Effect of support and NiO loading on adsorptive desulfurization of diesel fuel

Abstract

ABSTRACT In pursuit of cleaner energy, this study explored the role of support materials in NiO’s desulfurization capacity and selectivity in diesel fuel, thereby offering insight into sustainable fuel production. Nickel oxide (NiO) was loaded on different supports (activated carbon (AC), SiO2, Al2O3, and TiO2) for desulfurization. The adsorbent system was characterized using various techniques including FTIR, XRD, SEM, TPD-pyridine, TGA, and BET. At a low loading of approximately 5%NiO/support, the addition of NiO enhanced the adsorbent activity for all four supports at 30°C. However, increased NiO loading led to decreased adsorption activity due to agglomeration. The loading of NiO affected the selectivity of the adsorbents toward high molecular weight sulfur compounds differently. There was a decrease in selectivity for AC and Al2O3, a positive effect on SiO2, and no effect on TiO2. The positive effect on SiO2 resulted from NiO-SiO2 synergy. Additionally, NiO loading on SiO2 reduced hydrocarbon adsorption, thereby improving overall relative selectivity. When real diesel was used, the addition of 5%NiO on SiO2 and AC at a higher temperature (60°C) increased adsorption activity. This higher activity at elevated temperatures was attributed to poor adsorption of polyaromatic hydrocarbons and increased involvement of chemical-bonds. Lastly, all adsorption reactions were exothermic.