Chromatographic determination of adsorption and diffusion in a bidispersed porous solid
Mass transfer within a well defined bidispersed solid structurally similar to coal, namely 5A molecular sieves, was studied. It was hoped that such a study would ultimately yield more efficient liquefaction processes by better using the internal surface area in coal. The diffusion and adsorption of nitrogen, argon, and carbon dioxide have been studied using a chromatographic technique. A monodispersed pore model was used to describe the bidispersed pore system of the 5A molecular sieve. This model was an accurate representation of the 5A pore system since negligible mass transfer resistance was measured in the micropores. These studies indicate that much larger solid-adsorbate interactions occur with carbon dioxide than with argon or nitrogen. This may explain the enhanced penetrability of carbon dioxide into the microporous structure of zeolites. This study also cites the higher polarizibility and linear molecular geometry of carbon dioxide as a possible reason of its increased penetrability. Extrapolation of these results to coal suggests that highly polar solvents may exhibit better penetrability into coal due to the higher surface interactions. This should yield more efficient coal liquefaction processes by increasing the amount of internal surface area contacted by the solvent. The results obtained from the chromatographic technique illustrate the merits of this method for investigating mass transfer within bidispersed porous solids that do not exhibit transport resistances within their micropores. Extension of this technique to bidispersed solids which do exhibit mass transfer resistances in their micropores, such as coal and 4A molecular sieves at low temperatures, presents some difficulty, but it is believed that this problem can be overcome by increasing the temperature of the determinations.
- Research Organization:
- California Univ., Berkeley (USA). Lawrence Berkeley Lab.
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 7117634
- Report Number(s):
- LBL-5273
- Country of Publication:
- United States
- Language:
- English
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36 MATERIALS SCIENCE
360603 -- Materials-- Properties
ADSORBENTS
ADSORPTION
ARGON
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CHALCOGENIDES
CHROMATOGRAPHY
COAL LIQUEFACTION
CRYOGENIC FLUIDS
ELEMENTS
FLUIDS
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
LIQUEFACTION
MINERALS
MOLECULAR SIEVES
NITROGEN
NONMETALS
OXIDES
OXYGEN COMPOUNDS
RARE GASES
SEPARATION PROCESSES
SORPTION
SORPTIVE PROPERTIES
SURFACE PROPERTIES
THERMOCHEMICAL PROCESSES
ZEOLITES