Oxidative desulfurization of dibenzothiophene with molecular oxygen using cobalt and copper salen complexes encapsulated in NaY zeolite

Abstract

Abstract The objective of the research is to develop a new method for removal of organic sulfur in liquid fuels. Cobalt and copper salen (salen=N, N’-bis(salicylidene)ethylenediamine) complexes were simultaneously encapsulated in zeolite NaY by using the flexible ligand method, and employed as catalysts in the oxidation of dibenzothiophene (DBT) with molecular oxygen as the oxidant. The material was substantiated by UV–Vis spectroscopy, thermo-gravimetric and differential-thermal analyses, X-ray powder diffraction as well as scanning electron microscope. Effect of various parameters including reaction temperature, initial concentration of DBT, molar ratio of Cu to Co and recycle of the material were investigated. The prepared bimetal material showed much higher activity than single metal salen complexes CusalenY and CosalenY due to the synergetic effect of Cu2+ and Co2+. The desulfurization process was mainly governed by the activation of molecular oxygen using (Cu-Co)salenY. The results prove the feasibility of the proposed desulfurization process for industrial application.