Oxidative and Extractive Desulfurization of Dibenzothiophene and Denitrogenation of Pyridine using Mn-Co-Mo@Al2O3 And Acid Functionalized Il Using H2O2/Naclo as Oxidant
A comparison between the catalytic oxidative-extractive desulfurization (COEDS) of dibenzothiophene (DBT) and denitrogenation (COEDN) of pyridine over Mn promoted (Co or Ni)-Mo/Al2O3 catalysts and acid functionalized [Bmim]Cl/ZnCl2 ionic liquid (IL) using H2O2 and NaClO as oxidants was performed. Catalysts were characterized by SEM, BET, PXRD, EDX-elemental mapping and XPS techniques. Results showed that maximum DBT or pyridine conversion using H2O2 at O/S-12, O/N-16, 60 min, 45 oC, 0.2 g/15 mL catalyst, IL:oil-1.5:5, while using NaClO as oxidant, same activity was achieved under O/S-4, 15 min, 25 oC, 0.1 g/15 mL catalyst, IL:oil-1:5 for DBT and O/N-8, 35 oC, 0.1 g/15 mL catalyst, IL:oil-1.5:5 for pyridine. Activation energies (Ea) data of DBT (13 KJ/mol) and pyridine(13.2 KJ/mol) in the presence of H2O2-Mn-Co-Mo/Al2O3,while using NaClO-Mn-Co-Mo/Al2O3these values were 4.9 kJ/mol and 5.4 kJ/mol, respectively, suggesting the more feasible nature of the latter oxidant-catalysts system. Catalytic activity order for various catalysts was:Mn-Co-Mo/Al2O3>Mn-Ni-Mo/Al2O3> Co-Mo/Al2O3> Ni-Mo/Al2O3. Among the ILs tested, [C4mim]TFAranked at the top of activity order.Excellent COEDS and COEDN performance of DBT and pyridine in the presence of NaClO-catalyst system is accredited to the strong oxidizing power of NaClO and better synergism between the catalyst/IL which could be more benign and practicable in industrial processing of fuel oils.
Key words - Oxidative-extractive desulfurization and denitrogenation; acid functionalized IL; sodium hypochlorite; Mn promoted catalyst; XRD and XPS.