Synthesis of N-benzylated cobalt phthalocyaninetetrasulfonamide and its application in oxidative desulfurization catalysis

Abstract

The FeCl₂/K₂CO₃ catalyst system was used successfully for the synthesis of oil soluble N-benzylated cobalt phthalocyaninetetrasulfonamide by the reaction of benzyl alcohol on water-soluble cobalt phthalocyaninetetrasulfonamide via heating at 135 °C for 20 h under N₂. The new oil-soluble peripherally N-benzylated phthalocyanine was characterized by elemental analysis, FT-IR, UV–vis, TG and mass spectrometry. The catalytic activity of this new cobalt complex for oxidation of dibenzothiophene (DBT) was evaluated in n-dodecane (a middle distillate model compound) using H₂O₂ as an oxidant. The acetonitrile was taken as an extracting solvent for further extracting DBT sulfoxide and sulfone. The novel peripherally substituted cobalt(II) complex showed better oxidative desulfurization catalytic activity than cobalt phthalocyanine and cobalt phthalocyaninetetrasulfonamide. DBT oxidation kinetics were evaluated by lumped n^th- and first-order kinetic models. The maximum removal of the DBT was found to be 85% at the optimized dose and experimental conditions.

Keywords:

• Cobalt complex
• N-benzylation
• phthalocyanine
• oxidation desulfurization
• dibenzothiophene
• oxidation kinetics

Acknowledgements

The author kindly acknowledges the Director, IIT Roorkee and Director, CSIR-IIP for his permission to carry out the doctoral research. The authors thank the analytical science division and institute instrumentation center of the institutes for providing the analysis.

Disclosure statement

No potential conflict of interest was reported by the authors.