Amphiphilic polyoxoniobate-based recoverable Pickering emulsion for effective oxidative desulfurization

Recently, Pickering emulsions provide a green and efficient solution for interfacial catalysis. However, in an emulsion system the separation of products and the recycle of catalysts rely on time- and energy-consuming centrifugation and filtration. Herein, a straightforward emulsion assisted assembly strategy has been developed to fabricate amphiphilic polyoxoniobates (PONbs), [C n H 2n+1 N(CH 3 ) 3 ] 6 KHNb 6 O 19 /SiO 2 (C n -Nb 6 /SiO 2 ; n = 14, 16, and 18). The honeycomb-like C 16 -Nb 6 /SiO 2 composite not only can form stable Pickering emulsion in the n-octane/water system but also can effectively catalyze oxidative desulfurization under mild conditions. Notably, after the reaction, the oil phase and the emulsion phase were automatically separated: the clean oil was collected by decantation, while the recycled emulsion was directly used for the next run. Moreover, C 16 -Nb 6 /SiO 2 is highly robust and can be consecutively used for up to eleven cycles with negligible loss of its catalytic activity.