PMo12@UiO-67 nanocomposite as a novel non-leaching catalyst with enhanced performance durability for sulfur removal from liquid fuels with exceptionally diluted oxidant

In the present study, Keggin-type phosphomolybdic acid (H3PMo12O40) was encapsulated in a sized-matched Zirconium metal-organic framework (PMo12@UiO-67) to be used as a heterogeneous catalyst for oxidative desulfurization. A proper cage size and narrow window of UiO-67 were exploited to avoid the phosphomolybdic acid leaching to provide a suitable platform for a majority of the sulfur compounds. The prepared composite demonstrated remarkable catalytic activity for ultra-deep oxidative desulfurization of 5 sulfur compounds under mild conditions. 37.50 ppm sulfur remained in the oil after 20 min and no sulfur compounds were detected after 30 min. The trapping experiments indicated no contribution of the radical scavenger to the desulfurization activity. Also, it could be concluded that PMo12@UiO-67 can be readily regenerated and recycled for 6 successive cycles with no considerable loss of catalytic activities.