A Ti-based bi-MOF for the tandem reaction of H2O2 generation and catalytic oxidative desulfurization

In the past, H2O2 has been used as an oxidant when Ti-based materials are used as catalysts at ambient conditions. However, H2O2 suffers from high cost and safety concerns. Therefore, replacing H2O2 with O2 has been highly desired. In this study, a Ti-based bi-MOF, MIL-125(Ti)@NH2-MIL-125(Ti) has been synthesized through the internal extended growth of MIL-125(Ti) on NH2-MIL-125(Ti). This Ti-based bi-MOF performed in sequence to synergistically catalyze the oxidative desulfurization (ODS) reaction with O2. In this bi-MOF catalyst, MIL-125(Ti) is partly embedded and well distributed on the surface of NH2-MIL-125(Ti). NH2-MIL-125(Ti) serves as a catalyst for the production of H2O2 from O2/methanol under visible light, while MIL-125(Ti) serves as an ODS catalyst. The ODS over MIL-125(Ti) is the most effective as the in situ generated H2O2 could be used fully, and the consumed H2O2 (ODS reaction) also promotes further H2O2 production through the Le Chatelier's principle. MIL-125(Ti) and NH2-MIL-125(Ti) exist in close proximity in the bi-MOF material, which leads to an increase in the catalytic efficiency by 2.5-fold in comparison to that obtained from their physical mixture.