Ultra-deep desulfurization via reactive adsorption on Ni/ZnO: The effect of ZnO particle size on the adsorption performance

The effect of ZnO particle size on the adsorptive desulfurization performance for Ni/ZnO (5 wt% NiO) adsorbent was investigated using thiophene as a sulfur containing compound in model gasoline with a fixed bed reactor. The Ni/ZnO adsorbents with different ZnO particle sizes (8, 12, 20, 30 nm) were prepared by an impregnation method and characterized by powder X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM) and transmission electron microscopy (TEM). It was found that the adsorption capacity of the Ni/ZnO adsorbent for thiophene significantly increased with the decrease of the ZnO particle sizes. Typically at a breakthrough sulfur level of 1 mg/L, sulfur capacity of Ni/ZnO (8 nm) from model gasoline (500 mg/L) is much higher than that of Ni/ZnO (30 nm) from 84 mg sulfur per gram adsorbent to nearly 0 mg sulfur per gram adsorbent. This higher desulfurization activity and sulfur capacity for Ni/ZnO with smaller ZnO particle sizes could be derived from higher Ni dispersion on ZnO and lower mass transfer limitations of sulfur to ZnO from Ni in H2.

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► Both the desulfurization activities and the sulfur capacities of the Ni/ZnO adsorbents with smaller particle sizes are enhanced noticeably.
► The Ni/ZnO adsorbent with smaller ZnO particle size could remove sulfur at a lower operating temperature.
► The apparent activation energy of desulfurization via Ni/ZnO adsorbent with smaller ZnO particle size is much lower.