Revealing the influence of chemical compounds on the pyrolysis of lignocellulosic wastes from the Amazonian production chains

Abstract

Lignocellulosic wastes from Amazonian crops are promising for the production of biochar. However, there are scientific gaps concerning the thermodegradation mechanisms of widely diverse biomass. This research explored the relationships between the chemical compounds and the pyrolysis behavior of the açai seed, cocoa pod husk, coconut husk, palm empty fruit bunch, and maize cob by thermogravimetric analysis. The cocoa pod husk and palm empty fruit bunch showed the lowest temperatures of initial degradation (≤ 230 °C) because of the highest proportions of total extractives (≥ 17% dry basis) and ashes (≥ 5.7% dry basis) combined with the lowest contents of holocellulose (≤ 56% dry basis). Biomasses with higher extractives contents showed pronounced mass losses at temperatures ≤ 300 °C. The maize cob, with more holocellulose (68% dry basis), revealed a high maximum rate of thermal degradation of 7.9% min−1 and mass loss between 200 and 400 °C of 65.6% wet basis. The high level of acetone-soluble extractives raised the temperature necessary for the initial thermal degradation of açai seed. The coconut husk, açai seed, and cocoa pod husk were the most suitable wastes for the production of biochar based on the average mass yields (≥ 41% wet basis) at the pyrolysis final temperature of 400 °C.