Model diesel denitrogenation by modified activated carbon with iron nanoparticles: Sulfur compounds effect

• Iron nanoparticles in AC enhance 15% the adsorbents denitrogenation capacity.
• The improvement in denitrogenation capacity is mainly due to indoline uptake.
• The higher indoline uptake was related to its non-planar shape.
• Modified carbons are more selective for nitrogen than for sulfur compounds.
• Iron–nitrogen interactions are stronger than iron–sulfur.

In this work, iron-modified activated carbon was studied for the removal of nitrogen compounds (indoline and quinoline) naturally present in diesel. Model diesel was simulated using a mixture of decane and hexadecane that also contained the sulfur compounds dibenzothiophene and 4,6 dimethyldibenzothiophene. The results showed that iron enhances the indoline uptake of carbon by 30%, while quinoline adsorption also increased, but to a lesser extent. Increased iron denitrogenation capacity was also observed during the quinoline–indoline competition experiments; the iron-modified sample showed a 30% and 9% increase in indoline and quinoline uptake, respectively. When nitrogen and sulfur compounds compete for adsorption sites, the indoline and quinoline uptake in the iron materials increased. In contrast, carbon desulfurization performance decreased in iron-modified materials, indicating that these adsorbents are more selective for nitrogen than for sulfur compounds. The improved performance of the modified activated carbon was attributed to π–π interactions between quinoline and activated carbon and to the nitrogen in indoline and iron oxyhydroxides.

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