The Study Of The Separation Of N-hydrocarbons From High Temperature Oil Products Of Fischer-tropsch Synthesis

Fischer-tropsch synthesis is one of the important methods of coal liquefaction. Soit is very important to study the separation of mixed hydrocarbon of Fischer-tropschsynthesis products. In this paper, separation n-hydrocarbons from mixedhydrocarbons with urea inclusion method were studied and the optimal conditions forreaction by orthogonal experiments were obtained. The crystal growth characteristicsand the crystal structure of urea inclusion compounds（UICs）formed in differentconditions were studied with high-speed CCD camera, which would guide theapplication of urea inclusion method in n-hydrocarbon separation from mixedhydrocarbons.First, ethanol was chosen as the optimal activator by orthogonal experiments.From the orthogonal experiment results, the superior combination of experimentalconditions was that the urea consumption was2.75g/g oil, the ethanol consumptionwas3.5ml/g oil, the water consumption was1.125ml/g oil, the reaction temperaturewas5℃and the reaction time was1h. In this inclusion reaction conditions, therecovery rate of1-decene was87.75%, and the recovery rate of n-decane was89.90%.From the research of dissociation conditions, the higher recovery rate ofn-hydrocarbon can be gotten and the energy consumption was lower in thedissociation condition with water.Secondly, with CCD high speed camera,the growth character of UICs crystalswere studied, which showed that the growth rate of the crystals in the track directionwas much greater than the growth rate in the vertical direction. And the growth rate ofcrystals was faster in the early stage. Characters of urea inclusion compounds crystalshad a relation with functional group and carbon chain length of n-hydrocarbons. Thenumber of urea inclusion compounds crystals was more and the volume of the crystalswas larger when the methanol was taken as activator or in the presence of water.Finally, the IR spectra of urea inclusion compounds with mixed n-hydrocarbonswere analyzed, the results showed that the formation of urea inclusion compounds hada relation with the chain length of n-hydrocarbons. The arrangement of the differentguests in UICs was studied by13C CP/MAS NMR spectroscopy. It was indicated that the arrangement of guests in urea inclusion compounds was based on the interactionstrength between the end functional groups of neighboring guest molecules. IRspectra and DSC curves of urea inclusion compounds showed that the stability of ureainclusion compounds had a relation with the carbon chain length and the meltingpoint of n-hydrocarbons.