Study On Preparation Of Adsorbents And Adsorption Process For Ultra-Deep Desulfurization Of Gasoline

With the rapid upgrade of fuel quality standard（the V fuel quality standard stipulate that the sulfur content in gasoline lower than 10μg/g）and more concentration on the environment protection,the cleaning of gasoline is facing huge challenges.For ultra-deep desulfurization of the gasoline,producing only by hydro-treating process needs severe operating conditions and will cause much loss of octane number.The technique of hydro-treating and adsorption desulfurization can solve the problem,therefore,designing an adsorbent with high sulfur capacity and good stability is important.First of all,adsorbents prepared by nickel formate,nickel acetate,and nickel nitrate via incipient impregnation method were characterized and evaluated.The effect of different precursor species on metal dispersion of a Ni/γ-Al₂O₃ adsorbent was studied.Results show that adsorbent prepared by nickel nitrate exhibits better sulfur capacity and metal dispersion compared to adsorbents synthesized by nickel formate and nickel acetate.The size of Ni²⁺is smaller than that of[Ni（NH₃）₆]²⁺,so the steric hindrance is lower while Ni²⁺diffusing in the pores,hence,the metal dispersion is higher.The decomposition temperature of nickel formate and nickel acetate are lower than that of nickel nitrate,so the nickel particles would aggregate during calcination and make the metal dispersion decreased.Subsequently,nickel nitrate was chosen as the precursor,adsorbents prepared via strong electrostatic adsorption method（EC）,incipient impregnation method（DI）,and incipient impregnation method with pH modulation method（DI-pH）were characterized and evaluated to investigate the effect of different synthesis methods on metal dispersion of adsorbents.Results show that adsorbents prepared by EC method exhibits the best metal dispersion in three series adsorbents.The repulsive force between the hydroxyl groups and nickel ions is a crucial factor which affect the metal loading and metal dispersion.Different solution pH caused different metal loadings,though the nickel concentration in solution were the same.High metal loading and high metal dispersion can be achieved by EC method.In the end,adsorbents were prepared via EC method and Ce,La,and Cu were added into the adsorbents to investigate the influence of metal promoter on the metal dispersion of adsorbents.It is found that the metal dispersion of adsorbents which added Ce and La promoters improved dramatically compared to the nickel adsorbent while adsorbent added Cu promoter show no better performance.Rare earth metal can prevent the sinter of adsorbent,optimize the metal distribution,and decrease the interaction between metal and the support because of different structure.