Whole Components Conversion Of Algal Biomass And Upgrading The Liquefied Bio-oil:A Comparative Study

The massive use of fossil fuels has caused a series of problems such as energy crisis and environmental pollution.Therefore,it is imperative to look for renewable clean energy.As a kind of renewable energy,algae biomass has been highly concerned and studied by many scholars for its abundant resources,carbon neutrality and short growth cycle.The paper focused on four microalgae and four macroalgae to obtain bio-oils by thermochemical conversion.Recycling and reuse of aqueous phase,the liquefaction oil is upgraded to improve the quality of bio-oil.The main research contents include:Firstly,the hydrothermal and pyrolysis reactions of microalgae and macroalgae under the same conditions were investigated.The results showed that the yield of liquefied oil of microalgae was higher than that of macroalgae,and the highest yield of liquefied oil could reach 52.7 wt.%.The main components of liquefied oil are ketones and amides.Secondly,exploring the effect of ultrasonic pretreatment on the viscosity and elemental composition of bio-oil.The viscosity of the bio-oil will be increased by ultrasonic pretreatment and time was the most influential factor.Ultrasonic pretreatment has the greatest influence on the O content.The order of the four ultrasonic factors affecting the O content is:power>temperature>frequency>time.Ultrasonic pretreatment had a positive effect on the H/C molar ratio of bio-oil.Thirdly,the aqueous phase obtained by hydrothermal liquefaction?HTL?is rich in organic matter and nutrients.The high temperature gasification reaction of the aqueous phase can produce a large amount of H₂,CH₄,and CO₂.Studies have found that acidic substances in the aqueous phase are more easily converted to gases than amides under high temperature conditions.Finally,it is explored that the hydrothermal liquefied oil of chlorella is modified under different conditions.H₂,Pt/C and tetrahydronaphthalene can increase the yield of liquefied oil and decrease the N and S content of liquefied oil.H₂0 can reduce the yield of solids,but it will increase the viscosity and N,S content of the liquefied oil.16 kinds of liquefied oils were studied under the same conditions.The content of heteroatoms in liquefied oil is significantly reduced,and N is the most difficult to remove.The yield of liquefied oil was 82-91 wt.%.The main components of the liquefied oil were aromatic hydrocarbons,saturated hydrocarbons,and unsaturated hydrocarbons.The upgrading reaction improved the quality of the liquefied oil.