Indonesia has the largest rubberwood (Hevea brasiliensis) plantation area in the world. Rubberwood is mainly planted for latex production and as latex production declines with age, rubberwood is generally felled. The logging waste and industrial waste of rubberwood-based products could be utilized as raw materials to produce biomass pellets. The quality of biomass pellets can be increased through torrefaction, a thermal process in the temperature range of 200-300°C under an inert atmosphere. This study aimed to evaluate the effect of torrefaction on the characteristics of rubberwood pellets. The torrefaction of rubberwood pellets was conducted using the Counter-Flow Multi Baffle (COMB) reactor, a reactor that could perform torrefaction within a short residence time of up to 5 min. The temperature used in this study was 200°C, 250°C, dan 300°C with a residence time of 3 min. The color change, physical properties, chemical composition, and heating value were evaluated. The results showed that the pellet’s color changed from light brown into black pellets, showing the overall color change (∆E*) of 29,12, 54,27, and 66,71, after torrefaction at 200°C, 250°C, and 300°C, respectively. The equilibrium moisture content of the pellets decreased from 12,25% to 3,54%. The water immersion test also showed that the torrefied pellets have a better hydrophobicity, which is an advantage when pellets are stored in a humid condition. The oven-dry density of pellet decreased from 1,15 g/cm3 to 1,09 g/cm3, 1,04 g/cm3, and 0,96 g/cm3, after torrefaction at temperatures of 200°C, 250°C, and 300°C, respectively. Torrefaction caused a decrease of cellulose and hemicellulose contents, an increase of lignin content, and a remarkable increase in the heating value of 1,71-18,32% with increasing torrefaction temperature. The results proposed that torrefaction using the COMB reactor could provide a great improvement in the quality of rubberwood pellets to improve the additional value of the products.Keywords: black pellet, Counter-Flow Multi Baffle, rubberwood (Hevea brasiliensis), torrefaction

Rubberwood (Hevea brasiliensis) and Jabon (Anthocephalus cadamba) are two promising species that is widely planted in industrial plantation and community forests in Indonesia. The objective of this study was to improve the properties of rubberwood and jabon pellets through torrefacation. Torrefaction was performed at a temperature of 300°C and a residence time of 3 min, using Counter-Flow Multi Baffle (COMB) Dryer/Pyrolizer. The properties of torrefied wood pellets as equilibrium moisture content (EMC), density, and heating value. Black pellets were succefully obtained after torrefaction using COMB Dryer/Pyrolizer. The EMC of the black pellets from rubberwood and jabon was 3.54% and 2.85%, which is remarkably lower that their initial EMC of 12.25% and 12.76%, for rubberwood and jabon pellets, respectively. The density of black pellets from rubberwood and jabon and decreased 16.18% and 13.44% compared to control. Torrefaction using COMB Dryer/Pyrolizer also increased high heating value of wood pellets to 18.32% and 79.70%, for rubberwood and jabon pellets, respectively. Consequently, torrefaction using the COMB Dryer/Pyrolizer could improve the bioenergetic properties of jabon and rubberwood pellets.