Comparison of the Reactive Adsorption Desulfurization Performance of Ni/ZnO–Al2O3 Adsorbents Prepared by Different Methods

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• 作者：Rooh Ullah ; Peng Bai ; Pingping Wu ; Zhanquan Zhang ; Ziyi Zhong ; U. J. Etim ; Fazle Subhan ; Zifeng Yan
• 刊名：Energy & Fuels
• 出版年：2016
• 出版时间：April 21, 2016
• 年：2016
• 卷：30
• 期：4
• 页码：2874-2881
• 全文大小：443K
• 年卷期：0
• ISSN：1520-5029

文摘

In this study, a series of Ni/ZnO–Al₂O₃ mixed oxide (MO) adsorbents were prepared by the one-step homogeneous precipitation method and the cation–anion double hydrolysis (CADH) method for reactive adsorption desulfurization (RADS) using thiophene as a model fuel in a fixed bed reactor. The synthesized adsorbents were characterized by N₂ sorption, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), H₂ temperature-programmed reduction (H₂-TPR), ultraviolet–visible (UV–vis) diffuse reflectance spectroscopy (DRS), and Raman spectroscopy. Results show that both Ni loading and the preparation method have a significant effect on the RADS activities of the adsorbent. Among the studied adsorbents, 10% Ni/ZnO–Al₂O₃ prepared by the one-step urea precipitation method showed the best RADS performance, with a thiophene conversion up to 96% and a sulfur adsorption capacity of 86 mg of S/g, which is 34% larger than that of CADH adsorbents. In addition, upon five RADS–regeneration cycles, sample 10% Ni/ZnO–Al₂O₃ exhibited a drop of only 3% in thiophene conversion, indicating the high stability of the Ni/ZnO–Al₂O₃ adsorbent prepared by homogeneous precipitation. Characterization results show that the one-step homogeneous precipitation method could facilitate the formation of small ZnO particles while suppressing the formation of inactive ZnAl₂O₄. On the other hand, by decreasing the formation of NiAl₂O₄, the homogeneous precipitation method could also generate high concentration of Ni⁰ sites, which are the active centers for the hydrogenolysis of C–S bonds. These findings indicate that a high-performance adsorbent for RADS can be obtained by employing a proper preparation method with good control on the adsorbent structure.