Influence of lignin distribution, physicochemical characteristics and microstructure on the quality of biofuel pellets made from four different types of biomass

Abstract The worldwide increase in the demand for wood pellets has led to increased interest in the use of biomass feedstock. However, the quality of pellets depends directly on the biomass feedstocks. This paper brings new insights about the influence of lignin distribution, physicochemical characteristics, and microstructure on the quality of pellets. The aim of the study was to characterize the physical, chemical, mechanical and energy properties of pellets produced from Pinus radiata (PR), Eucalyptus nitens (EN), Paulownia elongata × fortune (P), and Miscanthus × giganteus (MG), as well as to use microscopic techniques to examine how lignin distribution influences the mechanical properties. The findings show that the pellets made from PR were more suitable for bioenergy production compared to those produced with EN, P, and MG. Anatomical structure proved to be important in relation to pellet quality. The clear areas on the surface of the pellets presented relationship with the percentage of biomass lignin (which ranged from 26.4–34.2%). The P and PR pellets were more durable and had fewer empty spaces between particles. The pellets made from EN, which was the material most difficult to compact, had abundant cracks.