Catalytic oxidation of sulfur and nitrogen compounds from diesel fuel

The oxidation of nitrogen or sulfur pollutants, using organic substrates as model compounds, was monitored with electrospray ionization mass spectrometry. Quinoline, dibenzothiophene and methylene blue were found to be oxidized through a successive hydroxylation mechanism. These results strongly suggest that highly reactive hydroxyl radicals, generated during the reaction of H₂O₂ on the catalyst surface, are responsible for this oxidation, and confirm that the material is an efficient heterogeneous Fenton-like catalyst, which is able to eliminate around 90% of the sulfur molecules. This is, therefore, an important and useful tool for the elimination of refractory sulfur in the hydrotreatment process with potential application to meet future environmental legislation indexes. It is important to remember that only the heteroatom fraction is degraded, preserving the hydrocarbons of interest in the diesel flows. The catalyst showed activity in successive oxidation cycles presenting a high regeneration capacity.