Co-pyrolysis of pine sawdust with nickel formate for understanding interaction mechanisms and enhancing resistance toward biochar deposition

Abstract

The objective of this work was to further understand the interaction mechanisms between pine sawdust (PS) and nickel formate (NF). As a result, the thermal behaviour of PS, NF, and PS/NF blends was determined by thermogravimetric analysis (TGA) using mass changes as monitoring parameters. Activation energies were obtained using model-free integral methods, and reaction models were estimated employing Criado mater plots (hereinafter referred to as mater plots). Besides, with the obtained activation energies, variation in pre-exponential factor (A), enthalpy (ΔH), Gibbs free energy (ΔG), and entropy (ΔS) were calculated. In higher temperatures, the presence of NF favors the decomposition of PS. When the value of PS content divided by NF content falls below 1, the temperature at which positive synergy occurs gradually decreased. Besides, the existence of NF enhanced resistance toward biochar deposition. Predominant reaction mechanisms for the samples were different at low (α ≤ 0.5) and high (α ≥ 0.5) conversion rates. Notably, the A value was linearly positively related to the activation energy. Positive ΔG and ΔH values were obtained from the pyrolysis of PS, NF, and PS/NF blends.