Advanced NMR-based techniques for pore structure analysis of coal
One of the main problems in coal utilization is the inability to properly characterize its complex pore structure. Coals typically have micro/ultra-micro pores but they also exhibit meso and macroporosity. Conventional pore size techniques (adsorption/condensation, mercury porosimetry) are limited because of this broad pore size range, microporosity, reactive nature of coal, samples must be completely dried, and network/percolation effects. Small angle scattering is limited because it probes both open and closed pores. Although one would not expect any single technique to provide a satisfactory description of a coal's structure, it is apparent that better techniques are necessary. We believe that measurement of the NMR parameters of various gas phase and adsorbed phase NMR active probes can provide the resolution to this problem. We will investigate the dependence of the common NMR parameters such as chemical shifts and relaxation times of several different nuclei and compounds on the pore structure of model microporous solids, carbons, and coals. In particular, we will study the interaction between several small molecules and the pore surfaces in coals. These molecules have been selected for their chemical and physical properties. A special NMR probe will be constructed which will allow the concurrent measurement of NMR properties and adsorption uptake at a variety of temperatures. All samples will be subjected to a suite of conventional'' pore structure analyses. These include nitrogen adsorption at 77 K with BET analysis, CO[sub 2] and CH[sub 4] adsorption at 273 K with D-R (Dubinin-Radushkevich) analysis, helium pycnometry, and small angle X-ray scattering as well as gas diffusion measurements.
- Research Organization:
- New Mexico Univ., Albuquerque, NM (United States). Center for Micro-Engineered Ceramics
- Sponsoring Organization:
- DOE; USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG22-91PC91296
- OSTI ID:
- 6746347
- Report Number(s):
- DOE/PC/91296-5; ON: DE93009659
- Country of Publication:
- United States
- Language:
- English
Similar Records
Advanced NMR-based techniques for pore structure analysis of coal. Quarterly report No. 3, March 1, 1992--June 30, 1992
Advanced NMR-based techniques for pore structure analysis of coal
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