Exploration of hydrothermal liquefaction of multiple algae to improve bio-crude quality and carbohydrate utilization

Abstract

With the growing emphasis on biofuels research, enhancing the utilization efficiency of the hydrothermal liquefaction (HTL) process for biomass has emerged as a focal point for researchers. In this study, HTL products from various algae species were analyzed to compare the quality of bio-crude, with a specific focus on the utilization of carbohydrates in biomass. Notably, bio-crude yields from high-lipid algae exhibited less fluctuation with temperature, while the quality showed a significant improvement with increasing temperature, as evidenced by the fatty acids and esters contents in the bio-crude. The results of elemental analysis indicated that bio-crude derived from high-lipid algae had a lower nitrogen content. In the analysis of carbohydrate utilization, it was observed that the aqueous phase products of Chlorella protothecoides demonstrated relatively high yields of furfural and 5-HMF. Similarly, the aqueous phase product of Spirulina exhibited comparatively high yields of levulinic acid. The inclusion of platform compounds in elemental recoveries contributed to an enhancement in the carbon and hydrogen recovery of the product. This study establishes a theoretical foundation for the selection of feedstocks for alternative fuels and highlights the potential of carbohydrates utilization from algal biomass.