Theoretical Calculation And Experimental Study On The Mechanism Of Pour Point Depressing Based On Long-chain Hydrocarbons

Energy has always been the focus of human attention,and its related diesel,diesel pour point depressants and developmental vegetable oil fuels have become the focus of research.For the study of pour point depressants,domestic and foreign researchers focus on experiments,mainly to study the effects of acrylate pour point depressants on oils,but there are few theoretical studies.Therefore,based on the experimental data,this paper simulated 10 kinds of acrylate pour point depressant structure,hexadecane structure and 3 kinds of plant oil molecular structure,and conducted a series of theoretical research and experimental research.This paper is mainly divided into the following parts:（1）Theoretical study on the interaction between acrylate pour point depressants and hexadecaneIn this paper,the M06-2X method was combined with the 6-31G（d）basis group to optimize the pour point depressant and hexadecane model.The same method was used and the intermolecular interactions were calculated at the level of 6-311G（d,p）basis group.Function energy(ΔE_int).In addition,the gas properties of the interacting molecular model were further analyzed by a reduced density gradient function（RDG）,molecular electrostatic potential（MESP）,and the like.Computational studies show that the intermolecular interaction energy values of pour point depressant&hexadecane are negative,indicating that the pour point depressant is added to diesel to reduce the energy of the system and reach a more stable state.Based on the calculated data,the correlation between interaction energy and experimental data was studied.The RDG isosurface and MESP analysis indicated that the pour point depressant&hexadecane interaction was dominated by weak van der Waals interactions.（2）Theoretical study on the interaction between vegetable oil and acrylate pour point depressantIn this paper,M06-2X method was combined with 6-31G（d）basis group to optimize the model of vegetable oil molecule and pour point depressant.The same method was used to calculate the intermolecular interaction at the level of 6-311G（d,p）basis group.Energy(ΔE_int),analysis of interaction energy and optimized geometry.Theoretical calculations have shown that the intermolecular interaction energy values of vegetable oil molecules&pour point depressants are negative,indicating that the addition of pour point depressants to vegetable oils reduces the energy of the system to a more stable state.The average distance between the carbon chain of the long chain of the vegetable oil molecular model and the hydrogen atom of the pour point depressant is within the van der Waals range.It is speculated that there is a weak van der Waals interaction between the carbon atom of the vegetable oil molecule and the hydrogen atom of the pour point depressant.（3）Experimental study on the interaction between diesel oil,vegetable oil and pour point depressantIn this paper,the effect of pour point depressant on the freezing point of mixed oil system was investigated.It was showed that CQU-P-5 additive had the best pour point depressing effect by experiments.Among them,when the sunflower oil composition is80%,the diesel oil is 20%,and the pour point depressant addition ratio is 1.5%,the decondensation effect on the mixed oil is the best.The vegetable oil can replace the diesel oil as the extended-range fuel by adding the additive.