The Mechanism Of The Influence Of Process Regulation On The Product Characteristics Of The Hydrothermal Reaction Of Animal-based Model Compounds

There is a primary problem of the treatment of dead animals and poultry bodies,that restricts the sustainable and healthy development of the livestock and poultry breeding industry.It can effectively realize the harmless treatment and resource utilization of dead animals and poultry bodies by Microwave Hydrothermal Treatment(MHT),which a green and efficient thermochemical conversion technology.However,it is just in the early stages of development of the research on MHT of dead animals and poultry bodies nowadays.There are still many key problems to limits its progress.For example,it’s unclearly for the conversion mechanism of the main components and the interaction mechanism with the animal-based biomass,especially dead animals and poultry bodies,in the microwave hydrothermal treatment process.Whereas,the model material of death pig,a kind of typical disease dead poultry,rich in proteins,lipids and carbohydrates was chosen to be the substrate of MHT.Reaction pathways and actor of proteins,lipids and carbohydrates,which the main components of animal-based biomass,was studied in the microwave hydrothermal conversion process.These studies will provide constant theoretical basis for the high-value utilization of animal-based biomass with multi-target products.Firstly,based on the compound of the fattening pig,glycerin and oleic acid(Lipids,L),bovine albumin(Proteins,P),and carbohydrates(glucose,G)were used as main composition of the model compounds.And the reaction pathways of each component and the interaction law model compound were investigated at different MHT temperatures(160 ℃-240 ℃).The results show that the yields of gas phase products of all single model compounds are low,which can be negligible.Meantime,there was no solid phase products for L single model and binary mixtures mixed with P+G.And there was antagonistic effect on the production of bio-oil for the ternary mixtures mixed with both L+P+G,which more conducive to the production of water phase products.The studies on the formation and composition of bio-oil indicated that the main product components of bio-oil were mainly aldehydes and ketones for the G single model.While unsaturated C18 fatty acids(linoleic acid accounted for the largest proportion)and fatty acid methyl esters were the mainly components of the P single model.For the L single model,N-heterocyclic compounds(diketopiperazine accounted for the largest proportion)and amides were the main product components of bio-oil.There was a significant influence on the composition of bio-oil products of temperature.With the increasing of temperature,the proportion of N-heterocyclic substances in bio-oil increased,through the Maillard reaction of proteins and carbohydrates intensified.What’s more,proteins and carbohydrates can promote the decarboxylation and degradation of fatty acids to produce long-chain alkanes.While lipids and carbohydrates can promote the conversion of proteins and make N elements migrate into the liquid phase products.The studies on the solid phase product indicated that it was carbonized and formed abundant mesocarbon microbeads obviously for the G single model during MHT process.In addition,fusion and cross-linking of mesocarbon microbeads affects the preparation of mesocarbon microbeads with the temperature increases,For the other mixtures models,the solid phase product mainly used protein as the backbone,maintained a relatively smooth and complete surface in the low temperature stage.And it became rough and loose the surface of the solid-phase products with the temperature increases.Secondly,the proportions of the 3 compounds(P,L and G)for the mixtures model were adjusted according to the proportions of the main components of the pigs at different feeding stages.And the conversion characteristics of model compounds and their interaction laws under different ratios of P,L and G on MHT process have been studied.The result showed that the yield of bio-oil was directly proportional to the lipid content in the lipid-containing mixtures model,which illustrated the leading role of lipids in the conversion of bio-oil again.What’s more,there was a significant synergistic effect on bio-oil production at higher temperatures as the protein content increased of binary mixtures mixed with P+G.For the aqueous phase product of the mixed model compound,there was a basically law of decreasing of the total amino acid conversion rate as the protein ratio increases under lower temperature conditions.However,it showed a trend of increasing as the protein ratio increases under higher temperature conditions.It was conducive to increasing the relative content of alkanes in the bio-oil by increasing the content of carbohydrates in the binary mixtures model of L+G appropriately.Under the same reaction temperature,the relative content of amides in bio-oil increased with the increase of protein ratio in ternary mixtures and binary mixtures model rich in protein.The surface of the solid phase product of the mixed model compound presented a rougher morphology,and it was more conducive to the hydrolysis and decomposition of the model compound as the protein ratio decreased in the mixed model.There was no obvious carbonization in the mixtures model of high-L and high-P compound.Thirdly,in order to study on the regulating effect of the hydrothermal process on the target product.two-step hydrothermal treatment of model compound for dead livestock combined with MHT and conventional hydrothermal(CHT)was used.It can improve the bio-oil yield of the ternary mixtures model with two-step of MHT-CHT significantly.On the contrary,there was a little effect on the yield of solid phase products.It contained a high proportion of nitrogen and oxygen of the products of the ternary mixtures model with two-step of MHT-CHT.Noteworthy,it was reduced greatly for the amino acid content in the water phase product of the ternary mixtures model with two-step of MHT-CHT.It is not conducive to the recovery of amino acids.To a certain extent,it promoted the migration of N elements into the bio-oil and water phase products,and increase the ammonia nitrogen content in the water phase products with two-step of MHT-CHT.However,it caused the N element to migrate into the products of other phases at a high treatment temperature.The comprehensive combustion performance of bio-oil products was poor in the ternary mixtures model of high-P,while the comprehensive combustion performance of bio-oil products is excellent in the ternary mixtures model of high-L.It reduced the ignition point temperature of bio-oil products,but there was no effectively improve of its comprehensive combustion performance with two-step of MHT-CHT.