Metal-organic framework encapsulated high-loaded phosphomolybdic acid: A highly stable catalyst for oxidative desulfurization of 4,6-dimethyldibenzothiophene

Phosphomolybdic acid (HPMo) has been proved to be a highly active species for catalytic oxidation of sulfur compounds in fuel oil, but limited by its homogenous, soluble, and less-stable characteristics. In this work, the HPMo is encapsulated into a metal-organic framework (HPMo-x@MOF-199) to obtain a stable catalyst for oxidative desulfurization. It is found that the abundant channels of MOF-199 can accommodate and confine HPMo, which can effectively increase the HPMo loading amount and promote the stability of the catalytically active sites. Because of the confining effect, the HPMo-x@MOF-199 shows excellent performance and stability in catalytic oxidative desulfurization of 4,6-dimethyldibenzothiophene, which one of the is the most stubborn sulfides in fuel oil. Moreover, the catalyst can be recycled 9 times, showing much better stability than the sample without confining. Moreover, the oxidizing product (4,6-dimethyldibenzothiophene sulfone), a high value-added product, can be well separated. In addition, in the case of desulfurizing real diesel, the HPMo-x@MOF-199 catalyst also exhibits satisfying catalytic performance (reaches 90.2%), indicating its potential application perspective.

Automated summary

Encapsulating phosphomolybdic acid into a metal-organic framework improves the stability and activity of the oxidative desulfurization catalyst, showing excellent performance in treating the most stubborn sulfides in fuel oil. The catalyst can be recycled multiple times and the oxidizing product can be well separated, indicating promising potential for real diesel desulfurization.