Preparation Of Ru@Pt_polyimide Composite Membrane Catalyst And Its Research For Selective Hydrogenation Of Benzene To Cyclohexene

Cyclohexene with active C=C is a very important organic synthesis intermediate and is widely used in the oil and drug industry.Among them,there are many ways to synthesize cyclohexene.The selective hydrogenation of benzene to cyclohexene has attracted much attention as a low cost,simple process and abundant raw material.However,the reaction of cyclohexene is difficult to achieve in thermodynamics.Therefore,in order to ensure higher benzene conversion and improve cyclohexene selectivity,designing suitable catalyst has become an important way to achieve this goal.At present,a large number of studies have found that the Ru based catalyst has a high selectivity for cyclohexene in the active components of benzene selective hydrogenation to cyclohexene.In fact,platinum?Pt?,rhodium?Rh?,nickel?Ni?and other transition metals also have certain hydrogenation activity.Pt,because of the high surface atomic distribution and high specific surface,a large number of surface atoms can contact with substrate,so that it has high hydrogenation activity.On the one hand,in view of the high hydrogenation and selectivity of Ru and the high activity of Pt hydrogenation,our research group will combine these two metals in the form of core-shell structure with unique physical and chemical properties,and be used as catalysts in the selective hydrogenation of benzene to cyclohexene.On the other hand,the research,the research group has always been engaged in polyimide functional materials so that the Ru@Pt core-shell nanoparticles loaded on polyimide?PI?,Ru@Pt_PI composite membrane catalyst was prepared,characterized,and applied to the selection of benzene hydrogenation selectivity of cyclohexene the target product,expected yield of cyclohexene.The specific contents include the following aspects:1.Using the continuous polyol method,with RuCl₃ xH₂O and PtCl₂ as precursors,ethylene glycol as reducing agent and polyvinylpyrrolidone as stabilizer,the average particle size of 3.57nm was monodisperse,and the shell shell thickness of Ru@Pt core shell nano particles was prepared.Using transmission electron microscopy?TEM?,X-ray diffraction?XRD?,X-ray photoelectron spectroscopy?XPS?analysis methods were characterized.The results show that The shell of metal Pt with crystal good,Pt atoms are mainly{111}crystal,metal metal Ru and Pt core shell of the core-shell nanoparticles are produced electronic effects make the electronic Ru,Pt combination can produce a certain offset,and a preliminary study on the effective control of the core-shell structure nanoparticles and the shell thickness factor between the core and shell of two metal electronic enhancement effect,found that the shell thickness of the particle is small,the electronic effect between the two metals more.2.With 4,4'-two amino two phenyl ether?ODA?,3,3',4,4'-two four two phenyl ketone acid anhydride?BTDA?,and the laboratory has synthesized two rigid diamine monomer 1,5-two amino phenyl-1,4-diene-3-ketone?BAPO?as raw materials,polyimide films with different amine monomer ratio of two was synthesized by thermal imidization method.Through the infrared spectrometer?FT-IR?,thermogravimetric analyzer?TGA?,differential scanning calorimetry?DSC?,the structure and properties were characterized by Ubbelohde viscometer and other test methods,and the factors influencing the thermal stability and film forming of a preliminary inquiry.The results show that when n?BAPO?:n?ODA?is 6:4,polyimide film under nitrogen atmosphere 5%thermal decomposition temperature is 506?,10%thermal decomposition temperature is 550?,the glass transition temperature of379?,showed high thermal stability prepared by thermal imidization method;Polyimide film has excellent forming properties;with the increase of the molar ratio of BAPO and ODA,PAA viscosity increases,when the molar ratio of BAPO and ODA increased to 7:3,the viscosity of PAA is still increasing,polyimide film brittle,poor film.3.The dispersed N-methyl pyrrolidone?NMP?Ru@Pt core-shell nanoparticles in adding to the n?BAPO?:n?ODA?PAA mixing solution of 6:4,and then after thermal imidization into Ru@Pt_PI composite membrane.By transmission electron microscopy?TEM?,X-ray diffraction?XRD?,X-ray photoelectron spectroscopy?XPS?,infrared spectroscopy?FT-IR?analysis methods were used to characterize the results showed that Ru@Pt nanoparticles can be stably and uniformly dispersed in PI and Ru@Pt core-shell nanoparticles changed little particles the size is not supported,and well maintained the original crystal type,occurred between N and O complexation of Pt and PI in the shell of metal elements,generating force.4.Ru@Pt_PI was used as catalyst in the selective hydrogenation of benzene to cyclohexene,and compared with the catalytic effect of Ru@Pt as catalyst.The catalytic products were analyzed by gas chromatography.The effects of reaction temperature,pressure,time,amount of catalyst,water content and membrane swelling rate on the yield of cyclohexene and the reutilization rate of catalyst were discussed.The results show that under the same reaction conditions,Ru@Pt_PI composite membrane catalyst because of the complexation between synergy between the core-shell structure of double metal and polyimide,catalyst Ru@Pt core-shell structure had the conversion of benzene and cyclohexene selectivity is not load significantly increased,the yield of cyclohexene by up to 26.25%.And finally through the state density calculations confirmed the rationality of the conclusion.