Direct preparation of [(CH3)3NC16H33]4Mo8O26 and its catalytic performance in oxidative desulfurization

Abstract

The catalyst [(CH₃)₃NC₁₆H₃₃]₄Mo₈O₂₆ has been synthesized by a direct precipitation method under room conditions from commercially available (NH₄)₆Mo₇O₂₄·4H₂O and (CH₃)₃NC₁₆H₃₃Cl, avoiding the use of any toxic organic solvents. The catalyst was employed in oxidative desulfurization using H₂O₂ as an oxidant under mild conditions. High dibenzothiophene (DBT) removal (99.4%) was achieved after an adsorption process to remove the residual DBT sulfone (DBTO₂), and the catalyst could be used for at least nine cycles without a noticeable decrease in activity. Leaching of Mo species was found to be negligible during the reaction. Moreover, it was found that the sulfur removal remained unchanged, decreased slightly or dramatically in the presence of 10 wt% n-octene, para-xylene or naphthalene, respectively, which was attributed to the different solubilities of DBTO₂ in these solvents. The reaction system was further applied for the desulfurization of a kerosene-range jet fuel and a diesel fuel. After oxidation and extraction, 86.4% and 93.2% sulfur removals were derived for the diesel fuel and jet fuel, respectively.