Pyrolysis behavior and kinetics of corn residue pellets and eucalyptus wood chips in a macro thermogravimetric analyzer

Pyrolysis of corn residue in pellet form and eucalyptus wood in chip form was conducted on a continuously weighing fixed bed reactor acing as a macro thermogravimetric (TG) analyzer with 40 +/- 1.0 g of sample loading under high purity nitrogen environment. Effect of heating rate (5, 10, and 15 degrees C/min) was investigated and pyrolysis behaviors of the pellets and wood chips were also compared with those performed on a typical TG analyzer. Experimental results showed that bigger particle size and higher heating rate significantly delayed the pyrolysis reaction, meanwhile the heating rate affected the characteristic temperatures of the pellets and wood chips more than the smaller size. By differential derivative TG technique, the pyrolysis behaviors could be divided into three stages. Within the main stage of pyrolysis process, only a peak could be differentiated clearly in the derivative TG curve, accounted for approximately 67-81% of weight loss. Flynn-Wall-Ozawa method was used to calculate the activation energy against conversion of reaction on the whole temperature domain. It was found that the activation energy values from the macro TG analyzer, which were 60-70 and 59-71 kJ/mol with average values of 64 and 62 kJ/mol for the pellets and wood chips, respectively, were about four times lower than that obtained from the typical TG analyzer.