Investigation on solvolysis liquefaction mechanism of Chlorella pyrenoidosa in ethanol-water solvent based on major model compounds: Protein and starch

This work explored the liquefaction mechanism of Chlorella pyrenoidosa in ethanol -water solvent. Model compounds (soya protein and corn starch) were liquefied in water, ethanol and ethanol-water solvents to investigate the synergistic effect between ethanol and water on the biocrude oil yield. To reveal the cross-interaction between protein and starch, the effect of different mixed ratios on biocrude oil yield was studied. The protein/carbohydrate ratio of feedstock was adjusted by mixing starch with microalgae to reveal the effect of Maillard reaction on the yield and quality of biocrude oil. The results showed that ethanol-water solvent contributed better to the decomposition of protein and starch compared with pure water and ethanol. The ratios of protein/starch at 2/1 and microalgae/starch at 100/14 achieved the highest biocrude oil yield and energy recovery. Based on chemical compositions of biocrude oil and light oil, a possible reaction pathway of solvolysis liquefaction of microalgae in ethanol-water solvent was proposed.