Effects of Kraft Lignin and Corn Residue on the Production of Eucalyptus Pellets

Pellets have become an important renewable energy source. Aiming to contribute for diversifying the Brazilian energy matrix, the goals of this work were to evaluate the quality of the pellets of lignocellulosic residues (Eucalyptus and corn) produced with the addition of different percentages of Kraft lignin. For the production of pellets, mixtures of wood with bark of a Eucalyptus urophylla and Eucalyptus grandis , and corn residue were used as raw material. The proportions of corn residue in the mixture were 0, 20, 25, and 30% (w/w). Except for the control (0% lignin), 2 and 5% (w/w) Kraft lignin were added to a dry mass of raw material in the 4 different mixtures. Pellets were produced in a laboratory press pelletizer with horizontal circular array. The following properties of the pellets were evaluated: proximate analysis, high heating value (HHV), elementary analysis, energy density, bulk density, diameter and length, hardness, mechanical durability, and fine content. The pellets were classified according to European marketing standards. The addition of Kraft lignin to eucalyptus and corn residue pellets contributed to improving the physical and mechanical pellet properties, as regards the bulk density, mechanical durability, and fine content, allowing the transportation of a greater amount of mass and energy, besides maintaining the integrity of the biofuels during handling and use. The mixing of eucalyptus with corn residue is an effective way to optimize properties of biomass solid fuel. The treatment with higher corn addition, in relation mechanical properties, showed a better performance in accordance with the European standards. The mechanical properties were above to 97.5%, besides that has no impact from the addition of Kraft lignin. The addition of up to 20% of corn residue has the potential to improve physical and mechanical pellet quality, with or without Kraft lignin addition. Thus, similar amounts to that of the treatment with the proportion of 80% eucalyptus and 20% corn residue can be a viable alternative to the production of pellets. Graphical Abstract