A comprehensive kinetic study of hemicellulose pyrolysis: TGA datasets and detailed quantitative speciation for xylan, glucomannan and arabinoxylan

This study investigates the thermal decomposition and product distribution of three representative hemicellulose polysaccharides: xylan (hardwoods), glucomannan (softwoods), and arabinoxylan (herbaceous biomass) to obtain data aimed at the development of accurate kinetic models. A novel thermogravimetric analysis (TGA) based methodology, previously developed for cellulose, was applied, integrating kinetic analysis with detailed online and offline product speciation at multiple heating rates (3–100 °C/min). Results revealed distinct devolatilization patterns among the hemicelluloses. While xylan exhibited a two-step decomposition with significant gas formation, glucomannan displayed a single sharp degradation peak, yielding the highest bio-oil fraction. Arabinoxylan showed yields more distributed among the different product categories, with bio-oil characterized by high anhydrosugars formation. Online mass spectrometry (MS) analysis identified CO, CO2 , CH4 , and H2 O evolution closely linked to thermal degradation pathways. Quantitative gas chromatography (GC-MS/FID) analysis of bio-oil unveiled diverse product distributions: xylan primarily formed ketones and furanic compounds, glucomannan produced C6 anhydrosugars, and arabinoxylan yielded significant C5 sugar derivatives. Comparison with lumped kinetic models for hemicellulose pyrolysis highlighted substantial discrepancies, particularly in bio-oil composition and water mass yield, underscoring the need for refined reaction pathways. The high-quality dataset presented in this study provides significant insights into hemicellulose pyrolysis kinetics, enabling the improvement of predictive models for biomass thermochemical conversion.