Experimental study of thermochemical behavior and pyrolysis kinetics of tea plant residues via TG-FTIR

Tea, as a promising biomass energy source, has been extensively studied in terms of waste tea pyrolysis. However, existing research predominantly focuses on waste tea leaves or limited components, overlooking the potential of tea plant residues (roots, stems and leaves), especially considering the challenges in waste tea collection. In this study, the Shuffled Complex Evolution (SCE) algorithm is used for systematically investigating the pyrolysis process of multiple tea plant residues. The thermochemical behavior, kinetics, and volatile products of tea roots, stems, and leaves under three heating rates in inert conditions were analyzed using Thermogravimetry - Fourier Transform Infrared Spectroscopy (TG-FTIR). The resulting thermogravimetric and differential thermogravimetric curves revealed distinct pyrolysis stages, with shoulder peaks uniquely appearing in the first and third sub-stages of TL. Kinetic parameters, calculated using Flynn-Wall-Ozawa, Kissinger-Akahira-Sunose and Starink methods, showed consistent trends across tea roots, stems, and leaves, particularly in their pre-exponential factor and activation energy patterns. Notably, remarkable alignment with experimental data was achieved by the SCE-optimized three-component parallel model, validating the reliability of the dynamic parameters. FTIR spectrum analysis identified major gaseous products, including CO₂, CH₄, CO, HCN, and organic compounds (CO, C-C, and C-O-C), along with H₂O. Gaps in the systematic analysis of tea plant residues pyrolysis were addressed in this study, and methodological innovations were introduced through the application of the SCE algorithm, significantly promoting the understanding of tea plant residues conversion.