Abstract:
The growth of environmental pollution due to extensive use of fossil fuels has raised concerns over the use of the fossil fuels. Thus, search for alternate renewable and sustainable resources of fuels has started in the last few decades. Biomass is one of the most attractive resource in terms of its potential and benign environmental impact. Hydrothermal liquefaction (HTL) is a promising thermo-chemical process for producing liquid biofuels. This study was focused on investigating effects of cellulose and lignin on product yield and quality from HTL of biomass. Four types of biomass used in the experimental tests were bagasse, cassava rhizome, cellulose, and lignin. The experiments were carried out in in a batch reactor and a semi-continuous reactor at 300 and 350°C with the reaction time of 60 min. Liquid products were characterized by an elemental analyzer and GC/MS. The result indicated that the cassava rhizome gives higher liquid yields than bagasse. This was attributable to high lignin content in the former. The addition of lignin to the real biomass by physical mixing gave the lower liquid yield than that expected by the weight-average calculated value. However, the yield became higher with increasing the amount of lignin addition from 10 to 20 wt.%. The liquid yield of 60.26 wt.% was obtained at 300°C for mixture between cassava rhizome and 20 wt.% of lignin. The maximum HHV of 24.39 MJ/kg was obtained from the HTL of cassava rhizome mixed with lignin in the ratio of 80:20. The HHVs of bio-crude oil from HTL were in the range of 10.42-24.39 MJ/kg. The experiments were carried out in a semi-continuous reactor at the solvent flow rate of 1.0 mL/min at 300°C for 60 minutes. The addition of cellulose and lignin to the real biomass by physical mixing gave the higher liquid yield than that expected by the weight-average calculated value. This indicated a synergistic effect in semi-continuous reactor. The GC-MS results revealed that the biocrude contains mostly hydrocarbon and other oxygenates compounds.