Deep desulfurization of diesel fuel by selective adsorption over Ni/Al2O3 and Ni/ZSM-5 extrudates

Adsorptive desulfurization using porous materials is based on the ability of a solid sorbent to selectively adsorb organic sulfur compounds from a refinery stream. In the present study, different sorbents were prepared by varying the Ni/Cu loadings onto ZSM-5 (Si/Al = 20) and activated alumina for the removal of sulfur from commercial diesel fuel containing approximately 325 ppmw total sulfur (S). To improve the adsorbent efficiency for sulfur removal, hydrogen peroxide was used as an oxidizing agent. The total sulfur in the sample was determined using X-ray fluorescence (XRF) analyzer. Effect of metal loading on sorption performance in the presence of H2O2 oxidant was investigated and compared on the basis of total sulfur removal, sorption capacity and adsorption breakthrough curves. Investigations revealed that sulfur removal strongly depends on the nature of metal, its amount and the nature of the support material. 10% Ni/Al2O3 adsorbent resulted in higher sulfur removal as compared to Ni/ZSM-5 and Cu/Al2O3 adsorbents. More than 90% removal of sulfur was observed with Ni/Al2O3 in presence of H2O2 oxidant. Fixed bed column experiments were carried out using Ni/Al2O3 and the performance of the column break through curves was investigated. Effect of flow rate, bed height and oxidizing agent was investigated in column experiments using 10% Ni/Al2O3. From the analysis of bed depth service time model the values of adsorption capacity and rate constant were found to be 496 mg S/kg and 0.006 (mg/kg)−1 h−1 respectively.