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Hydrodynamic properties, such as solution viscosity and diffusivity, were measured at 298 K to investigate the solution state characteristics of coal extracts in pyridine obtained from Upper Freeport (UF) and Illinois No. 6 (IL) coals. The solvation constants obtained by applying the Pal-Rhodes equation to the viscosity of the extracts in pyridine are 2.9 and 4.6 for the UF and IL extracts, respectively. A larger content of acidic hydroxyl groups in IL extract than UF extract make pyridine solvate IL extract more extensively than UF extract. However, the solvation constant of the O-methylated IL extracts is 9.3, unexpectedly larger than that of the original IL extract. To have further insight into this observation, the change in the molecular shape of the extracts by the O-methylation were examined, using the combination of intrinsic viscosity and diffusion coefficient. The shapes of the coal extracts have been found to be prolate ellipsoids with axial ratio of 6.5 and 4.0 for UF and IL extracts, respectively. The axial ratio of the O-methylated IL extract is 13.1, suggesting that the elimination of the hydrogen bonds or the steric effect of added methyl makes the shape of IL extract stretched out. This deformable nature of coal extracts makes the interpretation of the solvation constants from Pal-Rhodes equation inaccurate, as it assumes that the particles are monodispersed hard spheres.

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The CO 2 reforming of methane with a thermal diffusion column (TDC) reactor by using an alumina tube coated with nickel-loaded carbon as the pyrogen, acting as a heated catalyst, was studied. Large surface area of carbon-coat support (400-500 m 2 /g) was obtained by carbonization of a novolak-type phenolic resin. Although the coated carbon showed a minor effect, Ni loading increased the activity of the pyrogen for the reaction. For example, by using 10 wt % Ni-loaded pyrogen at the surface temperature 1260 K, each conversion of methane and carbon dioxide exceeded 65% with upward feeding of 0.44 mmol/min (CO 2 /CH 4 ) 1). The downward feeding of reactant gas showed lower conversions but better stability of the catalytic action of the pyrogen. Performance of TDC reactor for CO 2 reforming of methane can be improved by the better preparation of the pyrogen to increase the activity and with downward feeding to reduce the carbon formation.