Understanding the impacts of pyrolysis temperature on the energy performance of eucalyptus charcoal

The charcoal production is considered a rudimentary activity nowadays even though it lasts centuries of practice. Controlling the process and homogenizing the raw material are the challenges in the process required to obtain a high-quality product. Thus, understanding the influence of different pyrolysis temperatures becomes of importance since the temperature is an essential variable in the energy quality of the charcoal. This study aimed to investigate the influence of two pyrolysis temperatures on a mix of commercial eucalypt woods. For this, pyrolysis was carried out at a heating rate of 3.33 °C.min-1, 3 h of duration, and two final temperatures (300 °C e 450 °C). The apparent density, bulk density, moisture content, proximate analysis and heating calorific, energy density, and combustibility index of the charcoal were measured. The apparent density and ash content were the same for both pyrolysis temperatures (p-value> 0.05), with averages of 310 kg/m³ and 1.09%, respectively. The charcoal pyrolyzed at 450 °C provides the higher value of fixed carbon content (82.98%), lower volatile matter content and higher heating value. The charcoal at 300 °C showed the highest bulk density and, presented the higher energy density (3.58 GJ/m³). As it generates more heat and reaches a higher temperature peak, the higher combustibility index (0.135) is in the charcoal produced at a temperature of 450 °C. Under the conditions analyzed, pyrolysis performed at a final temperature of 450 ° C results in better energy performance of charcoal than at 300 °C.