This work deals with the catalytic denitrogenation of a simulated fuel (quinoline (QN) in 2,2,4-trimethylpentane) by oxidation with hydrogen peroxide in a biphasic medium. As catalysts, three materials were used (i) iron supported on alumina (Fe/Al2O3) obtained by sol-gel, carbon nanotubes (CNT) produced by chemical vapor deposition of propylene (PP) growth on the previous catalyst (Fe/Al2O3) and (iii) a commercial sample of CNT supplied by Sigma Aldrich. The contribution of adsorption and extraction was also assessed, both being considered negligible or ineffective for the removal of QN. The performance of each catalyst was analysed in 4 h reaction tests, at 80 °C, by monitoring the degradation of H2O2 and the concentration of QN in the oily and aqueous media. As a result, all catalysts used met the proposed objective, with 100% of QN being removed from the oily phase in the biphasic oxidation tests. In summary, all the catalysts produced were efficient in the proposed process and are comparable to the performance obtained by the commercial CNT sample.