Abstract

Biomass pyrolysis allows waste valorisation by converting it into valuable liquids. Elevated acid and oxygen compound concentrations diminish pyrolytic liquid quality. This study assessed biomass torrefaction's effect on decreasing acid content in pyrolysis and increasing value-added compounds. Chilean oak received four torrefaction treatments with variations in final temperatures and isothermal durations. Biomass samples underwent pyrolysis using a thermogravimetric analyser and an analytical pyroliser to assess kinetic behaviour and identify decomposition products. Torr3 (573 K, 30 min) exhibited the highest torrefaction severity index (TSI). Results indicated that elevated TSI correlated with a 3.29 % decrease in hemicellulose content, a nearly 90 % increase in total lignin, and stable cellulose levels. The activation energy for biomass decomposition rose with TSI. The results indicated that torrefaction enhances lignin-carbohydrate complex formation, allowing for effective pyrolysis control via temperature modifications. Thus, torrefaction enhanced temperature-dependent selectivity in pyrolysis, resulting in 30 % ketones, 37 % phenols, 16 % furans, and 2 % acids. Torrefaction raises the quality of pyrolytic products through efficient biomass pre-treatment.