peat- Properties & Composition