Optimization Of Fuel Oil Desulfurization Process Based On Ionic Liquid And Low Eutectic Solvent

The combustion of fossil fuels has brought about the emission of sulfur-containing substances.The problem of desulfurization of fuel oil has attracted widespread attention from all over the world.With the advantages of low vapor pressure,non-toxicity and low cost,it has attracted more and more attention as a green solvent.In this paper,the n-heptane-dibenzothiophene system is used to represent the model oil,and the extraction and desulfurization of the above two types of solvents are carried out respectively.Experimental and Mechanistic Studies.In the laboratory,nine kinds of low-covalent compounds with diethylene glycol,ethanolamine,and ethylene glycol as hydrogen bond donors,and tetrabutylammonium bromide,tetrabutylphosphonium bromide,and choline chloride as hydrogen bond acceptors were prepared.Melt solvent was used as the extraction agent,and the extraction and desulfurization experiments were carried out on model oils with sulfur concentrations（0.1%-1.00%）common in my country,and the ratios of different hydrogen bond donors and acceptors,the sulfur Extractant ratio and liquid-liquid equilibrium data of n-heptane debenzothiophene at extraction temperature,and compare the extraction efficiency under different conditions.The comparison shows that under normal temperature conditions,when the DES of choline chloride/diethylene glycol（1:4molar ratio）is used,and the fuel oil and the extractant are 1:1（mass ratio）,the initial sulfur concentration of 0.5mol The extraction efficiency of the model oil can reach up to 67.138%.Based on the COSMO-SAC theory,theσ-shielding charge density distribution diagram was used to analyze the hydrogen bond interaction between various hydrogen bond donors and acceptors,and it was found that the deep eutectic solvent constructed by choline chloride/diethylene glycol was The active region can have a stronger interaction with dibenzothiophene and has a better extraction effect.Based on molecular dynamics theory,various parameters such as radial distribution function graph,spatial distribution function graph,interaction energy,and mean square displacement are used.The internal mechanism of DES was explored,and finally the conclusion of molecular dynamics was found to be consistent with the experimental results after comparison.After verifying the validity of quantum chemical simulation and molecular dynamics simulation,the ionic liquid extractant was screened by related quantum chemical simulation.The best ionic liquids are[C_2COOCH3Im C₆H₁₃][NTF₂]and[C_2COOCH3Im C₆H₁₃][N（CH）₂],further through the molecular dynamics analysis mechanism,the best ionic liquid extractant is[C_2COOCH3Im C₆H₁₃][N（CH）₂],but limited to the long experimental production period of the ionic liquid,the difficulty of the production method and other factors,the suboptimal solution[C_2COOCH3Im C₆H₁₃][NTF₂]ionic liquid was prepared in the laboratory as the extraction agent,and the liquid-liquid equilibrium experiment of extraction desulfurization was carried out,it was found that ionic liquids are suitable for extracting and desulfurizing fuel oil with low sulfur concentration at room temperature.When extracting and desulfurizing 0.5mol%model oil,the desulfurization effect can reach 59.924%,which is slightly worse than that of eutectic solvent.The experimental results are consistent with the predicted results of molecular dynamics,which further illustrates the necessity of using molecular dynamics method to theoretically predict and explore the desulfurization performance of ionic liquids.Finally,the processes of ionic liquid extraction desulfurization and conventional sulfolane extractant extraction desulfurization were simulated by Aspen,and the process was optimized with the goal of the lowest total annual cost（TAC）.Extractant,the desulfurization process is simpler,the desulfurization efficiency is higher,and the amount of extractant added is less.When the desulfurization efficiency is guaranteed to be higher than 99.99%,the ionic liquid process TAC can save 87.30%,which guides the use of ionic Feasibility of liquid for extractive desulfurization.