Research On The Preparation Of Bio-Oil From Black Soldier Fly Larvae By Liquefaction In Organic Solvents And Water Co-Solvent

Black soldier fly is a type of scavenging insect whose larvae can consume organic matter as much as possible and convert it into fat and protein stored in their bodies.The black soldier fly conversion technology has attracted much attention due to its efficient degradation of organic waste.Black soldier fly larvae can degrade various types of organic waste,including kitchen waste,industrial waste,human feces,and animal manure,and can produce valuable biomaterials with high protein and fat content.With the increasing demand for fuel and the growing need for organic waste treatment,the use of black soldier fly larvae to efficiently convert organic waste into fuel can help reduce people’s dependence on limited fossil fuels and promote sustainable energy development.Based on this,this study used the method of organic solvent-water co-solubilization to convert black soldier fly larvae into bio-oil.The study focused on the screening of organic solvents,the optimization of the reaction conditions of the organic solvent-water co-solubilization,and the enhancement of the catalytic effect to improve the yield and quality of bio-oil through the synergistic effect of water and organic solvents and the enhancement effect of the catalyst.Firstly,under the conditions of reaction temperature,organic solvent-water ratio,and type of organic solvent,an experimental study was conducted using bio-oil yield and raw material conversion rate as evaluation indicators,by means of orthogonal experiments.The results showed that the organic solvent-water ratio was the most important factor affecting the bio-oil yield,and the significance of the various influencing factors was as follows:organic solvent-water ratio>reaction temperature>type of organic solvent.When bio-oil yield and raw material conversion rate were used as indicators,methanol was found to be superior to other solvents as the organic solvent.The black soldier fly larvae bio-oil was prepared using a methanol-water co-solvent liquefaction method,and the effects of process parameters such as reaction temperature,methanol-water ratio,reaction time,and methanol consumption on bio-oil yield and quality were investigated.The results showed that the optimal reaction conditions were a hydrothermal liquefaction temperature of 260℃and a methanol-water ratio of 4:1.Under these conditions,the bio-oil yield was 68.24%,with a high heating value of 34.2 MJ·kg-1,an O/C ratio of 0.13,and an H/C ratio of 2.39.Methanol consumption had a significant impact on the bio-oil yield,and when taken into account,the bio-oil yield was 48.69%,with an energy recovery rate of 65.35%and an energy efficiency of 56.36%.GCMS analysis showed that the major components of the bio-oil obtained with a methanol-water ratio of 4:1 were esters and hydrocarbons,with a low content of amides（1.92%）.Methanol can react with fatty acids to form fatty acid methyl esters and with amides to generate ammonia and esters,reducing the nitrogen content of the bio-oil.Ester compounds were the most abundant compounds in the methanol-water co-solvent bio-oil.The addition of methanol can increase the content of low-boiling-point compounds in the bio-oil and improve its combustion performance.At a reaction temperature of 260℃and a methanol-water ratio of 1:0,the bio-oil yield of the black soldier fly larvae was the highest,reaching84.83%.However,the overall performance of the bio-oil obtained under this condition was poor,with the highest nitrogen and oxygen content.Moreover,this condition requires drying the black soldier fly larvae,which consumes a lot of energy and is not suitable as the optimal process parameter condition.By comparing and analyzing the characteristics of light oil obtained with a methanol-water ratio of 1:0 and bio-oil obtained with a methanol-water ratio of 4:1,this study found that there is still room for further improvement in the quality of bio-oil obtained with a methanol-water ratio of 4:1.Therefore,this study selected iron-based catalysts（Fe S,Fe SO₄）,molecular sieve catalysts（ZSM-5,Y-type molecular sieve）,bimetallic catalysts（Ni/Ti O₂）,and molecular sieve-supported metal catalysts（Ni/Y-type molecular sieve）to investigate the effects of catalyst type on the liquefaction product distribution and characteristics with a methanol-water ratio of 4:1.The catalysts significantly improved the bio-oil yield,and the bio-oil yield reached a maximum value with Fe SO₄ catalyst,which increased by 13.94%compared to the bio-oil yield obtained without catalyst（68.23%）.The addition of Fe SO₄ catalyst significantly inhibited the formation of solid products,and the raw material conversion rate reached a maximum of 91.1%,with the highest energy recovery rate,energy efficiency,and carbon recovery rate.Due to the hydrogenation effect of in-situ hydrogen generated by Fe element catalysis during liquefaction,the content of saturated fatty acid methyl esters and monounsaturated fatty acid methyl esters was the highest with FeSO₄ catalyst.