Effect of Torrefaction Temperatures on Bio-Oil Properties from Leucaena leucocephala

Abstract

Biomass is an important source of renewable energy which is derived from the living mechanismsuch as photosynthesis of plant due to the lower contents of sulfur and nitrogen in the biomass. Pyrolysisis a technology that can directly produce a liquid fuel from biomass which can be readily stored ortransported. However, many researches have reported the negative properties of the bio-oils compare withthe conventional fuel oil. The undesirable properties of the bio-oils included low heating value, low pHvalue, incompatibility with conventional fuels, high viscosity, and chemical instability. These undesirableproperties of the bio-oils are mainly brought about by the high oxygen content in the biomass. On theother hand, it is known that the oxygen content in the biomass could be reduced by the torrefaction at thetemperatures below 300 °C. So, in this work, the effect of torrefaction at difference conditions on bio-oilproduction from Leucaena leucocephala was studied. It was found that the oxygen content of leucaenadecreased from 46.2 wt% to 37.3 wt% when torrefy at 295 °C whereas the torrefied leucaena yieldsdecreased with the increase in torrefaction temperature. Then, the torrefied leucaena was pyrolysed at550 °C to produce bio-oils. The bio-oils were then fractionated into light oil and heavy oil fractions. Light oilfraction was analyzed by GC-MS technique to examine the effect of torrefaction on the bio-oils properties.It was found that acetic acid and furans were decreased in light oil fraction with the increase in torrefactiontemperature. The decrease in acetic acid in the bio-oils resulted in the increase of the pH value of bio-oils.Moreover, it was found that carbon content in solid char increased while the oxygen content slightlydecreased with the increase in torrefaction temperature. These results indicated that not only torrefactionprocess could improve bio-oils properties prior pyrolysis process but also affected the properties of solidchar.

Keywords : Torrefaction / Pyrolysis / Leucaena leucocephala / Bio-oilsAbstractEffect of Torrefaction Temperatures on Bio-Oil Properties fromLeucaena leucocephala*