In this presentation, we demonstrate that Zr6O4(OH)4(BDC)aYb (BDC = 1,4-benzenedicarboxylate; Y = PhCOO-, HCOO-, or [-OH + H2O]), the Zr cluster nodes of UiO-66 MOFs, can serve as catalysts for sulfide oxidation in the presence of H2O2 and that tuning of the environment at these cluster nodes can improve the reaction rate. By tuning the Y component, we determined that Zr cluster nodes with higher numbers of –OH groups have higher catalytic activity in the oxidation of sulfide to sulfoxide. This led us to propose that these –OH groups can be converted to hydroperoxide (Zr-OOH) moieties that are active in catalytic oxidation. Such species also explains the observation of sulfone at late-stages in our sulfide oxidation: this secondary product, which arises from the oxidation of the sulfoxide, is likely due to a computationally observed intermediate where the initial sulfoxide product is strongly bound to the Zr-OOH moieties. This scenario is supported by an experimentally observed faster rate for the oxidation of sulfoxide in comparison to that for sulfide, in spite of the higher energy barrier for the former. Consistent with this behavior is a slower production of sulfone when the sulfide oxidation is conducted in a solvent that competes with sulfoxide in binding to the catalysts.

Enhanced sulfide oxidation activity via tuning site environment of Zr cluster nodes in UiO-66 MOF: A synergistic experimental and computational study

255th National Meeting (2018)

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