Enhancing lignocellulosic energetic properties through torrefaction and hydrothermal carbonization processes

• Main Authors: Chadatip Lokmit, Kamonwat Nakason, Sanchai Kuboon, Anan Jiratanachotikul, Bunyarit Panyapinyopol
• Other Authors: Thailand National Nanotechnology Center
• Format: Article
• Published: 2022
• Subjects: Energy
• Online Access: https://repository.li.mahidol.ac.th/handle/123456789/73902
• Institution: Mahidol University

In this study, energetic properties of cellulose (CL) and lignin (LN) were enhanced through torrefaction (TF) and hydrothermal carbonization (HTC) processes. TF was conducted at 200 to 300 °C for 30 min under 100 mL/min CO2. HTC was conducted at 180 to 220 °C for 30 min using liquid fraction (LF) recirculation. The derived biochar and hydrochar were investigated in the parameters of mass yield, proximate and ultimate analysis, energetic properties, thermal decomposition properties, surface chemical functional groups, and surface morphology. TF affected CL and LN properties rather than HTC. Energetic properties of CL and LN were greatly enhanced using TF. On the other hand, HTC affected the energetic properties of CL and LN marginally, and the effect of LF recirculation on hydrochar energetic properties could have been negligible. CL and LN chars with maximum HHV improvement (0.73 and 0.13) and energy yield (161.61 and 96.37%) could be derived through TF. The O/C and H/C ratios of the biochar were decreased and found to be similar to those of lignite and sub-bituminous coal. In addition, HHV of CL hydrochar was much lower than that of CL biochar, while HHV of LN hydrochar could be comparative with LN biochar. These results suggested that TF constitutes an outstanding technology for producing char fuel from lignocellulosic biomass. LF recirculation during the HTC process could enhance its economic feasibility and environmental friendliness. Biomass with high LN content could serve as a promising material for producing solid fuel.