Synthesis of PW–coupled Ionic Liquids Catalysts and Research on Catalytic Oxidative Desulfurization of Oil

Author:Yuan Dan Dan

Supervisor:song hua

Database:Doctor

Degree Year:2018

Download:31

Pages:128

Size:15172K

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With the increasing awareness of environmental protection,more and more stringent requirements have been put forward for the sulfur content in fuel oil in the world,and the production of ultra-low sulfur fuel has become an inevitable trend.Oxidative desulfurization(ODS)has the characteristics of mild reaction conditions,simple process and high desulfurization rate for heterocyclic sulfides.Hence,ODS is considered to be a promising new method for the deep desulfurization of fuel oil.A signal POM catalyst can show good activity coupled with extraction.However,as semi-homogeneous catalyst,recovery of the POMs after ODS is very difficult,which limits the application of this method.In order to overcome these drawbacks,considerable effort has been put into the development of POMs with high catalytic activity and excellent reusability for ODS.In this work,a simple and reusable solid POMs catalysts based on PW–coupled ionic liquids,PW–coupled polyionic liquid and PW–coupled cross-linked polyionic liquid were designed and prepared,and the catalyst was characterized.Catalyst oxidation removal thiophene-typed S-compounds in octane was performed as probe reaction to study the catalytic activity of catalyst with carbon chains of different lengths and different types of ionic liquids.As-prepared catalysts were selected to undergo series of parallel experiments to systematically investigatre the effects of factors shuch as reaction temperature,dosage of catalyst,reaction time,recycling on desulfuraiztion.The reaction mechanism for oxidation desulfurization was also proposed.The research work in this paper opens up a new way for POMS catalyst to be used in green catalytic oxidation desulfurization.The study of this paper is divided into three topics,which are briefly described as follows.1.Catalytic oxidative desulfurization with PW–coupled ionic liquidsSolid POMs catalysts of alkyl substituted pyrrolidine-based,pyridine-based and imidazole-based ionic liquid with different carbon chain lengths were prepared.The effects of carbon chain length and ionic liquid type on desulfurization performance of catalysts were investigated.The results show that:(1)The catalysts have been successfully synthesized and characterized by SEM,XRD,FT-IR and TG.(2)Desurlfurization performance of catalysts increased with carbon chains of lengths,the frist increase and then decrease.The maximum value was reached at the alkyl chain length of 4.(3)Compared with PW–coupled ionic liquid of different types,the desulfurization performance of PW–coupled imidazole-based ionic liquid was the most superior.(4)The BT removal of 90.1%over BMImPW could be obtained at the following optimal conditions:model oil of 5mL,catalyst amount of 0.1 g,the n(H2O2)/n(S)of 8:1,the reaction temperature of 50°C.(5)The desulfurization performance of BMImPW decreased from 97.1 to 85.3%after repeated use for 4 times,down by 6.4%.2.Catalytic oxidative desulfurization with PW–coupled polyionic liquidsSolid POMs catalysts of alkyl substituted pyrrolidine-based,pyridine-based and imidazole-based polyionic liquid with different carbon chain lengths were prepared.The effects of carbon chain length and ionic liquid type on desulfurization performance of catalysts were investigated.The results show that:(1)The catalysts have been successfully synthesized and characterized by SEM,XRD,FT-IR,TG,13CNMR,31PNMR,ICP and elemental analysis.(2)Desurlfurization performance of catalysts increased with carbon chains of lengths,the frist increase and then decrease.The maximum value was reached at the alkyl chain length of 4.(3)Compared with PW–coupled polyionic liquid of different types,the desulfurization performance of PW–coupled imidazole-based polyionic liquid was the most superior.(4)The BT removal of 99.4%over PBVImPW could be obtained at the following optimal conditions:model oil of 5mL,catalyst amount of 0.06 g,the n(H2O2)/n(S)of 8:1,the reaction temperature of 50°C.(5)The desulfurization performance of PBVImPW decreased from 99.4 to 95.3%after repeated use for 4 times,down by 4.1%.3.Catalytic oxidative desulfurization with PW–coupled polyionic liquidsSolid POMs catalysts of alkyl substituted pyrrolidine-based,pyridine-based and imidazole-based cross-linked polyionic liquid with different carbon chain lengths were prepared.The effects of n(DVB)/n(IL),carbon chain length and ionic liquid type on desulfurization performance of catalysts were investigated.The results show that:(1)The catalysts have been successfully synthesized and characterized by SEM,XRD,FT-IR,TG,13CNMR,31PNMR.(2)the desulfurization performance of PW–coupled cross-linked ionic liquid wtih n(DVB)/n(IL)of 1:1was the most superior.(3)Desurlfurization performance of catalysts increased with carbon chains of lengths,the frist increase and then decrease.The maximum value was reached at the alkyl chain length of 4.(4)Compared with PW–coupled cross-linked polyionic liquid of different types,the desulfurization performance of PW–coupled imidazole-based cross-linked ionic liquid was the most superior.(5)The BT removal of 99.6%over PBVImPW-DVB could be obtained at the following optimal conditions:model oil of 5mL,catalyst amount of 0.06 g,the n(H2O2)/n(S)of 8:1,the reaction temperature of 50°C.(6)The desulfurization performance of PBVImPW-DVB did not decrease after repeated use for 9 times.