Research on Reactive Adsorption Desulfurization over Ni/ZnO−SiO₂−Al₂O₃ Adsorbent in a Fixed-Fluidized Bed Reactor

Abstract

Reactive adsorption desulfurization of FCC gasoline over a Ni/ZnO-SiO 2 -Al 2 O 3 adsorbent was carried out in a fixed-fluidized bed reactor at low pressures in the presence of hydrogen. The results show that high temperature, high pressure, high molar ratios of hydrogen-to-oil, and low weight hourly space velocity are favorable to improve the desulfurization ability of adsorbent but not conducive to maintaining the octane number of FCC gasoline throughout the condition range examined. Under optimal operating conditions, ultralow sulfur gasoline can be produced, and the RON loss is only 1 unit. Furthermore, the effect of prereduction and adsorbent characterization data (SEM/EDX, N 2 adsorption) reveal that reduction increases the interaction between Ni and S compounds and improves the pore structure of adsorbent, leading to a significant improvement in the desulfurization capability of adsorbent. Take 3-methylthiophene for example, after adsorbing on an active Ni atom via the S-Ni bond, the sulfur of 3-methylthiophene is removed by direct hydrogenolysis of the C-S bond, resulting in the formation of NiS x and 2-methyl-1,3-butadiene in hydrogen atmosphere. The latter is mainly hydrogenated to 2-methyl-2-butene and 2-methylbutane. ZnO acts as a sulfur-acceptor, which can regenerate the active Ni in situ in hydrogen atmosphere. The complete sulfidation of adsorbent particles takes place by ion diffusion.

An evaluation of desulfurization technologies for sulfur removal from liquid fuels

“…286 Conoco Phillips Petroleum Co. developed a new S-Zorb process for the production of low-sulfur gasoline by reactive adsorption of sulfur compounds over a solid sorbent at elevated temperatures under a low hydrogen pressure. 88,238,243,[286][287][288][289][290][291][292][293][294][295][296] Tawara et al 288 used Ni/ZnO for bringing down sulfur in kerosene to ,0.1 mg g 21 in the temperature range 270-300 uC under H 2 atmosphere at a pressure of 0.60 Mpa. Ni/ZnO is an ideal adsorbent, in which the ZnO acts not only as an acceptor of sulfur released during the regeneration of sulfided Ni species, but also acts as a co-catalyst for the hydrogenation of sulfur-containing compounds over the surface of Ni species.…”

Pervaporative desulfurization of gasoline: A review

“…The hydrocarbons can be returned to the final product without any structural modifications, whereas hydrogen sulfur is retained by the surface of sorbents. The zinc oxide modified with transition metals such as Nickel or Copper is the most important adsorbent mentioned in literature [35]. Petroleum Co., USA, used the principal of reactive adsorption to develop the socalled Phillips S Zorb process to remove sulfur from gasoline and diesel fuels [36,37].…”

Remarkably high performance of clew-like ZnO superstructure in reactive adsorption desulfurization

“…Alternative technologies, such as adsorption desulfurization [7][8][9], oxidation desulfurization [10,11], extraction [12,13] and bio-catalytic treatment [14,15] have been developed. Among them, the reactive adsorption desulfurization (RADS) using a solid adsorbent is considered to be the most effective approach for the ultra-deep desulfurization of gasoline [16].…”