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A TDS STUDY ON THE REACTION INTERMEDIATES IN THE CATALYZED GASIFICATION OF ACTIVATED CHARCOAL

Choi KH Lee WY Rhee HK Moon SH Lee HI

Korean Journal of Chemical Engineering, April 1993, 10(2), 78-84(7), 10.1007/BF02697398

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Abstract

Catalytic coal gasification was studied by using thermal desorption spectroscopy （TDS） under high vacuum conditions. Activated charcoal was used as a model compound of coal, and Na₂CO₃ and K₂CO₃ as catalysts. Catalysts enhanced oxygen adsorption and decomposed at temperatures below their own decomposing temperatures. After pretreatment of the catalyst at high temperature the CO₂ desorption pattern represented characteristics of reaction intermediates. There were two peaks, -peak and -peak, in CO₂ TDS curves. From the experimental results, -peak was interpreted to the result from intercalatd metal-carbon (M-C) complex, and -peak from metal-oxygen (M-O-C) complex. A higher pretreatment temperature led to decrease both the number of M-O-C complex and its thermal stability. The increase of catalyst loading in Na₂CO₃-containing sample resulted in relative increase of the number of M-O-C complex than that of intercalated M-C complex, and also increase of thermal stabilities of both reaction intermediates. Major difference between K₂CO₃ and Na₂CO₃ appeared in -peak, intercalated M-C complex. That is, the contribution of intercalated metal-carbon complex to total reaction intermediates was larger in K₂CO₃ than Na₂CO₃. This could be attributed mainly to the better intercalating ability of potassium due to its lower ionization potential.

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