Pyrolysis of rice husk, bagasse and wood chips blends: Distributed activation energy modelling and pyrolysate composition analysis

Blending of diverse lignocellulosic biomass feedstocks, such as rice husk, sugarcane bagasse and wood chips, provides a promising strategy to improve feedstock flexibility for pyrolysis. This study deals with kinetics and pyrolysate composition analysis to elucidate the possible interactions during pyrolysis of blends of rice husk-sugarcane bagasse and rice husk-wood chips, for a strategic utilization of biomass feedstocks in thermochemical biorefinery. Thermogravimetric analysis was used to investigate the pyrolysis behaviour of feedstocks, while a distributed activation energy model using cellulose, hemicellulose and lignin pseudocomponents was developed to elucidate the kinetics. The results reveal that lignin consistently exhibits higher activation energy compared to hemicellulose and cellulose, with wood chips showing the highest value for lignin decomposition (265.9 kJ mol⁻¹). Notably, the activation energy of lignin varied significantly with blend composition, increasing with higher wood chips content and decreasing with sugarcane bagasse content. However, cellulose and hemicellulose kinetics remained invariant with blending of biomasses. This suggested that interactions between the lignins from different biomass feedstocks were predominant, possibly influencing both biomass decomposition kinetics and product composition, especially phenolics. The pyrolysate composition evaluated at 590 °C using an analytical curie point pyrolyzer showed high selectivity to phenolic compounds, especially for wood chips (56.3 %) followed by rice husk (34.1 %) and sugarcane bagasse (17.3 %). For sugarcane bagasse-rice husk blend, the pyrolysate distribution closely followed the additive effect with selectivity deviation for most of the compositions lying within ±2 %, while a few compounds like pyrans deviating within ±5 %. Importantly, in the case of wood chips-rice husk blends, the inclusion of rice husk increased the selectivity deviation for most of the compounds, suggesting major interactions among the pyrolysates. These findings demonstrate that strategic biomass blending can optimize the quality and energy potential of bio-oils, providing new pathways for utilizing pyrolysis process.