The effect of catalyst impregnation conditions on activity of Ca, Na, and Na + Ca composite catalysts for swelling reduction and gasification of Illinois No. 6 coal was investigated. The asreceived coal and samples cleaned by panning with water and heavy liquid separation were studied. The coals were impregnated with catalyst solutions at various levels of pH, catalyst loading, and NdCa molar ratio. Catalyst loadings of a few tenths to about 4 wt % metals were examined. Impregnated coals were characterized by free swelling index, diffise reflectance infrared spectroscopy, and X-ray powder diffraction. Catalyst initial dispersion was measured by C02 chemisorption at 573 K after pyrolysis in argon at 1073 K. Carbon dioxide gasification rates were measured by TGA at 1073 K. Impregnation of Illinois No. 6 coal with catalysts consisting of Ca or Na + Ca using a pH 3 solution leads to better wetting of the coal and enhanced interaction of catalyst with coal surface functional groups relative to impregnation at pH 9. Higher activity for decaking and gasification results. Solution pH had no effect on activity of Na.Synergistic effects were observed for Na + Ca composites prepared at low pH and NdCa molar ratio greater than one. Calcium and Na + Ca catalysts deactivated by reaction with sulfur and mineral matter. Sodium-containing catalysts retained their activity to high conversion levels but were less active than Ca or Na + Ca. Deactivation was reduced significantly by heavy liquid cleaning of the coal to remove most of the inorganic sulfur and more than 80 w t % of the ash. Panning (water washing) to remove roughly 50% of the ash and 30% of the sulfur was not effective.
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