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<title>Dual mode sorption and coal microporosity
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PCS-439
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Dual mode sorption and coal microporosity
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Green, T.K.;  Selby, T.D.
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ACS Division of Fuel Chemistry Preprints
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1993
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38(4)
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1316-1322
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Pyridine sorption isotherms were determined for three Argonne Premium coals at
          50[degrees]C. It is proposed that the isotherms are best interpreted in terms of a
          dual-mode sorption model originally developed to explain sorption of vapors into glassy
          polymers. This model considers two different populations of sorbed gas; one is dissolved
          into the polymer and is described by Henry's law (i.e. sorption is linear with pressure)
          while the second population is considered to occupy unrelaxed free volume (micropores)
          within the polymer and is described by a Langmuir isotherm. The authors propose that the
          high pressure linear portion of the pyridine isotherms for two coals represent dissolution of
          pyridine in the coal matrix and that the low pressure regions represent primarily
          adsorption into micropores. The intercepts of the linear portion thus represent micropore
          volume accessible to pyridine. The pyridine-extracted coals all show a dramatic increase
          in intercept value, suggesting that pyridine extraction creates new micropores.
          O-alkylation with bulky alkyl groups yield reduced intercepts, which correlate with the size
          of the added alkyl group. It is suggested that the added alkyl groups occupy micropores in
          the structure.

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3. Illinois #6 (IL)<br>
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