Pretreatments and model fitting to identify in-situ decomposition of fir wood constituents

Multi-step devolatilization mechanisms of lignocellulosic material are generally based on the summative contributions of pseudo-components owning a mathematical character. Herein innovative five-step kinetics is proposed for fir wood, based on natural components (two steps for hemicellulose and lignin-extractives and one step for cellulose). Klason isolation and severe torrefaction provide samples rich in lignin and extractives. Also, hot water washing or washing followed by mild torrefaction reduces or eliminates the overlap between hemicellulose and cellulose decomposition. TG-DTG curves of untreated and pretreated fir wood are measured for several heating rates and subjected to kinetic analysis by a model fitting method to estimate the kinetic parameters. The predicted in-situ decomposition of natural components/mixtures exhibits dynamics and biochar yields different from those of commercial or isolated compounds, whose mutual bonds and chemico-physical properties are altered by invasive chemical pretreatments. • Close to natural components are introduced in fir wood decomposition kinetics • Klason extraction and severe torrefaction are used to identify lignin kinetics • Washing and washing with mild torrefaction separate holocellulose components • A five-step mechanism is developed of fir wood decomposition • Natural components degrade differently from isolated or pseudo-components