Spherical Polymer Brushes Bearing Imidazole Groups As Novel Nickel Remover For Crude Oil

As the crude oil becomes heavier and worse,the content of metals in the crude oil continues to increase.Nickel is a common harmful metal in crude oil,and its retention will cause many adverse effects on the subsequent processing of crude oil,leading to the deactivation of the hydrocracking and catalytic cracking catalysts,affecting product quality and constraining heavy oil processing capacity.The main nickel usually exists as the oil-soluble organometallic compound with a stable structure,such as metalloporphyrins and nonporphyrins so that it is extremely difficult to be separated by traditional electric desalination process,which becomes an urgent problem to be solved.Presently,strong acids are widely applied to remove these nickels,but they cause severe corrosion to the subsequent catalytic cracking and processing equipment.Therefore,finding a highly efficient,clean,non-corrosive nickel removal agent has attracted more and more attentions in recent years.Based on the unique structural characteristics of the spherical polymer brushes and their obvious advantages in the adsorption of heavy metals,this paper proposes a new idea that designing a polymer brush material with core-shell structure combined with electric desalination technology to realize a high nickel removal efficiency.In the present work,micro-sized spherical polymer brushes（PVIm@SiO₂）are synthesized and various types of characterization were used to demonstrate the successful preparation of the material.The PVIm@SiO₂ is used as the crude oil nickel removal agent and the conditions of the crude oil nickel removal are studied,such as the effects of the feed concentration,the water-oil ratio,the shear strength,the shear time,electric desalination temperature,electric field strength,settling time and other factors on the effect of crude oil de-nickel.The results show that when the concentration of PVIm@SiO₂ is 5000ppm,the ratio of water to oil is 1/10,the shear strength of emulsifier is 8 kr/min,the shear time was 1.5 min,the electric desalting temperature is 130℃,the high voltage is 1000V/cm,low voltage is 500V/cm and settling time is 60 min,the maximum crude oil de-nickel rate reaches about 66.7%.In addition,the regeneration of polymer brushes are achieved by a rapid and simple process using diluted HCl.As well as,the removal efficiency of Ni remains 62.5%in 5 consecutive cycles.Consequently,these spherical polymer brushes bearing imidazole groups are reasonable nickel remover for crude oil.VIm,PVIm and PVIm@SiO₂ show different removal capabilities and the sequence is VIm<PVIm<PVIm@SiO₂.In combination with the properties of the spherical polymer brush material and the Donnan effect,a possible nickel removal mechanism by PVIm@SiO₂ is proposed.The successful application of spherical polymer brush material in the field of crude oil de-nickeling provides a material design idea for crude oil removal of other metals,which is of great significance and prospect.