Removal of Sulfur and Nitrogen Compounds from Diesel Oil by Adsorption Using Clays as Adsorbents

Stringent specifications for sulfur compounds content and the need to use oils with large amount of nitrogen compounds are challenges for fuel producers. Adsorption is an alternative process to remove sulfur and nitrogen compounds and clays are promising adsorbents for this removal. In this work, the adsorption performance of different commercial claysClay A (attapulgite), Clay B (bentonite), and Clay C (bentonite)for the removal of sulfur and nitrogen compounds from a real diesel stream was studied through kinetic and isothermal experiments. The bentonite clays showed the best adsorptive capacity for the removal of sulfur and nitrogen compounds, probably due to the presence of Brønsted acid sites. The highest adsorption capacity was observed for Clay B: 0.174 mol kg^–1 for sulfur compounds and 0.127 mol kg^–1 for nitrogen compounds. Clay A was more selective to the removal of nitrogen compounds. Equilibrium data showed that adsorbate–absorbate and adsorbate–surface interactions predominate for sulfur and nitrogen compounds, respectively, for Clay A and Clay B.