Towards oxidative denitrogenation of fuel oils: Vanadium oxide-catalysed oxidation of quinoline and adsorptive removal of quinoline-N-oxide using 2,6-pyridine-polybenzimidazole nanofibers

The study provides a technological method for the removal of nitrogen compounds from fuels, via oxidation and extractive adsorption. The use of batch process resulted in lack of specificity of the quinoline oxidation reaction with several products produced via ring-opening while the flow micro-reactor presented a high degree of selectivity to quinoline-N-oxide (67%). The application of molecularly imprinted 2,6-pyridine-polybenzimidazole nanofibers displayed excellent quinoline-N-oxide removal (86%) with an adsorption capacity (qe) of 4.8 mg/g. Isothermal titration calorimetry (ITC) interactions between quinoline-N-oxide and 2,6-PyPBI confirmed a favourable interaction. DFT studies on quinoline-N-oxide vs 2,6-PyPBI further indicated: (i) a hydrogen bonding (through amino group of 2,6-PyPBI and oxygen atoms of the quinoline-N-oxide), (ii) pi-pi stacking and (iii) van der Waals interactions. The selective oxidation and adsorption of nitrogen compounds present in fuel, which has been demonstrated here, would be a sustainable green chemistry technology for the production of clean fuel. Keywords: Vanadium(V) oxide, tert-Butylhydroperoxide (t-BuOOH), Quinoline, Oxidatio