Study On Synergistic Law Of Co-hydrogenation Of Coal Tar And Biomass Oil

With the development of the national economy,the dependence on petroleum-based liquid fuels is increasing.The establishment of diversified production technologies for liquid fuels represented by coal-to-liquid,bio-liquid,and shale oil is of great strategic significance to national security and economic prosperity.Coal tar is a by-product of coal pyrolysis,and biomass oil is mainly derived from waste kitchen oil of catering industry or waste oil of food factory.Both of these two fuel production technologies face the characteristics of unstable sources of raw materials and small production scales.Based on the original coal tar hydrogenation and biomass oil hydrogenation technology,this paper revealed the synergy law between the two raw materials through co-hydrogenation of the two raw materials,and explored the combination of the two processes.The co-hydrogenation technology of coal tar and biomass oil was obtained,which laid a theoretical foundation for subsequent research.The specific research content includes:Firstly,the model compounds composed of different hydrogen-donor solvents(naphthalene,tetralin,decalin,benzene,cyclohexane)are mixed with kitchen waste oil at a ratio of 1:1(wt%),and the mixed raw materials were subjected to thermal cracking and hydrogenation reactions under N₂and H₂atmospheres respectively.By analyzing the composition distribution of C₁₅?C₁₈in the hydrogenated product and the conversion rate of fatty acids in the waste oil of the kitchen,it was determined that the solvent occurred hydrogen donor phenomenon in the co-hydrogenation process of the two raw materials.It was found that saturated or partially saturated aromatic hydrocarbons can released highly active hydrogen radicals under thermal reaction,which can effectively promote the hydrogenation saturation of C=C bond on fatty acids and the hydrodeoxygenation of carboxyl groups.Secondly,based on the co-hydrodeoxygenation experiment of the two raw materials at different temperatures and different ratios,the product composition distribution and the conversion of fatty acids and phenols were analyzed,and the reaction law of co-hydrogenation of coal tar and biomass oil was summarized.The study found that the hydrodeoxygenation conversion rate of fatty acids in biomass oils after co-hydrogenation with coal tar increased by1.36%,and the content of sulfur,nitrogen,oxygen and other heteroatoms in the oil after hydrogenation was reduced,and the degree of lightening of the oil was improved.The reason is that during the co-hydrogenation process,the hydrogen-donating solvent in the hydrogenation product of coal tar undergoes dehydrogenation and hydrogen transfer,which realizes the conversion of gas-phase hydrogen to adsorbed active hydrogen,thereby promoting the hydrogenation reaction process of biomass oil.Finally,a seven-lumped kinetic model for the co-hydrodeoxygenation reaction of low-temperature coal tar and kitchen waste oil was established by MATLAB software,and the activation energy of the five reactions were obtained by fitting the Marquardt algorithm.Among them,the activation energy of the reaction of aromatic hydrocarbon hydrogenation to form cycloalkanes is 71973.643 J/mol,and the activation energy of the reaction of cycloalkane hydrocracking to form low-paraffin hydrocarbons is 81727.372 J/mol.The influence factor f of hydrogen radicals produced by aromatic hydrocarbons in low-temperature coal tar on fatty acids is 1.011,and the reactor releases 317 k J of heat.It is experimentally verified that the relative error between the model and the calculated value does not exceed 5%.In this paper,by analyzing the phenomenon of saturated or partially saturated aromatic hydrocarbons to the solvent hydrogen supply of fatty acids,the synergistic mechanism of the co-hydrogenation of coal tar and biomass was clarified,and through the parameter fitting of a set of seven lumped kinetic-thermodynamic models,the influencing factors of the synergistic effect were obtained.The study found that the co-hydrogenation of the two raw materials has theoretical feasibility and can promote the hydrogenation conversion of fatty acids,thereby obtaining products with a higher degree of lightness.