Influence of Bran and Peat Binder Components on the Pyrolysis Products of Agricultural Residue-Based Biomass Pellets

Agricultural residues represent an abundant lignocellulosic resource for the production of renewable fuels and value-added products through thermochemical conversion. In this study, the influence of bran and peat as organic and mineral-rich binder components on the pyrolysis behaviour and product distribution of biomass pellets was investigated. Wheat straw, barley straw, and oat husks were pelletized using barley bran or peat as binders and analysed by thermogravimetric analysis coupled with Fourier-transform infrared spectroscopy (TGA-FTIR). The thermal degradation behaviour, product yields, evolution profiles of non-condensable gases, and composition of condensable products were evaluated during pyrolysis at 700 °C. The results indicated that pelletization modified the thermal degradation pathways and product distribution through interactions between biomass and binder components. Bran-bonded pellets promoted the formation of bio-oil and oxygen-containing condensable compounds, with bio-oil yields reaching up to 45.2%, whereas peat-bonded pellets showed increased formation of non-condensable gases and solid residue. CO2 and CO were the dominant gaseous products, while CH4 formation mainly occurred at elevated temperatures in the passive pyrolysis region. The results indicate that binder composition plays an important role in controlling pyrolysis pathways and product distribution, providing opportunities for the optimization of agricultural residue-based pellets for bioenergy and circular bioeconomy applications.