Energy and exergy analyses of bio-jet fuel production from full components in lignocellulosic biomass via aqueous-phase conversion

Abstract

• Aqueous conversion of three components in corn stalk to bio-jet fuel is simulated. • Energy and exergy analyses of bio-jet fuel production are performed. • Lignin to bio-jet fuel is beneficial to thermodynamic performance. • Aqueous-phase conversion has a higher bio-jet yield compared with GFT. • High-temperature combustion and gasification are disadvantageous to energy quality. Lignin is usually burned for heat supply in aqueous-phase conversion of lignocellulosic biomass to aviation fuel due to its difficult utilization by hydrolysis, which limits the increase in the bio-jet fuel yield. To improve the performances, this study investigates novel processes to produce aviation ranged hydrocarbons by utilizing lignin combined with cellulose and hemicellulose to achieve alternative utilization of full components. The aqueous-phase conversion processes of lignocellulosic biomass to bio-jet fuel via different utilization methods for lignin are simulated based on Aspen Plus. The thermodynamic performances of the different cases, i.e., lignin to bio-jet fuel (Case 1), lignin to co-production of bio-jet fuel and hydrogen (Case 2), lignin to hydrogen and combustible fuel (Case R), and biomass gasification with Fischer–Tropsch synthesis, are compared by energy and exergy analyses. Also, the energy-quality improvement rate is proposed to evaluate the process performance. The results show that Case 1 has the highest bio-jet fuel yield (107.7 kg/t-bio) and the highest overall energy and exergy efficiencies (43.5% and 27.2%, respectively); however, Case 2 has the best energy-quality improvement rate (14.7%). In addition, the hydrolysis of lignin to bio-jet fuel combining gasification to hydrogen is beneficial for conversion of the biogenic carbon into bio-jet fuel. Energy and exergy analyses indicate that the largest energy loss occurs in the furfural unit (∼19.5%), followed by combustion unit (∼10.4%) and levulinic acid unit (∼10.3%), while the greatest exergy loss occurs in the combustion unit (∼34.0%). The results indicate that the mild reaction conditions can alleviate the decreases in energy quality of conversion processes. Compared to the Fischer–Tropsch synthesis case with the bio-jet fuel yield of 86.4 kg/t-bio, the aqueous-phase conversion leads to a higher bio-jet fuel yield but a lower systematic efficiency. Moreover, the results show that the conversion of cellulose, hemicellulose, and lignin to bio-jet fuel is not sufficiently high and more consumption of chemicals also leads to the lower systematic efficiency. This work is valuable to the future improvement of the full conversion of lignocellulosic biomass for bio-jet fuel production.