Simultaneous desulfuration and denitrogenation of model diesel fuel by Fe-Mn microwave modified activated carbon: Iron crystalline habit influence on adsorption capacity

Abstract

Nowadays, diesel desulfuration is of the utmost importance for the petrochemical industry in order to achieve efficient technologies for the production of clean fuels. Adsorption under normal conditions has the potential to produce ultra-low sulfur diesel if advanced materials capable of simultaneously removing both sulfur and nitrogen can be designed. This work contributes to the technology of clean fuels by using iron oxide-activated carbons (AC) that were produced with a microwave-assisted technique in the simultaneous adsorption of sulfur (dibenzothiophene and 4,6-dimethyldibenzothiophene) and nitrogen (indole and quinoline) compounds from model diesel fuel. Crystal habit was tailored with the addition of Mn-ions. The materials were characterized and their capacity was measured at batch and dynamic conditions. The use of Mn during Fe synthesis led to the deposition of reactive iron oxide twinning particles, while keeping most of the pore structure of the activated carbon. This modification allowed a higher total and simultaneous denitrogenation and desulfurization capacity and faster adsorption kinetics unlike iron and manganese modifications of activated carbon. Column dynamic experiments demonstrated that it is feasible to remove the adsorbates up to 200 bed volumes without reaching saturation of the adsorbent. The results demonstrated that twinned iron oxide particles deposited onto activated carbon were more reactive towards sulfur and nitrogen compounds. These particles were only obtained when Mn was present.