Design And Synthesis Of Molecular Sieve Immobilized Ionic Liquids And Their Application In Oil Denitrification

When the nitrogen compounds in the oil were burned,harmful substances such as NO_x will be produced which seriously pollute the environment.With the increasingly strict environmental protection laws,countries all over the world are working to obtain cleaner fuels.Based on the advantages of ionic liquid(IL)denitrification process,such as mild conditions and high denitrification rate,as well as the advantages of molecular sieve MCM-41 such as larger specific surface area,adjustable pore size,and high adsorption capacity of nitrogen compounds in oil.Therefore,a novel denitrification agent was synthesized by immobilizing IL on MCM-41 in the form of covalent bond,which could combine the advantages of molecular sieve and IL denitrification.And the basic nitride quinoline and non-basic nitride indole were used as the model oil to further verify the denitrification efficiency of denitrification agent.The main research contents are as follows:(1)Imidazole and triazole were used as cations,a variety of ILs with different anions were synthesized.The ILs were immobilized on MCM-41 through the Si-O-Si covalent bond.The synthesized denitrification agent was characterized by FT-IR,TG-DSC,XRD,TEM,SEM,N₂ adsorption and desorption.The results showed that the synthesized denitrification agent had good thermal stability and successfully immobilized IL on MCM-41 without significantly affecting the structure of MCM-41.(2)When basic nitride quinoline was used as model oil,the denitrification effect of different denitrification agents on the quinoline model oil was investigated.The results showed that the 0.8 MMS-HSO₄ denitrification agent could achieve 98.97%denitrification efficiency of quinoline under the conditions of 35?and m(denitrification agent):m(model oil)=100:1 in 2 h.This was because that the N atoms in the quinoline molecule could form a more polar charged ion with H⁺in the IL in the denitrification agent and the?-?complexation between the imidazole cation and the quinoline molecule increases the denitrification rate.Simultaneously,the adsorption of quinoline molecules on molecular sieves includes both the early Langmuir monolayer adsorption and the later Freundich adsorption of capillary condensation.Meanwhile,the denitrification agent can still achieve a 96.69%removal rate of quinolone model oil when it was used for 3 times.Through response surface experiments,the effects of different factors and their interactions on the denitrification rate were studied.The results showed that the experimental data conforms to the quadratic regression model and the value of R² is 0.9445,indicating that the experimental results were highly reliable;The data residuals conform to the normal distribution;The order of the influence of various factors was that the denitrification oil agent ratio>the denitrification temperature>the denitrification time>the interaction of denitrification oil agent ratio and denitrification temperature>the interaction of denitrification temperature and denitrification time>the interaction of denitrification time with denitrification oil agent ratio;After optimizing different factors through the model,the 0.8 MMS-HSO₄denitrification agent could achieve 99.76%denitrification efficiency of quinoline under the conditions of 44?and m(denitrification agent):model oil=96:1 in 2.4 h.(3)When the non-basic nitride indole was used as the model oil,the denitrification effect of different denitrification agents on the indole model oil was investigated.The results showed that the 0.6 MTS-HSO₄ denitrification agent could achieve 97.42%denitrification efficiency of indole under the conditions of 35?and m(denitrification agent):m(model oil)=20:1 in 2 h.This was due to the stronger aromatic structure of?-?complexation and the high polarity complex formed by the electrostatic attraction of HSO₄^-in IL and the N in the indole molecule.Meanwhile,the adsorption of indole by MCM-41 belongs to Langmuir monolayer adsorption.The denitrification agent could still achieve a denitrification rate of 95.08%for the indole model oil when it was used for 3 times.Through response surface experiments,the effects of different factors and their interactions on the denitrification rate were studied.The results showed that the experimental data conforms to the quadratic regression model and the value of R² is0.9644,indicating that the experimental results were highly reliable;The data residuals conform to the normal distribution;The order of the influence of various factors and their interactions on the denitrification rate was that the denitrification oil agent ratio>the denitrification temperature>the denitrification time>the interaction of denitrification time and denitrification temperature>the interaction of denitrification oil agent ratio and denitrification time>the interaction of denitrification oil agent ratio and denitrification temperature.After optimizing different factors through the model,the 0.6 MTS-HSO₄denitrification agent could achieve 99.61%denitrification efficiency of indole under the conditions of 35?and m(denitrification agent):m(model oil)=10:1 in 2.5 h.In this paper,Br(?)nsted acidic IL was synthesized and immobilized on MCM-41 by covalent bonding.Through the response surface experiment,the effect of denitrification temperature,denitrification time,denitrification oil ratio and their interaction on the denitrification rate was systematically studied,which provides a theoretical basis for the low-nitrification trend of oil products in the future.