Kinetic Study of Thermal Decomposition of Sugarcane Bagasse Pseudo-Components at Typical Pretreatment Conditions: Towards the Establishment of a Feasible Primary Biorefining

Abstract

A deeper understanding of the kinetics and thermodynamics parameters of sugarcane bagasse (SCB) thermal degradation could define appropriate conditions for primary biorefining in the production of renewable fuels. In this work, the kinetics of thermal degradation of SCB’s high polymers are investigated through thermogravimetric data. From this data, model-free and model fitting methods are used to calculate apparent activation energies (Ea) and other related kinetic parameters. DTG curves present three major peaks associated with pseudo-components (PSEs): PSE 1 (hemicelluloses + extractives and lignin), PSE 2 (cellulose + extractives and lignin), and PSE 3 (lignin + extractives and residual holocelluloses). An essential advance is related to the quantitative interpretation of the degradation process by multi-stage modeling governed by diffusion-controlled reactions and order-based models. The Kissinger-Akahira-Sunose method provided Ea ranges of 124–154, 147–153, and 230–530 kJ‧mol-1, while the ranges obtained by the Flynn-Wall-Ozawa method were 120–152, 144–150, and 232–545 kJ‧mol-1, both for PSE 1, PSE 2, and PSE 3, respectively. Data could support the calculation of many critical operating parameters in biorefinery process, such as the pretreatment minimum temperature. SCB biorefining could lead to a degradation of up to 10, 0.5, and 11% for PSE 1, PSE 2, and PSE 3, respectively, at 473.15 K for 200 min. Thermodynamic parameters (∆H, ∆G, and ∆S) determined SCB endothermic and non-spontaneous thermal degradation.