Characterization And Production Of Lipid-rich Biomass Derived Biocrudes By Hydrothermal Liquefaction

The rapid consumption of fossil energy has brought great challenges to the survival of human beings.The clean utilization of renewable energy is one of the effective means to alleviate the rapid consumption of traditional fossil energy and reduce the increasingly serious environmental pollution.Based on the carbon neutrality theory,the use of biomass energy to control CO₂emission reduction is an inevitable trend of human survival and development,and the application of biomass to thermal conversion technology to produce biofuels has become a current hot spot.In this paper,the lipid-rich biomass chlorella vulgaris and trichospora fermentum are used as raw materials,and the hydrothermal liquefaction technology（HTL）is used to realize the utilization of resources,and the production of hydrothermal bio-oil is attempted to slow down the consumption of oil.Based on the preparation of raw materials,the construction of the reactor platform,the determination of the oil separation and purification process,and the analysis of components,experiments were carried out to explore the characteristics of high-protein algae-based hydrothermal oil and high-lipid yeast-based hydrothermal oil.Analysis and comparison are carried out from the perspectives of oil yield and quality,and in-depth molecular analysis of hydrothermal mechanism and discussion of co-combustion reliability and economy are carried out.First,the overall process of the biomass hydrothermal experiment is summarized as follows:raw material pretreatment,cleaning equipment,adjusting parameters,tank sealing experiment,pressure relief and oil collection,centrifugal filtration,fractional extraction,rotary evaporation,weighing collection,etc.The algae-based liquefaction experiments were carried out in the temperature range of 260°C to 300°C and the time range of 0 to 60 min.The results show that the reaction end temperature and residence time have significant effects on the bio-oil yield.The optimal condition is 280℃,30 min,and the liquefaction rate can reach up to 32.04%.The main product of hydrothermal liquefaction of high-protein biomass is a mixture of C/H-containing compounds and N/O-containing compounds.The main components are amides,nitrogen-containing heterocyclic compounds,carboxylic acids and ketone-aldehydes,etc.The components are nitrogen-containing heterocycles,followed by amines and amides and higher carboxylic acids.The more intense the reaction conditions are,the more the acylation reaction will be promoted and the Maillard reaction will be inhibited.Secondly,the main chemical compositions of yeast and algae are similar,both of which are rich in lipid biomass,but there is a certain difference in relative content,yeast has relatively higher lipid content and lower protein content while algae In contrast,the ratio of lipids,proteins and carbohydrates in the feedstock directly affects the composition of the hydrothermal product.Under the same reaction conditions,the liquefaction rate of yeast was higher than 43.36%.The highest content of carboxylic acid in yeast-based oil was much lower than that of algae-based oil,which also resulted in a relatively low calorific value of32.79 MJ/kg.Hydrothermal oil with high N content can be denitrified by adding catalyst or co-solvent in a hydrogen environment,thereby increasing the content of hydrocarbons in the components.The main reaction processes of the two biomasses,algae and yeast,are basically the same.The overall hydrothermal mechanism can be divided into three substrates,hydrolysis reaction,bond breaking and repolymerization of intermediate products,deamination and decarboxylation of amino acids,amidation reaction and Maillard reaction.Wait for three parts.Finally,compared with pyrolysis technology,hydrothermal technology has the advantages of low energy consumption and high oil production,and has a brighter future.However,under the condition of no catalyst and special atmosphere,more small molecular alkanes can be obtained by pyrolysis,and the quality of pyrolysis oil is relatively higher.But if the quality of hydrothermal oil can be improved by hydrogenation,it is more suitable for biofuels in general.The water-heat oil is put into mixed combustion with aviation kerosene.Judging by observing the flame characteristics,the co-firing prolongs the ignition delay period and increases the time required to achieve stable combustion,but for the industry,short-term use is sufficient to meet the combustion conditions.The bio-oil produced by the hydrothermal liquefaction of lipid-rich biomass is put into quantitative production,and the investment in the hydrothermal oil industry chain under certain conditions meets the economic requirements.