CALORIMETRIC EVIDENCE FOR THE WATER-VAPOR COAL INTERACTION AT LOW-TEMPERATURE

Calorimetric study shows that at 423 and 523 K, the water vapour/oxidised coal interaction is an exothermic process. It results in the superimposition of a rapid reversible adsorption (also encountered with unoxidised coal) on an irreversible and slow reaction. This later is correlated with a CO2 formation. The enthalpy of the reaction is independent of the amount of CO2 formed. Calorimetry clearly demonstrates that the water vapour reaction proceeds via a true hydrolysis mechanism rather than a catalytic one.