Oxidation reactivity of chars generated from the acid-catalyzed pyrolysis of corncobs

• Chars are produced from the acid catalyzed pyrolysis of corncobs.
• Catalysts modify the structural morphology and the oxidation reactivity.
• Thermogravimetric curves are well described by a two-step mechanism.
• Kinetic parameters are dependent upon the catalysts

Thermogravimetric measurements are made in air, at three heating rates between 5 and 10 K/min, of chars produced from the pyrolysis of corncobs catalyzed by sulfuric acid, ferric sulfate and zinc chloride and, for comparison, of washed corncobs. The catalyst concentrations are those which maximize the furfural production and give rise to char yields between 27 and 32% (versus 22% in the absence of catalysts). The structural morphology and the reactivity, especially at high conversion, are largely affected by catalysts. Thus the kinetic evaluation also reveals that, although a two-step reaction mechanism is applicable in all cases, the estimated parameters are highly dependent on the catalytic treatment undergone by corncobs during the pyrolysis stage.