Selective oxidative pretreatment enhances biomass torrefaction: Effects of low-concentration H2O2 and thermal severity

초록

Growing demand for renewable and carbon-neutral solid fuels has intensified interest in upgrading biomass through efficient thermochemical pathways. This study investigates the combined effects of low-concentration hydrogen peroxide (H2O2, 0-6.04%) pretreatment and torrefaction on the physicochemical evolution and fuel quality of lignocellulosic biomass. Mild oxidative pretreatment selectively modified early-stage composition, with 2.5% H2O2 promoting partial dehydration and carbon densification while temporarily reducing the heating value. Higher concentrations stabilized compositional changes without causing extensive degradation. Torre-faction temperature emerged as the dominant factor governing mass yield, elemental composition, devolatilisation behaviour, and carbonization severity, whereas the influence of H2O2 was secondary but strongly temperature dependent. Oxidation enhanced delignification and oxygen removal at <= 210 degrees C, approached kinetic balance at 250 degrees C, and promoted rapid deoxygenation and aromatic condensation at >= 290 degrees C. Energy-related indicators revealed that H2O2 pretreatment can either suppress or enhance fuel performance depending on process severity. Response surface methodology demonstrated strong predictive capability (R2 = 0.9620-0.9920) and identified 288.5 degrees C and 6.04% H2O2 as optimal operating conditions. Overall, peroxide-assisted torrefaction provides a controllable and scalable strategy for upgrading solid biofuels, with promising potential for industrial integration.

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