EFFECT OF COAL RANK ON MOLECULAR PROBE CHROMATOGRAPHY OF COKE AND CHAR

The effect of coal rank on the gas chromatographic behavior of probe molecules measured on the corresponding coke and char has been studied. The specific retention volume of oxygen and carbon dioxide, and gas permeability measured on coke and char have been found to depend on the rank of the parent coal. A relatively large specific retention volume of probes found with lignite char has been attributed to its open geometric structure. The heats of adsorption values for argon, oxygen and nitrogen measured on lignite char in the temperature range of 313 to 333 K, have been found to lie between 2.0 and 3.0 kcal/mol. The above adsorbates are thus sorbed in the char-gas interface largely by dispersion forces. The rank permeability relationship shows a maximum for coke obtained from high rank bituminous coal. A good selectivity has been found for noble gases on lignite char. Baseline separation for a mixture of helium and argon gases has been achieved even above ambient temperature. A low specific efficiency for lignite char has been attributed to a large stationary phase non-equilibrium coefficient which stems from slow interfacial mass transport rate within the micropores. © 1990.