Preparation Of Nano-Demulsifier And Its Demulsification Performance In Crude Oil Emulsion

At present,crude oil is still one of the most important energy sources.Most of the crude oil is existed with stable W/O and O/W emulsions.The natural surfactants such as asphaltenes and resins in the crude oil are adsorbed at the oil-water interface,hindering the coalescence of the droplets.It is a serious challenge for petroleum industry to separate water from the crude emulsion.Chemistry demulsification named adding the chemical demulsifiers into the emulsion is the most widely used method in oil fields.Due to the unique physical and chemical properties,nanomaterials has been received extensive attention in the petroleum industry.Therefore it is significant to develop new nano-demulsifiers.Based on the unique properties ofnanomaterials,threekindsof nano-demulsifiers for demusification of crude oil emulsions were prepared,and their demulsifying perfoemace and mechanism were comprehensively studied.The main contents of this paper are as follows:An acrylate P?AA-BA-MA?nano-demulsifier was prepared by using a novel micro-suspension method,using acrylic acid?AA?,methyl acrylate?MA?and n-butyl acrylate?BA?as monomers.The structure of P?AA-BA-MA?was characterized by FT-IR,1H-NMR,laser particle size analyzer et.al.The demulsifying performance of nano-demulsifier for O/W crude oil emulsion was investigated by bottle test.The results showed that the average particle size of P?AA-BA-MA?was 83.81 nm and it could reduce the surface tension of toluene solution effectively.when the ratio of AA:MA:BA was 3:1:6,the demulsification efficiency could reach above85.91%.Moreover,the water phase was clear,and the oil-water interface was regular.A nano-composite demulsifier?CNTs/SiO₂?was prepared via hydro-thermal method.In this process,the oxidized carbon nanotubes from mixed acid oxidation was modified with SiO₂ using a silane coupling agent and TEOS.The structure of CNTs/SiO₂ was characterized by FT-IR,UV,XRD and SEM.The demulsifying performance and mechanism were further studied by bottle test and optical microscope,repectively.It was showed that the?value of CNTs/SiO₂ was about 92.8°.The CNTs/SiO₂ with interfacial activity could diffuse rapidly to the oil-water interface and the aggregation and distribution at the interface provided a possibility to accelerate the coalescence of the droplets.The coalescence of the droplets could easily achieve rapid demulsifying of the 22%W/O emulsion.When the demulsifier concentration and time are 500ppm and 30minrespectively,the demulsifying efficiency could reach 87.40%,and the water phase was clear.A kind of magnetic carbon nanotube demulsifier?CNTs@Fe₃O₄?was prepared by grafting Fe₃O₄ nanoparticles onto the surface of oxidized carbon nanotubes using thermal decomposition of Fe?acac?₃ solution.The structure of CNTs@Fe₃O₄ was characterized by FT-IR,XRD,FT-SEM,TEM and VSM.And the demulsifying performance of CNTs@Fe₃O₄ for O/W oily wastewater was further studied by bottle test.The results showed that CNTs@Fe₃O₄ with good interfacial activity and could migrate rapidly to the oil-water interface.It was believed that destruction of the interfacial protective film at the oil-water interface was a crucial step to break up emulsion.CNTs@Fe₃O₄ could interact with asphaltenes and resin molecules through?-?interaction,resulting in discontinuous interfacial film.When the Fe₃O₄ content is70%,the concentration and settling time are 600 ppm and 30 min,the water phase transmittance is 92.1%,and the corresponding demulsification efficiency is 99.6%.Moreover,after recycle test for 4 times,the demulsifing performance of CNTs@Fe₃O₄was not significantly reduced,suggesting its excellent recyclability.