(142f) Spherical Polymer Brushes Bearing Pyrrolidone Groups As Novel Nickel Remover for Crude Oil

Today, fossil fuels are still the main sources of the energy demand. However, metals in heavy oils create significant detrimental impact on hydrocracking and cracking processes. Especially, Nickel(Ni) poison the catalyst by accumulating on its surface and lead to the reduction of light oil yield. Therefore, it becomes a hot issue to be solved urgently in crude oil processing. Currently demetallizers are mainly organic acids and their salts. Due to their strong acidity, adding these demetallizers will cause the corrosion of equipment. Nowadays polymer brush materials with a core-shell structure show good performance in the fields of biomedicine, homogeneous catalysis, heavy metals adsorption and other fields.

In our previous research(Fuel,2018,226:47-53), polymer brushes bearing imidazole groups has good nickel efficiency. By further discussion and research, it is found that pyrrolidone(VP) groups have many excellent physical and chemical properties, adsorption and good thermal stability. In this work, N-vinyl pyrrolidone(VP) is grafting onto the SiO₂ using “grafting to” method to build spherical polymer brushes with strong chelating ability on nickel (PVP@SiO₂). PVP@SiO₂ is applied to remove trace nickels in crude oil with the help of electric demulsification. The results show that when the concentration of PVP@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 120℃, 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 64.4%. 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 58.9% in 6 consecutive cycles. VP, PVP and PVP@SiO₂ show different removal capabilities and the sequence is VP < PVP < PVP@SiO₂. Ultraviolet-visible spectrophotometry and mass spectrometry were employed to characterize the molecular structure of nickel porphyrins, and in combination with the properties of the spherical polymer brush material and the Donnan effect, a possible nickel removal mechanism by PVP@SiO₂ is proposed.